硒对栽培平菇产量及营养成分影响的研究

采用向平菇栽培料中直接添加无机硒的方法，可使无机硒转化为有机硒并在菇体中得到有效的富集。实验表明：当加硒浓度在10～20mg／kg时，可使菇体中硒的富集量达70～120μg／100g鲜重，菇产量可增产3成左右。硒的利用率达4．081％和3．493％。菇体中生物活性物质多糖含量可达146．7299mg／g干重，VC含量可达20～21mg／100g干重，且采收的鲜菇不需经特殊处理即可上市出售。     

食用富硒平菇菌丝生产因子筛选

通过培养基种类、pH值、硒浓度和平菇不同品种影响平菇菌丝体富硒量的研究,筛选出平菇菌丝体富硒理想的条件为马铃薯葡萄糖液体培养基,添加浓度为7.5mg/L的亚硒酸钠,pH值7.0,平菇菌种选用P13,每g菌丝含硒量达到371.1μg。     

富硒平菇蛋白测定与氨基酸成分分析

目的:研究培养料添加10～50mg/kg不同浓度无机硒后,所采收的富硒平菇中蛋白的含量,并对菇体中硒含量为7～10μg/g干重(10mg/kg处理组),可直接上市供鲜食的富硒平菇组进行氨基酸成分分析。方法:考马斯亮蓝G-250法测定富硒平菇干粉的可溶性蛋白,凯氏定氮法测定总蛋白含量,氨基酸自动分析仪进行氨基酸成分分析。结果:富硒平菇干粉中可溶性蛋白含量都明显高于对照组,最高达对照的2.25倍;可直接上市供鲜食的富硒平菇体内的氨基酸成分分析:人体必需的7种氨基酸(色氨酸没测定)占氨基酸总量的47.44%,半必需氨基酸占氨基酸总量的14.39%,支链氨基酸占氨基酸总量的20.37%。结论:富硒平菇是一种具有较高的保健和药用开发价值的功能性产品。     

富硒平菇液态深层发酵试验研究

采用平菇作为富硒的载体,将亚硒酸钠(Na2SeO3)添加到液体培养基中,进行液态深层发酵试验,研究平菇对无机硒的生物转化能力.通过单因素试验及正交试验确定出液态深层发酵最优工艺参数.结果表明,在摇床频率为200r/min、培养6d的条件下,富硒平菇液态深层发酵最优工艺参数为装液量50mL,pH6.5,温度30℃,加硒浓度7.5mg/L.此时平菇总富硒量为1714μg/L.     

响应面法优化灰黑平菇富硒培养条件

目的:为了优化富硒平菇的生长配方,以周口农科院提供的平菇菌种为实验材料,对其进行了耐硒范围的测定。方法:通过单因素实验和响应面法Box-behnken Design(BBD)优化实验,采用3,3'-二氨基联苯胺盐酸盐法测定不同成分比例条件下平菇中的硒含量。结果:单因素实验结果表明:最佳初始硒含量为300mg/kg培养料,麦麸含量的最佳值是200g/kg棉籽壳,蔗糖含量的最佳值是12g/kg棉籽壳。响应面实验得出适宜富硒平菇生长的最佳配方为:麦麸200.14g/kg、蔗糖11.77g/kg、初始硒含量318.27mg/kg。在此条件下的进行实验验证,平菇的硒含量为2.1859mg/kg,与预测含量为2.1878mg/kg接近。结论:通过多元回归拟合方程,所得的回归方程可以正确反映麦麸、蔗糖、初始硒含量与平菇中硒含量之间的关系,说明预测模型适用、可靠,可应用于富硒平菇发酵条件的优化。     

酶法水解富硒平菇蛋白工艺优化

研究碱性蛋白酶对富硒平菇蛋白的水解作用,并优化其工艺条件。以恩施产地的富硒平菇粉为原料,选取碱性蛋白酶进行试验,研究料液比、加酶量、温度、pH、水解时间五个因素对碱性蛋白酶水解富硒平菇蛋白的影响。以水解度和蛋白质溶出率为评价指标,在单因素试验的基础上进行正交试验,优化碱性蛋白酶水解富硒平菇的工艺条件。结果表明,酶法水解富硒平菇蛋白的最佳工艺条件为:料液比1:30,碱性蛋白酶添加量为4200 U/g,水解温度55 ℃,pH为10.5,水解反应时间为4 h。在此条件下,富硒平菇蛋白水解度可达到28.46%,蛋白质溶出率为82.85%,水解所得蛋白肽中硒含量为2739.78 μg/g。本研究确定了碱性蛋白酶水解富硒平菇蛋白工艺的最佳条件。     

