不同生物保护菌种对低温发酵酸乳品质的影响

目的探究不同生物保护菌种对低温发酵酸乳品质的影响。方法将6组不同组合的生物保护菌种(RP80、LPRA、LRB、BG112、YM-C、GP101)应用于低温发酵搅拌型酸乳,比较不同生物保护菌种对酸乳发酵特性和品质的影响及对酵母菌、霉菌的抑制效果。结果 6组生物保护菌种均对发酵剂的产酸能力没有影响;其中LPRA对霉菌菌抑制效果较好,RP80和LPRA对酵母菌抑制效果较好。相同发酵条件下接入生物保护菌种LPRA的低温长时间发酵酸乳品质指标略优。结论生物保护菌LPRA对霉菌和酵母菌具有较好抑制的作用,能够较高提高酸乳品质。     

乳酸菌对酸奶保鲜作用的研究

目的比较4种具有保鲜作用的乳酸菌对酸奶中霉菌的抑制效果及在发酵和贮藏过程中对酸奶品质的影响。方法将4种乳酸菌添加到发酵乳中,比较对酸乳中霉菌的抑制作用,并对酸奶酸度、活菌数、质构和感官品质进行检测。结果按厂家推荐量和相同活菌数(2.0×10~6 CFU/m L)添加4种乳酸菌均对霉菌的生长具有抑制作用,其中,乳酸菌A和C的抑菌效果较好;按照厂家推荐量添加4种乳酸菌发现,乳酸菌A和B的添加对酸奶的发酵时间、贮藏期内的酸度、活菌数、质构和感官均无影响,而乳酸菌C和D的添加会对酸奶贮藏期内的酸度和感官产生影响。结论乳酸菌A能够有效抑制酸奶中霉菌滋生,同时不会对酸奶的品质产生影响。     

嗜热链球菌与保加利亚乳杆菌的不同比例对酸乳发酵性能和产香特性的影响

对嗜热链球菌株st和保加利亚乳杆菌株iv-3,按照不同比例组成酸乳发酵剂zh1,zh2,zh3和zh4。结果表明,两株乳酸菌具有较好的互配共生性,是可利用的酸乳发酵剂组合菌株,4个发酵剂的发酵酸乳在凝乳时间、产酸速度、黏度、发酵乳活菌数和感官评价等方面均好于单菌株发酵乳。4个发酵剂适合酸乳生产,发酵乳在比较长的货架期内品质保持稳定,其中发酵剂zh3的综合表现最好,发酵凝乳时间短,产酸速度快,酸乳冷藏期间黏度好,乳酸活菌含量多,香味物质比例最协调,感官评定最好,具有较好的应用价值。     

乳酸菌与酵母菌对牦牛酸乳品质形成的影响

为明确乳酸菌和酵母菌在牦牛酸乳品质形成中发挥的作用,以牦牛乳粉为原料、牦牛酸乳为发酵剂发酵酸乳,在发酵过程中分别抑制乳酸菌和酵母菌的活性,测定并比较正常发酵、抑制乳酸菌发酵、抑制酵母菌发酵酸乳的风味、口感、质构等相关指标。结果表明,乳酸菌和酵母菌对牦牛酸乳品质形成均起到关键作用,乳酸菌对酸乳酸度、质构、氨基酸态氮、有机酸、V_(B1)及酮类和酸类风味物质的贡献较大,酵母菌对乙醇、V_(B2)及醇类和酯类风味物质的贡献较大。     

生物保鲜菌种Yo-guard360在酸乳保鲜中的应用

本文主要测试保鲜菌种Yo-guard360在酸乳保鲜中应用效果,旨在为提高发酵乳制品质量安全提供解决方案。为综合评价保鲜菌种对酸乳发酵状态、质构、后酸及抑菌保护效果的影响,以基础发酵菌种Yo-cul175和Yo-cul975为测试对象,通过人工污染腐败菌和加速贮藏实验来放大测试条件。实验表明,保鲜菌种能够抑制酸乳中初始含量为20～30 CFU/mL的酵母和霉菌的繁殖,降低酸乳的污染率,延长自然贮藏酸乳保质期2～3周。通过发酵过程监测和酸乳感官测评,保鲜菌种的额外添加并不干扰酸乳的正常发酵过程,对酸乳的质构、风味、持水力均无负面影响。跟踪酸乳在6℃和12℃贮藏条件下酸度的变化,添加保鲜菌种的实验组产酸略高于对照组,带来微弱的口感差异。作为一种保证酸乳质量安全的措施,生物保鲜菌种显示出了较好的应用潜力。     

乳酸菌发酵对曲奇饼干品质的影响

为考察乳酸菌发酵对曲奇饼干品质的影响,选用4种酸乳发酵剂对曲奇面团进行发酵,4号发酵剂发酵效果较好,采用单因素和正交实验优化发酵条件,测定了发酵组和对照组的感官评分、理化指标及储存期微生物数量的变化。结果表明,最佳发酵条件为:发酵温度42 ℃、发酵时间4 h、接种量（质量分数）4.5％。经过发酵的曲奇饼干口感更香脆清新,感官评分90分,对照组80分。发酵组的还原糖质量分数、脂肪质量分数、胆固醇质量分数比对照组分别低2.67 g/hg、6 g/hg、205 mg/kg,丙烯酰胺质量分数也有所下降。乳酸菌发酵对菌落总数和大肠菌群的抑制效果明显,对霉菌总数的抑制效果不明显。实验结果为乳酸菌应用于曲奇饼干生产工业化打下理论基础。     

