Effect of basil seed gum (BSG) on textural, rheological andmicrostructural properties of model processed cheese
Seyed H. Hosseini-Parvar a, b, *, Lara Matia-Merino a, Matt Golding a
a Institute of Food, Nutrition and Human Health, Massey University, Private Bag 11222, Palmerston North, New Zealandb Department of Food Science and Technology, Sari Agricultural Sciences and Natural Resources University, Khazar Abad Road, PO Box 578, Sari, Iran
a r t i c l e i n f o
Article history:Received 16 March 2014Accepted 14 July 2014Available online 22 July 2014
This study focuses on the textural, rheological and microstructural properties of a model processedcheese (44e48% wt/wt dry matter and 30% fat content) developed with different concentrations ofrennet casein (6e10% wt/wt) and basil seed gum (BSG) (0e1% wt/wt). The frequency sweep test showedthe h*, G0 and G00 values increased with increasing BSG concentration in all formulations with the sameprotein/solid content. Increasing levels of BSG also led to more elastic behaviour in the structure ofprocessed cheeses. Regardless of the protein content, the “solegel transition” temperature of the modelprocessed cheeses increased significantly (p < 0.05) when the concentration of the added BSG wasincreased. The concentration of added BSG had much more effect on meltability of the processed cheesethan the protein content. However, flowability of the samples was dependent mainly on the proteincontent. The particle size data and confocal laser scanning microscopy (CLSM) images showed that BSGcontributed to the emulsification of the oil and both the oil droplets and BSG chains were dispersed in acontinuous protein phase. Similar to the BSG/milk proteins aqueous systems, the BSG chains possiblycreated a web network throughout the protein matrix of the processed cheese and strengthened thenetwork formed by casein strands. By adding BSG, it was possible to make processed cheeses with higherfirmness but slightly lower meltability, and at lower cost owing to the lower protein and higher moisturecontents.
Processed cheese/imitation cheese products can be described asstable oil-in-water emulsions. They are manufactured by blendingnatural cheeses/dairy proteins and edible oils/fats, in the presenceof emulsifying salts and other dairy and nondairy ingredients, fol-lowed by heating and continuous mixing, to form a smooth ho-mogeneous product. As processed cheeses/imitation cheeses areused mainly as an ingredient in prepared foods such as pizzas,burgers and toasted sandwiches, their rheological properties suchas firmness and meltability during heat treatment are veryimportant (Guinee, Caric,& Kalab, 2004; Lazaridis& Rosenau,1980;Rohit Kapoor&Metzger, 2008). Rheological properties of processed
and Human Health, Masseyw Zealand. Tel.: þ64 6 356
z, s.h.hosseiniparvar@sanru.
cheeses have been studied extensively as function of ingredientsand processing conditions using various determination methods,e.g. small strain and large strain rheological tests (Bowland &Foegeding, 1999, 2001; Brighenti, Govindasamy-Lucey, Lim,Nelson, & Lucey, 2008; Dimitreli & Thomareis, 2007, 2008; Guineeet al., 2004; Gupta & Reuter, 1993; Lee & Anema, 2009; Lee &Klostermeyer, 2001; Shirashoji, Jaeggi, & Lucey, 2006).
Hydrocolloids such as starch, xanthan, carrageenan, guar,pectin, alginate, locust bean gum, gelatin, inulin and gumArabic areamong the ingredients that have been used in formulation of lowfat natural and processed cheeses.
Basil seed gum (BSG) is a novel hydrocolloid extracted fromOcimum basilicum L. seeds. It has shown promising stabilizing andemulsifying properties, which makes it a potential functionalingredient for the food industry (Hosseini-Parvar, 2009; Hosseini-Parvar, Matia-Merino, Goh, Razavi, & Mortazavi, 2010; Osano,Hosseini-Parvar, Matia-Merino, & Golding, 2014; Razavi et al.,2009). BSG is a surface-active hydrocolloid that can form smallemulsion droplets (<1.0 mm) and stabilize 30% O/W emulsionsagainst phase separation for at least one month by using as little as
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0.3% (wt/wt) (Osano et al., 2014). BSG mainly composed of twomajor fractions: the glucomannan which is the hydrophobicsegment and the xylan fraction that is responsible for its hydro-philic behaviour (Anjaneyalu & Channe Gowda, 1979; Hosseini-Parvar, Matia-Merino, Mortazavi, & Razavi, 2014). BSG have alsobeen compared to gum arabic for ultrasound-assisted emulsifica-tion of mint essential oil (Hosseini-Parvar, Alimardani, Shahidi, &Matia-Merino, 2013). It has a heat-resistant nature and exhibitshigher zero-shear viscosity and yield stress than xanthan, konjacand guar gum at similar concentrations (Hosseini-Parvar, 2009;Hosseini-Parvar et al., 2010). The interactions between BSG andmilk proteins have been shown synergistic in dispersions (SarabiAghdam, Hosseini-Parvar, Motamedzadegan, & Matia-Merino,2013a, 2013b), O/W emulsion (Khorrami, Hosseini-Parvar, &Motamedzadegan, 2014) and gel systems (Rafe, Razavi, & Farhoosh,2013; Rafe, Razavi, & Khan, 2012). These interactions create a weakgel throughout the system and thereby stabilise the systems. It hasalso been reported that BSG chains can create web network insidethe protein matrix and led to decrease the amount of syneresis andhysteresis area as well as to increase the firmness of low-fat setyoghurt (Afshar Nik, Raftani Amiri, & Hosseini-Parvar, 2011).
The present study explores another potential application forBSG, through investigating its effect on the rheology, meltingproperties and microstructure of a model processed cheese. Largestrain and small strain dynamic rheological measurements wereused to understand the macro-structural properties of the modelprocessed cheese. The thermo-physical properties of the modelprocessed cheese (e.g. meltability and flowability) were alsoinvestigated. Confocal laser scanning microscopy and particle sizedetermination were also used to examine any changes in themicrostructural properties of the processed cheese.
2. Materials and methods
2.1. Materials
Basil seeds were obtained from a local market in the city ofIsfahan, Iran. The Basil seed gum (BSG) was extracted according tothe procedure of Hosseini-Parvar et al. (2010). The chemicalcomposition of BSG on a dry weight basis (wt/wt) was: 1.32 ± 0.09%protein, 6.5 ± 0.21% ash, 4.38 ± 0.14% fat, 79.63 ± 0.73% total car-bohydrate, 0.55 ± 0.07% soluble sugars and 1.53 ± 0.15% starch. Themoisture content of BSG was 9.1 ± 0.17% (wt/wt) (Hosseini-Parvaret al., 2010). The other ingredients included Milli-Q water, ren-netecasein (ALAREN 779, Fonterra Co-operative Group Ltd, Auck-land, New Zealand), soya oil (Davis Trading Co., Palmerston North,New Zealand), lactose (New Zealand Milk Products, Auckland, NewZealand), sodium chloride (Pacific Salt NZ Ltd, Auckland, NewZealand), trisodium citrate (TSC) and citric acid (Jungbunzlauer,Basel, Switzerland). Rennet casein, which does not suffer fromproteolysis or variations in composition (Pereira, Bennett, Hemar,&Campanella, 2001), has a calcium level similar to that of youngcheese and is able to form a stable structure, was used as a source ofprotein in the formulation of model processed cheese. All otherchemicals used were of analytical grade and were obtained fromeither Sigma Chemical Co. (St. Louis, MO, USA) or BDH Chemical(BDH Ltd, Poole, UK).
2.2. Manufacturing procedure of model processed cheese
A Rapid Visco Analyser (RVA Super 4, Newport Scientific Ltd,Warriewood, NSW, Australia) was used to manufacture the modelprocessed cheese in triplicate. The RVA machine was used previ-ously to mimic the manufacture of processed cheese in the labo-ratory scale (Kapoor, Lehtola, & Metzger, 2004; Kapoor & Metzger,
2005). The basic formulation used for the model processed cheesewas 10% rennet casein, 30% oil, 52%moisture, 3.5% lactose, 2.8% TSC,1% sodium chloride and 0.7% citric acid.
