Characterization of alkali-modified soy protein concentrate

To study the influence of the preparation mode, including mild alkali modification, of soy protein concentrate on soluble protein content and composition, some of its nutritive and functional properties were investigated. Soy protein concentrate prepared by aqueous alcohol leaching was modified in mild alkaline solutions (pH 8.0) at 40, 50 and 60° C for 60 minutes and compared with two principal types of commercial soy protein concentrate. Soluble protein content, composition and properties of soy protein concentrate, as well as their potential use are essentially determined by the preparation mode. Limited mild alkali hydrolysis increased protein solubility by 40-71%, while emulsion stability was increased by 18-56%. Major storage soybean proteins exhibited different stability to alcohol denaturation and mild alkali modification. The most susceptible were acidic -A3 - and -A5- subunits of glycinin

Soy protein modification: A review

Soy protein products such as flour, concentrates and isolates are used in food formulation because of their functionality, nutritional value and low cost. To obtain their optimal nutritive and functional properties as well as desirable flavor different treatments are used. Soybean proteins can be modified by physical, chemical and enzymatic treatments. Different thermal treatments are most commonly used, while the most appropriate way of modifying soy proteins from the standpoint of safety is their limited proteolysis. These treatments cause physical and chemical changes that affect their functional properties. This review discusses three principal methods used for modification of soy protein products, their effects on dominant soy protein properties and some biologically active compounds

Tehno-funkcionalne osobine izolata proteina graška

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.Zahvaljujući visokoj nutritivnoj vrednosti, dobrim tehno-funkcionalnim karakteristikama i niskoj ceni, proteini leguminoza postaju najprihvatljivija alternativa za proteinske proizvode animalnog porekla. U industriji hrane ovi proizvodi najčešće se koriste kao tehno-funkcionalni aditivi kojima se obezbeđuje neka od karakteristika finalnog proizvoda. Proteini leguminoza najčešće se koriste kao proteinska brašna, koncentrati i izolati. U industrijskim razmerama najveću primenu imaju proteini soje i u znatno manjoj meri, u poslednjih 20 godina, proteinski izolati graška. Ređa upotreba proteina graška delom je posledica još uvek nedovoljno informacija o njihovim tehno-funkcionalnim karakteristikama. Ovaj rad predstavlja pregled tehno-funkcionalnih karakteristika proteina graška i njegovih izolata. Takođe, u ovom radu razmatra se i delimična proteoliza kao metod za poboljšanje tehno-funkcionalnih karakteristika proteina graška

Primarna proteoliza bijelog sira u salamuri proizvedenog od sirovog kravljeg mlijeka praćena visokomolarnim SDS-PAGE elektroforetskim sistemom

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.Cilj ovog rada bio je istražiti proces primarne proteolize bijelog sira u salamuri pripremljenog od sirovog kravljeg mlijeka metodom SDS-poliakrilamidne gel elektroforeze zasnovane na primjeni visoko molarnog sistema Tris pufera i korelirati s rezultatima uobičajeno korištenih parametara. Proteolitičke promjene bijelog sira u salamuri praćene su pomoću tri parametra: ukupnih proteina, proteina topljivih u vodi i stupnja proteolize. Promjena glavnih kazeinskih frakcija praćena je SDS-elektroforetskom metodom u reducirajućim uvjetima. Zrenje je značajno utjecalo na sadržaj ukupnih proteina i sadržaj vlage u kravljem bijelom siru. Ovaj proces povećao je sadržaj proteina topljivih u vodi i stupanj proteolize. Glavne kazeinske frakcije bile su različito otporne na proteolizu. αs-CN je bio mnogo osjetljiviji na djelovanje proteolitičkih enzima u odnosu na β-CN. Količina αs-CN u jakoj je negativnoj korelaciji sa trajanjem zrenja i proteinima topljivim u vodi, dok nije utvrđena značajna korelacija između sadržaja β-CN i ovih parametara. Također, značajna korelacija utvrđena je između količine produkata male molekulske mase i trajanja zrenja, sadržaja αs-CN i proteina topljivih u vodi. SDS-elektroforetska metoda korištena u ovim istraživanjima može biti korisna za praćenje proteolitičkih promjena tijekom zrenja kravljeg bijelog sira u salamuri

Grape seed flour of different grape pomaces: Fatty acid profile, soluble sugar profile and nutritional value

