浓醪发酵玉米蛋白粉饲料生产工艺的研究

利用纳豆杆菌采用浓醪发酵法对玉米蛋白进行改性.通过对浓醪发酵条件的优化研究,确定适宜的改善玉米蛋白溶解性的发酵条件,提高玉米蛋白的溶解性,有利于动物对蛋白的消化吸收,从而提高玉米蛋白作为饲料的利用率.适宜的发酵条件为:培养基干基与水的比例为1:3.5,培养基初始pH值为7.0,接种量4.29%,培养温度32℃,摇瓶转速190 r/min,培养时间20 h.在此条件下,培养液中可溶性蛋白质含量可达到(29.05±0.67)mg/ml.     

枯草芽孢杆菌发酵玉米黄粉制备可溶性肽

采用枯草芽孢杆菌发酵玉米湿法生产淀粉的副产物来制备玉米可溶性肽。通过单因素和响应面试验对发酵培养基及培养条件进行了系统优化,得到最佳发酵培养基为:脱淀粉玉米黄粉(destarch corn gluten meal,DCGM)添加量100 g/L、蔗糖添加量8 g/L、Na Cl添加量1. 0 g/L。最佳发酵条件为:发酵时间42 h、培养基初始p H 9. 0、发酵温度37℃、接种量4%、发酵转速180 r/min。在此优化条件下,摇瓶发酵获得可溶性肽含量为22. 7 g/L,是优化前的13. 3倍。理化分析显示,该可溶性肽以分子质量<1 000 Da的低聚肽为主(将近80%),具有突出的抗氧化活性,尤其是O2-·清除率达60%,DPPH·清除率达80%,远优于目前的商品肽。该研究表明,利用枯草芽孢杆菌发酵玉米黄粉产可溶性肽是可行的,为玉米黄粉的高值化利用提供技术依据。     

枯草芽孢杆菌发酵芝麻香白酒酒醅制备抗氧化活性肽

利用产酸性蛋白酶的枯草芽孢杆菌对洋河酒厂的芝麻香型酒醅进行固态发酵,使蛋白大分子转化成小分子肽。在发酵温度、发酵时间和含水量条件的单因素试验基础上,利用响应面方法优化固态发酵条件以生产小分子肽的含量,同时考察了提取得到的酒醅肽的分子质量、氨基酸组成和抗氧化活性。经响应面优化后,最优发酵条件为:发酵温度30℃、发酵时间47 h、含水量1. 2 mL/g,在此条件下提取液中小分子肽的含量为7. 04mg/mL,并多为分子质量低于2 000 Da的肽。所制备的小分子肽具有较好的抗氧化活性,在0. 4 mg/mL质量浓度下对DPPH和ABTS自由基清除率分别达到85. 5%和66. 24%。初步建立了一种基于白酒酒醅固态发酵的方法,分解酒醅中的蛋白制备抗氧化活性小分子肽,为降低产品中的高级醇,提高产品品质提供了一种参考。     

两步水解法制备玉米抗氧化活性肽及产物的稳定性

采用麦芽粉和碱性蛋白酶Alcalase对玉米醇溶蛋白进行两步水解制备玉米肽,以水解度、可溶性蛋白含量和抗氧化活性为指标,对第二步Alcalase的酶解条件进行优化,以确定制备玉米抗氧化肽的最适条件。另外,对玉米抗氧化肽的稳定性进行了研究。结果表明：制备玉米抗氧化肽的最适条件为：第一步麦芽粉水解,在底物浓度10%、pH5.5、温度50 ℃、酶底比30%条件下水解3 h;第二步Alcalase酶解,在底物浓度10%、pH8.5、温度60 ℃、酶底比0.75%条件下水解6 h。在此条件下,水解度、可溶性蛋白含量、羟基自由基清除率及亚铁离子螯合率分别为24.53%、33.43 mg/mL、30.59%、38.32%,分子量主要分布在300-6500 u（92.51%）范围内。玉米抗氧化肽具有热及贮藏稳定性,在中性和碱性条件下稳定,但不耐受酸性条件（pH3-5）。     

Alcalase酶解高底物浓度玉米蛋白工艺优化

以玉米蛋白粉为原料,研究底物浓度、加酶量、水解液pH值和水解温度对酶解产物水解度、可溶性蛋白含量、抗氧化活力和蛋白转换率的影响.首先将玉米蛋白粉顺次进行碱洗、α-淀粉酶去淀粉和高温蒸煮预处理,以破坏蛋白高级结构和去除淀粉,然后以碱性蛋白酶Alcalase为生物催化剂进行玉米蛋白(10％～15％,m∶V)的限制性水解.结果表明,最适酶解条件:底物浓度13.5％(m∶V),加酶量2％,水解温度68℃,反应体系pH值7.7,总水解时间210min.在上述条件下,蛋白水解度为28.81％,水解液的可溶性蛋白含量为31.69mg/mL,水解物抗氧化活性为547.83U/mL,蛋白转化率为36.92％.获得的玉米蛋白水解物的溶解性显著增加,具有良好的抗氧化活性,显示了其在食品和药品等行业应用的潜力和前景.     