The rennet casein, TSC, BSG, lactose and water were weighedand put into an RVA canister then thoroughly mixed and allowed tohydrate for at least 40 min at room temperature. After hydration,salt, citric acid, and soya oil were added and the canister was setinto the RVA machine. The mixture was then heated to 85 �C over4 min and was held at 85 �C for 6 min at a shear rate of 1500 revmin�1. The shearing profile of the RVA in five steps were: a)0e100 rev min�1 for 0.5 min; b) 100�200 rev min�1 for 0.5 min; c)200�500 revmin�1 for 1 min; d) 500�1000 rev min�1 for 2 min; e)1000e1500 rev min�1 for 6 min.
The processing conditions (e.g. processing time, temperatureand mixing speed) were the same for all the formulations. Themolten sample was cast into a slice with uniform thickness of2.2 mm and a cylindrical mould (for textural analysis), sealed in aplastic bag, cooled down to 4 �C and then stored at 4 �C for furtheranalysis.
BSG was added to the model processed cheese formulationswith three levels of rennet casein concentration (6, 8 and 10%) atadditional rates of 0%, 0.1%, 0.3%, 0.5% and 1% of the total weight. Forthe sake of simplicity, the rennet casein will be called proteinthroughout this article. We could not prepare the sample contain-ing 10% protein and 1% BSG, as its viscosity was higher than theviscosity range of RVA machine.
The total solids were maintained at a consistent level throughthe addition of lactosewhen BSGwas added to the formulation. Thesamples with the same protein concentration had the same totalsolids content. Therefore, the effect of BSG concentration onproperties of the model processed cheese was investigated only forthe samples with the same protein/solid content. The final lactosecontent of the formulations in this work was less than themaximum amount suggested by previous research (7.48% for pro-cessed cheese foods containing 44% moisture content and 10.20%for processed cheese spreads containing 60% moisture content)(Kapoor & Metzger, 2008). The loss of moisture content for thesamples during the RVA processing and cooling downwas less than1%.
2.3. pH measurement
The pH of the samples was estimated 24 h after the production,at 20 �C with the direct insertion of a glass electrode into thesample, using a previously standardized digital pH meter (Mettler-Toledo pH meter, Mettler-Toledo Inc., USA).
2.4. Rheological measurements
The dynamic rheological properties of the model processedcheeseweremeasured after 24 h storage at 4 �C, using a controlled-stress rheometer (Physica MCR 301, Anton Paar GmbH, Stuttgart,Germany) fitted with a 25 mm diameter parallel plate with a2.0 mm gap. Cheese samples were carefully cut to 25 mm diameterdiscs using a cylindrical cutter and glued to the surface of the lowerplate. The upper serrated plate was lowered until it reached a 2mmgap distance and the sample was trimmed. A thin layer of low-density mineral oil was used around the periphery of the sampleto prevent evaporation during the measurement. A strain sweep(0.01e100%) at 20 �C and frequency of 1 Hz was used to determinethe limits of linear viscoelastic behaviour of the model processedcheese. A frequency sweep test was performed at 5 �C and a strainamplitude of 0.5%, with the frequency varied from 0.01 to 10 Hz. Atemperature sweep test was performed at a constant frequency of0.1 Hz and a constant strain amplitude of 0.5%, with the
temperature varying from 5 to 85 �C at 3 �C/min using a Peltierheating element. The complex viscosity (h*), the storage modulus(G0), the loss modulus (G00) and the loss factor (tan d) were deter-mined. The loss tangent represents the ratio between the viscous-like property, G00 and the elastic-like property, G0. The gelesoltransition temperature was determined at G0 ¼ G00 (tan d ¼ 1) as anindicator of meltability (the ability of weakening during heating)(Guggisberg, Bütikofer, & Albrecht, 2007). The maximum tan d wasalso determined as a measure of flowability (the ability to spreadand flow at a certain temperature) (Guinee, Auty, & Mullins, 1999;Schenkel, Samudrala, & Hinrichs, 2013). All the rheological mea-surements were made at least in triplicate and the average re-ported. Any stresses induced during sample loading on therheometer plate were assumed to have relaxed during the tem-perature equilibration time (10 min).
2.5. Textural analysis
The textural properties of the cylindrical processed cheesesamples of 19 mm diameter and 25 mm height were evaluatedusing a texture analyser TA.XT.Plus (Stable Micro Systems Ltd.,Godalming, UK). The texture profile analysis (TPA) was carried outby two sequential compression events (strain 80%, probe speed0.83 mms�1 and trigger force 10.2 g) at 5 �C. The test was per-formed using a 60 mm Teflon cylinder probe and the force/timecurve was recorded. Firmness (force needed to attain a givendeformation- maximum force during the first compression cycle;N); adhesiveness (the strength of adhesiveness between the cheeseand the probe surface- the absolute value of the negative force areato the positive force area of first compression; N.s); and cohesive-ness (strength of the internal bonds of cheese- ratio of the positiveforce area of the second peak to that of the first peak; unitless) weredetermined. The collected data were reported as the average with astandard deviation from at least four measurements for eachsample.
2.6. Particle size analysis
The average diameter and size distribution of the oil droplets inthe model processed cheese samples were determined by a staticlaser light scattering technique, using a Malvern Mastersizer MS2000 (Malvern Instruments Ltd, Worcestershire, UK). Approxi-mately 0.5 g of the processed cheese sample was dispersed over-night in 50 ml of a chelating solution (0.375% w/w EDTA, 0.125% v/vTween 20, pH 10) at 5 �C (Lee, Anema, & Klostermeyer, 2004). Thesamples were allowed to equilibrate to room temperature beforethe analysis at 20 �C. Deionised water was used as a dispersant andthe relative refractive index (N), i.e., the ratio of the refractive indexof soy oil droplets (1.470) to that of the aqueousmedium (1.33), was1.105. The oil droplet size of the samples was measured in triplicateand the results reported as average with a standard deviation of theSauter diameter, d32.
2.7. Confocal laser scanning microscopy
A confocal scanning lasermicroscope (Leica SP5 DM6000B, LeicaMicrosystems GmbH, Wetzlar, Germany) was used to visualise themicrostructure of the cheese samples containing 8% protein anddifferent concentrations of BSG. A small section of the cheesesamples (0.5 mm thickness) was cut and placed into the laboratory-made welled microscope slide, using a plastic ring (0.5 mm thick-ness and 5 mm diameter), and stained with a fluorescent solutioncontaining 0.2% Nile Blue, which stained the oil phase, 0.2% FastGreen FCF, which stained the protein phase, and wheat germagglutinin (WGA) Alexa FLOUR 488 (0.2%), which stained the
polysaccharide. A cover slip was placed on top of the stainedsamples and left for 2 h at room temperature. The samples werethen observed at a depth of 15 mm with a 63 � oil-immersionobjective lens at 25 �C. Illuminationwas provided by an Argon laserat 488 nm and a Helium/Neon laser at 633 nm.
2.8. Data analysis
All the formulations were prepared in triplicate. The experi-mental data were analysed using Minitab 16.0 statistical software(Minitab Inc., State College, PA, USA). One-way analysis of variancewas used to determine if the means of responses were significantlydifferent. The level of significance (p) was set at 0.05. Tukey's HSTtest at 5% significance level was used as the multiple comparisontest on all main effect means.
3. Results
3.1. pH of model processed cheese
Adding BSG to the processed cheese samples had no significant(p > 0.05) effect on the final pH. However, the processed cheesescontaining different protein concentration showed significantlydifferent pHs: the pH values of the samples with 6, 8 and 10%protein were 5.36 ± 0.02, 5.50 ± 0.03 and 5.66 ± 0.03, respectively.The final pH of processed cheese is an important factor controllingthe final structure and therefore the final functional properties ofthe process cheese (Rohit Kapoor & Metzger, 2008). In this study,the pH of samples were in the pH range of a good-quality processedcheese (5.4e5.8) as suggested by previous researchers(Marchesseau, Gastaldi, Lagaude, & Cuq, 1997; Palmer & Sly, 1943).
