Physical properties of yogurt fortified with various commercial whey protein concentrates

The effects of whey protein concentrates on physical and rheological properties of yogurt were studied. Five commercial whey protein concentrates (340 g kg^?1 protein nominal) were used to fortify milk to 45 g protein kg^?1. Fermentation was performed with two different starters (ropy and non‐ropy). Resulting yogurts were compared with a control yogurt enriched with skim milk powder. The water‐holding capacity of the yogurt fortified with skim milk powder was 500 g kg^?1 and ranged from 600 to 638 g kg^?1 when fortified with whey protein concentrates. Significant rheological differences have been noticed between the yogurts fortified with different whey protein concentrates, independent of the starter used. Three whey protein concentrates generated yogurts with a behavior similar to the control. The two others produced yogurt with lower firmness (15 g compared with 17 g), lower Brookfield viscosity (6 Pa s compared with 9 Pa s), lower yield stress (2 Pa compared with 4 Pa), lower complex viscosity (13 Pa s compared with 26 Pa s), and lower apparent viscosity (0.4 Pa s compared with 1 Pa s) than the control, respectively. The yogurts with the lowest firmness and viscosity were produced with concentrates which contained the highest amount of non‐protein nitrogen fraction (160 g kg^?1 versus 126 g kg^?1 of the total nitrogen), and the highest amount of denaturation of the whey protein (262 versus 200 g kg^?1 of the total nitrogen). Copyright © 2004 Society of Chemical Industry     

Electrophoretic studies of chhana whey and effect of temperature and time of storage on its quality

Chhana whey contains less protein than Cheddar cheese whey, acid casein and cottage cheese whey, and the protein composition is quite different. Electrophoretic methods demonstrated that most of the proteins in chhana whey were denatured, and there was considerable variation in the protein composition between samples of chhana whey and paneer whey obtained from different sources. The effect of storage temperature and time (up to 10 h at 40°C, 50°C, 60°C, 70°C and 80°C) on the quality of chhana whey was investigated. There were no significant changes in the pH and titratable acidity in any of these cases. Electrophoretic separation showed no qualitative changes in the protein composition pattern of chhana whey after up to 10 h of storage at 70°C.     

Studies on the use of chhana and paneer whey in the preparation of puras (pancakes)

Puras (pancakes) are widely accepted traditional Indian foods. Studies were conducted on the use of chhana and paneer whey in the preparation of sweet and salty puras . Six samples of chhana and paneer whey were substituted in sweet and salty puras at different whey to water ratios (0 : 100, 20 : 80, 40 : 60, 60 : 40, 80 : 20, 100 : 0). The effects of chhana and paneer whey on sensory evaluation showed that sweet puras containing mixed milk chhana whey and salty puras containing cow's milk chhana whey scored highest with respect to appearance, body and texture, flavour and taste, and overall acceptability. In general, commercial samples scored less, which may be due to poor handling and maintenance of whey by commercial manufacturers. Whey substitutions also improved fat, total solids, protein and ash of both sweet and salty puras . It is interesting to note that none of sweet and salty pura samples was below the limits acceptable to the panellists. It can be thus concluded that chhana and paneer whey can be used successfully in the preparation of puras for value addition.     

The effect of coagulants on the texture of chhana (an acid and heat coagulated product made from milk)

Chhana (a heat and acid coagulated milk protein mass and an Indian equivalent to cottage cheese) can be used as a raw material for the manufacture of various types of sweets popular all over India. Texture Profile Analysis (TPA), using an Instron Universal Testing Machine, was used to determine the effect of different coagulants on the textural characteristics of chhana. Chhana was made using three different coagulants: citric acid, lactic acid and calcium lactate, at five different concentrations, 0.5, 1, 2, 4 and 8%. Two types of dilution media, distilled water and acid whey, were used. The textural characteristics obtained when aqueous 0.5% citric acid, aqueous 0.5% lactic acid and 4–8% calcium lactate solutions, using acid whey as the solvent, gave similar TPA readings to normal chhana.     

