Addition Of Whey Protein Isolate Research Articles

Rheology, texture and microstructure of gelatin gels with and without milk proteins

Abstract The effects of gelatin concentration, pH and addition of milk proteins on the physical and microstructural properties of type B gelatin gels were studied by small deformation rheology, texture analysis and scanning electron microscopy. Whey protein isolate (WPI), milk protein concentrate (MPC) and skim milk powder (SMP) were used as sources of milk proteins. The elasticity of gelatin gels was significantly affected by the concentration of gelatin. Higher gelatin concentrations led to a stronger gel, and higher gelling and melting temperatures. However, all the gelatin gels at concentrations from 1.0 to 5.0% melted below human body temperature. Rheological properties of gelatin gels were independent of pH in the range pH 4.6–8.0. At pH 3.0 gelation of gelatin was significantly inhibited. Addition of SMP and MPC significantly enhanced the rheological properties of gelatin gels, while addition of WPI had a negative effect on them. However, the effect of addition of milk proteins was dependent on the gelatin concentration. Textural results showed that addition of all milk powders increased the hardness of gelatin gels at high gelatin concentration (5.0%). The fracturability of the gels was greatly influenced by pH. Addition of milk proteins and high gelatin concentration (5.0%) both caused loss of gel fracturability. Microstructural results showed that gelatin concentration and pH had a marked influence on the gel structure, and the addition of MPC and SMP changed the structure of the gelatin gels; a structure similar to pure gelatin gel was observed after addition of WPI.

Electrospraying of water in oil emulsions for thin film coating

Abstract Electrospraying of water-in-oil emulsions was investigated to produce thin edible barriers. A reproducible model surface was used, namely cellulose membranes of which permeability is well-established. PGPR-based emulsions were stable during electrospraying and produced a fine stable jet spray; emulsions prepared with lecithin and span80 produced unstable jets and only sporadic sprays. The droplet size decreased to 50 ± 10 μm by the addition of water droplets till 3% but remained constant at higher water volume fractions. On the other hand, the addition of protein and salt influenced the droplet size and radius values up to 200 μm were found. The addition of whey protein isolate (10% w/w) resulted in films with water vapour barrier properties that were at least 70% better than lipid only, therewith showing that addition of protein enhances the integrity of the films.

Characteristics of soy sauce powders spray-dried using dairy whey proteins and maltodextrins as drying aids

Abstract This study investigated the effect of adding whey protein isolate (WPI) as a complementary drying aid of maltodextrin (MD) on spray drying of soy sauce powders. Soy sauce powders were prepared by spray drying soy sauce liquid adding 5%, 10% and 15% of WPI respectively together with MD as the drying aids. Tests were conducted to evaluate the powder properties relevant to the caking issue of the soy sauce powders. Results showed that addition of just 5% WPI could significantly increase the product yield for the spray drying process. At the same time, the caking strength of the spray dried soy sauce powders were significantly reduced during storage with WPI addition. XPS results indicated that WPI have preferential migration to the surface of the soy sauce powder. The over-expression of WPI on powder surface after spray drying might explain the improved stability for soy sauce powders during the caking test.

Functional Characteristics of Extruded Blends of Potato Flakes and Whey Protein Isolate

The purpose of the present study was to explore the effects of feed moisture and the addition of whey protein isolate on some physicochemical properties of the obtained extrudates from potato flakes. Extrudates were produced using a laboratory single-screw extruder. Conditions during extrusion were: screw speed - 200 rpm; compression ratio - 3:1; extruders temperature zones - 120, 150, 160 °C; diameter of the nozzle - 5 mm. With increasing of feed moisture content and protein level, there was a significant rise of density as well as lowering of expansion of extrudates. As the feed moisture content increased from 13 to 20 percent w.w. the water absorption index (WAI) increased and the water solubility index (WSI) decreased. The feed protein level increased the protein content and decreased WAI. A maximum of WSI was observed at feed moisture content 20 percent w.w. and protein level 18 percent w.w. The extrusion and the protein addition do not affect the equilibrium moisture of the potato flakes extrudates.

Evaluation of yogurt with enhanced cysteine content (2012)

Amino acids are the building blocks of protein and assist with metabolism in the body. In the human body, the amino acid cysteine can be synthesized from methionine by the enzyme Υ-cystathionase. Because certain human subpopulations such as those prone to cataracts have decreased Υ-cystathionase activity, dietary cysteine may be beneficial. Nutritionally, yogurt mix is one of the best dairy food sources of methionine and cysteine, but the heat treatment used in manufacturing yogurt decreases the dietary availability of cysteine. Last year, it was shown that supplementing yogurt mixes with whey protein isolate (WPI) (>90% protein) and processing yogurt mixes at a lower temperature produced yogurts with increased cysteine. Because the quality or cysteine content of the yogurt during the expected storage life is unknown, this study was conducted to determine if a combination of WPI addition and non-optimal process conditions could produce a yogurt with higher cysteine content and an acceptable shelf life. In this study, control yogurt mixes were made with nonfat dry milk (NDM) and processed at 90oC for 7 minutes, whereas the experimental yogurt mixes were made with NDM and WPI and processed at 70oC for 20 minutes. Both mixes were cooled, inoculated, fermented into yogurt, stored at 4°C, and evaluated periodically over a 60-day period. The experimental yogurts had ~2X more cysteine than the control yogurt; this trend was present throughout storage. After 60 days of storage, the water-holding capacity (WHC) and firmness was greater and the syneresis was less for the experimental yogurt than the control yogurt. These results show that yogurt supplemented with WPI and processed at less optimal conditions may be a good source of the conditional amino acid cysteine during storage.