3.2. Dynamic rheological behaviour of model processed cheese
The dynamic rheological measurements were performed at thelinear viscoelastic region (LVR) of the model processed cheesesamples. The frequency sweep of the model processed cheesesshowed the difference in their textures. The h*, G0 and G00 values ofthe samples containing 8% protein and different concentrations ofBSG as function of angular frequency are shown in Fig. 1AeB. Allsamples had G0 > G00, regardless of the protein and BSG content ofthe formulation, indicating that solid-type structures were presentand both parameters increased with frequency (Fig. 1B).
The G0 and G00 values of the samples with different protein andBSG concentrations determined at angular frequency of 1 rad/s arecompared in Fig. 2AeB. Generally, at all formulations with the sameprotein/solid content, G0 and G00 increased with increasing BSGconcentration. However, there was no significant difference(p > 0.05) between the G0 values of the samples containing 0 and0.1% BSG (at 6% protein) as well as the samples containing 0, 0.1 and0.3% BSG (at 8 and 10% protein) (Fig. 2A).
The changes in G00 were not as large as changes in G0 when BSGwas added to the formulations. One possible explanation is thatwith increasing concentration of BSG, more intensive interactionsbetween BSG chains take place, leading to the formation of a densernetwork structure. Similar results were reported with k-carra-geenan and i-carrageenan (�Cerníkov�a et al., 2008). However,increasing amounts of BSG led to a more elastic structure in theprocessed cheese, which could be attributed to the formation ofBSG network throughout the casein matrix. Other research re-ported that a pectin gel, which acted as a linkage with other in-gredients in a processed cheese analogue, made the product morecompact with less pores and as a result higher storage modulus(Liu, Xu, & Guo, 2008). Mack�u, Bu�nka, Pavlínek, Leci�anov�a, andHrab�e, (2008) also reported that processed cheeses containing
Fig. 1. The effect of BSG addition on viscoelastic properties of model processed cheese:(A) Changes in complex viscosity (h*) as function of angular frequency and concen-tration of added BSG measured at strain of 0.5% and 20 �C for model processed cheesescontained 8% protein. (B) Changes in storage modulus (G0) and loss modulus (G00) asfunction of angular frequency and concentration of added BSG measured at strain of0.5% and 20 �C for model processed cheeses contained 8% protein.
S.H. Hosseini-Parvar et al. / Food Hydrocolloids 43 (2015) 557e567560
pectin were more firm and less spreadable compared to the controlprocessed cheeses without pectin (Mack�u et al., 2008).
Increasing protein content resulted in a significant (p < 0.05)increasingly solid-like behaviour of the control samples with no
Fig. 2. The effects of added BSG on the viscoelastic properties of model processedcheeses containing different concentrations of protein, measured angular frequency of1 rad/s and 20 �C: (A) Storage modulus, and (B) Loss modulus. The same letters showno significant difference (p > 0.05).
added BSG. It has been reported that proteins reinforce the strengthof the three-dimensional matrix, leading to processed cheeses withmore solid-like behaviour. In contrast, moisture contributes to amore liquid-like behaviour (Dimitreli & Thomareis, 2008).
Temperature sweep from 5 to 85 �C were also performed on themodel processed cheeses with different protein and BSG content.The values of G0 and G00 of all samples decreased as the temperatureincreased. The changes in G0 value of the model processed cheesescontaining different protein and BSG concentrations as a functionof temperature are shown in Fig. 3AeC. Clearly, the elastic modulus(G0) of all samples decreased significantly with an increase in thetemperature (p < 0.05). The G0 values at 20 and 85 �C for modelprocessed cheeses containing different protein and BSG concen-trations determined at frequency of 0.1 Hz and strain of 0.5% arepresented in Table 1. At constant protein content, the values of G0 atboth 20 and 85 �C were increased by adding BSG concentration.However, in some formulations, G0 values were not increasedsignificantly (e.g. at 20 �C there were no significant difference be-tween G0 values of the samples containing 6e8% protein and0.5e1% BSG). The protein content showed a different effect on G0 attemperatures 20 and 85 �C. At 20 �C, G0 increased with an increasein protein/solid content from 6 to 10% when the added BSG wasconstant. However, the opposite effect was observed at the tem-perature 85 �C (Table 1). This means that increasing the protein/solid content at the same concentration of BSG led to a more rigidstructure in processed cheese at 20 �C. However, at 85 �C the in-crease of protein content resulted in weaken structure.
The data of Table 1 show that G0 of the model processed cheesesat a constant temperature increased significantly with an increasein the protein and BSG content (p< 0.05). The G0 values at frequencyof 1 rad/s and 20 �C for a solution of 0.5% BSG and a 30% O/Wemulsion contained 0.5% BSG, have been reported by Osano et al.(2014) and Hosseini-Parvar et al. (2010) as 10.09 ± 1.40 Pa and28.55 ± 1.25 Pa, respectively. In this study, the G0 values of theprocessed cheese contained 6% protein (control) and the samplewith 6% protein and 0.5% BSG were 72.02 ± 14.25 Pa and840.85 ± 45.75 Pa, respectively. The results indicate that addingBSG to the processed cheese formulation significantly strengthensthe cheese structure, so that for the latter sample adding only 0.5%BSG increased the elasticity of the processed cheese by more than11 times.
Tan d (G00/G0) may be a useful indicator of processed cheesemeltability (Mounsey & O'Riordan, 1999). Fig. 4AeC depicts thechanges in the damping factor (tan d) of the samples containingdifferent concentrations of the protein and BSG as the function oftemperature. Tan d of the samples containing different concentra-tion of BSG at the same protein content increased up to ~60 �C anddecreased after this temperature. This shows that heating of theprocessed cheese samples up to 60 �C increased the viscousbehaviour. However, the proteineprotein and protein-polysaccharide interactions might increase with heating up to85 �C leading to less viscous behaviour of the samples. The tan d
values of the control samples (no added BSG) decreased with theincreasing of the protein concentration while heating the samplesup to ~32 �C. Further heating up to 85 �C showed a reverse trend inthe value of tan d. At lower temperatures (<32 �C), the highermoisture content of the samples contained 6% protein led to higherviscous behaviour. However, at the temperatures >32 �C the pro-teineprotein interactions caused less viscous behaviour.
In the temperature sweep test, G0 and G00 curves crossed eachother (G0 ¼ G00 or tan d ¼ 1) at a certain temperature (gelesoltransition) and at higher temperatures, viscous behaviour of thesamples dominated the elastic one. Regardless of the protein con-tent of the model processed cheeses, the transition temperatureincreased significantly (p < 0.05) as the concentration of added BSG
Fig. 3. The changes in storage modulus during a temperature sweep (5e85 �C) atfrequency of 0.1 Hz and strain amplitude of 0.5% for the processed cheeses containingdifferent concentrations of added BSG (0e1%) and protein: (A) 6%, (B) 8%, and (C) 10%.
was increased (Fig. 5A). Adding BSG to the formulation of theprocessed cheeses up to 0.5% to the samples containing 6, 8 and 10%protein, increased the transition temperature from 16 ± 1.2 to45 ± 0.4 �C, 21.9 ± 0.3 to 34.3 ± 0.7 �C and 24.8 ± 1.6 to 31.4 ± 1.1 �C,respectively. However, increasing the protein content of the pro-cessed cheeses from 6 to 10% increased the transition temperature
Table 1The G0 values at 20 and 85 �C for model processed cheeses containing different concentrasweep (5e85 �C) at frequency of 0.1 Hz and strain amplitude of 0.5%.