Influence of skimmed milk concentrate replacement by dry dairy products in a low fat set‐type yoghurt model system. I: Use of whey protein concentrates,milk protein concentrates and skimmed milk powder

Ten commercial samples of dry dairy products used for protein fortification in a low fat yoghurt model system at industrial scale were studied. The products employed were whey protein concentratres, milk protein concentrates, skimmed milk concentrates and skimmed milk powder which originated from different countries. The gross chemical composition of these dried products were determined, including polyacrylamide gel electrophoresis (SDS‐PAGE) and isoelectric focusing of the proteins, and minerals such as Na, Ca, K and Mg. Yoghurts were formulated using a skim milk concentrated as a milk base enriched with different dry dairy products up to a 43 g kg⁻¹ protein content. Replacement percentage of skim milk concentrated by dry dairy products in the mix was between 1.49 and 3.77%. Yoghurts enriched with milk protein concentrates did not show significantly different viscosity (35.12 Pa s) and syneresis index (591.4 g kg⁻¹) than the two control yoghurts obtained only from skimmed milk concentrates (35.6 Pa s and 565.7 g kg⁻¹) and skimmed milk powder (32.77 Pa s and 551.5 g kg⁻¹), respectively. Yoghurt fortified with the whey protein concentrates, however, was less firm (22.59 Pa s) and had less syneresis index (216 g kg⁻¹) than control yoghurts. Therefore, whey protein concentrates may be useful for drinking yoghurt production. © 1999 Society of Chemical Industry     

Functional properties of chhana whey powders

The protein solubility, emulsifying, foaming and gelation properties, and viscosity of solutions of chhana whey protein powders, produced by ultrafiltration and reverse osmosis followed by drying, were studied over the pH range 2.5–9.0. Protein solubility varied from 57–100% and was greatest at low pH values. Chhana whey protein powders had similar emulsifying properties to commercial cheese whey protein powders of similar protein content, although the capacity to form gels when heated to 80°C was much lower, particularly at alkaline pH. the viscosity of solutions of the chhana whey powders was sensitive to pH, but was particularly high in the acidic range. These studies demonstrate considerable potential for the utilization of chhana whey, products in the food industry.     

Heavy metals in cow’s milk and cheese produced in areas irrigated with waste water in Puebla,Mexico

The aim of this work was to determine Ni, Cr, Cu, Zn, Pb, and As levels in raw milk and Oaxaca and ranchero type cheeses, produced in areas irrigated with waste water from Puebla in Mexico. Milk results showed a mean Pb level of 0.03 mg kg^?1, which is above the maximum limit as set by Codex Alimentarius and the European Commission standards. For As a mean value of 0.12 mg kg^?1 in milk was obtained. Mean As and Pb levels in milk were below the Mexican standard. Milk whey and ranchero cheese had mean Pb levels of 0.07 and 0.11 mg kg^?1, respectively. As was higher in Oaxaca and ranchero cheese at 0.17 and 0.16 mg kg^?1, respectively. It was concluded that cheeses made from cow’s milk from areas irrigated with waste water are contaminated with Pb and As, which may represent a health risk.     

Production of a yogurt-like product from plant foodstuffs and whey. Sensory evaluation and physical attributes

A mixed substrate composed of soya milk, oat flour and dried cheese whey (820, 110 and 70 g kg^?1 respectively) was heat treated (80°C, 20 min) and fermented using two different yogurt starters. Sensory evaluation was conducted in order to get the basic flavour profile and to assess the acceptability of the product. Unfermented mixed substrate and fermented milk were used as references. Two yogurt starter combinations were used. Some additives such as sugar and calcium were also assessed. The addition of an equal weight of milk to the mixed substrate, and flavours such as strawberry jam or honey, were tried as well. Acceptability of the mixed substrate was increased by fermentation and added sugar, milk and/or flavours. A suitable combination of strains was very important to get good acceptability of the fermented product. Colour and syneresis were also evaluated. Heat treatment had very little influence on the colour of the mixed substrate. The mixture was less white and a little less green than milk. Syneresis was lower than that of a yogurt made from milk with 145 g litre^?1 total solids.     

