Minerals and antioxidative capacity of raw okara that was obtained as a byproduct from six soybean varieties during hydrothermal cooking (HTC) of soy milk were assessed. Lipoxygenase (Lox), an enzyme ...deteriorating the sensory characteristics of okara, was also investigated. All genotypes had very similar concentrations of Lox (4.32–5.62%). Compared to raw soybeans, the applied HTC significantly reduced Lox content in okara (0.54–0.19%) and lowered its activity to 0.004–0.007 μmol g–1 min –1. Correlation between the content of Lox in soybeans and that in okara (r = 0.21;p < 0.05) was not registered. This indicates that the content of this enzyme in okara depended much more on the technological process than on soybean genotype. Very strong correlation (r = 0.99; p < 0.05) between okara Lox content and its activity was found. The most abundant minerals in raw okara were potassium (1.04–1.21 g/100g), phosphorus (0.45–0.50 g/100 g), calcium (0.26–0.39 g/100 g), and iron (5.45–10.95 mg/100 g). A very high antioxidant capacity (19.06–29.36 mmol Trolox kg–1) contributes to the nutritional value of raw okara.
Protein quality, based on its subunit composition, in okara obtained as a byproduct during hydrothermal cooking of soy milk was assessed. The composition of 7S and 11S protein fractions was ...correlated with the physicochemical properties of protein in okara produced from six soybean varieties. The basic 7S globulin (Bg7S) and 11S protein were two main proteins in okara. Investigated soybean genotypes produced okara with mainly acidic A5 and basic B1,2,4 polypeptides of 11S proteins. Soybean 11S content was not an indicator of okara protein recovery or extractability. Of all tested relationships, extractable soluble protein content of okara was influenced only by soybean Bg7S (r = 0.86; p < 0.05) and its light subunit contents (r = 0.93; p < 0.05). Okara protein recovery depended on Bg7S heavy subunit content in soybeans (r = 0.81; p < 0.05). The high quantity of vegetable protein in okara (around 35%) and very high protein extractability (around 85%) qualify this byproduct for potential application in food preparation as a functional ingredient.
The aim of this study was to evaluate the content and profile of the phenolic compounds (PCs) and antioxidant properties of field-grown leaves, in vitro leaves and in vitro callus cultures of the ...blackberry ‘Čačanska Bestrna’ and blueberry ‘Toro’. In vitro shoots of the selected genotypes were grown either on original Murashige and Skoog (MS) medium containing 1 mg/L BA, 0.1 mg/L IBA and 0.1 mg/L GA3 (‘Čačanska Bestrna’) or on MS medium with macroelements reduced to ½, 2 mg/L zeatin and 0.2 mg/L IAA (‘Toro’). Callus cultures were induced from in vitro leaves and established on MS medium with 2 mg/L BA and 2 mg/L 2,4-D (‘Čačanska Bestrna’) or MS medium with half strength macroelements, 2 mg/L BA, 2 mg/L 2,4-D and 1 mg/L NAA (‘Toro’). Total phenolic (TPC) and flavonoid content (TFC) were the highest in blueberry leaves, whereas low TPC and TFC values were obtained in callus cultures of both cultivars. A higher content of PCs in blueberry leaves compared to blackberry leaves was determined by the UHPLC-DAD MS/MS technique. Quercetin derivatives and phenolic acids were the dominant PCs in the leaves of both berries, whereas gallocatechin was present in a significant amount in blueberry leaves. Callus cultures of both berries had a specific PC profile, with none detected in the leaves except quercetin-3-O-glucoside and quercetin-3-O-rutinoside. Blackberry leaves showed the best antioxidant properties as estimated by ferric reducing power (FRP), ABTS•+ and DPPH• scavenging activity assays. Callus cultures of both berries exhibited three to five times lower ABTS•+ and ten to seventeen times lower DPPH• scavenging activity compared to corresponding leaves. The analyzed leaves and callus cultures can be a good source of PCs with good antioxidant properties and specific phenolics, respectively, for applications in the food and pharmaceutical industries.
This paper is a study on the distribution of the denatured whey proteins and κ-casein in soluble and micelle-bound complexes in heat treated caprine and bovine milk (90°C, 10min) at natural pH ...(6.71). Proteins were fractionated using fractionation technique based on renneting and were analysed by three electrophoretic techniques: native PAGE, SDS-PAGE under reducing and non-reducing conditions. Lower than 3% of the total β-LGs remained stable after heat treatment of both milk species, but bovine α-LA was more heat stable than its counterpart in caprine milk (29.6% against 3.82%). Denatured caprine whey proteins (>95%) were part of micelle-bound complexes whereas soluble complexes were not observed. Conversely, about 30% of denatured bovine whey proteins were involved in soluble complexes. About 24.2% of total κ-CN was included into complexes formed in heat-treated bovine milk whereas in heat-treated caprine milk this percentage is about three times higher. Caprine micelle-bound complexes, apart from whey proteins and κ-casein included also β-casein and αs2-casein, which were not found in their bovine counterparts. This knowledge could be very useful in understanding the differences in technological–functional properties of caprine and bovine milk and to enable better control of dairy processes.
Soybean soaking water whey (SWW) is obtained as the waste of soy milk production and mostly represents an environmental problem. The aim of this study was to assess the content of proteins and ...content and activity of trypsin inhibitors of fresh SWW, obtained during soy milk production. Two zones of Bowman-Birk trypsin inhibitors (BBI) were detected. One was identified as a monomeric form of BBI (0.61-2.93%) and the other one was identified as a polymeric form of BBI (0.45-3.33%). The degree of BBI extraction (1.88-5.49%) was influenced by the soybean genotype and the grain size, i.e. it increased with increasing grain size. Kunitz trypsin inhibitor was not detected. Total proteins were found in traces in SWW (0.03-0.06%). Low residual trypsin inhibitor activity (0.32-0.55%) suggested that SWW can potentially be applied for preparing food or feed. In that case it will not be waste but a cheap functional supplement with BBI as a biologically active component.
