Effect of different pasteurization conditions on bioactivities of Lupinus albus protein isolates

Lupin protein isolate was extracted following the procedure in European Patent (EP 1024 706 B1) in order to use lupin protein for food and pharmaceutical applications. The acid insoluble/neutral pH soluble protein isolate was pasteurized at 65-125 °C for 10-1000 s. The objective of this study is finding out reasonable pasteurization condition for food use, or for good bioactivities like radical scavenging, angiotensin converting enzyme inhibition, and bile acid binding activity. Pasteurization at 65 °C for 10 s did not reduce the microbial count of the protein sufficiently for use in foods. The chemical composition of lupin protein isolates had no change by various pasteurization. The angiotensin converting enzyme inhibition decreased and the DPPH radical scavenging capacity increased after high temperature treatment at 125 °C. The sodium cholate binding capacity was not affected by tested conditions. Pasteurization at higher temperature is useful for producing selective bioactive fractions with suitable microbiological properties.     

Functional and bioactive properties of rapeseed protein concentrates and sensory analysis of food application with rapeseed protein concentrates

In order to investigate the use of rapeseed (Brassica napus) protein from oil industry waste for food applications, two rapeseed cultivars (Express, Lion) were pretreated to remove the hulls and oil. Rapeseed protein concentrates were then prepared by washing with 450 ml/l isopropanol. A portion of each protein concentrate was steamed before undergoing isopropanol treatment to deactivate myrosinase. Deactivation of myrosinase prevents glucosinolate decomposition and improves the extractability of sinapin acids. Lion rapeseed protein concentrates showed higher water and oil binding capacities than Express protein concentrates. The steaming process reduced the oil binding capacity, emulsification capacity and protein solubility. When steamed rapeseed protein concentrate was added to sausage preparations in place of casein, sensory analysis showed that the rapeseed protein sausage had improved taste, good texture and a characteristic aroma. Hydrolysed de-oiled rapeseed and protein concentrates were prepared using gastrointestinal enzymes. The cholate binding capacity, angiotensin converting enzyme (ACE) inhibition and DPPH radical scavenging activity were then investigated. Pepsin-hydrolysed protein concentrates showed the strongest ACE inhibition. Hydrolysed protein concentrates showed 2.3-3.0 times higher DPPH radical scavenging activity than non-hydrolysed samples. The cholate binding capacity was not affected by the hydrolysis. The steaming process did not significantly alter the bioactivities.     

棉籽蛋白功能特性的研究

考察了棉籽浓缩蛋白、沉淀蛋白和溶解蛋白3种棉籽蛋白的氮溶指数、吸水性、吸油性、起泡性与泡沫稳定性、乳化性与乳化稳定性等功能特性。结果表明,棉籽溶解蛋白的乳化性和起泡性较佳;棉籽浓缩蛋白和沉淀蛋白,除吸油、吸水能力强之外,其他的功能特性均较差。在吸水性方面,棉籽蛋白的吸水性要低于菜籽沉淀蛋白,但高于大豆沉淀蛋白。在吸油性方面,棉籽蛋白均低于菜籽蛋白和大豆蛋白。     

In vitro binding of bile acids by lupin protein isolates and their hydrolysates

This study investigates the in vitro binding of bile acids by lupin, lupin protein isolates, and their hydrolysates compared to soybean products and cholestyramine. Sodium cholate, sodium deoxycholate, sodium chenodeoxycholate, sodium glycocholate and sodium taurocholate were individually tested and analyzed spectrophotometrically by enzymatic reaction. A degree of hydrolysis of up to 20% did not affect the bile-acid binding capacity. De-oiled lupin and its hydrolysate bound all the bile acids to a significantly greater extent than de-oiled soy and its hydrolysate. Acid-soluble protein isolate from lupin showed a greater bile-acid binding capacity than acid-insoluble protein isolate. The amount of bile acid bound by acid-soluble lupin protein isolate was sometimes greater than the amount of bile acid bound by cholestyramine, which is well known as a cholesterol-reducing agent. There was no selective binding of particular types of bile acids. It can be concluded from these results that acid-soluble protein isolate from lupin may have potential application as a cholesterol-reducing agent for hypercholesterolemic patients.     

