正交法优化小石花菜膳食纤维提取工艺

以小石花菜为原料,采用酶与化学结合的方法提取膳食纤维.就影响膳食纤维含量7个因素:酶用量、酶解时间、酶解温度、氢氧化钠浓度、氢氧化钠提取温度、氢氧化钠用量、氢氧化钠提取时间进行单因素试验和正交试验.研究确立提取小石花菜膳食纤维的最佳工艺条件为蛋白酶与纤维素酶用量比为20:1、在50℃条件下酶解1.5 h,再用40倍1.0%氢氧化钠溶液在65℃提取1 h,其产率可达18.16%,色泽近淡黄色.     

小米麸皮膳食纤维提取工艺的研究

以非糯性小米麸皮为原料,研究了酶与化学结合法提取膳食纤维的工艺技术。结果表明,提取膳食纤维的最佳工艺条件为:在65℃条件下用4%的混合酶(α-淀粉酶∶糖化酶=1∶4)酶解100min,再用5%NaOH在100℃下处理70min,膳食纤维纯度为92%。     

生姜可溶性膳食纤维的酶法提取工艺中植物蛋白酶条件的确定

采用植物蛋白酶和糖化酶联合提取生姜中可溶性膳食纤维,固定糖化酶提取条件,探讨植物蛋白酶的工艺条件。在固定糖化酶加酶量1%,酶解温度60℃,酶解时间1h的条件下,确定了植物蛋白酶的优化条件为加酶量6%,酶解温度55℃,酶解时间5h,此条件下生姜中可溶性膳食纤维提取率高达13.24%。     

双酶法提取花生粕中总膳食纤维的研究

以花生粕为原料,采用双酶法探讨花生粕中总膳食纤维提取工艺条件。通过单因素实验,考察木瓜蛋白酶的加酶量、酶解时间、温度和糖化酶的加酶量、酶解时间、温度对总膳食纤维提取率的影响。结果表明,木瓜蛋白酶的最佳提取工艺条件:加酶量8%,时间4h、温度50℃;糖化酶的最佳提取工艺条件:加酶量1.2%,时间1h、温度60℃,在该条件下花生粕中膳食纤维提取率为40.45%。     

化学法结合酶法提取牛蒡中的可溶性膳食纤维

本文以牛蒡为原料,先用化学方法处理得到牛蒡可溶性膳食纤维(SDF)和牛蒡渣,然后再用酶法处理前一步得到的牛蒡渣,进一步提取牛蒡可溶性膳食纤维。通过单因素试验及正交试验对化学法和酶法条件进行了优化。结果表明,化学法制备可溶性膳食纤维的较佳工艺条件是:温度100℃,反应时间20 min,pH10.0,物料比1∶15,在此条件下,牛蒡提取SDF得率为11.2%。使用复合多糖酶处理前一步得到的牛蒡渣,酶法提取可溶性膳食纤维的较佳条件为:复合多糖酶的用量8%、酶解温度40℃、酶解时间1h、pH 3.9、料液比为1∶18,在此条件下,SDF得率为4.82%。     

酶法提取生姜中可溶性膳食纤维及抗氧化活性的研究

探讨酶法辅助提取生姜中可溶性膳食纤维的工艺条件及其抗氧化活性。在固定糖化酶加酶量1%,酶解温度60℃,酶解时间1h条件下,通过单因素实验探讨了植物蛋白酶加酶量、酶解时间、酶解温度等因素对生姜中可溶性膳食纤维提取率的影响,结果为植物蛋白酶加酶量6%,酶解温度55℃,酶解时间4h。在单因素实验的基础上,通过正交实验优化最佳提取条件,结果表明:植物蛋白酶最佳工艺条件为加酶量6%,酶解温度60℃,酶解时间5h,生姜中可溶性膳食纤维提取率高达12.82%。生姜中可溶性膳食纤维对.OH自由基表现出较强的清除能力,在0.6mg/mL~3mg/mL浓度范围内清除率与浓度呈较好的量效关系,IC50为1.95mg/mL。     

双酶法分离提取米糠膳食纤维的研究

米糠是稻谷加工的副产物之一,其中米糠膳食纤维含量高达35%~50%,是理想的膳食纤维来源。实验研究了双酶法分离提取米糠膳食纤维的最佳工艺条件,并对所提膳食纤维的基本成分进行了分析。根据正交实验结果表明,提取米糠膳食纤维时,除淀粉的最佳条件为:耐高温淀粉酶,酶解时间3.5 h,酶解温度75℃,酶用量20μL;除蛋白的最佳条件为:碱性蛋白酶,酶解时间2.5 h,酶解温度60℃,酶用量2%。在最优条件下分离提取得到的米糠膳食纤维:总膳食纤维、不溶性膳食纤维和可溶性膳食纤维纯度分别为87.26%、68.23%和3.99%。根据扫描电镜结果显示,不溶性和可溶性膳食纤维表面均具有明显的蜂窝状结构。     

武夷岩茶茶渣非水溶性膳食纤维提取工艺研究

以冲泡后的岩茶茶渣为原料,采用酶法研究膳食纤维(IDF)的提取工艺参数,得出用α-淀粉酶处理茶粉的粗膳食纤维提取条件是:酶解温度55℃、酶添加量0.06 g/g、p H 9、酶解时间1 h、料液比1∶15(g/m L);木瓜蛋白酶精制IDF的最佳工艺条件是:酶解温度45℃、酶添加量0.004 g/g、p H值为4、酶解时间2 h、料液比1∶15(g/m L),此条件下膳食纤维的提取率最高,为97.12%。     

纤维素酶提取水溶性膳食纤维工艺的研究

目的 以番茄不溶性膳食纤维为原料,用酶解法提取可溶性膳食纤维(SDF).方法 经正交试验优化提取工艺,并在优化条件下循环提取.结果 制备SDF的最佳工艺条件为:酶用量10%,酶解时间6 h,酶解温度60℃,pH 4.0,以最佳条件连续反应,产率可达31.1%.结论 确定了酶提取SDF的最佳工艺;证实循环工艺可以提高提取效率.     

纤维素酶提取水溶性膳食纤维工艺的研究

目的 以番茄不溶性膳食纤维为原料,用酶解法提取可溶性膳食纤维(SDF).方法 经正交试验优化提取工艺,并在优化条件下循环提取.结果 制备SDF的最佳工艺条件为:酶用量10%,酶解时间6 h,酶解温度60℃,pH 4.0,以最佳条件连续反应,产率可达31.1%.结论 确定了酶提取SDF的最佳工艺;证实循环工艺可以提高提取效率.     

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.