The influence of limited proteolysis of soy protein concentrate on proteinextractability, the composition of the extractable proteins, their emulsifying properties andsome nutritional properties were ...investigated. Traditional concentrate (alcohol leachedconcentrate) was hydrolyzed using trypsin and pepsin as hydrolytic agents. Significantdifferences in extractable protein composition between traditional concentrate and theirhydrolysates were observed by polyacrylamide gel electrophoresis (PAGE) and by SDSPAGE.All hydrolysates showed better extractability than the original protein concentrate,whereas significantly better emulsifying properties were noticed at modified concentratesobtained by trypsin induced hydrolysis. These improved properties are the result of twosimultaneous processes, dissociation and degradation of insoluble alcohol-induced proteinaggregates. Enzyme induced hydrolysis had no influence on trypsin-inibitor activity, andsignificantly reduced phytic acid content.
The distributions of major whey proteins in acid wheys from different caprine/bovine and ovine/bovine milk mixtures were investigated using native-polyacrylamide gel electrophoresis (PAGE). ...Significantly different distributions of major whey proteins as individual proteins or as the sum of the same protein from different species were established. The caprine major whey proteins were dominant in mixtures with 10%, 20% and 30% bovine milk. The total β-lactoglobulin to α-lactalbumin (β-LGs/α-LAs) ratios ranged from 1.37 to 2.12 for caprine/bovine acid wheys. The corresponding ratios for ovine/bovine acid wheys were in the range 2.59–2.12. Linear relationships were estimated among the amounts of added bovine milk and the percentages of individual major whey proteins in all milk analysed, with square correlation coefficients from 0.990 to 0.997. These correlations enabled the use of native-PAGE as simple, reliable and low cost analytical method for determination the distributions of major whey proteins in caprine/bovine acid wheys.
This study describes the relationship between the two major trypsin inhibitors (TI) in soybean, i.e., the Kunitz (KTI) and Bowman-Birk (BBI) trypsin inhibitors, as well as between them and the ...corresponding trypsin inhibitor activity (TIA). Twelve investigated soybean genotypes showed significant differences in TI levels and TIA. A very strong positive correlation was found between the levels of KTI and total BBI (r = 0.94, P < 0.05). No relationship was found between KTI, BBI or total TI and TIA. Based on this data, it appears that the levels of major TI in soybean are related. Understanding the relationship between trypsin inhibitors and their activities could be useful for further improvement of the health impacts of soy proteins.
Tofu protein composition changes induced by a pilot plant processing method involving hydrothermal cooking, commercial rennet as coagulant and inulin as functional ingredient were assessed. ...Glycoproteins (γ-, β-conglycinin) were firmly bound to the matrix of the obtained gels. Extractable proteins of inulin-enriched tofu were with mainly basic 7S-globulin, and polypeptides of glycinin. Polypeptides A1,2,4 and B1,2,4 were found in higher concentrations in protein extracts of tofu than other 11S polypeptides. Tofu was characterized by high total (417.6–556.5 g/kg) and extractable soluble (155.3–367.5 g/kg) protein content, good protein extractability (37.2–68.6%), both total protein (52–69%) and soluble protein (50–76%) recovery. Increasing concentrations of inulin proportionally improved tofu hardness (6.23–8.98 N/cm2) contributing to the uniformity of gel microstructures. Inulin played an important role in incorporating β- and γ-conglycinins into the gel matrix and by increasing the concentration of inulin in soymilk before gelation, the content of extractable soluble proteins, protein extractability and soluble protein recovery of produced tofu were also proportionally increased. For all tested sensory attributes the grades were increased with increasing inulin content in the samples. Under the applied production method, protein composition and proportion of inulin had important roles in defining tofu quality.
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•Inulin plays an important role in binding proteins into the gel-matrix of tofu.•Inulin-enriched tofu is characterized by high total and soluble protein content.•Inulin-enriched tofu has good protein extractability and protein recovery.•Inulin improves tofu hardness and gives fine and uniform microstructure of gels.•New tofu products with higher consumer preferences have been developed.
This study describes the relationship between the emulsifying properties of soybean proteins and their composition, i.e., glycinin (11S) and β‐conglycinin (7S). Twelve investigated soybean genotypes ...showed significant differences in storage protein composition. The β‐conglycinin concentration positively correlated with extractable soluble protein content, which was positively correlated with protein extractability. These data suggest that the level of β‐conglycinin has a positive influence on protein extractability. The emulsion activity index (EAI) was strongly and positively correlated with the 11S∶7S ratio and strongly and negatively correlated with the concentration of β‐conglycinin. The emulsion stability index (ESI) showed a moderate positive correlation with the monomeric form of glycinin and a strong positive correlation with the ratio of the monomeric to dimeric form of glycinin. No association was evident between ESI and EAI. Also, no relationship was found between ESI or EAI and extractability. Based on these data, it appears that the 11S∶7S ratio strongly reflects the ability of soybean proteins to form emulsions, whereas the ratio of the two different forms of glycinin may be crucial factors for the stability of soybean protein emulsions. Thus, understanding the relationship between protein composition and functionality could be useful for further improvement of functional behavior of soy proteins in food systems.
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