聚丙烯微孔膜固定化转谷氨酰胺酶在大豆乳清废水处理中的应用

将固定化转谷氨酰胺酶酶膜应用到酶膜反应器中,对大豆乳清废水进行催化使其发生聚合并被截留,从而减轻大豆乳清废水对环境的污染,并确定其最佳影响条件,得出在最佳条件下进行处理的蛋白截留率为78.4%。对处理前后大豆乳清废水进行分析,其主要成分指标发生了很大变化,如蛋白质含量、生化需氧量(biochemical oxygen demand,BOD)值、化学需氧量(chemical oxygen demand,COD)值、灰分含量等指标较处理前发生显著下降。     

氨基酸折算法计算婴幼儿配方粉中乳清蛋白含量方法的评估

目的评价以氨基酸折算法计算婴幼儿配方粉中乳清蛋白含量的方法。方法本实验使用自配的流动相,采用酸水解氨基酸自动分析仪测定婴幼儿配方粉中氨基酸含量,再根据乳清蛋白中天冬氨酸/天冬酰胺、丙氨酸、苯丙氨酸和脯氨酸4种特征氨基酸含量的经验公式折算出婴幼儿配方粉中乳清蛋白占总蛋白的百分比。结果对我国市售多种品牌的婴幼儿配方粉中的水解氨基酸进行了检测,再计算出乳清蛋白含量,发现仅1阶段乳基婴儿配方粉基本符合大于60%的国标规定。结论该氨基酸折算法对婴幼儿配方粉中乳清蛋白含量的定量研究具有参考价值,但对掺有大豆蛋白的产品无法进行准确测定。     

Nutritional quality evaluation of commercial protein supplements

Protein supplements have received increasing attention by consumers over the last few decades. However, hundreds of them have recently exhibited irregularities including lower quantities of proteins than disclosed values. This study aimed to evaluate the nutritional quality of six commercial protein supplement powders (calcium caseinate, milk protein concentrate, egg white, pea protein isolate, whey protein concentrate and soy protein isolate). The chemical composition, amino acid content and in vitro digestibility were examined. Thus, calculate the amino acid scores corrected for amino acid and protein digestibility. In vitro digestion was also conducted and protein hydrolysis was monitored by SDS-page. Calcium caseinate powder and whey protein concentrate were only composed of proteinogenic amino acids and exhibited the highest essential amino acid content. As regards in vitro digestibility, these two supplements perfectly meet the quality expectations of the Food and Agricultural Organization (FAO). Conversely, the other four supplements exhibited a lower quality than the FAO reference protein. This was due to low digestibility (for egg white and milk concentrate) and/or lack of a specific essential amino acid (for milk concentrate and pea isolate).     

豆制品生产中高浓度废水的检测与分析

为了深入探讨豆制品生产废水的再资源化价值,文中对豆腐和大豆分离蛋白生产过程中所排放高浓废水的成分和水质进行了检测与分析。结果显示,高浓乳清废水的COD、BOD远远高于国家规定的排放标准,其主要成分为糖、乳清蛋白、脂肪以及含量相对丰富的生物活性成分。在豆腐生产所排放的黄浆水中含有的大豆皂苷占大豆原料中皂苷原含量的58%、大豆异黄酮的50%,功能性低聚糖———水苏糖和棉籽糖分别占83%和94%;蛋白质占17%,脂肪占17%。一步碱溶酸沉法生产大豆分离蛋白时所排放的乳清废水中含有的大豆皂苷、异黄酮、水苏糖、棉籽糖、蛋白质、脂肪分别占豆粕中的38%、34%、87%、65%、8%、28%。说明豆制品生产废水中的大豆皂苷、大豆异黄酮以及大豆低聚糖等生物活性成分的含量颇高、具有回收价值。     

