复合菌剂和酸化剂组合对玉米秸秆青贮的影响

以玉米秸秆为原料,设置对照组（CK）和5个试验组（分别添加布氏乳杆菌（L1）、植物乳杆菌（L2）、戊糖片球菌（L3）、复合菌剂（L4）、复合菌剂及酸化剂（L5））。选取不同发酵时间（0 d、15 d、30 d、45 d、60 d、90 d）取样,测定玉米秸秆中乳酸菌数、酵母菌数以及pH随时间的变化规律,并在青贮饲料发酵90 d结束后检测青贮发酵产物及有氧稳定性。结果表明,与对照组相比,乳酸菌剂的添加均能提高青贮饲料品质,但戊糖片球菌提升效果较差;复合菌剂与单独添加布氏乳杆菌或植物乳杆菌之间无明显差异（P＞0.05）;酸化剂的添加显著提高了青贮饲料有氧稳定性（P＜0.05）。     

复合发酵剂对发酵牛肉干理化品质及安全性能的影响

以清酒乳杆菌、戊糖片球菌及木糖葡萄球菌为复合发酵剂（1:2:2）制作发酵牛肉干,通过色差计及高效液相等仪器测定不同阶段牛肉干的pH、水分活度、色泽及生物胺含量等指标的变化,旨在探究复合发酵剂对发酵牛肉干理化品质和生物胺组成的影响。结果表明:接种上述复合发酵剂促使肉干中乳酸菌快速成为优势菌群,加快产品酸化速率,发酵结束时清酒乳杆菌+戊糖片球菌+木糖片球菌复合发酵剂组（LSS组）pH降为4.43,显著低于对照组（CO组）（P<0.05）;pH的快速下降促进肉干中水分快速蒸发和Aw的降低,显著抑制了肉干中肠杆菌的数量,使得LSS中肠杆菌数量降低到2.04 CFU/g。复合发酵剂的快速繁殖抑制了肉干中腐胺和尸胺的积累,LSS组尸胺和腐胺含量显著低于CO组（P<0.05）。随着加工温度和优势菌群数量的变化,对组胺产生较大抑制作用,使添加复合发酵剂的LSS组组胺含量（22.56 mg/kg）仅为CO组的1/2。因此,添加上述复合发酵剂有利于缩短发酵牛肉干加工周期、提高产品品质和安全性能。     

添加红枣汁对植物乳杆菌发酵胡萝卜品质的影响

为改善胡萝卜发酵制品的品质,本研究以植物乳杆菌为发酵菌株,探讨添加红枣汁对植物乳杆菌发酵胡萝卜(37 ℃发酵7 d)过程中理化指标和营养成分的影响。结果表明,与对照和未添加红枣汁发酵的胡萝卜相比,红枣汁发酵组的抗坏血酸和胡萝卜素含量显著升高,在发酵7 d后分别升高了8.48 mg/100 g(P<0.01)和1.29 mg/100 g(P<0.05)。红枣汁发酵组的总酚、总酸含量和活菌数显著高于对照和未添加红枣汁组(P<0.01)。红枣汁发酵组的多糖和亚硝酸盐含量降低,但与对照和未添加红枣汁组没有显著差异(P>0.05),同时,3组胡萝卜的质构特性、色差值和pH没有显著性差异(P>0.05)。上述结果显示,添加红枣汁对植物乳杆菌发酵胡萝卜的品质有一定程度的改善。     

不同发酵剂对羊肉发酵香肠理化特性的影响

通过测定添加不同发酵剂羊肉发酵香肠加工和贮藏过程中的pH值,Aw值,水分含量,TBARS值和色泽的变化,研究菌种对羊肉发酵香肠理化特性的影响。第1组为未添加菌种的对照组,第2组为添加植物乳杆菌组,第3组为按1:2添加植物乳杆菌和木糖葡萄球菌的混合组。结果表明:发酵过程中,3组发酵香肠pH值均有所下降,但添加植物乳杆菌和混合组下降较多,在发酵结束后的干燥、成熟和室温贮藏过程中pH值有上升的趋势,对照组pH值上升快,而植物乳杆菌组和混合组pH值上升缓慢。各组Aw值在加工阶段迅速下降,植物乳杆菌组最快,混合组其次。水分含量在发酵结束时变化不大,在随后的干燥、成熟阶段水分含量显著下降,贮藏过程中仍缓慢降低。TBA值在发酵、干燥、成熟和贮藏前2周表现上升趋势,而贮藏4周后TBA值显著下降。植物乳杆菌组和混合菌种组红度值(a)分别为16.91和17.17,均高于对照组;黄度值(b)和(L)明度值均显著低于对照组(P<0.05),而混合组略低于植物乳杆菌组。     

添加发酵剂对猪肉脯品质的影响

分别利用戊糖片球菌,植物乳杆菌,肉糖葡萄球菌单一菌种和复合菌种对原料肉进行发酵,生产发酵型猪肉脯,分析了成品质构、水分活度、肌原纤维小片化指数(MFI)和感官品质等指标的变化。结果表明:与对照组相比,发酵可以明显改善产品的质构和感官品质。其中经肉糖葡萄球菌和戊糖片球菌复配发酵的产品剪切力可降低39.8%,MFI由对照组42.87提高到84.73。各发酵组的水分活度(Aw)和水分含量无显著区别,但与对照组相比有显著下降(p0.05)。添加肉糖葡萄球菌发酵组和三组复配发酵组猪肉脯感官评分显著高于对照组(p0.05)。     

