Emulsifying Capacity and Emulsion Stability of Milk Proteins and Corn Germ Protein Flour

Comparative studies of emulsifying capacity (EC) and emulsion stability (ES) of corn germ protein flour (CGPF), nonfat dry milk (NFDM), whey protein concentrates (WPC), and sodium caseinate (SC) were carried out using response surface methodology. CGPF was an effective stabilizer of fat-protein-water emulsions. Tested proteins showed the following trend in EC and ES: SC > WPC = NFDM > CGPF. EC and ES increased with increased concentration of protein. No effect of incubation temperature on EC and ES of these proteins was detected. All protein samples showed a maximum EC at high pH (near 8.0) and 1.0% concentration under test conditions, except NFDM (about pH 7.0). Minimal pH effect on ES was found.     

Wheat Germ Protein Flour Solubility and Water Retention

The effects of pH and temperature on water retention (WR), protein solubility (PS), and total solubility (TS) of defatted wheat germ protein flour (WGPF) were studied in a model system. PS of WGPF was compared with those of corn germ protein flour (CGPF), soy flour (SF), nonfat dried milk (NFDM), and egg white powder (EWP) at 1–8%. WR increased with increase in pH from 4 to 8. Maximum WR occurred at 70°C, and slight variations were observed between 5 and 30°C. PS and TS increased with increases in pH and temperature. PS of proteins was in the order of NFDM > EWP > SF > CGPF=WGPF. The results showed the potential for usage of WGPF in comminuted meats, beef patties, breads, cakes, and cookies.     

FUNCTIONALITY OF MILK PROTEINS AND CORN GERM PROTEIN FLOUR IN COMMINUTED MEAT PRODUCTS1

Effects of corn germ protein flour (CGPF), nonfat dry milk (NFDM), whey protein concentrate (WPC), and sodium caseinate (SC) on quality characteristics of comminuted meat products were studied. Water holding capacity (WHC) was lowest and cooking loss was highest for the control formulation, whereas formulations extended with CGPF and milk proteins were higher in WHC and lower in cooking losses. Shear force and firmness increased as extenders were added, except WPC. All frankfurters with extenders were firmer than the control, except those extended with WPC. Hue angle was highest for samples with CGPF, while no differences were found in hue angle between control and milk proteins containing samples, except samples with WPC. Frankfurters with CGPF and SC add had a stronger atypical aroma than the control. Meaty aroma score was higher for the control than for the other products, except those with WPC. Meaty flavor score was higher for the control than for all other products. The product with CGPF added had a stronger atypical flavor than the control. Frankfurters containing extenders were not as juicy as the all-meat control.     

Response Surface Methodology for Reduction of Pinking in Cooked Turkey Breast Mince by Various Dairy Protein Combinations

Nonfat dry milk (NFDM), sodium caseinate (SC), whey protein concentrate (WPC), and combinations of each were evaluated for abilities to reduce pink color development in cooked, ground, uncured turkey breast. Protein treatments were also evaluated in the presence of pink-color-generating ligands (nicotinamide, 1%, sodium nitrite, 10 ppm, and sodium nitrate, 50 ppm) with and without ethylenedinitrilo-tetraacetic acid disodium salt (200 ppm). NFDM and WPC at levels as low as 1.5% were effective in reducing CIE a* values (P < 0.05) regardless of ligand treatment; SC was not. EDTA reduced pink color within all protein and ligand treatments. Poultry producers can reduce pink color development in further-processed products by selective addition of dairy proteins.     

Water Retention and Solubility of Soy Proteins and Corn Germ Proteins in a Model System

Response surface methodology was used to study water retention and protein solubility of soy flour (SF), concentrate (SC), and isolate (SI), and corn germ protein flour (CGPF). Water retention increased with pH (6 to 8) and incubation temperature (10–70°C), but not with increasing incubation time (10–30 min). SC had highest water retention per gTam, followed by CGPF, SF, and SI. Water retention in relation to protein content was higher in CGPF than in the three soy products. Protein solubility was significantly affected by pH and temperature of incubation. Protein solubility increased when pH (6 to 8) and incubation temperature increased (30–70°C) in all samples. SI had highest protein solubility, and CGPF had the lowest.     

