板栗真空爆壳工艺及热力学过程分析

板栗的脱壳去衣是板栗进行深加工的首道程序,在现有爆壳技术中选择了真空爆壳技术进行研究,首先对影响板栗真空爆壳工艺的重要因素进行实验,并利用SPSS软件建立了爆壳率和失水率的回归方程,考察其对板栗爆壳规律的影响;然后根据真空干燥理论,建立了一系列板栗干燥爆壳过程的理论数学模型,并再次进行实验对所建立的爆壳模型进行验证,探索出能够适用于板栗干燥、爆壳过程中的失水模型,从而发现爆壳过程影响失水率、爆壳率的规律,为今后爆壳工艺的进一步优化和加工生产提供理论依据和参考。     

无损伤栗果的微波爆壳工艺研究

栗果的脱壳去衣是板栗深加工的头道工序,历来是板栗加工的技术难题,已成为发展板栗加工业的制约因素。研究将微波技术引入栗果脱壳过程,以期找到一种有效的栗果脱壳去衣方法。研究结果表明:利用微波技术可实现对栗果的一次性脱壳去衣,一次性栗果爆壳率可达90%,栗果微波爆壳的合理工艺条件为:原料→ 称重分级 → 90℃预热干燥15 min →微波脉冲处理(平均功率495 W)→ 爆裂栗果 → 分离壳衣 → 栗仁(粉)。     

板栗壳色素的超声波提取及羊绒染色

采用超声波技术提取板栗壳色素,并用于羊绒纤维染色,研究了染液的提取、预处理和染色过程的各项工艺参数。结果表明,当板栗壳染液提取时的超声波频率为40 k Hz,50℃提取60 min时,提取效果较好;羊绒纤维染色的预处理和染色工艺条件为:媒染剂质量分数3%(omf),温度40℃,时间30 min,板栗壳染液质量浓度40 g/L,染色温度90℃,染色时间60 min。采用上述工艺染色的上染率可达75%以上,皂洗牢度达4级,羊绒单纤维的断裂强力与断裂伸长率分别为2.5 c N和14%以上。     

板栗微波去壳切口工艺优化

主要研究切口板栗的相关工艺条件,以期获得较好的爆壳效果。按照板栗背部中轴位置,对板栗进行纵向切口,且切口长度为全长,切口深度不伤及栗仁和切口数为1道时为宜;经切口的物料在微波功率700W、处理时间60s的条件下,板栗爆壳率达90%。     

脱水板栗片制备工艺的优化

以信阳大板栗为试验材料,以板栗片营养成分、色差值、复水率为考察对象,对热风干燥、真空干燥、微波干燥三种工艺脱水板栗片的工艺进行了研究。结果表明,板栗片经过护色后,切成0.1 cm薄片,在热风干燥工艺中,以始温35℃,以5℃/h的速度升温,至60℃条件下保持1 h,再以5℃/h的速度降温至50℃,干燥6 h,得到的板栗片能保留板栗原有的色、香、味;在真空干燥工艺中,最佳干燥条件为:真空度0.07 MPa,温度设定在80℃,干燥时间3 h,板栗片色差值最小;在微波干燥工艺中,最佳干燥条件为:微波功率为400 k W,干燥8 min,板栗片的色泽较好;经过比较脱水板栗片营养成分、色差值及复水率得出,真空干燥法板栗片的营养成分保留最高,色差最小,复水率最高。     

板栗壳天然染料对羊绒纤维染色性能的研究

采用板栗壳天然染料对羊绒纤维进行染色,考察了染色过程中板栗壳天然染料用量、染色温度、染色时间以及媒染方法等参数对染色效果的影响,并对板栗壳天然染料的上染率及色牢度、纤维断裂强力进行了测试。结果表明,经优化后板栗壳天然染料对羊绒纤维的最佳染色工艺为板栗壳天然染料用量8 g/L,染色温度为90℃,染色时间为60 min,媒染剂用量为4%,采用同浴媒染法染色法,此时板栗壳天然染料的上染率为84.83%,耐皂洗色牢度与耐干摩擦色牢度均达到4级,羊绒单纤维的断裂强力与断裂伸长率分别达到2.52 c N和17.3%,符合羊绒染后的粗纺纺纱要求。     

板栗壳植物染料在棉织物上的染色性能研究

采用壳聚糖对棉织物进行改性,并对改性后棉织物用板栗壳植物染料进行染色。探讨了棉织物改性过程中工艺条件对棉织物染色性能的影响,分析了染色过程中板栗壳植物染料浓度、染色温度、p H值、染色时间和媒染剂对棉织物染色性能的影响,测试了改性后棉织物白度和顶破强力以及染色后色牢度、防紫外线性能和抗氧化性能。结果表明:最佳的改性工艺条件是壳聚糖用量为3%,p H值为5,温度为80℃,时间为40 min;最佳染色工艺为板栗壳染料用量为5%,p H值为5,浴比为1∶30,温度为80℃,时间为60 min;染色棉织物具有良好的防紫外线性能和抗氧化性能,经硫酸亚铁后媒染之后,其色牢度有所提高。     

发酵法提取板栗壳水溶性膳食纤维及脱色工艺的研究

以板栗壳为原料,通过对枯草芽孢杆菌发酵提取水溶性膳食纤维(SDF)的工艺进行研究,考察了原料粒度、料液比、接种量及发酵时间对水溶性膳食纤维得率的影响。研究结果表明,发酵法提取板栗壳SDF最佳条件为原料粒度0.180 mm、料液比1∶55(g/mL),接种量10%、发酵时间24 h,在此优化条件下SDF得率为19.75%;并对提取得到的板栗壳SDF进行了脱色工艺的优化,研究结果表明,过氧化氢对板栗壳SDF的最佳脱色工艺为H2O2浓度4%、脱色时间4 h、pH 10、脱色温度55℃,在此优化条件下板栗壳膳食纤维脱色率为85.26%。     

纤维素酶法提取板栗壳色素的工艺条件优化

以板栗壳为原料,通过单因素试验,考察提取剂乙醇体积分数、提取时间、提取温度、纤维素酶添加量、料液比和提取液pH值对板栗壳色素提取效果的影响。在单因素试验的基础上,根据中心组合(Box-Behnken)试验设计原理,采用四因素三水平的响应面分析法,确定提取板栗壳色素的最佳工艺条件为pH6、纤维素酶添加量0.6%、提取温度94℃、提取时间120min。     

纤维素酶辅助提取板栗壳中原花青素的工艺研究

以板栗壳为原料,采用纤维素酶法辅助提取原花青素。在单因素试验的基础上,采用L~9(3~4)正交试验设计,研究酶解温度、提取时间、酶解浓度和pH对板栗壳中原花青素得率的影响。试验结果表明,影响酶法辅助提取原花青素的因素次序为:酶解温度提取时间酶解浓度pH,其最佳工艺条件为:酶解温度50℃,提取时间90 min,酶解浓度1.00%,pH 4.5。所得板栗壳中原花青素的得率为0.465%。     

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.