Added BSG (%) 6% protein 8% protein
G0 at 20 �C G0 at 85 �C G0 at 20 �C
0 72.02 ± 14.25 aa 0.99 ± 0.13 a 344.65 ± 70.1 192.3 ± 8.3 b 3.90 ± 0.27 b 493.65 ± 10.3 520.3 ± 8.6 c 9.49 ± 0.16 c 994.8 ± 10.5 840.8 ± 45.7 d 18.93 ± 1.10 d 1308.5 ± 51 1452.5 ± 78.5 d 86.81 ± 5.44 e 2202 ± 9
a The same letters at each column show no significant difference (p > 0.05)
from 16 to 24.8 �C. This proves that BSG is muchmore effective thanprotein at increasing the meltability of model processed cheese. Itshould be noted that decreasing protein content led to a strongereffect of BSG on the transition temperature. The present resultsindicate that replacing 4% of the protein content (i.e. the samplecontaining 6% protein) with 0.1% BSG and 4% water could make aprocessed cheese with the same meltability of control sample with10% protein. The meltability of processed cheese containing 6%protein and less than 0.1% BSG would also be the same as thecontrol sample with 8% protein (Fig. 5A).
For the processed cheese sample containing 6% protein and 1%BSG, the elastic behaviour dominated the viscous one throughoutthe temperature tested and no crossover point appeared. Thisphenomenon proves the dominant effect of BSG on the meltabilityof the processed cheese. The solid-like behaviour of BSG solutioneven at a concentration as lowas 0.1%, has been reported previously(Hosseini-Parvar, 2009; Hosseini-Parvar et al., 2014).
Hennelly, Dunne, O'Sullivan, and O'Riordan (2006) showed thatreplacing fat with Inulin in the imitation cheese formula showed nosignificant effect on meltability. However, G0 and G00 of the pro-cessed cheeses containing the higher level of Inulin increased attemperatures more than 55 �C (Hennelly et al., 2006).
The maximum tan d of the model processed cheeses containingthe same protein content was decreased (p < 0.05) by increasingthe concentration of added BSG (Fig. 5B). Adding up to 0.5% BSG tothe formulation of the processed cheeses containing 6, 8 and 10%protein decreased the maximum tan d value from 3.6 ± 0.1 to0.83 ± 0.02, 5.3 ± 1.0 to 1.33 ± 0.04 and 10.2 ± 0.1 to 2.46 ± 0.06,respectively. The flowability of the processed cheese containing 6%protein (3.6 ± 0.1) is approximately one third of the flowability at10% protein (10.2 ± 0.1). This indicates that the protein content ismore effective on flowability of the processed cheese samples thanthe concentration of added BSG.
3.3. Textural attributes of model processed cheese
The effects of BSG on firmness, adhesiveness and cohesivenessof the model processed cheeses containing different protein con-tent are presented in Fig. 6AeC. The firmness is used as an index ofproduct strength while cohesiveness indicates the strength of in-ternal bonding of the processed cheese. The firmness of the controlsamples (0% wt/wt added BSG) containing 6 and 8% protein wasnegligible, as the cylindrical shape collapsed while on the textureanalyser plate. Therefore, there was no textural data for these twosamples. However, the control processed cheese containing 10%protein had a textural firmness, adhesiveness and cohesiveness of16.42 ± 0.68 N, 3.88 ± 0.22 N.s and 0.38 ± 0.01 (dimensionless),respectively. Generally, the firmness of the cheese samples withdifferent protein content significantly increased (p < 0.05) whenthe concentration of added BSG was 0.5 and 1%. The firmness of thesamples containing 10% protein remained constant when theconcentration of added BSG was lower than 0.3% (Fig. 6A). The
tions of protein and added BSG which are determined from the data of temperature
10% protein
G0 at 85 �C G0 at 20 �C G0 at 85 �C
.00 a 0.89 ± 0.40 a 1067.2 ± 118.5 a 0.32 ± 0.03 a9.44 b 1.63 ± 0.42 ab 1312.5 ± 21.9 b 1.80 ± 0.12 b03.5 c 4.23 ± 0.34 bc 2067.5 ± 72.8 c 3.7 ± 0.22 b5.7 d 10.41 ± 0.58 bc 2526 ± 187 c 11.41 ± 0.53 b6 d 42.57 ± 5.97 c
Fig. 4. The changes in damping factor (tan d) during temperature sweep (5e85 �C) atfrequency of 0.1 Hz and strain amplitude of 0.5% for the processed cheeses containingdifferent concentrations of added BSG (0e1%) and protein: (A) 6%, (B) 8%, and (C) 10%.
Fig. 5. The effects of protein content (6e10%) and concentration of added BSG (0e1%)on the values of temperature at tan d ¼ 1 (A) and maximum tan d (B) which aredetermined from the data of temperature sweep (5e85 �C) at frequency of 0.1 Hz andstrain amplitude of 0.5%, as meltability and flowability indices of the model processedcheeses, respectively.
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results indicate that at the formulations containing BSG, with anincrease in the protein/solid content, the firmness of the samplessignificantly (p < 0.05) increased; however, the cohesiveness andadhesiveness of the samples did not change significantly. Thefirmness of a fat-free processed cheese using gelatin, carrageenan,locust bean gum and guar gum at a 2% level was increased up tofour times as compared to the control sample (Swenson, Wendorff,& Lindsay, 2000). Also reported, the replacing fat in imitationcheese formula by Inulin can increase the hardness of cheese(Hennelly et al., 2006). Recently, Han�akov�a, Bu�nka, Pavlínek,Hude�ckov�a, and Jani�s, (2013), showed that addition of 1% k-carra-geenan to the formulation of the processed cheese analogue leadsto the highest firmness as compared to the formulations containingi-carrageenan, l-carrageenan, gum Arabic and locust bean gum(Han�akov�a et al., 2013).
Adhesiveness, which is the tendency of the processed cheese toresist separation from a material it contacts, remained constant(p > 0.05) with all the processed cheeses except for the samplecontaining 8% protein and 1% BSG (Fig. 6B). The cohesiveness ofprocessed cheese samples decreased with the increasing of BSGconcentration, regardless of protein content of the formulations(Fig. 6C). However, the decreasing rate was more significant withBSG concentrations higher than 0.3%. Liu et al. (2008) reported thatadding pectin gel to the formulation of a low fat processed cheeseanalogue can increase the firmness up to three times and also in-crease the adhesiveness up to two times as compared to the controlsamples. Jana et al. (2010) also showed that adhesiveness of pro-cessed cheese analogues made by the mixture of carrageenan andother hydrocolloids (xanthan or locuast bean gum) was less thanthat of the samples made by the hydrocolloids individually.
3.4. Particle size analysis
Fig. 7 depicts the average size (d3,2) of the oil droplets in themodel processed cheeses with different protein content as functionof the added BSG concentration. Generally, adding BSG to themodel processed cheese formulation with 6 and 8% proteindecreased the average oil droplet size significantly (p < 0.05).However, at 10% protein content, the d3,2 value increased signifi-cantly when the concentration of added BSG was higher than 0.1%.The oil droplet size of the control samples (no added BSG) alsodecreased significantly (p < 0.05) when the protein content wasincreased, causing the d3,2 values of the samples containing 6, 8 and10% protein to be 12.68 ± 1.37, 7.16 ± 0.02 and 2.52 ± 0.05 mm,respectively.
Fig. 6. Textural properties of the model processed cheeses containing different con-centrations of protein (6e10%) and added BSG (0e1%): (A) Firmness, (B) Adhesiveness,and (C) Cohesiveness. The same letters show no significant difference (p > 0.05).
Fig. 7. Average size (d3,2) of oil droplets in 1 the model processed cheeses withdifferent protein content as function of added BSG concentration. Error bars representsthe standard deviations of repeated measurements.