Mixed aqueous chitin nanocrystal–whey protein dispersions: Microstructure and rheological behaviour

Abstract Chitin nanocrystals (ChN) and whey protein isolate (WPI) aqueous dispersions (at pH 3.0) of different polymer concentrations were mixed and examined with small deformation oscillatory measurements and polarized optical microscopy, under different conditions of ionic strength and temperature. The ChN–WPI mixed dispersions displayed a gel-like behaviour with increasing either the ChN or the WPI concentration. The network formation could be attributed to phase separation phenomena, as evidenced by the micrographs obtained, due to thermodynamic incompatibility between the two components; i.e. the addition of WPI, as a globular biopolymer mixture, in a dispersion of rod-like particles (ChN) leads to the formation of ChN-rich and ChN-poor domains. Increasing ionic strength did not significantly affect the viscoelastic properties of the network. However, heating of the ChN–WPI mixed dispersions resulted in further increase of the elastic modulus, which was irreversible upon cooling.

Systemic indices of skeletal muscle damage and recovery of muscle function after exercise: effect of combined carbohydrate–protein ingestion

Previous studies indicate that exercise-induced muscle damage may be attenuated when protein is included in a carbohydrate recovery supplement. This study was designed to examine systemic indices of muscle damage, inflammation, and recovery of muscle function, following strenuous exercise, with ingestion of either carbohydrate alone or a carbohydrate-protein mixture. Seventeen highly trained volunteers participated in 2 trials in a randomized order, separated by approximately 9 weeks. Each trial involved 90 min of intermittent shuttle-running, either with ingestion of a 9% sucrose solution during and for 4 h after (1.2 g.kg-1 body mass.h-1) or with the same solution plus 3% whey protein isolate (0.4 g.kg-1 body mass.h-1). Blood was sampled throughout and 24 h after each trial to determinate the systemic indices of muscle damage and inflammation. An isokinetic dynamometer was used to establish reliable baseline measurements of peak isometric torque for knee and hip flexors and extensors, which were then followed-up at 4-, 24-, 48-, and 168-h postexercise. The exercise protocol resulted in significantly elevated variables indicative of muscle damage and inflammation, while peak isometric torque was immediately reduced by 10%-20% relative to baseline, across all muscle groups tested. However, none of these responses varied in magnitude or time-course between the treatments, or between participants' first and second trials. The addition of whey protein isolate to a dietary carbohydrate supplement ingested during and for 4 h following strenuous exercise did not attenuate systemic indices of muscle damage or inflammation, nor did it restore muscle function more rapidly than when the carbohydrate fraction was ingested alone.

Rheological characterization of set yoghurt produced with additives of native whey proteins

Abstract The influence of native whey protein isolate (WPI) addition on the consistency and microstructure of set yoghurt was studied. Native WPI with nutraceutical properties was added (3–12%) to the yoghurt milk immediately before fermentation. The consistency of the yoghurts was analysed and compared using two rheological methods: the penetration resistance of a cylinder and an oscillation method for which a vane was used. The effects of the WPI on the rheologically determined values were quantified whereby a remarkably good correlation between the two methods was achieved. With both methods the texture characteristics of the different set yoghurts could be well characterized and enabled good comparisons. The addition of WPI gave rise to a weaker texture of the set yoghurt. Microstructure was observed by confocal laser scanning microscopy. The addition of WPI led to a less-coherent microstructure, which was in agreement with the rheological observations.

Effects of Dried Dairy Ingredients on Physical and Sensory Properties of Nonfat Yogurt

Physical and sensory attributes are important factors that influence food acceptance and choices. In this study, sensory and texture properties of nonfat yogurts made from reconstituted skim milk powder (SMP) fortified with SMP as a control, whey protein isolate (WPI), yogurt texture improver (TI), and sodium caseinate (NaCn) were investigated over a 12-d storage period. Viscosity and syneresis were measured as physical quality parameters. Descriptive sensory analysis was carried out for each sample to determine the profiles of the products. Consumer acceptance testing (n = 143 consumers) was also conducted to measure the acceptability of yogurts; panelists were asked to rank their preference for the different yogurt samples. Differences among physical and sensory attributes of yogurts were defined. Addition of WPI improved the physical properties of yogurts, resulting in the highest viscosity and the lowest syneresis. On the other hand, yogurt with WPI did not have desirable sensory properties. The descriptive panel indicated that yogurt with WPI had the lowest fermented flavor attribute. In general, yogurts fortified with NaCn and TI displayed better physical and sensory properties than did control and WPI-fortified yogurts. Consumer testing showed that yogurts with NaCn and TI were not different from the control with regard to their flavor acceptability. Yogurts fortified with NaCn and TI were the most preferred samples by Turkish consumers.