嗜酸乳杆菌KLDS 1.0901对酸奶发酵特性及抗氧化活性的影响

研究嗜酸乳杆菌KLDS 1.0901在发酵酸奶过程中对酸奶特性及抗氧化活性的影响,开发出一种抗氧化活性强的酸奶发酵剂。通过选取嗜热链球菌S1、德式乳杆菌保加利亚亚种KLDS 1.0207发酵酸奶以及向其中加入嗜酸乳杆菌KLDS 1.0901共同发酵制备酸奶,评价其产酸性能、活菌数含量,并分析所发酵酸奶的质构特性、乙醛和双乙酰产量,进行感官评价,最后对制备酸奶的体外抗氧化活性进行探索和研究,进而比较研究嗜酸乳杆菌KLDS 1.0901对发酵酸奶的发酵性能和抗氧化能力。结果表明:用嗜热链球菌S1、德式乳杆菌保加利亚亚种KLDS 1.0207及嗜酸乳杆菌KLDS 1.0901共同发酵的酸奶产酸速度快,5 h基本凝乳,与未添加嗜酸乳杆菌KLDS 1.0901发酵的酸奶相比,其中乳酸菌的活菌数为3.55×10~8CFU/g、风味物质乙醛的含量为22.8μg/mL、双乙酰含量为7.5μg/mL,以及感官评分为86分,仅次于3号汉森发酵剂。与3号汉森发酵剂相比,添加KLDS 1.0901的2号发酵剂在清除自由基的体外抗氧化能力方面与其相近。     

酸乳在加工贮藏过程中微生物菌相演变与卫生标准研究

应用选择性培养基对凝固型酸乳加工过程中细菌菌相演变情况进行分析,同时应用国家标准方法对酸乳加工储藏过程中的微生物卫生指标菌落总数、大肠菌群、霉菌和酵母菌的消长状况进行研究。结果表明假单胞菌、肠杆菌科和乳酸菌是原料乳中的优势菌群,经过杀菌、接种和发酵后,乳酸菌为优势菌群。贮藏一周后霉菌和酵母菌逐渐增加并成为次要优势菌群,三周后细菌菌落总数增加。霉菌、酵母菌和细菌是引起酸乳腐败的主要微生物类群。     

藏灵菇牦牛酸乳发酵过程中乳酸菌和酵母菌对品质的作用

藏灵菇酸乳是由乳酸菌、酵母菌、醋杆菌和霉菌共同发酵形成的一种发酵乳制品,其品质特征与普通酸乳有显著差异。为研究藏灵菇发酵酸乳中乳酸菌和酵母菌分别发挥的作用,利用放线菌酮和青链霉素分别抑制发酵过程中的酵母菌和乳酸菌,测定并比较正常发酵酸乳、抑制乳酸菌发酵酸乳和抑制酵母菌发酵酸乳的风味、口感和质构等相关指标。实验结果显示抑制酵母菌发酵的酸乳中乙醇含量由1.85g/kg上升为2.77g/kg,VB2含量由168μg/100g下降为157μg/100g,与正常发酵组差异较大;抑制乳酸菌发酵的酸乳中酸度由18°T上升为28°T,氨基酸态氮由65mg/100g下降为53mg/100g,乳酸含量持续2mg/g,乙酸由1mg/g下降为0.7mg/g,VB1含量由20μg/100g下降为18μg/100g,与正常发酵组差异较大。乳酸菌在酸乳发酵过程中,对酸度、氨基酸态氮、质构、乳酸、乙酸与VB1的生成贡献较大;酵母菌对乙醇、VB2的生成贡献较大。     

乙基麦芽酚对酸奶发酵的影响

对添加乙基麦芽酚的酸奶发酵工艺进行了研究。通过对发酵过程中乳酸菌总数、总酸度、感官品质等指标的定期观察检测,结果表明:在添加乙基麦芽酚后严重地抑制了酸乳发酵工程中乳酸菌的增殖和产酸作用。     

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.     

The Ministry of Environmental Protection Issued "Feasible Technology Guidelines for Pollution Prevention and Control in Wood Pulping Process of the Paper Industry (Trial)" and Two Other Guiding Technical Documents

On December 27t＂, 2013, the Ministry of Environmenta Protection announced that, in order to implement ＂The Environmental Protection Law of the People＇ s Republic of China＂, improve the working system in environmenta protection technologies, and promote technologica advancement in pollution prevention, the Ministry of Environmental Protection sponsored the formulation of three guiding technical documents including ＂Feasible Technology Guidelines for Pollution Prevention and Contro n Wood Pulping Process of the Paper Industry （Trial）＂     

1~(st) Intelli-Tissue~ EcoEc Tissue Machine Supplied by PMP Group Successfully Put into Operation in China

正On April 29th,2014,Intelli-Tissue EcoEc tissue machine supplied by PMP Group successfully put into operation at Hebei Xuesong Paper Co.,Ltd.,this is the first such kind of paper machine of PMP Group in China.