Emulsifying Capacity and Emulsion Stability of Soy Proteins Compared with Corn Germ Protein Flour

Both emulsifying capacity (EC) and emulsion stability (ES) increased with increasing concentrations from 0.4% to 0.8% of soy flour (SF), soy concentrate (SC), soy isolate (SI) and corn germ protein flour (CGPF) when studied by response surface methodology. EC and ES increased as pH increased from 6 to 8 in all samples. Increasing incubation temperatures of protein solutions from 20–70°C or from 4–20°C did not affect EC or ES, respectively. SF had the highest EC, followd by SI, SC, and CGPF.     

COMPARATIVE STUDY OF SHELF-LIFE OF FRANKFURTERS CONTAINING PLANT PROTEIN ADDITIVES1

Soy flour (SF), soy concentrate (SC), soy isolate (SI) and corn germ protein flour (CGPF) were incorporated in frankfurters. The sensory analysis, chemical, and microbiological tests were conducted to investigate the effect of plant proteins on stability during vacuum-packaged storage. No significant difference in meaty aroma was found between all samples after 45 days storage. Atypical flavor and aroma of all samples, including the all-meat control increased (P < 0.05) after 45 days storage. A tendency was found of increase in atypical aroma and flavor with increase in total volatile nitrogen values and total psychrophiles during storage. Salty flavor increased with storage time in experimental samples, but juiciness decreased. Samples containing SF and SC had higher total volatile nitrogen than SI and CGPF containing samples at 2, 30 and 45 days of storage. No significant differences were found in TBA values between tested samples, except higher TBA values for SI containing samples. There was no significant difference among samples in total psychrophilic counts.     

Effects of Iron Source on Iron Availability from Casein and Casein Phosphopeptides

ABSTRACT: :
Iron availability from FeSO₄ in samples containing sodium caseinate (SC), casein phosphopeptides (CPP) or whey protein concentrate (WPC), and from ferric citrate (Fe-CA) in samples containing SC or CPP was measured using an in vitro digestion/Caco-2 cell culture model. In FeSO₄ spiked samples, relative availability was CPP > SC, CPP = WPC, and CPP = FeSO₄ alone. In samples containing Fe-CA, a soluble iron chelate, relative availability was CPP = SC and CPP < Fe-CA alone. These results suggest that CPP enhances iron availability from foods with low availability but does not improve and may inhibit availability from soluble iron species.     

Ability of Various Dairy Proteins to Reduce Pink Color Development in Cooked Ground Turkey Breast

Dairy proteins were evaluated for their ability to reduce pink color in ground turkey samples. Sodium nitrite and nicotinamide were added to induce pink color formation. Nonfat dry milk (NFDM) and 1 of the whey protein concentrates (WPC) reduced CIE a* values in samples containing 10 ppm sodium nitrite. All of the dairy proteins tested reduced CIE a* values in nicotinamide-treated samples. In samples prepared without nicotinamide or nitrite, only WPC reduced CIE a* values, while the other proteins tested had no effect or increased redness. NFDM or specific WPC proteins could be used to reduce the pink color defect and increase yield.     

Interfacial dynamic properties of whey protein concentrate/polysaccharide mixtures at neutral pH

The effect of two non-surface active polysaccharides (sodium alginate, SA, and λ-carrageenan, λ-C) in the aqueous phase on the surface dynamic properties (dynamic surface pressure and surface dilatational properties) of a commercial milk whey protein concentrate (WPC) adsorbed film at the air–water interface has been studied. A whey protein isolate (WPI) was used as reference. The WPC and WPI concentration (at 1.0% wt), temperature (at 20 °C), pH (7), and ionic strength (at 0.05 M) were maintained constant, while the effect of polysaccharide (PS) was evaluated within the concentration range 0.0–1.0% wt. The surface dynamic properties of the adsorbed films were measured in an automatic pendant drop tensiometer. At short adsorption time and in the presence of PS, the rate of diffusion of WPC to the interface was affected by the interactions with PS in the aqueous phase, which could limit protein availability for the adsorption. On the other hand, at long-term adsorption, the magnitudes of the molecular penetration and configurational rearrangement rates of WPC in mixed systems (WPC/PS) reflected the viscoelastic characteristics of the adsorbed films. The attractive interactions between WPC and PS and/or the WPC aggregation in the presence of PS, which depend on the proper polysaccharide and its concentration in the aqueous phase, have an effect on the adsorption kinetic parameters, the amount of WPC adsorbed at the air–water interface, and the dilatational viscoelastic characteristics of WPC/PS mixed systems.     