Effect of high power ultrasonic treatment on whey protein foaming quality

High power ultrasonic energy at 20%, 40% and 60% amplitude was applied on whey protein suspension at concentrations of 100, 150 and 200 g kg^?1 for 5, 15 and 25 min to improve its foaming quality. Ultrasound‐treated whey protein suspension at 200 g kg^?1 showed improvement in terms of increased foaming capacity by 18%, foam stability by 35%, consistency index by 18%, storage modulus by 17%, loss modulus by 26% and viscosity by 21% compared with untreated whey protein. For maximally ultrasound‐treated samples of 60% amplitude treated for 25 min, the improved whey protein foams also had a 46% increase in the number of more evenly distributed fine bubbles which had a size smaller than 0.0025 mm³ as imaged using X‐ray microtomography.     

Effects of sodium caseinate‐ and milk protein concentrate‐based edible coatings on the postharvest quality of Bing cherries

Bing cherries were coated with sodium caseinate‐ or milk protein concentrate‐based edible coatings. Besides the proteins (100 g kg^?1), the coating formulations also included glycerol (about 300 g kg^?1 protein) and either beeswax or a stearic–palmitic acid blend at a concentration of 0, 100 or 300 g lipid phase kg^?1 of protein. All coatings, especially those containing 300 g kg^?1 stearic–palmitic acid blend, successfully reduced water loss of the fruits. The edible coatings had a beneficial effect on the sensory quality of the cherries, and there were significant (p < 0.05) effects of the coating treatments on soluble solids, titratable acidity and pH. Copyright © 2004 Society of Chemical Industry     

Effect of different time intervals on the viscosity of batter and on the sensory qualities of puras (pancakes) prepared using chhana and paneer whey

The viscosity of pura (pancakes) batter samples prepared with bovine, buffalo and mixed wheys (80 : 20 whey to water) was measured at different time intervals at a temperature of 25  ±  2°C using a Brookfield viscometer (LVT 98534). The viscosity of sweet pura batter samples increased after 1 h, remained constant for another 2 h and then decreased, whereas the viscosity of salty pura batter samples increased from freshly prepared batter to 1 h and then remained constant. Sensory evaluation of both sweet and salty puras at different time intervals from batter preparation was also carried out. The overall acceptability scores for sweet puras prepared using bovine milk chhana whey, buffalo milk paneer whey and mixed milk chhana whey and stored for up to 4 h at 25  ±  2°C and for 24 h at 4–5°C were not significantly different, and the same conclusion applied to salty puras made from bovine milk chhana whey. It was concluded that sweet and salty pura batters can be prepared from any chhana or paneer whey.     

Chemical composition and sensory analysis of cheese whey‐based beverages using kefir grains as starter culture

The aim of the present work was to evaluate the use of the kefir grains as a starter culture for tradicional milk kefir beverage and for cheese whey‐based beverages production. Fermentation was performed by inoculating kefir grains in milk (ML), cheese whey (CW) and deproteinised cheese whey (DCW). Erlenmeyers containing kefir grains and different substrates were statically incubated for 72 h at 25 °C. Lactose, ethanol, lactic acid, acetic acid, acetaldehyde, ethyl acetate, isoamyl alcohol, isobutanol, 1‐propanol, isopentyl alcohol and 1‐hexanol were identified and quantified by high‐performance liquid chromatography and GC‐FID. The results showed that kefir grains were able to utilise lactose in 60 h from ML and 72 h from CW and DCW and produce similar amounts of ethanol (～12 g L^?1), lactic acid (～6 g L^?1) and acetic acid (～1.5 g L^?1) to those obtained during milk fermentation. Based on the chemical characteristics and acceptance in the sensory analysis, the kefir grains showed potential to be used for developing cheese whey‐based beverages.     

Improved ELISA and dot-blot methods for the detection of whey proteins in meat products

Two techniques, ELISA and dot-blot, were applied to the qualitative detection of very low levels of whey proteins in liver pãtés. The use of an avidin-biotin amplification system for both methods led to a useful improvement of the detection limit. The detection level which was 4 g kg^?1 with the classical ELISA method was improved to I g kg^?1 with the amplified ELISA method. Using the dot-blot technique, the results showed that the minimum detectable level was 1–7 g kg^?1 for the classical method with nitrocellulose (NC), 0–7 g kg^?1 for the amplified method with NC, 0–7 g kg^?1 for the classical method with cyanogen bromide-activated NC (activated NC) and 0–3 g kg^?1 for the amplified method with activated NC.     