Fig. 8AeC shows the particle size distribution of the oil dropletsdispersed in the processed cheese as function of BSG and proteincontent. The particle size distribution curves of the control sampleswere monomodal and shifted to the left hand side (smaller dropletsizes) when the protein content increased. Increasing levels ofadded BSG in the formulations with the same protein content alsocaused shifting of the curves to the smaller particle size region. Thisproves that the added BSG contributed to the emulsification of theoil. However, a tail/second peak appeard when BSG was added tothe formulations.
The oil is emulsified to small droplets in the processed cheese byprotein. The surface activity of Basil seed gum in O/W emulsionscontaining 30% oil has already been reported (Hosseini-Parvar,2009; Osano et al., 2014; Osano, Martia-Merino, Hosseini-Parvar,Golding, & Goh, 2010). Therefore, BSG molecules might have gonepartly to the interface and emulsified the oil droplets because theparticle size curves shifted to the left hand side and the frequencyof smaller droplets increased significantly for the samples con-taining BSG compared to the control samples (Fig. 8AeC). The restof the BSG molecules could disperse throughout the protein matrixand contribute to the processed cheese structure.
3.5. Microstructure of model processed cheese
The confocal micrographs of the model processed cheesescontained 8% protein and different concentrations of BSG areshown in Fig. 9AeE. In the micrographs, the protein matrix is arusty colour, the dispersed polysaccharide (BSG) is green and the oildroplets are a dark colour. Generally, microstructure of the modelprocessed cheese samples are in agreement with the results ofparticle size. The microstructure of the model processed cheesewith no added BSG is shown in Fig. 9A. The oil was dispersed as1e15 mm droplets in this sample. Adding BSG to the samples up to0.5% decreased the average particle size and also changed theirdistribution, so that there were more smaller droplets as seen inFig. 9BeD. The number of larger oil droplets increased significantlywhen 1% BSG was added to the formulation (Fig. 9E). This could beexplained by the fact that adding 1% BSG to the model processedcheese containing 8% protein increased the proteineprotein andprotein-polysaccharide interactions, so that the viscosity increasedsignificantly. The high viscosity of the mixture presumably pre-vented complete emulsification and led to bigger oil droplets and amore compact microstructure (Fig. 9E). The value of complex vis-cosity of the sample contained 8% protein and 1% BSG(6880 ± 70 Pa s) was five time more than that of the control samplewith no added BSG (1260 ± 5 Pa s). Its complex viscosity also wastwo timesmore than the sample contained 8% protein and 0.5% BSG(3570 ± 141 Pa s). Fig. 9E shows the more compact microstructurefor the sample containing 1% BSG, due tomore proteineprotein andprotein-polysaccharide interactions and the less dispersed oildroplets.
Hennelly et al. (2006) showed that the addition of Inulin canreduce the level of honeycomb structures evident in the proteinmatrix, relative to the control sample (Hennelly et al., 2006).
The confocal micrographs showed that both the oil droplets andthe polysaccharide (BSG) dispersed in a continuous protein phase.However, BSG possibly creates a web network inside the proteinmatrix and strengthens the processed cheese structure.
4. Discussion
The pH of samples in this study was in the pH range of stableprocessed cheese. Palmer and Sly (1943) reported that the stabilityof the processed cheese emulsion was decreased when the pH ofthe processed cheese was out of the range 5.5e5.8. So, any changesin stability of the processed cheese samples in this study would notbe related to the pH.
Fig. 8. Particle size distribution of the oil droplets in the model processed cheeses withdifferent concentrations of added BSG: (A) 6% protein, (B) 8% protein, and (C) 10%protein.
S.H. Hosseini-Parvar et al. / Food Hydrocolloids 43 (2015) 557e567564
Rennet casein and basil seed gum could create a compositenetwork in the structure of developedmodel processed cheese. Theinteractions between rennet casein and BSG in cheese matrix, aswell as a likely web network created by BSG chains couldstrengthen the network formed by casein strands. In the rennetcasein, the negatively charged hairy portion of k-casein is notpresent (Kiziloz, Cumhur, & Kilic, 2009) which may increase itspositive charges and render it more available for interaction withnegatively charged BSG polysaccharides. According to SarabiAghdam, Hosseini-Parvar, Motamedzadegan, and Matia-Merino(2013b), the relative concentration of sodium caseinate (SCN) and
BSG determine the type and the dominant component of thenetwork formed in an aqueous mixed system. They showed thatgelation and phase separation occur simultaneously at SCN/BSGaqueous systems, so that the rate of each process and the ratio ofprotein/polysaccharide can control the system behaviour. They alsoreported synergistic interactions in these systems at high concen-trations of BSG (Sarabi Aghdam et al., 2013a, 2013b). The synergisticeffect of BSG on heat induced gels of b-lactoglubulin were alsodocumented elsewhere (Rafe et al., 2013).
In this study, part of the BSG contributed to the emulsificationprocess, located at the interface of the oil droplets, and dispersedin the processed cheese structure. This suggests that thenetwork formed by a higher concentration of BSG could becomeone of the continuous phases and make a dominant contributionto the properties of the processed cheese, rather than beingdispersed in the mixture as a filler to provide a reinforcing effect.This was previously shown in the microstructure of low-fatyoghurt containing BSG (Afshar Nik et al., 2011) and heatinduced gels using mixtures of BSG and sodium caseinate (SarabiAghdam et al., 2013b). A similar scenario was proposed for theeffect of high concentration of potato starch on the structure ofimitation cheese (Ye & Hewitt, 2009). Rafe et al. (2013) alsostated that b-lactoglobulin formed a continuous phase in BSG/b-lactoglobulin mixed gels, which accommodated BSG chains,acting as filler (Rafe et al., 2013). Similar conclusions were alsoreported for the mixture of glubular proteins and poly-saccharides, e.g. b-lactoglobulin/k-carrageenan (Capron, Nicolai,& Smith, 1999), WPI/Cassia gum (Goncalves, Torres, Andradeb,Azerob, & Lefebvrec, 2004), WPI/Locust bean gum (Tavares &Lopes da Silva, 2003) and WPI/k-carrageenan gels (Mleko, Li-Chan, & Pikus, 1997).
SCN/BSG mixtures containing less than 0.07% BSG and 0.5e5%SCN are reported to be thermodynamically incompatible systems,with phase separation occurring as a result of poly-saccharideepolysaccharide interactions and depletion flocculation.When BSG concentration was high, a gel network was formedpredominantly by BSG joining the casein micelles (Sarabi Aghdamet al., 2013b). Similar behaviour has been shown for carrageenan(Martin, Douglas Goff, Smith, & Dalgleish, 2006). Strengthening ofthe network, by increasing the amount of BSG in the formulation ofprocessed cheese, adversely affected its meltability. A similar effecthas been also reported for k-carrageenan by Kiziloz et al. (2009).
The results of the frequency sweep test revealed that increasingBSG concentration from 0.1 to 0.5% in formulations with 10% pro-tein had no significant effect (p > 0.05) on the dynamic rheologicalproperties of the samples. This shows that protein and BSG mole-cules competed for water in the processed cheese system and athigh protein concentrations (i.e. lower moisture content), the BSGmolecules might not be hydrated completely. This suggests a hy-pothesis that the effect of BSG addition on the viscoelastic prop-erties of processed cheese increases as the protein content of thecheese matrix is decreased. �Cerníkov�a et al. (2008) also observed asimilar trend for the effect of carrageenan on the viscoelasticproperties of processed cheese.
Moisture content reported to improve the processed cheesemeltability (Gupta & Reuter, 1993). The moisture acted as a plasti-cizer contributing to a more liquid-like behaviour of the processedcheese samples (Dimitreli & Thomareis, 2008). This could be thecase for the control samples (no added BSG). However, themoisturecontent could not improve the meltability of the processed cheesesamples when BSG was added to the formulation.
Water is also known to decrease the firmness of processedcheese (Gupta & Reuter, 1993; Pereira et al., 2001). Therefore,increasing the firmness of the control samples could be due to acombination of the effects of moisture and protein content.