混合发酵剂的筛选及对发酵猪肉香肠加工特性及安全性能的影响

通过比较不同比例植物乳杆菌与木糖葡萄球菌的复合发酵剂的生长活性、产酸能力、耐盐及耐亚硝酸盐特性,筛选最佳复配比例的混合发酵剂并制作发酵香肠。旨在探究复合发酵剂对发酵香肠理化品质及生物胺的影响。结果表明:植物乳杆菌与木糖葡萄球菌复合比为1:1时,具有较好的生长、产酸、耐盐及耐亚硝酸盐能力。接种1:1的植物乳杆菌与木糖葡萄球菌混合发酵剂制备的香肠pH值下降速率快于单一乳酸菌组和空白对照组;发酵结束混合组pH值降为4.95,显著低于对照组和单一组(P<0.05);pH值下降改变了蛋白质与水分结合能力、促使香肠Aw随之降低,使得混合组Aw低于单一组和对照组;相比香肠色泽,3组差异不显著(P>0.05)。成熟后期混合组尸胺和组胺检出量均低于单一组和对照组。由研究结果可知添加复合发酵剂有助于提高香肠安全性、缩短发酵成熟周期。     

盐酶混合添加对苜蓿发酵品质的影响

采用添加剂青贮是贮存和利用苜蓿的一种有效方式。试验以2龄第1茬苜蓿作为试验对象,选用青贮卫士（无机盐混合物）和纤维素酶两种青贮添加剂,分别设置对照组、青贮卫士（1．0 g／kg）、纤维素酶（20 mg／kg）和等剂量青贮卫士与纤维素酶混合添加处理组来研究盐酶混合添加对苜蓿青贮发酵品质的影响。在实验室条件下青贮45 d后开封取样,测定各组的相关发酵指标,结果显示,各处理组发酵品质相对于对照组发酵品质均有不同程度的提升,而且盐酶混合添加处理组发酵品质显著优于二者单独添加处理组。     

复合发酵剂对羊肉香肠发酵成熟过程中理化品质及安全性能的影响

为了探究微生物发酵剂对发酵羊肉香肠理化品质及安全性能的影响,以添加清酒乳杆菌、木糖葡萄球菌及肉葡萄球菌的复合发酵剂制作发酵羊肉香肠,用GC、HPLC等仪器测定香肠发酵成熟过程中亚硝胺、生物胺、pH、Aw、色差、亚硝酸盐等指标变化。结果表明:清酒乳杆菌+木糖葡萄球菌+肉葡萄球菌复合发酵剂组产酸速率显著快于LS(清酒乳杆菌+木糖葡萄球菌)、LB(清酒乳杆菌)及对照(CO)(P0.05),发酵结束时pH值降到组中最低;pH值下降改变蛋白质束缚水分能力,促使复合发酵剂LSS组Aw下降快于其它3组,成品时为0.67(Aw)。制作过程中香肠红度值(a)表现为:复合发酵剂LSS组LSLBCO,且差异显著(P0.05)。LB、LS、LSS 3组成品香肠亚硝酸盐残留量(18.54,18.43,19.34 mg/kg)显著低于对照组(26.47 mg/kg)及国家安全限量标准30 mg/kg(P0.05)。发酵成熟过程中LSS、LS组香肠无尸胺和组胺检出,且添加发酵剂3组成品香肠生物胺总量显著低于对照组(P0.05)。LB、LS、LSS3组仅检出N-甲基乙基亚硝胺(NMEA),含量依次降低,且3组亚硝胺种类及含量均少于CO组(P0.05)。结论:使用复合发酵剂可缩短羊肉香肠发酵周期,改善香肠色泽,抑制香肠中亚硝酸盐残留及降低有害生物胺、亚硝胺含量,提高产品安全性。     

不同发酵剂对发酵羊肉干中嘌呤形成的影响

研究添加乳清和复合发酵剂(木糖葡萄球菌、肉葡萄球菌、戊糖片球菌和植物乳杆菌比为1:1:2:1)对发酵羊肉干中嘌呤物质的抑制作用,以及对发酵羊肉干理化指标(pH、水分活度(Aw)、e值、水分含量)和蛋白质含量的影响。结果表明:4组产品(对照组、发酵剂组、乳清组和乳清+发酵剂组)蛋白质含量丰富。与其他3组相比,复合发酵剂的添加极大程度地降低了产品的pH值、Aw和水分含量,缩短了发酵羊肉干发酵周期、提高了产品的稳定性;同时抑制了嘌呤含量(主要是腺嘌呤、鸟嘌呤和次黄嘌呤)的升高,使其总嘌呤含量为266.50 mg/100 g,显著低于其他3组(P0.05)。乳清可以促进最终嘌呤含量的升高,使其嘌呤含量显著高于对照组和发酵剂组(P0.05)。4组产品显示次黄嘌呤是发酵羊肉干中的主要嘌呤成分。     

产叶酸乳酸菌的筛选及对发酵乳的影响

为筛选出高产叶酸的乳酸菌并研究该乳酸菌对发酵乳的影响,采用高效液相色谱(HPLC)法从5种乳酸菌菌株:植物乳杆菌、嗜热链球菌、保加利亚乳杆菌、干酪乳杆菌、嗜酸乳杆菌的发酵液中检测叶酸含量,并通过检测复合发酵乳的pH、持水力、质构特性和感官特性来研究产叶酸的乳酸菌对发酵乳品质的影响。结果表明:植物乳杆菌产叶酸量最高,其次是嗜酸乳杆菌,分别为51.40和34.77 μg/mL。并且以基础菌发酵乳为对照组,添加产叶酸乳杆菌发酵乳为实验组,实验组与对照组相比,其质构特性和感官品质会提高,同时pH也显著下降(p<0.05)。本实验为开发功能性发酵乳提供了一定的理论依据。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

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.     

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

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

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.     

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.