Liquid and vapour water transfer through whey protein/lipid emulsion films

BACKGROUND: Edible films and coatings based on protein/lipid combinations are among the new products being developed in order to reduce the use of plastic packaging polymers for food applications. This study was conducted to determine the effect of rapeseed oil on selected physicochemical properties of cast whey protein films. RESULTS: Films were cast from heated (80 °C for 30 min) aqueous solutions of whey protein isolate (WPI, 100 g kg^?1 of water) containing glycerol (50 g kg^?1 of WPI) as a plasticiser and different levels of added rapeseed oil (0, 1, 2, 3 and 4% w/w of WPI). Measurements of film microstructure, laser light‐scattering granulometry, differential scanning calorimetry, wetting properties and water vapour permeability (WVP) were made. The emulsion structure in the film suspension changed significantly during drying, with oil creaming and coalescence occurring. Increasing oil concentration led to a 2.5‐fold increase in surface hydrophobicity and decreases in WVP and denaturation temperature (T_max). CONCLUSION: Film structure and surface properties explain the moisture absorption and film swelling as a function of moisture level and time and consequently the WVP behaviour. Small amounts of rapeseed oil favourably affect the WVP of WPI films, particularly at higher humidities. Copyright © 2010 Society of Chemical Industry     

An investigation of varying composition and processing conditions on the organoleptic properties of chhana spread

Trials were conducted to standardise the buffalo milk chhana spread by using whey and buttermilk. The milk was standardised to 4% fat and 9% milk solids‐not‐fat and chhana was prepared. The chhana was blended with different quantities of water (0%, 10%, 20%, 30% and 40%) at varying blending temperatures (65, 70, 75, 80 and 85°C) and blending times (2, 3 and 4 min). The chhana spread was prepared by using different levels of oil (0%, 5%, 7.5%, 10% and 12.5%), cream containing 40% fat (0%, 10%, 20%, 30% and 40%) and salt (0%, 0.5%, 0.75%, 1.0%, 1.25% and 1.5%). It was observed that chhana spread prepared by using 20% water, 80°C blending temperatures and 3 min and 0.75% salt scored maximum for body and texture, spreadability and overall acceptability. This chhana spread was further incorporated with buttermilk or whey either alone each at 20% or in combination each at 10% by substitution of water. Incorporation of buttermilk or whey significantly (P < 0.05) improved the chemical and sensory quality of chhana spread and had better texture.     

Performance of an impact type device for continuous production of paneer

Chhana, a heat-acid coagulated product of milk, is pressed to make paneer. Like Tofu, paneer is extensively used for the preparation of a large number of culinary dishes. For the pressing, chhana was kept in cages made from a special type of screen and the cages were subjected to impact forces. Total amount of energy imparted to chhana during impacts was correlated with reduction of moisture, increase in hardness of pressed chhana and the solid lost through whey from pressed chhana. Rate of change of moisture content, hardness and solid loss with the energy imparted was found to follow first order reaction kinetics. Prototype of an impact type device was made from which compressed blocks of chhana could be taken out at regular intervals. Validity of first order reaction kinetics model was confirmed with the prototype device. Relative deviation percentage between the model and experimental values obtained from the prototype was found to lie between 3.7% and 4.1%.     