富硒平菇粉的抗癌活性评价及富硒代糖面包的研制

该研究采用不同总硒浓度的富硒平菇粉联合5-FU处理肝癌细胞HepG2,应用CCK-8法、流式细胞术双染法探讨富硒平菇粉联合5-FU的抑癌效果,并以富硒平菇粉为原料研制一款富硒代糖面包,为富硒功能食品研发提供参考依据。结果表明,富硒平菇粉对肝癌细胞HepG2增殖有抑制作用,抑制率范围为13.89%~27.39%;不同总硒浓度的富硒平菇粉联合5-FU干预HepG2肝癌细胞36 h后,凋亡细胞数量呈硒作用浓度依赖性增高（p<0.05）;总凋亡率分别是26.36%~49.72%,且凋亡率高于5-FU组（p<0.05)。富硒代糖面包的最佳加工工艺配方为：200 g面粉中富硒平菇粉添加量为0.06 g,复配代糖添加量为25 g,烘烤温度为上下火175 ℃,烘烤时间为20 min,总硒含量为（0.17±0.01）mg/kg。综上所述,采用不同总硒浓度的富硒平菇粉联合5-FU处理肝癌细胞HepG2,发现富硒平菇粉联合5-FU可抑制HepG2肝癌细胞生长,起到增效解毒的作用,并成功研制出富硒代糖面包的最佳工艺,具有较好的研究和应用价值。     

硒酸精氨酸对富硒平菇子实体品质的影响

通过向栽培料中添加硒酸精氨酸培育富硒平菇,研究硒酸精氨酸对平菇子实体富硒能力、谷胱甘肽过氧化物酶活性、挥发性物质组成、蛋白含量和蛋白分布等的影响。研究结果表明:平菇子实体中的硒含量与栽培料中的硒浓度线性正相关(R=0.9967),同一栽培料中子实体硒分布为:菌盖菌柄;硒在多糖中的含量较低,在蛋白质中大量积累,但富硒平菇子实体的蛋白含量和谷胱甘肽过氧化物酶活性没有显著变化;气相色谱结合质谱(GC-MS)分析表明,富硒平菇子实体与普通平菇子实体的挥发性物质组成简单,都以醇类为主,但是富硒平菇子实体中1-辛烯-3-醇相对含量较高,蘑菇风味更加浓郁;十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)分析表明,平菇子实体中蛋白质分布广泛,但硒对蛋白质的合成代谢途径没有影响,不改变平菇子实体蛋白的分布。     

三种杜仲原料栽培平菇效果的比较

采用矮林杜仲叶、乔林杜仲叶和乔林杜仲叶渣替代40%棉籽壳栽培平菇,考察其对平菇菌丝生长过程和平菇蛋白质、脂肪以及相关微量元素含量的影响,并采用紫外可见分光光度法测定了各组平菇总黄酮的含量、荧光法测定了各组平菇硒的含量。结果表明,乔林杜仲叶渣组平菇发菌实验结果最好,且蛋白质、脂肪、Cu和Mn含量最高,分别为对照组的1.13、1.73、3.75、2.71倍;乔林杜仲叶组平菇总黄酮、Ca、Na、K和Mg含量最高,分别为对照组的1.49、2.20、7.20、1.08、1.03倍;矮林杜仲叶组平菇Fe、Zn和Se含量最高,分别为对照组的1.72、2.10、2.38倍,且硒的含量为0.07524μg·g-1,达到了富硒标准。     

冬虫夏草深层发酵富硒初步研究

本文对冬虫夏草深层发酵富集微量元素硒进行了研究，结果表明，该菌具有较强的富集能力，其最大耐硒量为80μg／mL：，此时菌丝体硒合量为2662．8μg／g干重，在60μg／mL时菌丝体得率最高为1．514g／100mL，富硒率最高达到了50．85％，有机化程度能够达到77．2％以上，为富硒产品开发，解决我国人体硒摄入量不足提供了一条重要途径。     

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.