Functional properties of proteins isolated from phorbol ester-free physic nut (Jatropha curcas L.) seed cake

Phorbol ester-free physic nut (Jatropha curcas L.) seed cake is a nutritious protein source. Functional properties of the protein isolates obtained from various protein precipitation methods were investigated. Proteins isolated from the seed cake by ammonium sulfate gave the highest yield. The solubility of all proteins increased with increasing pH with their maximum and minimum solubility at pH of 12.0 and 4.0, respectively. The protein prepared by ethanol provided the maximum water holding capacity (3.34 mL water/g protein). The oil binding capacities of all proteins were 1.96–2.03 mL oil/g protein. The protein precipitated by ethanol showed higher emulsion activity and stability than that precipitated by acetone and ammonium sulfate. The protein obtained from ammonium sulfate gave the highest foam capacity, while the protein from acetone had the highest foam stability. Different functional properties of the proteins were achieved by various protein precipitation methods. The protein isolate obtained from each method could serve as a food ingredient applied to food products requiring a specific functional property.     

Functional properties of raw and heat processed cashew nut (Anacardium occidentale, L.) kernel protein isolates

The functional properties viz. solubility, water and oil absorption, emulsifying and foaming capacities of the protein isolates prepared from raw and heat processed cashew nut kernels were evaluated. Protein solubility vs. pH profile showed the isoelectric point at pH 5 for both isolates. The isolate prepared from raw cashew nuts showed superior solubility at and above isoelectric point pH. The water and oil absorption capacities of the proteins were slightly improved by heat treatment of cashew nut kernels. The emulsifying capacity of the isolates showed solubility dependent behavior and was better for raw cashew nut protein isolate at pH 5 and above. However, heat treated cashew nut protein isolate presented better foaming capacity at pH 7 and 8 but both isolates showed extremely low foam stability as compared to that of egg albumin.     

茶叶籽粕蛋白功能特性研究

以大豆分离蛋白为对照,研究碱法和酶法提取茶叶籽粕蛋白的功能特性。结果表明：酶法提取茶叶籽粕蛋白的溶解性、吸油性、乳化能力和乳化稳定性、起泡性、凝胶脆度优于碱法提取茶叶籽粕蛋白,而后者的吸水性、泡沫稳定性则优于前者,两者所形成蛋白凝胶的黏性和硬度相当。碱法和酶法提取的茶叶籽粕蛋白的乳化能力和乳化稳定性稍优于大豆分离蛋白,但起泡性和泡沫稳定性则不及大豆分离蛋白,溶解性与大豆分离蛋白相当,它们形成凝胶的最低质量分数分别为13%和15%,凝胶的黏性和硬度低于大豆分离蛋白。pH值、蛋白质量分数、NaCl浓度等因素对茶叶籽粕蛋白功能特性均有不同程度的影响。     

Effect of extraction conditions on composition,surface activity and rheological properties of protein isolates from flaxseed (Linum usitativissimum L)

Flaxseed protein isolates were prepared by micellisation (FM) and isoeletric precipitation (FI). The influence of preparation conditions on composition and functional properties was investigated. Contents of 0.6% phytic acid and 2.3% pentosans were found for FI, whereas FM was almost phytic acid‐free and had a low content of pentosans (0.6%). Chromatography and electrophoresis identified the 11S globulin (linin) as the main protein fraction in both isolates. Protein solubility, water‐ and oil‐binding capacities, emulsification and rheological properties of dispersions and gels were measured at pH 8 and 3. For the latter, interactions of protein with phytic acid and pentosans are highly probable. FI possesses a lower solubility (about 40–50%) and an overall higher water‐binding capacity than FM. For FI dispersions a higher storage modulus G′ than loss modulus G″ was measured, clearly pointing to the formation of protein networks. Moreover, FI formed stronger gels than FM (G′ about fivefold). The emulsifying activity, however, was distinctly lower for FI. These results point to enhanced complexation and aggregation of the isoelectric‐precipitated protein isolate. © 2002 Society of Chemical Industry     