Corn Germ Protein Flour as an Extender in Broiled Beef Patties

Beef patties were extended at levels of 10, 20, and 30% of the uncooked weight with hydrated defatted corn germ protein flour (CGPF). Extended patties had lower cooking losses and higher cooked yields than control patties. Adding CGPF did not affect moisture or fat contents in broiled patties, but lowered protein content. The amino acid composition of experimental patties was comparable to that of the control. The water-holding capacity and pH of raw patties increased with increasing levels of added CGPF. Incorporation of CGPF affected sensory characteristics of the product; meaty aroma and flavor of all-meat patties was significantly higher than experimental samples and decreased with an increase in added CGPF. CGPF has potential use as an extender in coarsely ground meats.     

Foaming Properties of Selected Plant and Animal Proteins

The foaming properties of proteins are important in predicting their fnnctionality in aerated foods. In model aqueous systems, foam expansion (FE) and foam stability (FS) of commercial plant proteins, wheat germ protein flour (WGPF), corn germ protein flour (CGPF), and soy flour (SF), were compared with those of nonfat dried milk (NFDM) and egg white powder (EWP) at 1, 2, 4, 6, and 8% using one- and two-way analyses of variance. The effects of pH 4, 5, 6, 7, and 8 on FE and FS of WGPF were also measured. The highest overall FE and FS were obtained for EWP. Among plant proteins, FE and FS were maximum for CGPF and SF, respectively. FS was lowest for NFDM. Except for SF, FE and FS increased with increasing protein concentration. The FE and FS of WGPF were highest at pH 8, lowest at pH 7, and intermediate at pH 4–6.     

Aroma Characteristics of Corn Germ Protein Flours

Eight sensory attributes were established to differentiate aroma characteristics among four kinds of corn germ protein flours (CGPF) processed by treatments to improve flavor quality. The projections of sample and conceptual spaces on a two-dimensional scale reflected aroma differences among samples evaluated by panelists. Volatiles of samples were separated by gas chromatography, and peaks that elicited olfactory responses were recorded as instrumental data. The projections of sample and volatile compound spaces reflected changes of volatiles by treatments. Relationships between sensory and instrumental data were elucidated by superimposing the two spatial maps. In general, treated CGPF samples had less grainy, brown, corn-like and sweet notes than untreated CGPF samples. However, there were more green, musty and chemical notes in the treated CGPF samples.     

Impact of Milk Protein Type on the Viability and Storage Stability of Microencapsulated Lactobacillus acidophilus NCIMB 701748 Using Spray Drying

Three different milk proteins — skim milk powder (SMP), sodium caseinate (SC) and whey protein concentrate (WPC) — were tested for their ability to stabilize microencapsulated L. acidophilus produced using spray drying. Maltodextrin (MD) was used as the primary wall material in all samples, milk protein as the secondary wall material (7:3 MD/milk protein ratio) and the simple sugars, d-glucose and trehalose were used as tertiary wall materials (8:2:2 MD/protein/sugar ratio) combinations of all wall materials were tested for their ability to enhance the microbial and techno-functional stability of microencapsulated powders. Of the optional secondary wall materials, WPC improved L. acidophilus viability, up to 70 % during drying; SMP enhanced stability by up to 59 % and SC up to 6 %. Lactose and whey protein content enhanced thermoprotection; this is possibly due to their ability to depress the glass transition and melting temperatures and to release antioxidants. The resultant L. acidophilus powders were stored for 90 days at 4 °C, 25 °C and 35 °C and the loss of viability calculated. The highest survival rates were obtained at 4 °C, inactivation rates for storage were dependent on the carrier wall material and the SMP/d-glucose powders had the lowest inactivation rates (0.013 day^?1) whilst the highest was observed for the control containing only MD (0.041 day^?1) and the SC-based system (0.030 day^?1). Further increase in storage temperature (25 °C and 35 °C) was accompanied by increase of the inactivation rates of L. acidophilus that followed Arrhenius kinetics. In general, SMP-based formulations exhibited the highest temperature dependency whilst WPC the lowest. d-Glucose addition improved the storage stability of the probiotic powders although it was accompanied by an increase of the residual moisture, water activity and hygroscopicity, and a reduction of the glass transition temperature in the tested systems.     