人乳、牛乳、羊乳中乳清部分氨基酸组成及乳清蛋白中蛋白质二级结构的对比

采用全自动氨基酸分析仪分别测定人乳、牛乳、羊乳氨基酸组成。应用模糊识别法和氨基酸比值系数、氨基酸比值系数分等指标全面评价3种乳乳清部分营养价值。采用傅里叶红外光谱的酰胺Ⅰ带和酰胺Ⅲ带测定3种乳中乳清蛋白的天然二级构象。结果表明:羊乳乳清部分必需氨基酸与总氨基酸比值为0.450,全鸡蛋蛋白贴近度与联合国粮食及农业组织/世界卫生组织贴近度分别为0.919 7、0.925 0,2种氨基酸比值系数分分别为68.47、76.56,在氨基酸营养评价上营养价值较高。羊乳乳清蛋白二级结构中的α-螺旋比例为20.26%,与人乳的27.37%更为接近,一定程度上更利于人体吸收。因此,羊乳是相比牛乳较好的婴幼儿功能性食品原料。     

Process improvement for semipurified oleosomes on a pilot-plant scale

Semipurified oleosomes were isolated on a pilot-plant scale using improved-process extraction conditions. The improved process consisted of continuous centrifugation in a three-phase decanter with recirculation of slurry until most of the oleosomes were recovered. Oleosome fractionation, oleosin identification, and isoflavone and saponin mass distributions and recoveries were investigated. The improved pilot-plant oleosome extraction process was achieved in 8 h. A total of 91%± 1% of soybean oil was recovered as intact oleosomes. The oil content of the aqueous supernatant and the residue fractions were low at 2% and 3%, respectively. The aqueous supernatant fraction contained 40% total soybean protein. About 76% of the proteins present in the oleosome fraction were soybean storage proteins. Washing the semipurified oleosomes with a 0.1 M Tris-HCl, pH 8.6 containing 0.4 M sucrose, and 0.5 M NaCl resulted in the recovery of the associated storage proteins. The recovery of these proteins in addition to the protein in aqueous supernatant accounted for 79% of the total soybean storage proteins fractionated by this process. Oleosins were detected at 17 and 18 kDa. Isoflavones and saponins partitioned into the oleosome, aqueous supernatant, and residue fractions at different ratios with the majority, about 82 and 63 mole%, respectively, in oleosome and aqueous supernatant fractions, making these fractions an attractive source for phytochemicals.     

利用微生物转谷氨酰胺酶回收大豆乳清废水

以大豆乳清废水为研究对象,以蛋白质含量为指标,通过单因素试验和正交实验研究了以微生物转谷氨酰胺酶(MTGase)对大豆乳清蛋白的聚合作用的条件,并对处理前后的大豆乳清废水中的蛋白质进行了分析.结果表明,微生物转谷氨酰胺酶对大豆乳清废水作用的最佳条件为:添加酶活为1 U/mL的酶6mL、反应时间1h、反应温度35℃pH ...     

Optimisation of protein-enriched gluten-free layer cakes using a mixture design

The effect of different protein mixtures (pea, whey and egg white proteins) on the physical characteristics of batters and baked gluten-free layer cakes after substituting 45% of flour was evaluated. A mixture design approach was used to determine the interaction effects of the three proteins on the cakes physical characteristics. For batter density, two interactions were observed, and higher values were found for batters containing a mixture of 60–80% egg white and 20–40% whey than in batter containing only one of these proteins, or a pea content of 70–90% than in batter containing only pea. For batter viscosity, significant interactions between egg white and pea, and between whey and pea proteins were observed, which explains the gentler decrease in viscosity at higher egg white and/or whey protein ratios. Regarding hardness, an interaction between egg white and whey occurred, and increasing whey content helped to reduce hardness to a greater extent than increasing pea content.     

