外源植酸酶对面粉的酶解条件优化

以无机磷含量为评价指标,以酶解温度、酶解pH值、酶解时间和植酸酶添加量为影响因素对帝斯曼、昕大洋、罗氏三种外源植酸酶(分别记为酶1、酶2和酶3)在面粉中的作用效果进行单因素试验。结果表明：三种外源植酸酶在不同条件下均有相一致的适宜酶解作用范围,分别为酶解温度50～60℃、酶解pH5.0～6.0、酶解时间约4h、外源酶添加量约0.5%,其中外源酶2较其他两种外源植酸酶在同等酶解作用条件下具有更好的作用效果。因此对外源酶2进一步以酶解温度、酶解pH值和酶解时间为三因素进行正交试验。结果发现各影响因素的主次顺序分别为酶解温度>酶解时间>酶解pH值,其最佳酶解条件为酶解温度55℃、酶解时间4.5h、pH5.5,此时磷利用率高达79.1%。     

单宁酶降解五倍子制备没食子酸的工艺优化

以五倍子为原料,单宁酶酶制剂为酶源,研究酶解温度、酶浓度、酶促反应时间以及酶促反应体系pH对单宁酶降解五倍子制备没食子酸得率的影响,再通过响应曲面法优化单宁酶降解五倍子制备没食子酸的工艺参数。结果表明,对没食子酸得率影响较大的因素依次为酶浓度、酶促反应时间、酶促反应体系pH以及酶解温度,最优工艺技术参数为酶浓度16.26 U/g,酶促反应时间5.88h,酶促反应体系pH 5.78,酶解温度40.70℃。在该参数条件下,没食子酸的得率为59.32%。     

响应面法优化眼点拟微绿球藻酶法提油工艺研究

采用纤维素酶酶解眼点拟微绿球藻提取胞内油脂。在单因素实验的基础上,以酶用量、酶解时间、酶解温度、酶解p H为自变量,油脂提取效率和EPA提取效率为响应值进行响应面法优化酶解反应条件。结果表明:对油脂提取效果影响的主次顺序为酶解温度酶解p H酶用量酶解时间,在酶用量1.59 g/kg(以干藻粉质量计)、酶解时间2.11 h、酶解温度39.3℃、酶解p H 4.17的条件下,油脂提取效率达到最大值98.72%#0.15%;对EPA提取效果影响的主次顺序为酶解温度酶解时间酶解p H酶用量,在酶用量1.60 g/kg(以干藻粉质量计)、酶解时间1.86 h、酶解温度37.9℃、酶解p H 4.10的条件下,EPA提取效率达到最大值97.86%#0.12%。     

酶在食品工业中的应用现状

综述了酶在食品工业中的应用现状,包括淀粉糖以及甜味剂相关酶、油脂相关酶、蛋白质相关酶、制造面包相关酶、酿造相关酶以及饮料相关酶等。     

酶辅助法提取脱脂葡萄籽蛋白的工艺研究

采用酶辅助碱溶酸沉法提取脱脂葡萄籽中的蛋白质,探讨酶添加量、酶解时间、酶解温度和酶解pH对脱脂葡萄籽蛋白得率的影响。结果表明:酶添加量为1.5%、酶解时间30 min、酶解温度36℃、酶解pH7.5,此条件下脱脂葡萄籽蛋白得率达31.87%,且影响因素的主次顺序为酶解pH酶解温度酶解时间。对得到的葡萄籽蛋白的溶解性、乳化性、起泡性进行了探讨。     

牡蛎肉酶解液的抗氧化工艺研究

采用胰蛋白酶酶解牡蛎肉蛋白,以酶解液清除DPPH自由基的效果为分析指标,采用单因素和正交试验,分析酶解的固液比、加酶量、时间、温度对酶解效果的影响,研究酶解的最佳工艺参数。结果显示,牡蛎肉酶解的最优水平组合为固液比1:3、加酶量0.25%、酶解时间2h、酶解温度45℃,牡蛎肉酶解液抗氧化性最强。     

酶解法制备香菇酱工艺条件的研究

在酶解法制备香菇酱的工艺中,采用正交试验设计分别对纤维素酶酶解条件和蛋白酶酶解条件进行了选择优化。结果表明,纤维素酶酶解的最佳工艺条件为酶解温度50℃、pH值6.5、酶用量0.3%、酶解时间60 min;蛋白酶酶解的最佳工艺条件为酶解温度50℃、pH值4.5、酶用量1%、酶解时间30 min,在此工艺条件下香菇酱的氨基酸含量为0.92%。     