Fig. 9. Confocal micrographs of the model processed cheeses contained 8% protein and different concentrations of Basil seed gum: (A) 0%, (B), 0.1%, (C) 0.3%, (D) 0.5%, and (E) 1%. Thescale bars represent 20 mm. The protein matrix is in rusty colour, the dispersed polysaccharides are in green and the oil droplets are in dark colour. (For interpretation of thereferences to colour in this figure legend, the reader is referred to the web version of this article.)
The more protein in the formulation allows more caseinecaseininteraction and stabilises the cheese matrix (Lucey, Johnson, &Horne, 2003). This can explain the higher transition temperatureof the control sample contained 10% protein (24.78 ± 1.56 �C) thanthat of the control sample with 6% protein (16 ± 1.25 �C).
The fat globules act as inert fillers in processed cheese structureand diminish the number of casein interactions (Lucey et al., 2003).Microparticulated whey proteins also act as inert fillers in themelting processed cheese matrix (Schenkel et al., 2013). The highersolegel transition temperature and lower flowability of the pro-cessed cheeses containing BSG compared to the control samplesmight be due to a structural strengthening effect of BSG, creating aweb network throughout the protein matrix and inducing moreproteineprotein interactions. Creation of a BSG gel network in milkprotein systems has previously shown by microscopic images oflow-fat yoghurt (Afshar Nik et al., 2011) and BSG/milk proteins heat
induced gels (Rafe et al., 2013; Sarabi Aghdam et al., 2013a, 2013b).The role of BSG gel network on the protein matrix is similar toreinforcing bars which are commonly used as tension devices inreinforced concrete structures. It was also found that the rheolog-ical behaviour of BSG/milk protein mixture systems was mainlycontrolled by the weak gel network made by BSG (Sarabi Aghdamet al., 2013a).
Dimitreli and Thomareis (2007) reported that cohesiveness ofcommercial Mozzarella cheese is related to the amount of protein.The results of this study, however, showed that protein content hadno significant effect on cohesiveness of model processed cheese.Although cohesiveness decreased with increasing amounts ofadded BSG, the values of cohesiveness of the samples contained 1%BSG were more than 0.26. This value is close to the target limit ofcohesiveness for a low protein formula of an imitation cheese usingk-carrageenan and starch (Kiziloz et al., 2009). These researchers
S.H. Hosseini-Parvar et al. / Food Hydrocolloids 43 (2015) 557e567566
also stated that the brittle nature of k-carrageenan gel possiblycontributes to low cohesiveness of the processed cheese.
The mechanical shear (mixing speed) in the cheese makingprocess is a critical parameter to emulsify thewhole fat and create ahomogenous structure (Rohit Kapoor & Metzger, 2008). It shouldbe enough to force the whole BSG to the interface due to higherviscosity that appeared when adding BSG. An unusual increase inthe d3,2 value (19.22 ± 0.10 mm) of the sample containing 8% proteinand 1% BSG could be due to this phenomenon. The hydration of BSGcould be another reason for this phenomenon. However, there is noevidence to show the ratio of the hydrated/non-hydrated BSG in theprocessed cheeses, prepared for this study.
Proteineprotein interactions increase in well-emulsified prod-ucts, providing stronger resistance to applied forces and thereforeproducing firmer processed cheese (Pereira et al., 2001). Previousresearchers also showed that an increase in the oil droplet size,decreases the firmness of cheese or processed cheese (Guinee et al.,2004; Shirashoji et al., 2006). The present results indicate a nega-tive relationship between the oil droplet size data (Fig. 7) of themodel processed cheeses and their firmness (Fig. 6A), as well astheir elasticity (Fig. 2A).
Small fat globules can behave like large protein units whichreinforce the gels by forming a copolymer network in a systemcontain casein and whey proteins (Aguilera& Kinsella, 1991). Theseprotein-coated fat globules can bind more proteins during heatingand can assist in gel matrix formation. In this study, an increase inthe protein content of the control samples resulted in significant(p < 0.05) decreases in the average particle size and also increasesin the size homogeneity (Fig. 7), thus enhancing the incorporationof oil into the protein matrix (between the casein strands) (Jost,Baechler, & Masson, 1986). The oil liquefies when it is warmedabove 40 �C, contributing to the flowing of the cheese matrix vialubrication (Schenkel et al., 2013). It can be concluded that the in-crease in protein content, in this work, caused increases in thenumber of small oil droplets, dispersed between the casein strandsproviding more lubrication and consequently more flowability.
The appearance of a tail/second peak in the particle size dis-tribution curves when BSG was added to the formulations, in-dicates that there should be a number of big oil droplets (>100 mm)dispersed into the cheese structure. However, these big oil dropletswere not seen in the microstructure of the processed cheeses. TheCLSM images show the cheese structure formed by rennet casein,BSG and oil droplets. Breaking down of this structure into achelating solution for the particle size analysis could induce thepartial coalescence (tail/second peak at particle size distributioncurves). This may raise a concern about the stability of thedeveloped cheese structure during the digestion process when it iseaten. The destabilisation of emulsions within the stomach alterstheir droplet size and surface area, which in turn influences therate and extent of fat digestion (Day et al., 2014). Wooster et al.(2014) showed that a caseinate/monoglyceride-stabilised emul-sion underwent extensive partial coalescence upon exposure togastric juice, and as a result had very slow lipolysis (in vitro andin vivo). They also found when the emulsion was incorporatedwithin the biopolymer networks (gelatine and starch) the rates oflipolysis were strongly correlated with the extent of partial coa-lescence of the emulsion, which was directly influenced by thestructure and breakdown properties of each different biopolymernetwork (Wooster et al., 2014). The design of food structures thatimpact on lipid digestion has received increasing attentionbecause of the need for solutions to combat obesity and metabolicsyndrome (Wooster et al., 2014). Therefore, exploring the effect ofBSG on the destabilisation of milk protein systems e.g. processedcheese, is an important issue to extend its application in foodformulations.
5. Conclusions
This research provides an extensive database on how the func-tional properties of a model processed cheese may be altered bychanging the content of rennet casein and added basil seed gum(BSG) in the formulation. Addition of BSG had no significant effecton the final pH of the processed cheese samples. The solid-typestructures were present in all samples and h*, G0 and G00 increasedwith increasing BSG concentration in all formulations with thesame protein/solid content. Increasing the level of added BSG alsoled to more elastic behaviour in the structure of the processedcheeses. Regardless of the protein content, the “solegel transition”temperature of themodel processed cheeses increased significantlyas the concentration of the added BSG increased.
The concentration of added BSG had a much greater effect onthe meltability of the processed cheese than the protein content.However, the flowability of the samples was mainly dependent onthe protein content. The results of the particle size and CLSM mi-crographs showed that BSG contributed to the emulsification of theoil, and both the oil droplets and BSG chains were dispersed in acontinuous protein phase. The results suggest that BSG chains couldcreate a web network throughout the protein matrix of the pro-cessed cheese and strengthen the network formed by caseinstrands. It can be concluded that by adding BSG, it is possible tomake processed cheeses with higher firmness but slightly lowermeltability, and at lower cost owing to the lower protein and highermoisture contents. Future studies on the hydration rate of BSG insystems containing proteins as well as the destabilisation of thesesystems during the digestion process may help to understand themechanism behind the functionality of BSG in protein based foodproducts.
Acknowledgements
The authors would like to acknowledge Dr Simon Loveday andAnna Wildey for reviewing the manuscript and their usefulsuggessions.
References
Afshar Nik, A., Raftani Amiri, Z., & Hosseini-Parvar, S. H. (2011). The effect of basilseed gum as a fat replacer on physico-chemical, microstructural and sensoryproperties of low-fat set yoghurt. Electronic Journal of Food Preservation &Processing (EJFPP), 3(2), 23e42.