大豆乳清蛋白特性及回收利用研究进展

大豆分离蛋白加工过程中产生大量乳清废水,直接排放会造成环境污染和资源浪费。大豆乳清废水中含有大豆乳清蛋白(Soybean Whey Proteins, SWP)、大豆异黄酮、大豆低聚糖等多种营养成分,其中大豆乳清蛋白应用价值极高,富含胰蛋白酶抑制剂、β-淀粉酶、大豆血球凝集素、脂肪氧合酶等多种功能因子。基于此,本文针对大豆乳清蛋白的回收利用,归纳总结了大豆乳清蛋白中的主要组成成分,并对各组分的研究利用以及其功能特性进行总结与分析,同时对大豆乳清蛋白的回收方法及利用进行了梳理,以期为工业生产实践中高值化利用提供理论和技术上的参考。     

致敏蛋白α亚基缺失型大豆氨基酸组成及营养评价

结合模糊识别方法评价的数学模型法和联合国粮农组织/世界卫生组织（Food and Agriculture Organization/World Health Organization,FAO/WHO）、鸡蛋蛋白两种模式下的化学分析法评价两个致敏蛋白α亚基缺失型大豆蛋白质氨基酸营养价值,解析α亚基缺失特性对大豆氨基酸组分及营养品质的影响。用氨基酸分析仪测定氨基酸的组分和含量,α亚基缺失特性用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（sodium dodecylsulfate polyacrylamide gelelectrophoresis,SDS-PAGE）确认,蛋白和脂肪含量用Perten 8620近红外谷物分析仪测定。结果表明：1）致敏蛋白α亚基缺失型大豆的氨基酸总量、必需氨基酸总量、蛋白质、油分含量不因α亚基的缺失而降低;2）致敏蛋白α亚基缺失型大豆的11S/7S比值在4.65以上,高于目前普遍报道的2.0～3.0;3）致敏蛋白α亚基缺失型大豆必需氨基酸含量接近或高于FAO/WHO标准;两种模式下,α亚基缺失型大豆的5种化学评分及贴进度值都很高,接近标准蛋白。致敏蛋白α亚基缺失型大豆蛋白质氨基酸组分平衡,11S/7S比值更优,营养品质更高。     

Tryptophan determination in proteins and feedstuffs by ion exchange chromatography

A chromatographic method was developed for the determination of tryptophan content in food and feed proteins. The method involves separation and quantitation of tryptophan (released from protein by alkaline hydrolysis with NaOH) by isocratic ion-exchange chromatography with O-phthalaldehyde derivatization followed by fluorescence detection. In this procedure, chromatographic separation of the tryptophan and α-methyl tryptophan, the internal standard, was complete in 15 min, without any interference from other compounds. The precision of the method was 1–4% relative standard deviation. Accuracy was validated by agreement with the value for chicken egg white lysozyme, a sequenced protein, and by quantitative recoveries after spiking with lysozyme. The method allows determination in a range of feed proteins, containing varied concentrations of tryptophan, and is applicable to systems used for routine amino acid analysis by ion-exchange chromatography.     

Model studies on reactions of plant phenols with whey proteins

Whey proteins were modified by reaction with selected phenolic compounds (ferulic-, chlorogenic-, caffeic- and gallic acid) and related substances (quinic acid and p-quinone) as well as with extracts from coffee, tea, potato and pear at pH 9. The derivatives formed were characterized in terms of their physicochemical and digestion properties. The derivatization was accompanied by a reaction at the lysine and tryptophan side chains, whereby their content was decreased in comparison to that in the control whey proteins. Moreover, the solubility of the derivatives decreased over a broad pH range and the derivatization influenced the hydrophobe-hydrophile character of the whey proteins. The isoelectric points were shifted to lower pH values in the order of reactivity as follows: gallic acid > p-quinone > caffeic acid > chlorogenic acid. The other derivatives showed no or few changes compared to the control whey proteins. The formation of high molecular fractions was documented with SDS-PAGE. Especially the derivatives of chlorogenic-, caffeic-, gallic acid and p-quinone showed an increase in molecular weight of beta-lactoglobulin fraction from 18,300 to 20,000 Da. A dimer formation in molecular range 40,000 was also registered. MALDI-TOF-MS was applied to characterize the binding of the individual phenolic compounds or their oxidation products to the whey protein fractions, alpha-lactalbumin and beta-lactoglobulin. In vitro experiments showed that the digestion of the derivatized whey proteins with the enzymes of the gastrointestinal tract (trypsin, chymotrypsin, pepsin and pancreatin) was adversely effected. Similar results with regard to physicochemical characterization and digestion properties of the whey proteins treated with the applied extracts from plant beverages, fruit and vegetable were also documented. Coffee and tee were comparatively the most reactive extracts.     