响应面试验优化中性蛋白酶辅助提取青稞淀粉工艺

采用中性蛋白酶辅助提取青稞淀粉,研究料液比、加酶量、酶解时间、酶解温度和pH值对青稞淀粉中蛋白残留量的影响,选择加酶量、酶解时间、酶解温度为影响因素进行响应面优化试验。以淀粉蛋白残留量和淀粉提取率为评价指标,确定最佳提取工艺条件。结果表明,加酶量、酶解温度、酶解时间、加酶量与酶解温度的交互作用及加酶量与酶解时间的交互作用对淀粉蛋白残留量有极显著影响,而对淀粉提取率无显著影响。实验范围内得到的最佳提取工艺条件为加酶量140.79 U/g、酶解温度45.01 ℃、酶解时间2.57 h,在此条件下青稞淀粉的提取率为60.36%,淀粉蛋白残留量为1.31%。     

牛乳中黄嘌呤氧化酶研究综述

综述了牛乳中黄嘌呤氧化酶的各种性质及其应用。其性质主要包括:酶的构成、酶的分子量、酶的活性部位、酶的最适pH与最适温度、酶所催化的反应、反应类型、反应底物及产物等。另外,还介绍了一些酶反应动力学、酶活力的评价方法和酶的抑制剂等方面的问题。     

具α-葡萄糖苷酶抑制作用的蚕豆蛋白酶解物的制备

以蚕豆为原料,通过碱溶酸沉法得到蚕豆蛋白,再通过酶解制备具有α-葡萄糖苷酶抑制作用的蚕豆蛋白酶解物。以α-葡萄糖苷酶抑制率与水解度为指标,考察蛋白酶种类、酶解温度、酶解pH、料液比、加酶量与酶解时间对蚕豆蛋白酶解的影响,在此基础上采用响应面法对工艺参数进行优化。结果表明：酶解蚕豆蛋白制备具有α-葡萄糖苷酶抑制作用酶解物的最优工艺条件为以碱性蛋白酶为最适用酶、酶解温度50 ℃、酶解pH 8.5、酶解时间4.3 h、料液比1∶ 10、加酶量14 000 U/g,在此条件下酶解物α-葡萄糖苷酶抑制率为（38.58±0.87）%,蛋白水解度为22.87%。     

ICP/MS and ICP/AES elemental analysis (38 elements) of edible wild mushrooms growing in Poland

Thirty-eight elements, including toxic cadmium, lead, mercury, silver and thallium, were determined in 18 species of wild edible mushrooms collected from several sites in Pomorskie Voivodeship in northern Poland in 1994. Elements were determined by double focused high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES), after wet digestion of the dried samples with concentrated nitric acid in closed PTFE vessels using a microwave oven. K, P and Mg were present at levels of mg/g dry matter; Na, Zn, Ca, Fe, Cu, Mn, Rb, Ag, Cd, Hg, Pb, Cs, Sr, Al and Si were present at µg/g levels, while Tl, In, Bi, Th, U, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, La, Lu and Ba were present at ng/g levels.     

蒽醌助剂对乙二醇溶剂脱胶苎麻纤维性能的影响

为解决苎麻在乙二醇有机溶剂脱胶中纤维易被氧化而导致性能下降的问题,在乙二醇溶剂中添加助剂蒽醌对苎麻进行脱胶,并对蒽醌不同添加量下制得的纤维进行结构和性能表征。结果表明:纤维中半纤维素含量随蒽醌添加量的增加而升高,纤维的聚合度、结晶度、物理力学性能先升高后降低,纤维的残胶率和线密度先降低后升高;当蒽醌质量分数为0.3% 时,这些性能均达到最佳值,此时纤维的聚合度、结晶度、制成率、断裂强度、断裂伸长率、断裂功比不加蒽醌时分别提高了7.32%、20.53%、1.46%、9.55%、6.89%、33.33%,纤维的残胶率、线密度比不加蒽醌时分别降低了17.91%、7.24%。     

Encapsulation of food ingredients

Microencapsulation is a relatively new technology that is used for protection, stabilization, and slow release of food ingredients. The encapsulating or wall materials used generally consist of starch, starch derivatives, proteins, gums, lipids, or any combination of them. Methods of encapsulation of food ingredients include spraydrying, freeze‐drying, fluidized bed‐coating, extrusion, cocrystallization, molecular inclusion, and coacervation. This paper reviews techniques for preparation of microencapsulated food ingredients and choices of coating material. Characterization of microcapsules, mechanisms of controlled release, and efficiency of protection/ stabilization of encapsulated food ingredients are also presented.     