Rheological Studies of Rice Four and Whey Protein Isolate

Rheological behavior of gelatinized rice flour dispersions (10%) of three varieties (Sona masoori, Hansa and Parboiled) has been investigated using flow tests. Effect of addition of Whey Protein Isolate (WPI) to the three varieties of rice flours has also been studied. All rice flours exhibited pseudo plastic behaviour. There was a decrease in flow behavior index and consistency index values with the increase in whey protein isolate concentration but exhibited synergistic behaviour at 1:1 concentration of WPI with all the rice flours. The time dependent rheological characteristics of all rice flours with and without protein combinations were studied and shown to follow antithixotropic behavior. All the data was correlated with the power law model. These studies carry commercial significance as mixed suspensions can be used as fat replacers in food industry and also economic viability.

Effect of surface tension and viscosity on the surface stickiness of carbohydrate and protein solutions

The effects of surface tension and viscosity on the measured tensile strength (surface stickiness) of carbohydrate (fructose, lactose and maltodextrin) and protein (Whey protein isolate (WPI)) solutions were studied. The effect of the addition of WPI on the surface tension and surface stickiness of lactose solutions was measured. Surface tension was found to better correlate with surface stickiness compared to viscosity. Cohesive failure occurred in all the cases indicating that the energy required to create new surfaces within the drops was lower than the energy required to achieve a clean (adhesive) failure at the probe-drop interface. WPI behaves as a surfactant and sharply lowers both the surface tension and tensile strength. This study shows that the surface forces are more dominant than the theological forces when the energy required to create new surface within the drop is less than the adhesive energy at the drop-probe interface. (c) 2006 Elsevier Ltd. All rights reserved.

Stability of water-in-oil-emulsions containing phosphatidylcholine-depleted lecithin

Abstract Water-in-oil (W/O, 30/70) emulsions were prepared with phosphatidylcholine depleted lecithin [PC/(PI;PE)=0.16] as W/O emulsifier in sunflower oil. The composition of the aqueous phase was varied by adding sodium caseinate (SC), whey protein isolate (WPI), gelatine and/or xanthan and their effect on the particle size distribution as well as on the sedimentation of the water droplets was investigated. Furthermore, the influence of the emulsion components on the interfacial tension between the oil phase (MCT-oil) and water was characterised. The additives in the aqueous phase differently influenced the water droplet size, aggregation behaviour and storage stability of W/O emulsions prepared with the phosphatidylcholine depleted lecithin. Emulsions were more stable and smaller in droplet size when they contained WPI in water. The droplet size was further reduced by combining WPI with xanthan in the aqueous phase. In contrast, the addition of gelatine or SC resulted in an increase in water droplet size and rapid sedimentation of the dispersed water. The formation and stabilisation of W/O emulsions prepared with the phosphatidylcholine depleted lecithin was supported by the addition of WPI with medium surface activity at the W/O interface. In comparison, the proteins gelatine or SC, which rapidly reduce surface tension at W/O interfaces had a detrimental effect on W/O emulsions otherwise stabilized by lecithin.

Reactive Crystallization Behaviour of Calcium Phosphate with and Without Whey Protein Addition

The reactive crystallization of calcium phosphate was studied by reacting potassium phosphate and calcium nitrate aqueous solutions in the batch system. When the solution has high supersaturation at the beginning of reaction, amorphous tricalcium phosphate (ACP), Ca3(PO4)2·nH20 was precipitated instantly as the initial solid phase. The formation of ACP depends on the ion activity product of ACP regardless of initial pH. ACP transforms to calcium phosphates such as dicalcium phosphate dihydrate (DCPD), CaHPO4·2H2O, hydroxyapatite (HAP), Ca5OH(PO4)3 and octacalcium phosphate (OCP), Ca8H2(PO4)6·5H2O. Effects of solution pH, reaction temperature and addition of whey protein on the behaviour of reactive crystallization of calcium phosphates have been studied. The precipitation diagram of calcium phosphates was obtained as a function of reaction temperature and initial solution pH, whose ranges were 15–50°C and 5–9. By the addition of whey protein isolate, the nucleation and growth of calcium phosphate were retarded. The existence of proteins slows down the reaction of calcium ions and phosphate ions. By the addition of WPI, the shape modification of DCPD and HAP was observed. DCPD became thicker, gathered in bundles and its surface was uneven and cracked. The surface state of HAP particles does not change, whereas the size changes slightly. The cubic form of HAP was also observed by addition of WPI, which may be formed by the crush after natural drying because HAP obtained was caked very hard by the addition of WPI.