Factors affecting production of a near-white protein isolate from grapeseed

Extraction and precipitation conditions were investigated to determine the optimum conditions for preparation of a near-white protein isolate from grapeseed flour, treated with ammonium hydroxide and defatted. Extraction and precipitation of protein was studied under the following conditions: Particle size (<20 to >80 mesh). flour to solvent ratio (1:5–1:40), pH (1–12), NaCl medium (1–10%), extraction time (15–60 min) and precipitation pH (3–5). Protein solubility was less than 65% above pH 10. Using 60–80 mesh flour and extracting at pH 11 for 30 min with a flour to solvent ratio of 1:15, a protein isolate was obtained by acidification to pH 4.5 containing 84.7% protein and representing 48.2% of the crude protein in the grapeseed. The isolate was relatively low in sulphur-containing amino acids and lysine but rich in other essential and non-essential amino acids and had a digestibility of 91.3%. The isolate showed reasonably good whipping and emulsifying characteristics as well as water and oil absorptions.     

White lupin protein isolate as a foaming agent

 In this work the foaming ability of white lupin protein isolates was investigated in order to evaluate the potential use of these isolates as functional additives in food products and to find a vegetable alternative to egg-white foams. Lupinus albus protein isolate, modified in order to improve its foaming ability, was tested. Thermal denaturation, chemical treatment (acylation) and enzymatic hydrolysis (with vegetal proteases) were used, and the best results were obtained by using an optimised thermal denaturation method. A series of additives was tried out in order to further improve foam stability; xanthan gum gave the best results. Prior heat treatment of the protein and the conditions under which foam was generated were optimised using response surface methodology. Texture and microstructure of the optimised lupin foam were objectively evaluated. The lupin foam, when boiled in water for 5 min became very similar in texture and microstructure to uncooked egg-white foams. This shows, therefore, some promise as a substitute of the latter for products like fruit and chocolate "mousses", with the advantage of being able to withstand heat treatments. Received: 30 October 1997 / Revised version: 21 January 1998     

影响大豆分离蛋白提取率因素及实际解决方法

该文结合原料和生产过程中各个环节,分析影响大豆分离蛋白得率因素,并提出相应解决方法或工艺条件控制。     

Cholesterol-lowering effect of whole lupin (Lupinus albus) seed and its protein isolate

This study describes the hypocholesterolaemic effect of whole lupin and its protein in hamsters. The diets were: casein (control group HC), lupin protein isolate (group HPI) and whole lupin seed (group HWS). Diets from HPI and HWS promoted a significant reduction of total cholesterol and non-HDL cholesterol in the hamsters’ plasma as compared with HC. The true digestibility of HPI and HC groups were similar and differed significantly from the HWS one, which in turn showed a significant difference in total sterol excretion as compared to the former groups. Histological analysis of the liver revealed that animals fed on HPI and HWS diets presented a low level of steatosis (level 1) as compared to the ones fed on HC diet (level 4). Our findings demonstrate that protein isolate from Lupinus albus from Brazil has a metabolic effect on endogenous cholesterol metabolism and a protector effect on development of hepatic steatosis.     

Model salad dressing emulsion stability as affected by the type of the lupin seed protein isolate

Model salad dressing emulsions of an oil volume fraction of 0.50 were prepared using two types of lupin seed protein isolate (LSPI) differing in the method applied for their isolation and their protein composition. The dressing stability against creaming and droplet coalescence were studied and correlated with data on oil droplet size, rheological characteristics and the amount of protein adsorption at the droplet surfaces. Model salad dressing emulsions containing the isolate, mainly composed of lupin globulins, exhibited higher stability and more pronounced rheological characteristics compared to those prepared with the isolate enriched in albumins or with the mixture of the two isolates. The lupin albumins appeared to displace the globulins from the droplet surfaces, following competitive adsorption from mixtures of the two types of the lupin isolates. The results are discussed in terms of droplet interaction and rearrangement as they are influenced by the presence of the adsorbed protein molecules and aggregates which appear to determine long‐term stability of the emulsion systems. Copyright © 2006 Society of Chemical Industry     

Composition and protein quality of sweet lupin seed

The proportion of seed coats (hulls) of four varieties of sweet lupin seeds ranged from 19 to 25%. The amount of hull varied inversely with the weight of the seed, within each variety. Lupinus luteus cv Weiko III had 40.1% protein (dry basis); of 3 cultivars of L. angustifolius cv Uniharvest had the highest protein (36.2%), while cv Uniwhite had the lowest (28.6%). The protein content of dehulled lupins was about 20% higher than that of the whole seeds. L. angustifolius cv Uniwhite and L. luteus cv Weiko III were analysed for moisture, protein, lipid, ash, fibre, amino acids, carbohydrates, calcium, phosphorus, zinc, iron, copper and manganese. Whole seed, hulls and kernels were examined. Sulphur amino acids were limiting. The protein efficiency ratios of the two varieties, supplemented with methionine, were 2.40 and 2.56, respectively; these values increased by about 10% when the protein of the dehulled lupin seeds were tested. The requirement for added methionine for maximum p.e.r. was 0.65 g/kg diet. When dehulled lupin seed was steeped in water for a day and boiled and included in the diet of rats, slightly superior growth and p.e.r. resulted. The two varieties of dehulled lupin seeds effectively supplemented the protein of barley meal in the diet of rats, especially when methionine supplements were added, but were less efficient in supplemental value than was casein.     