The aim of this study was to determine fatty acid and soluble sugar profiles of the grape seed flour originated from non-fermented dried pomace of international and autochthonous grape varieties in order to estimate their potential nutritional value. The grape seed flours were obtained from the grapes harvested in technological maturity. It has been shown that grape seed flours contained significant quantities of unsaturated fatty acids (UFAs), especially linoleic fatty acids, whose content ranged from 61.15 - 83.47 %. Oleic acid mostly contributed to the content of monounsaturated fatty acids, while the stearic acid was the most abundant saturated fatty acid (SFA). Among polyunsaturated fatty acids, mainly ω-6 FAs, were the most represented. The tested grape seed flours had the high UFA/SFA ratio (3.63-11.09), low atherogenicity (0.04-0.13) and thrombogenicity (0.16-0.47) indices. Fifteen different sugars were found in analysed samples with the total concentration ranging from 40588 to 91319 mg/kg seed with fructose and glucose as the most abundant. Principal component analysis based on the content of FAs and soluble sugars revealed unique composition of the seed flour of Prokupac variety. These findings indicate that the tested grape seed flours is a good source of nutritionally valuable FAs and sugars that can play an important role in the formulation of a new functional food products

Primarna proteoliza kozjeg bijelog sira u salamuri praćena SDS-PAGE sistemom visokog molariteta

The aim of this work was to investigate primary proteolysis of white brined goat cheese prepared from raw milk and to correlate with the results obtained with high-molarity Tris buffer electrophoretic system. Proteolytic changes of white brined cheese were monitored by three parameters, the total protein, the water soluble proteins and the degree of proteolysis, whereas the change of major casein fractions was followed by electrophoresis in reducing conditions. Ripening caused a decrease of the total protein content, whereas in the first forty days the water soluble protein and the degree of proteolysis increased. Both casein fractions (αs- and β-casein) of goat cheese were susceptible to primary proteolysis but to the different extent. αs1- casein disappeared during processing, whereas during 60-days of ripening the content of αs2 and β-casein was reduced by 38.90 %, and 30.72 %, respectively. Such trends of major casein fractions were strongly correlated with the degree of proteolysis and the moisture content, whereas no correlation was found between them and the water soluble protein content. The results of our investigation clearly suggested that SDS-PAGE method based on high-molarity Tris-buffer system could be a very useful for purposes of monitoring the white goat cheese proteolysis.Cilj ovog rada bio je ispitati proces primarne proteolize bijelog sira u salamuri pripremljenog od sirovog kozjeg mlijeka i staviti u korelaciju s rezultatima dobivenim SDS-elektroforetskom metodom koja se bazira na primjeni Tris pufernog sistema visokog molariteta. Proteolitičke promjene bijelog sira u salamuri praćene su pomoću tri parametra: ukupnih proteina, u vodi topljivih proteina i stupnja proteolize, dok je promjena glavnih kazeinskih frakcija praćena elektroforezom u reducirajućim uvjetima. Zrenje sira uzrokuje pad sadržaja ukupnih proteina, dok sadržaj u vodi topljivih proteina i stupanj proteolize raste tijekom 40 dana zrenja. Obje kazeinske frakcije (αs- i β-kazein) podliježu procesu proteolize, ali u različitom stupnju. αs1-kazein se razgrađuje tijekom pripreme sira, dok se tijekom zrenja sira sadržaji αs2- i β-kazeina reduciraju za 38.90 % i 30.72 %. Ovakva promjena glavnih kazeinskih frakcija u jakoj je korelaciji sa stupnjem proteolize, sadržajem ukupnih proteina i sadržajem vlage, dok nije uočena korelacija između ovih parametara i u vodi topljivih proteina. Rezultati naših istraživanja jasno pokazuju da SDSelektroforetski sistem zasnovan na visoko molarnim Tris- puferima može biti vrlo korisna metoda za praćenje proteolitičkih promjena tijekom zrenja kozjeg bijelog sira u salamuri

The Influence of the Addition of Polyacrylic Hydrogel on the Content of Proteins, Minerals and Trace Elements in Milk Protein Solutions