Alkaline Extraction of Protein from Spent Honey Bees

Adult honey bees killed after honey harvest were analyzed and evaluated as a raw material for protein extraction. Bees collected were 49.8% crude protein, 7.54% total lipid, and 27.1% reducing sugar (moisture-free basis). Whole bees were homogenized, body proteins solubilized in alkali, chitin removed by filtration, and protein recovered by acid precipitation. Amount of protein solubilized by NaOH addition varied from negligible without alkali (pH 6.1) to 93% of body crude protein with severest treatment at pH 11.2. With alkali extraction at pH 10.5 and acid precipitation at pH 5.5, 59% of total solids were found in the precipitate and 41% remained in the supernatant. The precipitate was 66.3% crude protein, 9.4% total lipid and 7.9% ash. Heads, thoraces and abdomens were separated and each separately extracted (pH 10.5) and precipitated (pH 5.5). Amino acid analyses of heads (70.1% protein), thoraces (54.9% protein) and abdomens (36.6% protein) permitted evaluation of protein quality. Thorax protein was most homogeneous for amino acids analyzed, and all were nutritionally limited by sulfur containing amino acids.     

锁阳螺旋藻营养片生产工艺及其蛋白质营养价值的评价

以锁阳提取物和螺旋藻粉为主要原料,经方差分析,筛选出最佳配比,采用直接成型制片工艺,生产锁阳螺旋藻营养片片。应用模糊识别法和氨基酸比值系数法,分别以鸡蛋蛋白质为标准蛋白,以WHO/FAO氨基酸参考模式为评价标准,对锁阳螺旋藻营养片蛋白质营养价值进行了全面评价。结果表明:锁阳螺旋藻营养片中含有18种氨基酸,总含量为42.75%,蛋白质中氨基酸种类齐全,必需氨基酸(EAA)占总氨基酸量的36.5%,色氨酸为第一限制氨基酸,含硫氨基酸为第二限制氨基酸,氨基酸比值系数为0.54和0.72。     

分步酶解法制备黄浆水活性肽

黄浆水是传统豆制品点脑成型过程压榨出的废弃物,富含低聚糖、蛋白质等营养成分。该研究通过比较酶种类及用量、酶解温度、酶解时间对黄浆水蛋白质水解度的影响,采用正交试验优化获得黄浆水短肽最佳分步酶解工艺：（1）酸性蛋白酶加酶量2 000 U/g,pH 4.0,温度55 ℃,水解2 h;（2）中性蛋白酶8 000 U/g,pH 6.0,温度50 ℃,水解6 h。在此条件下进行验证,水解度可达25.95%,血管紧张素转化酶体外抑制活性达92.0%。采用酸性蛋白酶和中性蛋白酶分步酶解黄浆水制备短肽,制备条件温和,水解度高,可为豆制品加工废弃物的高值化利用奠定基础。     

氨基酸分析仪检测牛乳中掺入的大豆蛋白

利用氨基酸分析仪对牛乳和大豆分离蛋白中的17 种氨基酸进行分离测定,氨基酸浓度在0.025～0.350 μmol/mL时,其峰面积和氨基酸浓度的线性相关系数均不小于0.988,重复性较好,牛乳加标回收率范围在94.2%～103.1%,相对标准偏差在0.89%～3.31%。通过对比分析牛乳和大豆的氨基酸图谱找到含量差异较大的6 种氨基酸,并根据模拟掺假实验样品的氨基酸分析6 种氨基酸含量和掺假量的线性关系,相关系数R2达0.889,建立牛乳中大豆蛋白掺假的定性定量检测方法。     