碱提酸沉法制取花生分离蛋白的优化条件

采用碱提酸沉法研究了制取花生分离蛋白的优化条件.结果显示,当花生粕的匀浆料液比为1:8(m/V)、碱浸提液pH为8.2、浸提温度为60℃,重复浸提两次,每次浸提2 h,酸沉pH为4.5时,制取的花生分离蛋白纯度可达90.21%,蛋白质回收利用率可达75.74%.研究结果可为花生蛋白的合理有效利用奠定基础.     

Aqueous processing of lupin seed

Processing of two species of lupin seed by an aqueous extraction process has been explored and the resulting products have been examined. It has been shown that aqueous processing is an effective method for the separation of oil, protein and alkaloids of lupin seeds.     

Preparation of protein from lupin seeds

Different methods based on the protein extraction from undefatted and defatted lupin flour in alkaline medium and neutral environment using water and NaCl solution were investigated. The highest yield and protein content were obtained using combined extraction with water and NaCl solution. This method also resulted in the highest level of sum of the sulphur amino acids. Digestibility of protein of the lupin preparations was high.     

Factors affecting production of melon seed kernel protein: Yield,composition and protein isolates quality

Extraction and precipitation were investigated to determine the opti-mal conditions for preparation of protein concentrates from defatted melon seed kernels flour. Protein concentrates were prepared by extraction with distilled water, salt or alkaline solution. Alkaline so-lution led to the highest extraction yield of 84.5%. The protein concen- trate has a good digestibility of 90.8% as determined by in vitro enzy-matic method. The protein is rich in lysine 6.35% but poor in sulphur-containing amino acids such as methionine 0.27%, and cystine 0.33%. The protein isolate showed good whipping and emulsifying character-istics as well as water and oil absorptions.     

中性蛋白酶对葵花分离蛋白水解作用的研究

利用中性蛋白酶对葵花分离蛋白进行水解,以水解度和氮溶指数为指标,考察了pH、温度、底物浓度、酶底比、酶解时间对水解效果的影响,确定了葵花分离蛋白的较佳水解条件:温度50℃,pH 7.5,底物浓度8%,酶底比3%,酶解时间4 h。同时,研究了不同水解时间下蛋白酶解产物的感观品质和功能性质。     

A simple procedure of lupin seed protein fractionation for selective food applications

A simple procedure aimed at fractionating the main proteins of lupin seeds is proposed. The protocol consisted of alkali extraction of all proteins and isoelectric precipitation of two classical storage globulins, namely conglutins and , and one albumin, conglutin . The supernatant of this separation contained conglutin , the other main lupin protein. Conglutin could easily be purified further by selective Zn²⁺ precipitation, leading to a more than eightfold enrichment with respect to the amount in the flour. Resuspension of the isoelectric precipitate in saline water/ethanol solution allowed us to isolate conglutin , a 2S sulphur-rich lupin protein, at a very high purity level. Conglutins and could not be separated further by simple procedures. Sodium dodecyl sulphate–polyacrylamide gel electrophoresis analysis confirmed the identities of the isolated protein fractions. The distribution of each separated protein type is close to that of the corresponding proteins in the seed. The results are discussed in view of the applicability of the method and the potential use of each protein type as a food ingredient.     

In vitro starch digestion and technological properties of spaghetti fortified with lupin protein isolate

Spaghetti commonly made with durum wheat, typically lacks essential amino acids and with low fibre. Legumes offer potential to improve these properties and lupin is a good choice because it is cheaper with fewer antinutritional compounds than other legumes. Spaghetti was prepared with 0%, 5%, 17% and 30% lupin protein isolate (LPI) using both single-screw (SSEP) and twin-screw extrusion (TSEP). LPI increased protein up to 129%, reduced cooking time, water absorption and cooked firmness while stickiness and cooking loss were increased, especially using TSEP. LPI made the dried pasta more red and yellow and decreased brightness. The percentage of starch digested under in vitro conditions was reduced using 17%LPI with TSEP and 30%LPI with SSEP compared vs. control. Microscopy revealed changes in structure by LPI which may explain impacts on technological properties and digestion. Inclusion of LPI in pasta represents a potential approach for a low-cost improvement of nutritional value of spaghetti and potentially reducing its starch digestibility.     