Functional Properties of Lupin Protein Isolates (Lupinus albus cv Multolupa)

Lupin protein isolates were prepared by alkaline extraction and precipitation at pH 5.1, 4.2 and 4.9 and their functional properties investigated. Solubility, emulsification capacity, swelling and gelation properties were determined under different conditions of pH, ionic strength and heat treatment. Lupin protein isolates showed better solubility than soybean isolate and a similar emulsification capacity. Swelling and gelation were found to be inferior, but when modifications in the methods of isolate preparation were introduced these properties were significantly improved. Consequently, it is possible to consider lupin proteins as a potential substitute for soybean proteins in food applications.     

Emulsifying and foaming properties of Phaseolus vulgaris and coccineus proteins

Protein isolates from two Phaseolus cultivars, common bean (Phaseolus vulgaris L.) and scarlet runner bean (Phaseolus coccineus L.), were prepared by wet extraction methods (isoelectric precipitation – 4000 rpm, ultrafiltration, extraction with NaCl 2%, and isoelectric precipitation – 9900 rpm). The protein isolates were characterized by sodium dodecyl sulfate–polyacrylamide gel electrophoresis and then evaluated for their solubility. The emulsion stability of emulsions produced at pH 7.0 and 5.5 with 1% or 2% or 3% w/v protein isolate was evaluated by average droplet size diameter, viscosity and creaming measurements. Emulsions with 1% protein content were unstable through storage. Emulsions with 3% w/v protein isolate concentration, extracted by ultrafiltration at pH 5.5 from both cultivars, were flocculated; this was more pronounced for coccineus isolates. The foaming properties, for the respective foams, were investigated. Foams with 1% w/v protein showed little foaming ability Ultrafiltration isolates produced more foam, which was especially stable at pH 5.5.     

Functional Properties of Chinese Rapeseed Protein Isolates

A membrane-based protein isolation process developed in our laboratory produced two protein isolates from CH₃OH/NH₃/H₂O-hexane-extracted Chinese rapeseed meal. Both contained ～99% protein (NX6.25), and they were essentially free of glucosinolates or their breakdown products (<2,2 μmol/g). Their functional properties were evaluated and compared with a commercial soybean protein isolate. The precipitated isolate gave high values for all properties except nitrogen solubility index (NSI) while the soluble isolate showed excellent NSI and fat absorption but poor emulsification characteristics. They both had good foaming properties. The two Chinese rapeseed protein isolates complemented each other and were comparable to soybean protein isolate in most functions.     

紫苏分离蛋白功能性研究

为了开发紫苏蛋白在食品工业中的应用,以大豆分离蛋白为对照,研究紫苏分离蛋白的功能特性。结果表明：紫苏分离蛋白的溶解性与大豆分离蛋白的溶解性随pH值变化的趋势基本一致,但在等电点时紫苏分离蛋白的溶解性高于大豆分离蛋白。在pH7.0时,紫苏分离蛋白的持水性、起泡性及泡沫稳定性、乳化性和凝胶性均不及大豆分离蛋白。但紫苏分离蛋白的吸油性仅稍小于大豆分离蛋白,此外,在紫苏分离蛋白的蛋白质质量浓度为3g/100mL以后,其乳化稳定性与大豆分离蛋白的乳化稳定性基本相当。紫苏分离蛋白在食品加工中作为一种蛋白质强化剂具有一定潜力。     

Functional properties of protein concentrates and isolates produced from cashew (Anacardium occidentale L.) nut