Influence of sucrose on cold gelation of heat‐denatured whey protein isolate

A solution of heat‐denatured whey proteins was prepared by heating 100 g kg⁻¹ whey protein isolate (WPI) at pH 7.0 to 75 °C for 15 min in the absence of salt. Heat treatment caused the globular protein molecules to unfold, but electrostatic repulsion opposed strong protein–protein aggregation and so prevented gel formation. When the heat‐denatured whey protein solution was cooled to room temperature and mixed with 15 mM CaCl₂, it formed a gel. We investigated the influence of the presence of sucrose in the protein solutions prior to CaCl₂ addition on the gelation rate. At relatively low concentrations (0–100 g kg⁻¹), sucrose decreased the gelation rate, presumably because sucrose increased the aqueous phase viscosity. At higher concentrations (100–300 g kg⁻¹), sucrose decreased the gelation rate, probably because sugar competes for the water of hydration and therefore increases the attraction between proteins. These data have important implications for the application of cold‐setting WPI ingredients in sweetened food products such as desserts. © 2000 Society of Chemical Industry     

Sensory and textural properties of chhana kheer made with three artificial sweeteners

Chhana kheer, a dessert containing chhana and sugar, is very popular in the Indian subcontinent. A process for manufacturing chhana kheer based on milk fat, aspartame, acesulfame‐K and sucralose was optimised. Aspartame and acesulfame‐K at the level of 0.015% and sucralose at the level of 0.05% were found to be the most appropriate levels for chhana kheer replacing conventional product. The predicted score of the suggested formulation was 7.28 for sweetness, 8.06 for colour and appearance, 7.04 for texture, 7.79 for flavour, 6.69 for overall acceptability and 4820 g s for consistency respectively.     

Use of acid whey protein concentrate as an ingredient in nonfat cup set-style yogurt

Acid whey resulting from the production of soft cheeses is a disposal problem for the dairy industry. Few uses have been found for acid whey because of its high ash content, low pH, and high organic acid content. The objective of this study was to explore the potential of recovery of whey protein from cottage cheese acid whey for use in yogurt. Cottage cheese acid whey and Cheddar cheese whey were produced from standard cottage cheese and Cheddar cheese-making procedures, respectively. The whey was separated and pasteurized by high temperature, short time pasteurization and stored at 4°C. Food-grade ammonium hydroxide was used to neutralize the acid whey to a pH of 6.4. The whey was heated to 50°C and concentrated using ultrafiltration and diafiltration with 11 polyethersulfone cartridge membrane filters (10,000-kDa cutoff) to 25% total solids and 80% protein. Skim milk was concentrated to 6% total protein. Nonfat, unflavored set-style yogurts (6.0 ± 0.1% protein, 15 ± 1.0% solids) were made from skim milk with added acid whey protein concentrate, skim milk with added sweet whey protein concentrate, or skim milk concentrate. Yogurt mixes were standardized to lactose and fat of 6.50% and 0.10%, respectively. Yogurt was fermented at 43°C to pH 4.6 and stored at 4°C. The experiment was replicated in triplicate. Titratable acidity, pH, whey separation, color, and gel strength were measured weekly in yogurts through 8 wk. Trained panel profiling was conducted on 0, 14, 28, and 56 d. Fat-free yogurts produced with added neutralized fresh liquid acid whey protein concentrate had flavor attributes similar those with added fresh liquid sweet whey protein but had lower gel strength attributes, which translated to differences in trained panel texture attributes and lower consumer liking scores for fat-free yogurt made with added acid whey protein ingredient. Difference in pH was the main contributor to texture differences, as higher pH in acid whey protein yogurts changed gel structure formation and water-holding capacity of the yogurt gel. In a second part of the study, the yogurt mix was reformulated to address texture differences. The reformulated yogurt mix at 2% milkfat and using a lower level of sweet and acid whey ingredient performed at parity with control yogurts in consumer sensory trials. Fresh liquid acid whey protein concentrates from cottage cheese manufacture can be used as a liquid protein ingredient source for manufacture of yogurt in the same factory.     

HPLC-MS/MS-Detection of Caseins and Whey Proteins in Meat Products

Screening methods for the mass spectrometric detection of caseins and whey proteins in meat products have been developed. After tryptic digestion, two α-S1-casein and two β-lactoglobulin marker peptides were measured by HPLC-MS/MS. For matrix calibrations, emulsion-type sausages with different concentrations of milk and whey protein (ppm level) were produced. The limits of detection (LODs) were below 1 ppm for milk protein and about 3 ppm for whey protein. The determination coefficients for the correlation between peak area of the marker peptides and the concentrations of milk and whey proteins were R²≥0.9899.