酵母固态发酵制备花生蛋白肽及抗氧化活性研究

研究啤酒酵母固态发酵制备花生蛋白肽,为进一步研究发酵花生粕产品提供理论基础。本研究运用单因素和正交试验方法对固态发酵制备花生蛋白肽工艺条件进行优化,其最佳制备工艺条件为:营养盐溶液添加量15 mL,啤酒酵母液添加量4 mL,30℃下发酵72 h。此工艺下制备的花生蛋白肽的可溶性氮浓度达到10.74 mg/mL,发酵液对1,1-二苯基苦基苯肼(DPPH)和羟自由基清除率分别为93.57%和98.40%。分子量小于5 kDa的花生蛋白肽具有较高的抗氧化活性。     

黑曲霉固态发酵制备花生蛋白肽及抗氧化活性研究

研究黑曲霉固态发酵制备花生蛋白肽,为进一步研究发酵花生粕的深加工产品提供理论基础。运用单因素和正交试验方法对固态发酵制备花生蛋白肽工艺条件进行优化,其最佳制备工艺条件为:营养盐溶液添加量15 mL,黑曲霉液添加量1 mL,30℃下发酵36 h。此工艺下制备的花生蛋白肽的可溶性氮浓度达到38.74 mg/mL,发酵液对1,1-二苯基苦基苯肼(DPPH)自由基清除率为81.22%,羟自由基清除率为84.88%。分子量小于5 ku的花生蛋白肽具有较高的抗氧化活性。     

玉米蛋白水解物对生鸡肉糜脂质氧化的影响

玉米蛋白粉是玉米湿法生产淀粉的主要副产物。以玉米蛋白粉为原料,对其先进行高温蒸煮预处理,然后采用碱性蛋白酶和复合蛋白酶对其进行双酶顺序水解,制得具有抗氧化活性的蛋白水解物,将其添加到生鸡肉糜中,研究肉糜的过氧化值(PV值)、硫代巴比妥酸值(TBA值)、巯基含量、盐溶性蛋白含量(SSP值)和感官评价的变化情况,考察玉米蛋白水解物对生肉糜脂质氧化的影响。结果表明:玉米蛋白水解物的水解度达到29.5%,抗氧化活性达到599.11U/mL;肉糜中玉米肽的添加延缓了脂质的氧化,且玉米肽添加量的不同对各指标有着不同程度的影响,其中,含0.05%玉米肽的肉糜脂质氧化程度最弱,具有良好的抗氧化效果。     

菌酶联合制备猪血抗氧化低聚肽

以猪血为原料,依次采用枯草芽孢杆菌发酵和碱性蛋白酶水解制备猪血抗氧化低聚肽,通过响应面试验优化发酵工艺和酶解工艺,最佳发酵参数为:底物浓度59.0 g/L、发酵时间56.5 h、接种量3.22∶100(体积比),此时多肽含量为2.31 mg/mL,·OH清除率为78.94%;最佳酶解参数为:酶解时间3.0 h、pH 9.5、酶解温度60℃、酶底比390 U/g,此条件下制备得到酶解液的多肽含量5.48 mg/mL,多肽含量较单一发酵提高2.39倍,·OH清除率为93.62%。采用超滤分离法,获得分子量分别为0~1 kDa、1 k Da~5 kDa和0~5 kDa的猪血抗氧化低聚肽,采用7种体外抗氧化指标(·OH清除率、·O~(2-)清除率,抑制脂质过氧化能力、还原力、ABTS~+·清除率、DPPH·清除率、总抗氧化力)评价3种不同分子量段的猪血低聚肽的抗氧化活性,结果表明:3种不同分子量段抗氧化肽活性大小为0~1 kDa0~5 kDa1 kDa~5 kDa,提示高抗氧化活性的猪血低聚肽的分子量集中在1 kDa以下。     

纳豆菌液态发酵谷物产纳豆激酶及发酵产物抗氧化活性研究

本文研究了纳豆菌液态发酵时间对纳豆菌生物量、蛋白酶酶活、纳豆激酶酶活的影响。在此基础上,研究添加四种谷物(糙薏仁、玉米、荞麦和糙米)对纳豆菌液态发酵产蛋白酶酶活、纳豆激酶酶活、谷物总酚迁移率、总酚残留率以及发酵产物抗氧化活性的影响。结果表明:添加糙米和荞麦可显著促进纳豆菌产蛋白酶(2444.19、1813.71 U/mL)、纳豆激酶(719.67、681.38 U/mL),且以荞麦为底物所产发酵产物的谷物总酚迁移率最高(0.64 mg/g干谷物)、抗氧化活性最强(30.37μmol trolox equiv/mL);采用浸泡蒸煮处理四种谷物、延长发酵时间可显著提高其发酵产物的蛋白酶酶活、纳豆激酶酶活、谷物总酚迁移率以及抗氧化活性。采用浸泡蒸煮处理荞麦,利用纳豆菌液态发酵其48 h,可制备富含纳豆激酶、谷物多酚、肽类物质且具有强溶栓、抗氧化活性的功能性食品。     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

Tests of potential functional barriers for laminated multilayer food packages. Part II: Medium molecular weight permeants

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status