Ispitana je mogućnost uporabe poliakrilnog hidrogela za uklanjanje iona teških metala iz otopina koncentrata proteina mlijeka, koncentrata proteina sirutke i albumina iz goveđeg seruma. Dobiveni rezultati pokazuju da bubrenje gelova u ovim otopinama različito utječe na udjel proteina i koncentraciju mineralnih tvari i elemenata u tragovima. Ukupan udjel proteina i koncentracija fosfora povećali su se nakon bubrenja hidrogela u otopinama koncentrata proteina mlijeka i proteina sirutke, bez promjene u sastavu proteina. Osim toga, smanjio se udjel proteina u otopini albumina iz goveđeg seruma. U otopini se proteina mlijeka nakon bubrenja hidrogela koncentracija natrija nije promijenila, dok se u otopini proteina sirutke znatno povećala. Koncentracija se kalcija i magnezija u otopinama koncentrata proteina mlijeka i proteina sirutke nakon bubrenja hidrogela smanjila za 20,3-63,4 %, ovisno o uzorku i mineralnoj tvari. Tijekom bubrenja hidrogela u svim je analiziranim uzorcima koncentracija cinka ostala nepromijenjena, dok su se one Fe, Cu, Mn, Ni i Pb znatno smanjile. Iz dobivenih se rezultata može zaključiti da se dodatkom poliakrilnog hidrogela otopinama koncentrata proteina mlijeka i proteina sirutke bitno smanjuje koncentracija teških metala, bez utjecaja na proteinski sastav otopina. Dobiveni bi se rezultati mogli primijeniti za razvoj novih tehnoloških procesa za uklanjanje iona teških metala iz mliječnih proizvoda.Solutions of milk protein concentrate, whey protein concentrate and bovine serum albumin (BSA) were treated with polyacrylic hydrogel to establish whether the hydrogel could be used for decontamination of heavy metal ions from milk protein-based products. The obtained results indicated that swelling of hydrogel in these solutions had different effects on their mineral, trace element and total protein content. Total protein and phosphorus content increased in milk protein concentrate and whey protein concentrate solutions after swelling of hydrogel without changes in their protein compositions. On the other hand, the protein content in BSA solution decreased after swelling. The content of Na did not change in milk protein concentrate solution, whereas it significantly increased in whey protein concentrate solution after hydrogel swelling. The content of Ca and Mg was reduced after the swelling in milk protein concentrate and whey protein concentrate solutions for 20.3–63.4 %, depending on the analysed sample and the mineral. The content of Zn did not change during swelling, whereas the content of Fe, Cu, Mn, Ni and Pb significantly decreased after hydrogel swelling in all analysed samples. According to the obtained results, the addition of polyacrylic hydrogel to milk and whey protein concentrate solutions can significantly decrease the content of heavy metal ions without affecting their protein composition. Therefore, this work could be useful in developing a new technological process for heavy metal purification of milk protein-based products

Comparison of sugars, lipids and phenolics content in the grains of organically and conventionally grown soybean in Serbia

The aim of the current study was to determine the content of several primary metabolites: total soluble sugars, starch and lipids, soluble sugars, fatty acids and triacylglycerols profile, and secondary metabolites: total phenolics and flavonoids, in the grains of soybean (Glycine max (L.) Merr.) cultivar ‘Kaća’. Additionally, grain antioxidant properties were assessed using ABTS•+ scavenging capacity and ferric reducing power (FRP) assays. Soybean was developed and grown in Serbia under two cultivation systems (conventional and organic) during two growing seasons (2016 and 2017). In both growing seasons and cultivation systems, soybean grains were characterised by reduced lipid content (8.16–14.34%) and as an excellent source of polyunsaturated fatty acids. Triacylglycerols (TAGs) with 44 equivalent carbon numbers (ECN44) represented the main fraction (30.95–32.79%) followed by ECN46 TAGs (23.27–26.36%). Low total soluble sugars (2.36–11.51%) content was determined. High-performance liquid chromatography (HPLC) analysis revealed a significant prevalence of non-reducing disaccharides (1.41–6.57%) among the individual sugars. Soybean grains were proved as a good source of phenolic (2493.9–4419.5 mg kg-1) and flavonoid (292.7–500.9 mg kg-1) compounds with the dominance of free (extractable) fractions. Strong positive correlations were observed between both cultivation systems and growing seasons indicating no clear differences for the majority of analysed parameters. All examined extracts possessed a significant ability (27.6–38.2%) to neutralize ABTS•+ radicals, while in the case of FRP assay a significant ability for iron ions (Fe3+) reduction was recorded for the samples from the second growing season

Mineral and nutritional assessments of soybean, buckwheat, spelt, and maize grains grown conventionally and organically

The present work determined complete mineral profile of four different types of grains (spelt, soybean, maize, and buckwheat) grown under two growing systems – conventional and organic. The contents of 20 macro-, micro- and trace elements were analysed in the examined grains by inductively coupled plasma-optical emission spectrometry (ICP-OES). In most samples, nine elements were present in concentrations higher than 10 mg/kg. The remaining elements were present at lower concentrations or in traces or not detected in certain samples. Aluminium and arsenic, as two toxic elements, were detected only in organic buckwheat grains. Based on the obtained results for the mineral contents, a nutritive assessment of the quality of grains of spelt, soybean, maize, and buckwheat were made. Results of nutritional assessment showed that spelt, soybean, and buckwheat grains could potentially be good sources of several minerals for human diet. On the other hand, the presence of some toxic elements, such as cadmium and strontium, should be monitored. Results of principal component analysis (PCA) and hierarchical cluster analysis (HCA) shown that the mineral composition, to a much greater extent, depended on the botanical origin of grains as compared to the production system