Protein isolates and concentrates were obtained from defatted cashew nut powder by two methods: alkaline extraction-isoelectric precipitation (IP) and alkaline extraction-methanol precipitation (MP). The functional properties of cashew nut protein isolates, concentrates and powder were significantly different (p < 0.05). Cashew nut protein isolate (CNPI) had higher water and oil absorption capacities (2.20 ml/g and 4.42 ml/g, respectively), emulsifying stability index (447%), foam capacity and stability (45% and 55%, respectively), and least gelation capacity (13.5%) than cashew nut protein concentrate (CNPC), which was also higher than that of defatted cashew nut powder (DCNP). However, emulsifying activity index (12.45%) and bulk density (0.31) of CNPI were lower than that of CNPC, which were also lower than that of DCNP. The water solubility of CNPI (95%) and CNPC (95%) was not significantly different (p > 0.05) among the samples, but was significantly different (p < 0.05) from that of DCNP (75%). The CNPI, CNPC and DCNP showed decreasing solubility with decreasing pH, with the minimum solubility being observed at a pH range of 4.0–4.5, confirming the isoelectric point of cashew proteins. However, higher water solubility, emulsifying activity, and foaming property were observed at an alkaline pH than at an acidic pH in all samples.     

A comparative study of the functional properties of amaranth and soybean globulin isolates

The functional properties of the amaranth globulin isolate were determined and compared to those of the well studied soybean globulin isolate. Functional properties investigated included protein solubility, heat coagulation, foaming and emulsifying activity and stabilities, as well as fat binding. Overall, the amaranth globulin isolate was found to have significantly higher solubility (p ⪇ 0.05) i.e., 9 times higher, and higher heat stability (p ⪇ 0.05) in the vicinity of its isoelectric point, pH 5–6, than the corresponding soybean globulin isolate. Between pH 3–9 the amaranth globulin isolate was found to have significantly higher (p ⪇ 0.05) foaming capacities and stabilities than the soybean isolate. Maximum foaming capacity for the amaranth globulin was determined to occur around its isoelectric point. The emulsifying activity of the amaranth globulin isolate was found to be significantly higher (p ⪇ 0.05) between pH 3–9 than the corresponding soybean globulin isolate. The most substantial difference between the two isolates was that the amaranth isolate showed maximal emulsifying activity and stability at pH 7.0. Little difference was observed in the fat absorption capacities between the two prepared isolates. Nutritionally, the amaranth globulin isolate was found to be of superior quality compared to the soybean globulin isolate due to its higher content of essential amino acids. Overall, the functional properties of the amaranth globulin isolate were much better than the soybean isolate especially in the vicinity of its isoelectric point, suggesting a potential advantage if used in various thermally processed food formulations that fall within this pH range; a range where more common isolates perform very poorly.     

Effect of digestive enzymes on the bioactive properties of goat milk protein hydrolysates

The aim of this research was to study the influence of the gastrointestinal digestion on the bioactivity of goat milk protein hydrolysates prepared with subtilisin, trypsin and a combination of these two enzymes. All hydrolysates had excellent angiotensin converting enzyme (ACE) inhibitory activity, antioxidant activity and bile acid-binding capacity. Peptide profiles and bioactivities were mainly altered during the intestinal digestion, whereas the effect of the gastric digestion was negligible. The influence of the intestinal digestion varied depending on the hydrolysate and the bioactivity studied. In the case of ACE inhibitory activity, it exclusively decreased when peptides were produced with trypsin. In contrast, antioxidant activity and bile acid-binding capacity improved after the gastrointestinal digestion, regardless the enzymatic treatment conducted. Hydrolysis employing mixtures of subtilisin and trypsin is considered a good approach to produce peptides that maintain, or even enhance, their bioactivity after digestion.     