Daily intake of trace metals through coffee consumption in India

The trace element contents of five varieties of instant coffee powder available in the Indian market have been analysed. Ca, Cr, Fe, K, Mg, Mn, Ni, Sr, Zn and Pb, Cd, Cu have been determined using atomic absorption spectrophotometry and differential pulse anodic stripping voltammetry, respectively. The metal levels in the coffee powders observed in this study are comparable with those reported for green coffee beans (Arabica and Robusta variety) reported worldwide with the exception of Sr and Zn, which were on the lower side of the reported values. Concentrations of these metals have been converted into intake figures based on coffee consumption. The daily intakes of the above metals through ingestion of coffee are 1.4mg, 1.58 mu g, 124 mu g, 41.5mg, 4.9mg, 17.9 mu g, 2.9 mu g, 3.8 mu g, 12.5 mu g, 0.2 mu g, 0.03 mu g and 15.5 mu g, respectively. The values, which were compared with the total dietary intake of metals through ingestion by the Mumbai population, indicate that the contribution from coffee is less than or around 1% for most of the elements except for Cr and Ni which are around 3% .     

Avena sativa (Oat), A Potential Neutraceutical and Therapeutic Agent: An Overview

The aim of the present review article is to summarize the available information related to the availability, production, chemical composition, pharmacological activity, and traditional uses of Avena sativa to highlight its potential to contribute to human health. Oats are now cultivated worldwide and form an important dietary staple for the people in number of countries. Several varieties of oats are available. It is a rich source of protein, contains a number of important minerals, lipids, β-glucan, a mixed-linkage polysaccharide, which forms an important part of oat dietary fiber, and also contains various other phytoconstituents like avenanthramides, an indole alkaloid-gramine, flavonoids, flavonolignans, triterpenoid saponins, sterols, and tocols. Traditionally oats have been in use since long and are considered as stimulant, antispasmodic, antitumor, diuretic, and neurotonic. Oat possesses different pharmacological activities like antioxidant, anti-inflammatory, wound healing, immunomodulatory, antidiabetic, anticholesterolaemic, etc. A wide spectrum of biological activities indicates that oat is a potential therapeutic agent.     

5—THE CONSTITUTION OF THE EPICUTICLE OF WOOL

Epicuticle, isolated from wool via the Allwörden reaction, was examined by electron microscopy and analysed chemically. It is proteinaceous; lipids and carbohydrates could not be detected. The component amino acids are: cystine, glycine, glutamic acid, serine, valine, alanine, lysine, α-amino-adipic acid, and threonine. A tentative model for the epicuticle is proposed.     

Influence of different non-grain commodities on the population growth of Trogoderma granarium Everts (Coleoptera: Dermestidae)

We investigated the population growth of the khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae) on seven groups of commercially available non-grain commodities. Six powdered spices were used in the first group of experiments: black pepper, clove, nutmeg, allspice, cinnamon and turmeric. The second group of the tested commodities included seven animal products: powdered cow milk, powdered pork zelatin, sheeps’ wool, goat’s skin, ducks’ feathers, dry dog food and dry cat food. The third group of commodities was consisted of six herbs: oregano, spearmint, basil, coriander, laurel and marjoram. The fourth group of commodities contained ten pulses: chickpeas, lentil, split peas, black-eyed peas, beans, soybean flour and whole kernels, lima beans, mung bean, and broad beans. The fifth group comprised six dried fruits: Corinthian currants, sultanas, banana chips, melons, apricots and figs. The sixth group was consisted of five non-grain commodities: cottonseed cake, tobacco, black tea, Turk kahvesi and potato flour. The seventh group included seven nuts: sunflower seeds, pumpkin seeds, pistachios, roasted chickpeas (yellow), almonds, hazelnuts and walnuts. Finally, six cracked containment categories (0% cracked kernels, 5% cracked kernels and 95% intact kernels, 10% cracked kernels and 90% intact kernels, 25% cracked kernels and 75% intact kernels, 50% cracked kernels and 50% intact kernels and 100% cracked kernels) from five pulses were tested: chickpeas, black-eyed peas, mung bean, soybean and split peas. The highest progeny production (3.01 individuals per vial) was recorded on powdered cow milk. On pistachios, split peas, sunflower seeds, soybean flour, pumpkin seeds, walnuts, almonds and coriander, T. granarium built high population densities rapidly, while on roasted chickpeas, cottonseed cake, hazelnuts, chickpeas, dog food and lentils, its population growth was much less. Broad beans, melons, figs, lima beans, beans, Corinthian currants, pork zelatin and potato flour were less suitable diets for the development of this species. On black pepper, clove, nutmeg, allspice, cinnamon, turmeric, sheeps’ wool, goat’s skin, ducks’ feathers, cat food, sultanas, banana chips, apricots, tobacco, black tea, Turk kahvesi, oregano, spearmint, basil, laurel and marjoram, no progeny production was recorded. The proportion of 100% cracked black-eyed peas or mung beans was more suitable for the population growth of T. granarium. Also, the percentages of 50% cracked chickpeas or 10% cracked soybeans enhanced the development of the species, in comparison with the whole kernels of each pulse. Our study indicated that several non-grain commodities are beneficial for the population growth of T. granarium, a fact that should be seriously taken into account in international trade, as this pest may utilize them as “vehicles” of expansion.     

