舟山海域光参酶解嫩化工艺研究

以舟山产光参为研究对象,考察复合酶对光参硬度的影响。结果表明:动物蛋白水解酶酶解效果最好,中性蛋白酶酶解后腥味较轻;两种酶复配后最佳酶解工艺条件为光参质量浓度4 g/100 mL,温度40℃,复合比1∶1,酶量6×10^3 IU/100 mL,pH 7,时间1 h;酶解处理后的光参网状结构密度降低,质构变得松散,肌纤维变细,硬度显著降低,光参嫩度显著改善;采用复合酶处理后的光参皂甙活性物质含量显著提高,酶解处理对光参保健功效有促进作用,而多糖含量有少许下降。     

生物酶法制备香菇提取物的工艺研究

以香菇粉为对象,研究生物酶法制备香菇提取物的最佳工艺条件。主要采用纤维素酶、果胶酶、复合蛋白酶(蛋白酶H+风味蛋白酶)进行酶解,研究酶解温度、pH、加酶量、酶解时间分别对酶解过程的影响,以还原糖和氨基态氮为指标分析以上三种酶的最佳酶解条件。最后通过响应面法对多酶酶解体系进行初步研究,优化多酶酶解工艺。结果表明:多酶酶解香菇的最佳工艺条件:温度50℃,pH 7,酶解时纤维素酶添加量为0.6%,果胶酶添加量为0.3%,蛋白酶H加酶量0.4%,风味蛋白酶加酶量0.2%,酶解时间2.5h。     

葵花脱脂粕膳食纤维提取工艺的研究

本实验以葵花脱脂粕为原料,通过生物酶法和化学法研究葵花脱脂粕中膳食纤维的提取工艺,其中生物酶法得到的膳食纤维得率较高。生物酶法主要用植物精提复合酶和酸性蛋白酶,提取的最佳工艺组合为:植物精提复合酶的用量为0.4%,植物精提复合酶的酶解时间为2.5h;酸性蛋白酶的用量为0.2%,酸性蛋白酶的酶解时间为45min,此时膳食纤维的得率为78.3%。     

柑橘生物酶法脱囊衣技术研究

本实验进行了生物酶法脱除柑橘囊衣的优化工艺条件研究。同时利用扫描电镜观察了酶解过程中囊衣结构变化。结果表明,复合酶制剂脱囊衣的优化酶解工艺为酶浓度0.35%(g/L)、变电频率40Hz、pH4.5、在40℃下酶解50min。柑橘生物酶法脱囊衣桔瓣呈现优良的外观,组织紧密和光泽好。     

生物酶法提取麦麸膳食纤维的研究

探讨了生物酶法提取麦麸中的膳食纤维的提取工艺.研究得出酶法提取的最佳工艺组合为:混合酶制剂用量为0.3%,α-淀粉酶与糖化酶用量的比值为l:1,混合酶的酶解时间为30min,蛋白酶制剂的用量为0.5%,蛋白酶的酶解时间为30min,此时提取的膳食纤维得率为:72%.     

一种舟山海域光参蛋白粉的制备工艺

采用嫩化光参为原料,研究其酶解和喷雾干燥工艺,光参蛋白粉营养成分指标。研究结果表明:采用风味酶为酶制剂,酶解嫩化光参的最佳参数:每100 g光参肉糜中风味酶用量1 200 U/g蛋白、温度50℃、pH 6.5、时间4 h、蒸馏水2 500 m L。用该工艺制备的光参酶解液中相对分子质量100~1 000的寡肽约占水解产物85%。光参酶解液最佳喷雾干燥条件:进料量25%、进风温度180℃、进料温度30℃、进料速度12 m L/min,由该工艺参数制备的光参蛋白粉各特性指标较好,呈白色粉状,吸湿性较强;光参蛋白粉同某市售品牌蛋白粉相比,蛋白质、脂肪和碳水化合物略低,而活性物质皂甙及Na、Ca、Fe等矿物元素含量较高,具备较强的商品开发潜力。     