Interaction between whey proteins and lipids during light-induced oxidation

Dairy products are a suitable group for polyunsaturated fatty acid (PUFA) fortification, but are very susceptible to light-induced oxidation. In this study, the combined effect of light and PUFA fortification on the stability of milk proteins and on the formation of protein-lipid complexes was studied. Therefore, emulsions were prepared containing whey proteins and lipids with a different degree of unsaturation (olive, soybean, fish and algae oil). PUFA stimulated the protein oxidation process, even after complete degradation of the photosensitizer. First order reaction kinetics were established for riboflavin and tryptophan degradation, as well as the formation of N-formylkynurenine, a tryptophan degradation product. Oxidation was further characterised by degradation of the essential amino acids lysine, histidine, methionine and tyrosine. Protein-lipid adduct formation, measured fluorometrically and by the protein-bound carbonyl groups, could be linked with a decreased extractability of the unsaturated lipids from the emulsion, but also caused the formation of protein aggregates of high molecular mass.     

Chemical Composition of White Bean (Phaseolus vulgaris L.) and Functional Characteristics of Its Air-Classified Protein and Starch Fractions

Four varieties of Canadian white bean and their air-classified fractions were analysed for amino acid and proximate composition. The protein enriched fraction (31–35% by wt) prepared by air-classification of finely ground dehulled flour contained 50.3–57.5% protein. Solubility of protein measured as percent of total nitrogen soluble at pH 7.5 was 81.1–83.0%. Water Hydration Capacity and heat thickening property of the protein fraction were similar to other vegetable proteins indicating its potential usefulness as a protein ingredient in processed foods. The amino acid composition was characteristic of leguminous seed proteins with a high lysine content and a low sulfur amino acid content. The lipids and the oligosaccharides were concentrated in the protein enriched fraction. The starch fraction (53% by wt) contained on the average 30% amylose and gave a torque-temperature curve typical of legume starches with slow swelling, no breakdown at constant temperature and shear, and a high set back.     

Walnuts (Juglans regia L): proximate composition,protein solubility,protein amino acid composition and protein in vitro digestibility

Walnuts contained 16.66% protein and 66.90% lipids on a dry weight basis. Non‐protein nitrogen values ranged from 6.24 to 8.45% of the total nitrogen when the trichloroacetic acid concentration was varied within the range 0.25–1.0 M . Albumin, globulin, prolamin and glutelin respectively accounted for 6.81, 17.57, 5.33 and 70.11% of the total walnut proteins. Walnut proteins were minimally soluble at pH 4.0. The majority of total walnut protein polypeptides had estimated molecular weights in the range 12 000–67 000. The Stokes radius of the major protein in walnuts (glutelin fraction) was 66.44 ± 1.39 Å. Lysine was the first limiting essential amino acid in total walnut proteins as well as in the globulin and glutelin fractions. Leucine and methionine plus cysteine were the second limiting essential amino acids respectively for the prolamin and albumin fractions. Hydrophobic and acidic amino acids dominated the amino acid composition in all protein fractions. Native and heat‐denatured walnut glutelins were easily hydrolysed by trypsin, chymotrypsin and pepsin in vitro. © 2000 Society of Chemical Industry     

Evaluation of the composition and functional properties of whole egg plasma obtained by centrifugation

Hen eggs have many applications in the food industry. Centrifugation split liquid whole egg in two fractions: supernatant plasma and precipitate granules. Plasma can be used directly by the food industry. The aim of this study was to analyse how the operational conditions affect the composition and functional properties of plasma obtained by centrifugation. Protein and cholesterol contents, dry matter, emulsion activity and foam activity were evaluated. Plasma showed lower protein content and dry matter than liquid whole egg. Within the operational conditions studied, plasma contained 74–85% of egg cholesterol, maintaining the emulsifying activity and increasing the foaming properties. Prediction models were obtained for all the parameters studied except for emulsifying activity. Plasma doubled the foam capacity and increased until almost 15% the foam stability compared with liquid whole egg. Whole egg plasma could be a great substitute of whole egg for the food industry.