Physico-Chemical Properties of the Flour, Protein Concentrate, and Protein Isolate of the Cupuassu (Theobroma grandiflorum Schum) Seed

ABSTRACT:  Defatted flour, protein concentrate, and protein isolate obtained from Amazonian cupuassu seeds were evaluated for their solubility properties, water and oil retention capacity, foam formation and stability, gelling properties, emulsifying ability, and emulsion stability. The protein contents of defatted flour, the concentrate, and the isolate were 27.65%, 31.18%, and 64.29%, respectively. As expected, the protein isolate exhibited higher solubility than the protein concentrate, achieving more than 90% solubility at pH 8.0. The flour and the protein concentrate, however, showed excellent water and oil retention capacities. High emulsifying capacity at pH 7.0 was also observed for all 3 products: 987 mL oil/g, 977 mL oil/g, and 1380 mL oil/g for the flour, protein concentrate, and protein isolate, respectively. Gelling properties were not exhibited by any of the products, but all of them exhibited good utilization potential, not only to enrich other foods but also to enhance relevant functional properties.     

Functional Properties of Protein Isolate from Cowpea (Vigna unguiculata L. Walp.)

ABSTRACT: Functional properties of protein isolates prepared from 3 cowpea varieties and 2 soybean varieties in each of 2 y were determined. Both cowpea protein isolate (CPI) and soy protein isolate (SPI) showed a u-shaped curve for solubility with the minimum solubility occurring at pH 4.5. The CPI had lower emulsifying activity than SPI but was similar in stability. Foaming capacity and foaming stability ranged from 58.6 to 60.2 mL and 63.7 to 64.4 min for CPI and from 31.9 to 33.0 mL and 43.4 to 45.0 min for SPI, respectively. Gels were formed at 70 °C for 40 min and 30 min for CPI (12%) and SPI (10%), respectively. The CPI needs modification to enhance functional properties for potential application in food products.     

Purification and characterisation of Aspergillus sojae naringinase: The production of prunin exhibiting markedly enhanced solubility with in vitro inhibition of HMG-CoA reductase

Aspergillus sojae isolated from a traditional Korean fermented soybean product exhibited strong naringinase activity. The naringinase enzyme was purified and had a molecular weight of 70 kDa. The α-l-rhamnosidase activity of this enzyme was optimal at pH 6.0 and stable in the pH range of 5.5–8.0. The purified enzyme also had β-d-glucosidase activity, but the activity was relatively weak compared to the activity of the naringinase from Penicilliumdecumbens. The enzymatic bioconversion by A. sojae naringinase of naringin to prunin was efficiently performed with a 91% yield and a negligible amount of naringenin. The bioconversion was achieved by repetitive batch reactions with enzyme recycling. Prunin exhibited a markedly enhanced solubility compared to naringenin and naringin while maintaining the in vitro inhibition of HMG-CoA reductase. The results reported in this paper show that the naringinase produced by A. sojae will be useful in enhancing the potential bioavailability of naringin by efficiently converting it to prunin as a food component in citrus.     

Comparison between protein functional properties of two rice cultivars

The functional properties of proteins from a high-protein–content rice cultivar (Nutriar) were analyzed and compared with those from a usual Latin-American cultivar (El Paso 144). Isolates from brown and milled flours were prepared and their emulsifying, foaming, and hydration properties studied. The four isolates displayed a very low solubility within a wide range of moderate pH, but demonstrate a significantly higher solubility at extreme pHs (either high or low). Nutriar isolates had a significantly higher solubility and greater surface properties than El Paso 144 isolates. The Nutriar isolate from brown flour was more soluble at pH 9 than the other isolates and moreover showed the highest capacity for forming and stabilizing foams and emulsions. In contrast, the Nutriar isolate from milled rice exhibited a higher solubility and greater foaming properties at an acid pH. The surface properties and solubility were significantly correlated among the four samples. All four isolates exhibited good water-imbibition and water-holding capacities.     

Functional properties of protein hydrolysates from pea (Pisum sativum,L) seeds

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.