Emulsifying Properties of Lipid-Reduced, and Calcium-Reduced Whey Protein Concentrates

Emulsifying properties of six experimental and three commercial control, lipid-reduced, and calcium-reduced whey protein concentrates (WPC) were evaluated on the basis of mean droplet size and creaming intensity in model emulsions. Mean droplet sizes ranged from 225 to 395 nm. Model emulsions made with a commercial control (WPC F), experimental lipid-reduced (WPC MF. 1, MF. 45), commercial lipid-reduced (WPC E), and experimental calcium and lipid-reduced (WPC B) samples had low stabilities. Emulsion stabilities of the WPC most strongly correlated with protein solubility and fatty acid compositions, but did not correlate with mean droplet size.     

COMPARATIVE STUDY OF CORN GERM AND SOY PROTEINS UTILIZATION IN COMMINUTED MEAT PRODUCTS1

Soy flour (SF), soy concentrate (SC) and corn germ protein flour (CGPF) at 3.5%, or 2% of soy isolate (SI) were incorporated in the formulations of frankfurters. There was no significant differences in proximate composition of frankfurters containing SF, SC. SI, and CGPF. Frankfurters formulated with high plant protein flour had lower cholesterol, and higher protein content than the all-meat control frankfurters. Control frankfurters had lower water holding capacity and higher cooking losses than those containing plant proteins. No significant differences (P < 0.05) were found in textural and color characteristics. Atypical aroma and flavor profiles increased in frankfurters with SF nd CGPF extension.     

Dynamic high pressure-induced gelation in milk protein model systems

The structure-functional properties of milk proteins are relevant in food formulation. Recently, there has been growing interest in dynamic high-pressure homogenization effects on the rheological-structural properties of food macromolecules and proteins. The aim of this work was to evaluate the effects of different homogenization pressures on rheological properties of milk protein model systems. For this purpose, sodium caseinate (SC) and whey protein concentrate (WPC) were dispersed at different concentrations (1, 2, and 4%), pasteurized, and then homogenized at 0, 18 MPa (conventional pressure, CP), 100 MPa (high pressure, HP), and 150 MPa (HP+). Differences in viscosity were observed between WPC and casein dispersions according to concentration, heat treatment, and homogenization pressure. Mechanical spectra described the characteristic behavior of solutions except for the WPC 4% pasteurized sample, in which a network formed but was broken after homogenization. Dispersions with different ratios of WPC and SC were also made. In these systems, pasteurization alone did not determine network formation, whereas homogenization alone promoted cold gelation. A total concentration of at least 4% was required for homogenization-induced gelation in pasteurized and unpasteurized samples. Gels with higher elastic modulus (G′) were obtained in more concentrated samples, and a bell-shaped behavior with the maximum value at HP was observed. The HP treatment produced stronger gels than the CP treatment. Similar G′ values were obtained when different concentrations, pasteurization conditions, and homogenization pressures were combined. Therefore, by setting appropriate process conditions, systems or gels with tailored characteristics may be obtained from dispersions of milk proteins.     

Insolubilized Whey Protein Concentrate and/or Chicken Salt-Soluble Protein Gel Properties

Properties of gels prepared from five whey protein concentrates (WPC) with protein solubilities ranging from 27.5% to 98.1% in 0.1M NaCl, pH 7.0, chicken breast salt-soluble protein (SSP), or a combination of SSP and WPC at pH 6.0, 7.0 or 8.0 were compared. WPC did not form gels when heated to 65°C. SSP gels heated to 65°C were harder than those heated to 90°C at all pHs and hardness decreased as pH was increased. Hardness of combination gels heated to 65°C increased as WPC solubility decreased at all pHs; however, the opposite trend was observed at 90°C. Combination gels of the same WPC solubility at 65°C were more deformable than those heated to 90°C.     

Effect of microbial transglutaminase, sodium caseinate and non-fat dry milk on quality of salt-free, low fat turkey döner kebab

Effects of microbial transglutaminase (MTGase) and its combinations with sodium caseinate (SC) or non-fat dry milk (NFDM) on quality of salt-free, low fat turkey döner kebab were investigated. The purpose of this study was to prevent quality deteriorations (e.g. cooking loss, textural problems) caused by a lack of salt in the product. The results of this study indicated that the use of MTGase can minimize textural quality loss caused by a lack of salt in turkey döner manufacture (p < 0.05). When the enzyme was combined with SC, or NFDM, its effect on texture was enhanced (p < 0.05) and improved cooking yield, moisture and sensory properties compared to the corresponding control manufactured without the enzyme, salt, SC and NFDM. (p < 0.05), however, there was no significant effect on pH and color As a result, the possible quality problems which may occur in salt free, low fat turkey döner can be overcome by the use of combinations of MTGase with SC or NFDM.