The aim of this work was to investigate primary proteolysis of white brined cow cheese prepared from raw milk by SDS-electrophoretic method based on high-molarity Tris buffer system and to correlate ...with the results of other commonly used parameters. Proteolytic changes of white brined cow cheese were monitored by three parameters: total protein, water soluble proteins and degree of proteolysis. Changes of major casein fractions were followed by SDS-electrophoretic system in reducing conditions. The total protein content and moisture content of white brined cow cheese were significantly affected by ripening. Ripening in brine increased water soluble proteins and degree of proteolysis. Major caseins were differently resistant to proteolysis; αs-CN was more susceptible than β-CN. The αs-CN content was highly and negatively correlated with time of ripening and water soluble proteins whereas no significant correlation (p<0.05) between β-CN content and these parameters was found. Also, a strong significant correlation (p<0.05) between the amount of low molecular weight products and time of ripening, water soluble proteins and αs-CN content was observed. SDS-PAGE method used in this study could be useful for monitoring the white cow cheese proteolysis.
The effects of subunit composition of two major proteins of soybean: glycinin (11S) and β‐conglycinin (7S) in nine different genotypes, on solubility and emulsifying and gelling properties at ...different pH (3, 5, 6, and 8) were examined. High‐protein genotypes (more than 40%) contained low amounts of the β′ subunit. The main factors influencing solubility at pH 6 were the content of α′, α (r = 0.89 and r = 0.91 at P < 0.05, respectively) and β′ subunit contents (r = −0.71 at P < 0.05) of β‐conglycinin, while at pH 3 acidic subunits in glycinin had a positive correlation with solubility (r = 0.69 at P < 0.05). Emulsion activity at pH 6 was higher for genotypes synthesizing β′ subunit (r = 0.57 at P < 0.05). Genotypes synthesizing higher amounts of α′ and α subunit had higher emulsion stability at pH 6 (r = 0.85 and r = 0.92 at P < 0.05, respectively) and pH 8 (r = 0.91 and r = 0.97 at P < 0.05, respectively). The rheological measurements showed that genotypes with 11S/7S ratio higher than 2.2 formed gels with enhanced storage moduli. This influence was largely due to the high content of SH groups in glycinin acidic polypeptides resulting in stabilization of gels via disulfide bonding. Gels prepared from genotypes containing higher amounts of β′ subunit of β‐conglycinin exhibited reduced elastic properties. Genotypes showing better solubility also had higher emulsion stability, but formed weaker gels and had lower emulsion activity near neutral pH.
Skim caprine and bovine milk, adjusted to pH 6.5–7.1 were heated at 90 °C for 10 min. The distribution of caseins, α-lactalbumin (α-LA) and β-lactoglobulin (β-LG) between micellar and serum phases of ...both types of milk were determined. Depending on milk pH, the involvement of κ-casein (κ-CN) ranged from ∼8 to 52% and from ∼65 to 70% of total κ-CN in bovine and caprine milk, respectively. αS2-Casein and β-casein were only a part of micelle-bound complexes at all pH values in caprine milk. Denatured bovine β-LG and α-LA were involved in both soluble and micelle-bound heat-induced protein complexes. Conversely, denatured caprine β-LG was mainly associated with casein micelles (98–86% at pH 6.5–7.1) and was found in soluble complexes at higher pH (6–12% at pH 6.9–7.1). All denatured caprine α-LA was micelle-bound at all pH values. This knowledge could be very useful for understanding, controlling and modification of technological–functional properties of caprine milk.
Summary
The aim of this study was to investigate the effects of partial enzymatic hydrolysis on functional properties of two different pea protein isolates obtained from two pea genotypes, Maja and ...L1. Papain and commercial protease (Streptomyces griseus protease) were used for protein modification. Solubility, emulsifying and foaming properties were estimated at four different pH values (3.0, 5.0, 7.0 and 8.0). Papain increased solubility of L1 pea protein isolate at pH 3.0, 5.0 and 8.0, emulsifying properties and foaming capacity at all pH values. Otherwise, papain increased solubility of Maja pea protein isolate only at pH 8.0. This pea protein isolate modified with both enzymes formed emulsions with improved stability at lower pH (3.0, 5.0). The commercial protease‐prepared pea protein isolates showed generally low solubility and different emulsifying and foaming properties. Proper selection of enzyme, conditions of hydrolysis and genotypes could result in production of pea protein isolates with desirable functional properties.
