紫甘薯色素废渣淀粉提取工艺参数研究

为了提高紫甘薯综合利用率,该文以提取色素后的紫甘薯废渣为原料,分别采用水和柠檬酸为提取剂,在不同的料液比、浆料pH、浸泡时间、浸泡温度下提取淀粉。通过单因素实验和正交试验确定淀粉的最佳提取工艺条件为:料液比1︰4、浆料pH 5.0、浸提时间2.0 h、浸提温度30℃,此时淀粉提取率为57.49%,淀粉纯度为85.37%。     

竹芋淀粉的提取工艺研究

以竹芋淀粉的提取率为指标,通过单因素试验和正交试验确定了竹芋淀粉的最佳提取工艺。结果表明:料液比1∶6(g/mL),浸提时间1.5 h,浸提温度35℃,浆料pH8时,竹芋淀粉的提取率最高,约为80.0%。     

超声波辅助水剂法提取茶叶籽油工艺的研究

研究了超声波辅助水剂法提取茶叶籽油工艺中原料粉碎度、兑浆水pH、液料比、浸提温度、浸提时间和超声时间对油脂提取率的影响.获得的最佳工艺条件为:原料粉碎度60～80目,兑浆水pH 6,液料比4:1,浸提温度70℃,浸提时间4 h,超声时间30 min.在最佳工艺条件下,油脂提取率为70.79%,副产品淀粉提取率为56.13%.     

白芷淀粉的提取工艺研究

以NaOH为浸泡剂,探讨了料液比、pH、浸泡时间、浸泡温度对淀粉提取率的影响,并用正交试验确定了白芷淀粉提取的最佳工艺.结果表明:淀粉提取的最适宜的提取工艺条件为料液比1:6,NaOH浸提液的pH9.0,浸泡时间6h,浸泡温度30℃.在此工艺条件下,淀粉的提取率为84.56%.     

紫甘薯色素水提工艺参数的研究

采用水溶液提取紫甘薯色素.选择pH值、料液比、浸提时间和浸提温度作为单因素进行梯度试验,确定其条件范围,通过正交试验确定紫甘薯色素提取的最佳工艺条件:pH值3(HCl)、料液比1∶2(g/mL)、浸提时间2h、温度25℃,共提取3次,紫甘薯色素提取率可达94.85％.     

贺兰山紫蘑菇中蛋白质提取工艺研究

以宁夏贺兰山紫蘑菇为原料,研究了料液比、pH、提取温度、提取时间对其蛋白质提取率的影响。在单因素实验分析基础上,进行了正交实验,同时考虑到实际操作可行性,最终确定了贺兰山紫蘑菇中蛋白质最佳提取工艺条件为:料液比1:25,pH11.0,40℃条件下浸提3h,蛋白质提取率为72.3%。     

米酒糟制备蛋白粉的研究

本文采用碱溶后酸沉的方法对米酒糟蛋白质进行提取.研究了料液比、pH值,浸提时间、浸提温度等条件对蛋白提取率的影响,确定了最佳提取条件为:料液比1:2,pH 10.0,温度40℃,浸提时间1.5h.上述各因素对提取率的影响强弱关系顺序:料液比>浸提温度>浸提时间>pH值.     

栀子渣中植物蛋白提取工艺的研究

本实验以栀子渣为原料,采用"碱溶酸沉"原理,通过对料液比、浸提温度、浸提时间及浸提液pH值进行单因素试验,采用L9(34)正交试验对栀子渣中植物蛋白提取工艺条件进行优选。结果表明:浸提液的pH值对植物蛋白提取率的影响程度达到极显著水平,料液比、浸提温度及浸提时间对植物蛋白提取率没有显著影响。栀子渣中植物蛋白提取的最佳工艺条件为:浸提液pH值为9.0、料液比1:20、浸提时间1.5h、浸提温度40℃。     

新鲜葛根中总黄酮和淀粉的提取工艺研究

根据葛根黄酮和淀粉在葛根中的分布情况,探讨了从葛根韧皮部、木质部中提取总黄酮及淀粉的工艺.正交试验结果表明,从葛根韧皮部中提取总黄酮的优化工艺条件:以95%乙醇为浸提溶剂,料液比1:8,浸提时间1h,浸提次数3次,其总黄酮提取率为75.43%.综合考虑淀粉提取率和总黄酮的保留情况,从葛根木质部中提取淀粉的优化浸泡工艺参数:料液比1:4,浆液pH8．5,浸泡时间3h,浸泡温度25℃,其淀粉提取率为85.35%,淀粉中总黄酮含量在0.15%以上.     

蜂幼虫分离蛋白提取研究

研究采用"碱溶酸沉"原理,对蜂幼虫蛋白质进行提取。主要讨论料液比、浸提碱液pH值、浸提时间等条件对提取率及纯度的影响,确定最佳提取条件。结果表明:料液比1∶2,pH值10.5,温度20℃,浸提2.5h。各因素对提取率的影响强弱关系:提取时间>提取温度>浸提pH>料液比。所得产品蜂蛋白质粉液提取率42.03%,纯度为61.22%。     

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.