牡丹籽分离蛋白提取工艺及乳化特性

采用单因素试验及响应面试验优化盐溶法提取牡丹籽分离蛋白工艺,并测定不同p H下牡丹籽分离蛋白的乳化特性。结果表明:牡丹籽分离蛋白的最佳提取工艺条件为提取时间69 min、提取温度40℃、料液比1∶20、Na Cl浓度1.03 mol/L,在此条件下牡丹籽分离蛋白得率为(23.49±1.21)%,纯度为(90.75±0.87)%;牡丹籽分离蛋白乳液在p H为8时,乳化能力、乳液热稳定性均最高,分别为(85.27±1.23)%和(90.74±1.07)%;乳液在p H 2~5时,形成Pickering乳液,显著增加乳液热稳定性、粒径,改变乳液颜色;乳液p H 8~10,形成O/W型乳液,乳液p H越高,乳化能力、乳液热稳定性越低,乳液粒径越小,乳液颜色越深;乳液中性条件下,粒径较大,热稳定性较低。     

影响大豆分离蛋白流动性和扬尘性的因素研究

通过单因素实验研究中和工序蛋白溶液质量分数、中和p H、消泡剂添加量、干燥喷嘴孔径和添加抗结剂对大豆分离蛋白流动性和扬尘性的影响。结果表明:高蛋白溶液质量分数、低中和pH、大喷嘴孔径均利于提高大豆分离蛋白粉的流动性,降低其扬尘性;其中高流动性、低扬尘度大豆分离蛋白粉加工的最佳工艺参数为蛋白溶液质量分数14%、中和pH 6. 5、干燥喷嘴孔径1. 6 mm、消泡剂添加量0. 05%,另可根据需要添加适当二氧化硅类的抗结剂。     

Nutritional potential and functional properties of sweet and bitter lupin seed protein isolates

Protein isolates were prepared from both sweet and bitter lupin seed flours by two different methods, i.e. by alkaline water extraction/isoelectric precipitation (P1) and by micellisation (MI), and studied with regard to nutritional quality and functional properties. Protein solubility of both lupin seed flours was increased as sodium chloride concentration increased up to 1.0 M, then decreased. The minimum protein solubility of bitter lupin seed flour was quite sharp at pH 4.5, while it exhibited a broad pH range of 4.3–4.9 for sweet lupin seed flour. No significant (P<0.05) differences were found between any isolates in their dry matter, fiber, lipids and moisture contents. Isolates-PI from both sources had significantly (P<0.05) higher crude protein and ash contents than their isolates-MI. Bitter and sweet isolates-PI had lower values of total essential amino acids and higher values of tyrosine, phenylalanine, threonine, tryptophan and valine than isolates-MI. There was no significant (P>0.05) difference between bitter isolates in their alkaloid contents, while both sweet lupin isolates were free of total alkaloids. Bitter lupin isolate-PI had significantly (P<0.05) lower tannins, but sweet lupin isolate-MI had a significantly (P<0.05) higher phytic acid content than other isolates. Isolates-MI from both sources had higher chemical scores than their isolates-PI. The first and second limiting amino acids were total sulfur amino acids and valine, respectively, for all types of isolates. Sweet lupin isolate-MI had a higher essential amino acid index and protein efficiency ratio than other isolates. The protein solubility index, fat absorption and emulsification capacities of both isolates-MI were significantly (P<0.05) higher than their isolates-PI. Both sweet lupin isolates had significantly (P<0.05) higher water absorption capacity than bitter lupin isolates. Sweet lupin isolate-MI had significantly (P<0.05) higher foam capacity and foam stability than other lupin isolates.     

白木通籽分离蛋白的理化与功能性质研究

以白木通籽为原料,采用碱提酸沉法,制备白木通籽分离蛋白（API）,并对其理化性质与功能性质进行了分析。结果表明:白木通籽分离蛋白含17种氨基酸,其中谷氨酸和天门冬氨酸的含量相对较高,有贮藏蛋白的共性。苏氨酸为白木通籽分离蛋白的第一限制性氨基酸。通过SDS-PAGE分析,白木通籽分离蛋白的亚基分子量范围为25～35ku。圆二色性光谱分析表明,白木通籽分离蛋白的二级结构主要由β-折叠和无规则卷曲组成,含量分别为31.2%和36.6%。白木通籽分离蛋白的等电点在pH4～5之间,在此pH范围内,蛋白的溶解性和起泡能力均最低。      

大豆分离蛋白溶解性和乳化性影响因素研究

研究了pH、大豆分离蛋白(SPI)质量浓度、NaCl浓度、搅拌时间和温度等因素对SPI溶解性和乳化性的影响.结果表明,0.8%的SPI在pH 6.0的条件下,实验浓度范围内的NaCI均使SPI溶解性和乳化性降低,适当的延长搅拌时间和升高温度可以显著提高SPI溶解性和乳化性.在室温条件下,搅拌50 min时SPI溶解度最...