Aguilera, J. M., & Kinsella, J. E. (1991). Compression strength of dairy gels andmicrostructural interpretation. Journal of Food Science, 56(5), 1224e1228. http://dx.doi.org/10.1111/j.1365-2621.1991.tb04739.x.
Anjaneyalu, Y. V., & Channe Gowda, D. (1979). Structural studies of an acidicpolysaccharide from Ocimum basilicum seeds. Carbohydrate Research, 75,251e256.
Bowland, E. L., & Foegeding, E. A. (1999). Factors determining large-strain (Fracture)rheological properties of model processed cheese. Journal of Dairy Science,82(9), 1851e1859. http://dx.doi.org/10.3168/jds.S0022-0302(99)75418-4.
Bowland, E. L., & Foegeding, E. A. (2001). Small strain oscillatory shear and micro-structural analyses of a model processed cheese. Journal of Dairy Science, 84(11),2372e2380. http://dx.doi.org/10.3168/jds.S0022-0302(01)74686-3.
Brighenti, M., Govindasamy-Lucey, S., Lim, K., Nelson, K., & Lucey, J. A. (2008).Characterization of the rheological, textural, and sensory properties of samplesof commercial US cream cheese with different fat contents. Journal of DairyScience, 91(12), 4501e4517. http://dx.doi.org/10.3168/jds.2008-1322.
Capron, I., Nicolai, T., & Smith, C. (1999). Effect of addition of k-carrageenan on themechanical and structural properties of b-lactoglobulin gels. CarbohydratePolymers, 40(3), 233e238. http://dx.doi.org/10.1016/S0144-8617(99)00058-2.
�Cerníkov�a, M., Bu�nka, F., Pavlínek, V., B�rezina, P., Hrab�e, J., & Val�a�sek, P. (2008). Effectof carrageenan type on viscoelastic properties of processed cheese. Food Hy-drocolloids, 22(6), 1054e1061. http://dx.doi.org/10.1016/j.foodhyd.2007.05.020.
Day, L., Golding, M., Xu, M., Keogh, J., Clifton, P., & Wooster, T. J. (2014). Tailoring thedigestion of structured emulsions using mixed monoglycerideecaseinate in-terfaces. Food Hydrocolloids, 36(0), 151e161. http://dx.doi.org/10.1016/j.foodhyd.2013.09.019.
Dimitreli, G., & Thomareis, A. S. (2007). Texture evaluation of block-type processedcheese as a function of chemical composition and in relation to its apparent
viscosity. Journal of Food Engineering, 79(4), 1364e1373. http://dx.doi.org/10.1016/j.jfoodeng.2006.04.043.
Dimitreli, G., & Thomareis, A. S. (2008). Effect of chemical composition on the linearviscoelastic properties of spreadable-type processed cheese. Journal of FoodEngineering, 84(3), 368e374. http://dx.doi.org/10.1016/j.jfoodeng.2007.05.030.
Goncalves, M. P., Torres, D., Andradeb, C. T., Azerob, E. G., & Lefebvrec, J. (2004).Rheological study of the effect of Cassia javanica galactomannans on the heat-set gelation of a whey protein isolate at pH 7. Food Hydrocolloids, 18, 181e189.
Guggisberg, D., Bütikofer, U., & Albrecht, B. (2007). Melting and solidificationcharacteristics of swiss raclette cheese measured by small amplitude oscillatoryshear measurements. Journal of Texture Studies, 38(3), 297e323. http://dx.doi.org/10.1111/j.1745-4603.2007.00099.x.
Guinee, T. P., Auty, M. A. E., & Mullins, C. (1999). Observations on the microstructureand heat-induced changes in the viscoelasticity of commercial cheeses.Australian Journal of Dairy Technology, 54, 84e89.
Guinee, T. P., Caric, M., & Kalab, M. (2004). Pasteurized processed cheese and sub-stitute/imitation cheese products. In P. F. Fox, P. L. H. McSweeney, T. M. Cogan, &T. P. Guinee (Eds.), Major cheese groups: Vol. 2. Cheese: Chemistry, physics andmicrobiology (pp. 349e394). London: Elsevier Allied Science.
Gupta, V. K., & Reuter, H. (1993). Firmness and melting quality of processed cheesefoods with added whey protein concentrates. Lait, 73(4), 381e388.
Han�akov�a, Z., Bu�nka, F., Pavlínek, V., Hude�ckov�a, L., & Jani�s, R. (2013). The effect ofselected hydrocolloids on the rheological properties of processed cheese ana-logues made with vegetable fats during the cooling phase. International Journalof Dairy Technology, 66(4), 484e489. http://dx.doi.org/10.1111/1471-0307.12066.
Hennelly, P. J., Dunne, P. G., O'Sullivan, M., & O'Riordan, E. D. (2006). Textural,rheological and microstructural properties of imitation cheese containinginulin. Journal of Food Engineering, 75(3), 388e395. http://dx.doi.org/10.1016/j.jfoodeng.2005.04.023.
Hosseini-Parvar, S. H. (2009). Basil seed gum (BSG): Physico-Chemical, Rheologicaland Emulsifying Characterization and Its Synergistic Interactions in Combinationwith Locust Bean Gum and Guar Gum. Doctor of Philosophy, Dissertation (Ph.D.).Mashhad: Ferdowsi University of Mashhad.
Hosseini-Parvar, S. H., Alimardani, E., Shahidi, S. A., & Matia-Merino, L. (2013). Ul-trasound-assisted emulsification of mint essential oil in basil seed gum aqueoussolution: Comparison with gum Arabic. Paper presented at the NZIFST Conference2013, Hastings, New Zealand.
Hosseini-Parvar, S. H., Matia-Merino, L., Goh, K. K. T., Razavi, S. M. A., &Mortazavi, S. A. (2010). Steady shear flow behavior of gum extracted fromOcimum basilicum L. seed: effect of concentration and temperature. Journal ofFood Engineering, 101(3), 236e243. http://dx.doi.org/10.1016/j.jfoodeng.2010.06.025.
Hosseini-Parvar, S. H., Matia-Merino, L., Mortazavi, S. A., & Razavi, S. M. A. (2014).Characterization of gum extracted from basil seed (Ocimum basilicum L.): aphysicochemical and rheological study. Submitted for publication in Carbohy-drate Polymers.
Jana, A. H., Patel, H. G., Suneeta, P., & Prajapati, J. P. (2010). Quality of casein basedMozzarella cheese analogue as affected by stabilizer blends. Journal of FoodScience and Technology, 47(2), 240e242. http://dx.doi.org/10.1007/s13197-010-0034-0.
Jost, R., Baechler, R., & Masson, G. (1986). Heat gelation of oil-in-water emulsionsstabilized by whey protein. Journal of Food Science, 51(2), 440e444. http://dx.doi.org/10.1111/j.1365-2621.1986.tb11150.x.
Kapoor, R., Lehtola, P., & Metzger, L. E. (2004). Comparison of pilot-scale and rapidvisco analyzer process cheese manufacture. Journal of Dairy Science, 87(9),2813e2821. http://dx.doi.org/10.3168/jds.S0022-0302(04)73409-8.
Kapoor, R., & Metzger, L. E. (2005). Small-scale manufacture of process cheese usinga rapid visco analyzer. Journal of Dairy Science, 88(10), 3382e3391.
Kapoor, R., & Metzger, L. E. (2008). Process cheese: scientific and technologicalaspectsdA review. Comprehensive Reviews in Food Science and Food Safety, 7(2),194e214. http://dx.doi.org/10.1111/j.1541-4337.2008.00040.x.
Khorrami, M., Hosseini-Parvar, S. H., & Motamedzadegan, A. (2014). The influence ofbasil seed gum on the stability, particle size and rheological properties of O/Wemulsion stabilised by whey protein isolate. Electronic Journal of Food Preser-vations & Processing (EJFPP), 5(2), 91e114.