Soybeans are an inexpensive, high-quality protein source. Soybeans have long
been a staple of the human diet in Asia, especially as tofu, which is
prepared from soymilk. In this study, tofu was made ...using a new production
method which includes hydrothermal cooking (HTC) and rennin-pepsin coagulant.
The effects of the addition of gallic acid to the slurry during tofu
processing were studied. Tofu was made from two soybean genotypes: Lana and
Balkan. The observed genotypes are characterized by relatively high content
of total proteins in flour, from 45.88% to 48.83%. The prepared tofu samples
are characterized by extremely high content of total proteins (52.17% - Lana
tofu and 56.08% - Balkan tofu). The presence of gallic acid significantly
affects the solubility of tofu protein. The applied modifications of
traditional procedure of tofu production significantly improved sensory
properties of soybean protein products.
Tofu je zelirani proteinski proizvod, koji se dobija koagulacijom zagrejanog
sojinog mleka. Potrosacima nase populacije ne odgovara aroma ?zelenog zrna?,
takozvani ?leguminozni miris i ukus?, koji se oseca u proizvodima soje
pripremljenim na tradicionalni nacin. Sa namerom poboljsanja arome dobijenih
sireva, pripremljen je tofu primenom hidrotermickog tretmana i enzima za
koagulaciju mleka (himozin-pepsin) uz dodatak galne kiselina, koja je jak
antiseptik i antioksidant. Zahvaljujuci visokom sadrzaju ukupnih proteina
sojinog semena (45,88-48,83% u obezmascenom brasnu) i pripremljeni tofu se
karakterise visokim sadrzajem ukupnih proteina (52,17% s.m.- Lana tofu i
65,08 % s.m. - Balkan tofu). Postupak dodatka galne kiseline menja sadrzaj
rastvorljivih proteina (27,48% - Lana tofu i 41,55% - Balkan tofu) koji se
znacajno razlikuje u odnosu na uzorke bez nje (14,20% - Lana tofu i 28,88% -
Balkan tofu). Poliakrilamidnom-gel elektroforezom ekstrakta tofua
pripremljenog uz dodatak galne kiseline razdvojen je veci broj komponenata,
koje se ne uocavaju na elektroforegramima tofua nemodifikovanog kvaliteta.
Gasnohromatografskom analizom isparljivih komponenata tofua registrovan je
uglavnom acetaldehid, tako da je postignut cilj ublazavanja legulinoznog
mirisa. Poboljsanje senzornih karakteristika potvrdjuju i povoljne senzorne
ocene koje su dobili uzorci pripremljeni sa galnom kiselinom (3,65 - Lana
tofu i 3,87 - Balkan tofu).
PR Projekat Ministarstva nauke Republike Srbije
Native-PAGE (polyacrylamide gel electrophoresis) was used for the simultaneous qualitative and quantitative analysis of bovine milk adulteration in caprine and ovine milk using whole milk samples as ...well as their whey protein fraction. Quantification was based on measuring band intensity of bovine β-lactoglobulins in all milk mixtures and bovine α-lactalbumin in caprine/bovine milk blends. Linear relationships were established between the band intensity of bovine β-lactoglobulins and α-lactalbumin vs. volume percentage of added bovine milk in all milk analysed, with the correlation coefficient from 0.9950 to 0.9998. These correlations enabling the quantification of bovine milk percentage within the wide range from 3% or 5% to 90% in caprine/bovine and ovine/bovine milk blends, respectively. The differences between the actual percentages of bovine milk present in the adulterated milk samples and those calculated using the regression lines were less than or equal to 5% for all samples. This method offers a rapid determination combined with unequivocal identification of the bovine whey proteins in almost every caprine/bovine or ovine/bovine milk mixtures.
Due to high nutritive quality, good techno-functional properties and low
cost, legume protein products are becoming the most appropriate alternative
to protein products of animal origin. In food ...industries, these products are
usually used as techno-functional additives which provide specific
characteristics of final food products. Legume proteins are commonly used as
flour, concentrates, and isolates. The greatest application on industrial
scale has soy proteins, and to a lesser extent, in the past 20 years, pea
protein isolates. The modest use of pea protein is partly a result of
insufficient information relating to their techno-functional properties. This
paper is an overview of techno-functional properties of pea proteins and
their isolates. Also, the paper deals with the possible use of limited
enzymatic hydrolysis as a method for the improvement of their
techno-functional properties.
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