Matrix effects on flavour volatiles release in dark chocolates varying in particle size distribution and fat content using GC–mass spectrometry and GC–olfactometry

Influences of matrix particle size distribution (PSD) (18, 25, 35 and 50 μm) and fat content (25%, 30% and 35%) on flavour release of dark chocolate volatiles were quantified by static headspace gas chromatography using GC–MS. Sixty-eight (68) flavour compounds were identified, comprising alcohols, aldehydes, esters, ketones, furans, pyrans, pyrazines, pyridines, pyroles, phenols, pyrones and thiozoles. From GC–olfactometry, 2-methylpropanal, 2-methylbutanal and 3-methylbutanal had chocolate notes. With cocoa/roasted/nutty notes were trimethyl-, tetramethyl-, 2,3-dimethyl-, 2,5-dimethyl-, 3(or 2),5-dimethyl-2(or 3)-ethyl- and 3,5(or 6)-diethyl-2-methylpyrazine and furfuralpyrrole. Compounds with fruity/floral notes included 3,7-dimethyl-1,6-octadien-3-ol and 5-ethenyltetrahydro-R,R,5-trimethyl-cis-2-furanmethanol. Caramel-like, sweet and honey notes were conferred by 2-phenylethanol, phenylacetaldehyde, 2-phenylethylacetate, 2,3,5-trimethyl-6-ethylpyrazine, 2-carboxaldehyde-1H-pyrrole, furancarboxaldehyde, furfuryl alcohol and 2,5-dimethyl-4-hydroxy-3(2H)furanone. There were direct relationships of fat content with 3-methylbutanal and branched pyrazines but inverse ones with 2-phenylethanol, furfuryl alcohol, methylpyrazine, phenylacetaldehyde, 2, 3, 5-trimethyl-6-ethylpyrazine and 2-carboxaldehyde-1-H-pyrrole. Particle size influenced higher alcohol, aldehyde, ester, ketone and pyrazine concentrations at all fat contents. A multivariate product space suggested flavour effects of the interacting factors.     

Bioactivation of Phytoestrogens: Intestinal Bacteria and Health

Phytoestrogens are polyphenols similar to human estrogens found in plants or derived from plant precursors. Phytoestrogens are found in high concentration in soya, flaxseed and other seeds, fruits, vegetables, cereals, tea, chocolate, etc. They comprise several classes of chemical compounds (stilbenes, coumestans, isoflavones, ellagitannins, and lignans) which are structurally similar to endogenous estrogens but which can have both estrogenic and antiestrogenic effects. Although epidemiological and experimental evidence indicates that intake of phytoestrogens in foods may be protective against certain chronic diseases, discrepancies have been observed between in vivo and in vitro experiments. The microbial transformations have not been reported so far in stilbenes and coumestans. However, isoflavones, ellagitanins, and lignans are metabolized by intestinal bacteria to produce equol, urolithins, and enterolignans, respectively. Equol, urolithin, and enterolignans are more bioavailable, and have more estrogenic/antiestrogenic and antioxidant activity than their precursors. Moreover, equol, urolithins and enterolignans have anti-inflammatory effects and induce antiproliferative and apoptosis-inducing activities. The transformation of isoflavones, ellagitanins, and lignans by intestinal microbiota is essential to be protective against certain chronic diseases, as cancer, cardiovascular disease, osteoporosis, and menopausal symptoms. Bioavailability, bioactivity, and health effects of dietary phytoestrogens are strongly determined by the intestinal bacteria of each individual.     

Evaluation of mycotoxin-contaminated cereals for their use in animal feeds in Hungary

In the period between December 5, 1991 and September 17, 1998, 760 maize, 367 wheat, 119 soybean, 222 barley, 85 bran, 32 triticale, 60 oat, 14 rye and 22 sunflower samples were investigated for the presence and concentration of seven fusariotoxins (T-2 toxin, zearalenone, deoxynivalenol, nivalenol, diacetoxyscirpenol, HT-2 toxin, fusarenone-X) and OTA. The comparison of analytical data with those of the relevant literature revealed that although the incidence rate and/ or concentration of Fusarium mycotoxins and OTA in Hungarian-grown cereals is occasionally considerable, the position of the country is not worse than the average of countries. Our findings indicate that soybean tends to be good substrate for trichothecene-producing fungi and the rate of contamination is regarded as substantial. The commodities were assorted into one of three quality categories. The proportion of objectionable samples was only 3.0, 2.2, 2.3 and 1.7% in maize, wheat, barley and soybean samples, respectively. However, this low rate of objection might still be a source of great economic loss. The proportion of objectionable samples was much higher in the case of bran, oat and triticale (7.1, 6.7, and 6.3%, respectively). The results of the present investigation indicate a need for regular screening for mycotoxins of importance and individual appraisal of each commodity from the point of their use in animal feeds.