无水奶油中脂肪酸成分分析

以无水奶油为原料进行生物酶解,通过对不同酶解产物的脂肪酸成分进行气相-质谱联用(GC-MS)分析,结果表明,奶油生物酶解的最佳时间为6h,油脂中主要脂肪酸成分在生物酶解前后没有变化。     

酶法辅助提取大叶麻竹笋多糖

通过正交实验,优化了大叶麻竹笋多糖水提法的提取工艺条件:水料比为40∶1,乙醇终体积分数为80%,温度为80℃,时间为1 h,在此条件下,竹笋粗多糖的提取率为2.19%。采用单一生物酶(果胶酶、纤维素酶、中性蛋白酶)辅助提取竹笋多糖,在推荐的最佳酶解条件下,中性蛋白酶辅助提取率最高。通过单因素变化法优化,中性蛋白酶辅助提取大叶麻竹笋多糖的最佳酶解条件为:酶解2次,酶添加量为3.0%,在45℃、pH值4.6条件下,酶解60 min后,结合水提醇沉法,提取率为2.91%,比传统水提醇沉法,提高了32.9%。     

响应面优化南极磷虾蛋白酶解工艺及蛋白肽组分分析

以南极磷虾蛋白酶解液中的氨基氮含量为指标,采用甲醛电位滴定法测定胰蛋白酶、木瓜蛋白酶、碱性蛋白酶、胃蛋白酶、风味蛋白酶、枯草杆菌蛋白酶6种生物酶在其最适酶解条件下对南极磷虾蛋白酶解效果,筛选出酶解南极磷虾蛋白最佳生物酶。在单因素试验基础上,以酶解液中氨基氮含量为响应值,选择酶解温度、时间、pH为自变量,通过三因素三水平Box-Bohnken响应面分析法对筛选出来的生物酶解工艺进行优化。在优化酶解工艺的基础上,利用SDS-PAGE凝胶电泳方法分析南极磷虾酶解蛋白肽及南极磷虾蛋白的分子量分布范围。结果表明:胰蛋白酶为酶解南极磷虾蛋白的理想蛋白酶;响应面分析法建立二次多项回归方程:Y=51.07-0.83A+1.72B-2.06C+0.25AC+1.15BC-3.06A2-2.77B2-3.69C2,模型p0.0001,而失拟项p0.05,表明模型极显著且比较稳定,通过模型分析得最佳条件:酶解温度44.48℃、酶解时间8.52 h、pH 7.88,考虑实际应用可行性,我们在酶解温度45.0℃、酶解时间8.5 h,pH 7.9条件下实验得到的氨基氮含量为50.96±1.07mg/g,与理论预测值51.57mg/g基本一致。通过电泳分析得到南极磷虾蛋白分子量范围在15 ku以上,主要集中分子量范围为15 ku～45 ku;胰蛋白酶解多肽分子量在25 ku以下,主要分子量分布在5 ku以下。     

生物酶法提取葡萄籽油的工艺研究

生物酶法提取植物油脂是一种新型的油脂加工方法，它既可提高油脂的提取率，又可获得品质较优的植物油脂。以葡萄籽为原料分别加入纤维素酶和中性蛋白酶进行酶解，通过试验分别得出两种酶提取葡萄籽油的最佳工艺参数：纤维素酶提取葡萄籽油的最佳工艺参数为：酶解温度为45℃、酶解时间为1．5h、酶解pH值为4．5、酶用量为3000U／g葡萄籽，油脂提取率为84．1％；中性蛋白酶提取葡萄籽油的最佳工艺参数为：酶解温度为55℃、酶解时间为2．0h、酶用量为2000U／g葡萄籽，油脂提取率为80．3％。对两种酶解提油工艺进行比较可知：中性蛋白酶提油工艺所需成本较低，提取率较高，适合于葡萄籽油的提取。     

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.