Kiziloz, M. B., Cumhur, O., & Kilic, M. (2009). Development of the structure of animitation cheese with low protein content. Food Hydrocolloids, 23(6),1596e1601. http://dx.doi.org/10.1016/j.foodhyd.2008.11.006.
Lazaridis, H. N., & Rosenau, J. R. (1980). Effects of emulsifying salts and carrageenanon rheological properties of cheese-like products prepared by direct acidifica-tion. Journal of Food Science, 45(3), 595e597. http://dx.doi.org/10.1111/j.1365-2621.1980.tb04108.x.
Lee, S. K., Anema, S., & Klostermeyer, H. (2004). The influence of moisture contenton the rheological properties of processed cheese spreads. International Journalof Food Science & Technology, 39(7), 763e771. http://dx.doi.org/10.1111/j.1365-2621.2004.00842.x.
Lee, S. K., & Anema, S. G. (2009). The effect of the pH at cooking on the properties ofprocessed cheese spreads containing whey proteins. Food Chemistry, 115(4),1373e1380. http://dx.doi.org/10.1016/j.foodchem.2009.01.057.
Lee, S. K., & Klostermeyer, H. (2001). The effect of pH on the rheological propertiesof reduced-fat model processed cheese spreads. LWT e Food Science and Tech-nology, 34(5), 288e292. http://dx.doi.org/10.1006/fstl.2001.0761.
Liu, H., Xu, X. M., & Guo, S. D. (2008). Comparison of full-fat and low-fat cheeseanalogues with or without pectin gel through microstructure, texture, rheology,thermal and sensory analysis. International Journal of Food Science & Technology,43(9), 1581e1592. http://dx.doi.org/10.1111/j.1365-2621.2007.01616.x.
Lucey, J. A., Johnson, M. E., & Horne, D. S. (2003). Invited review: perspectives on thebasis of the rheology and texture properties of cheese. Journal of Dairy Science,86(9), 2725e2743. http://dx.doi.org/10.3168/jds.S0022-0302(03)73869-7.
Mack�u, I., Bu�nka, F., Pavlínek, V., Leci�anov�a, P., & Hrab�e, J. (2008). The effect of pectinconcentration on viscoelastic and sensory properties of processed cheese. In-ternational Journal of Food Science & Technology, 43(9), 1663e1670. http://dx.doi.org/10.1111/j.1365-2621.2008.01734.x.
Marchesseau, S., Gastaldi, E., Lagaude, A., & Cuq, J. L. (1997). Influence of pH onproteininteractions andmicrostructure of process cheese. Journal of Dairy Science, 80(8),1483e1489. http://dx.doi.org/10.3168/jds.S0022-0302(97)76076-4.
Martin, A. H., Douglas Goff, H., Smith, A., & Dalgleish, D. G. (2006). Immobilization ofcasein micelles for probing their structure and interactions with poly-saccharides using scanning electron microscopy (SEM). Food Hydrocolloids,20(6), 817e824. http://dx.doi.org/10.1016/j.foodhyd.2005.08.004.
Mleko, S., Li-Chan, E. C. Y., & Pikus, S. (1997). Interactions of k-carrageenan withwhey proteins in gels formed at different pH. Food Research International, 30(6),427e433. http://dx.doi.org/10.1016/s0963-9969(97)00071-9.
Mounsey, J. S., & O'Riordan, E. D. (1999). Empirical and dynamic rheological datacorrelation to characterizemelt characteristics of imitation cheese. Journal of FoodScience, 64(4), 701e703. http://dx.doi.org/10.1111/j.1365-2621.1999.tb15114.x.
Osano, J. P., Hosseini-Parvar, S. H., Matia-Merino, L., & Golding, M. (2014). Emulsi-fying properties of a novel polysaccharide extracted from basil seed (Ocimumbacilicum L.): effect of polysaccharide and protein content. Food Hydrocolloids,37(0), 40e48. http://dx.doi.org/10.1016/j.foodhyd.2013.09.008.
Osano, J. P., Martia-Merino, L., Hosseini-Parvar, S. H., Golding, M., & Goh, K. K. T.(2010). Adsorption properties of basil (Ocimum basilicum L.) seed gum. R&DJournal Of University Of Southern Mindano, 18(2), 113e117.
Palmer, H. J., & Sly, W. H. (1943). Oil separation in processed cheese. Dairy Industry,(8), 427e430.
Pereira, R. B., Bennett, R. J., Hemar, Y., & Campanella, O. H. (2001). Rheological andmicrostructural characteristics of model processed cheese analogues. Journal ofTexture Studies, 32(5e6), 349e373. http://dx.doi.org/10.1111/j.1745-4603.2001.tb01242.x.
Rafe, A., Razavi, S. M. A., & Farhoosh, R. (2013). Rheology and microstructure of basilseed gum and b-lactoglobulin mixed gels. Food Hydrocolloids, 30(1), 134e142.http://dx.doi.org/10.1016/j.foodhyd.2012.05.016.
Rafe, A., Razavi, S. M. A., & Khan, S. (2012). Rheological and structural properties of b-lactoglobulin and basil seed gum mixture: effect of heating rate. Food ResearchInternational, 49(1), 32e38. http://dx.doi.org/10.1016/j.foodres.2012.07.017.
Razavi, S. M. A., Mortazavi, S. A., Matia-Merino, L., Hosseini-Parvar, S. H.,Motamedzadegan, A., & Khanipour, E. (2009). Optimization study of gumextraction from basil seeds (Ocimum basilicum L.). International Journal of FoodScience & Technology, 44, 1755e1762.
Sarabi Aghdam, V., Hosseini-Parvar, S. H., Motamedzadegan, A., & Matia-Merino, L.(2013a). An investigation on interactions between basil seed gum and wheyprotein isolate in aqueous systems. Electronic Journal of Food Preservations &Processing (EJFPP), 4(2), 15e35.
Sarabi Aghdam, V., Hosseini-Parvar, S. H., Motamedzadegan, A., & Matia-Merino, L.(2013b). Sodium caseinate and Basil seed gum interactions in aqueous systems: Aphase behavior and rheological study. Paper presented at the NZIFST Conference2013, Hastings, New Zealand.
Schenkel, P., Samudrala, R., & Hinrichs, J. (2013). The effect of adding whey proteinparticles as inert filler on thermophysical properties of fat-reduced semihardcheese type Gouda. International Journal of Dairy Technology. http://dx.doi.org/10.1111/1471-0307.12036. n/a-n/a.
Shirashoji, N., Jaeggi, J. J., & Lucey, J. A. (2006). Effect of trisodium citrate concen-tration and cooking time on the physicochemical properties of pasteurizedprocess cheese. Journal of Dairy Science, 89(1), 15e28. http://dx.doi.org/10.3168/jds.S0022-0302(06)72065-3.
Swenson, B. J., Wendorff, W. L., & Lindsay, R. C. (2000). Effects of ingredients on thefunctionality of fat-free process cheese spreads. Journal of Food Science, 65(5),822e825. http://dx.doi.org/10.1111/j.1365-2621.2000.tb13594.x.
Tavares, C., & Lopes da Silva, J. A. (2003). Rheology of galactomannanewhey proteinmixed systems. International Dairy Journal, 13(8), 699e706. http://dx.doi.org/10.1016/S0958-6946(03)00095-5.
Wooster, T. J., Day, L., Xu, M., Golding, M., Oiseth, S., Keogh, J., et al. (2014). Impact ofdifferent biopolymer networks on the digestion of gastric structured emulsions.Food Hydrocolloids, 36(0), 102e114. http://dx.doi.org/10.1016/j.foodhyd.2013.09.009.
Ye, A., & Hewitt, S. (2009). Phase structures impact the rheological properties ofrennet-casein-based imitation cheese containing starch. Food Hydrocolloids,23(3), 867e873. http://dx.doi.org/10.1016/j.foodhyd.2008.05.004.
