荔枝酒发酵工艺的优化及风味成分的分析研究

以荔枝为原料,对荔枝酒发酵条件及风味成分进行分析研究。结果表明,荔枝酒发酵最佳工艺条件为:发酵温度25℃、发酵时间8 d、起始pH4.0、接种量18%。随后采用气相色谱法对荔枝酒中的风味成分进行初步分析发现,荔枝酒中含有正丙醇、异丁醇、异戊醇3种高级醇及乙酸乙酯、乙酸异戊酯2种酯,这些有效成分赋予了荔枝酒特有的香醇美味。     

三种不同生产工艺的荔枝酒品质对比

为了探索冷冻浓缩工艺对荔枝酒品质的影响,以荔枝汁为原料,通过直接发酵、发酵-冷冻浓缩、冷冻浓缩-发酵3种工艺分别生产发酵荔枝酒、发酵-浓缩荔枝酒、浓缩-发酵荔枝酒,并对比分析3种荔枝酒的基本组分、游离氨基酸含量、挥发性物质和感官评价。结果显示:发酵荔枝酒的酒精度为8.48%、总酸为4.80 g/L、单宁含量为0.53 g/L、游离氨基酸总量为40.38 mg/L、醇酯比为0.86,果香清淡,口感一般。发酵-浓缩荔枝酒和浓缩-发酵荔枝酒的酒精度为16.10%和16.47%、总酸为9.57 g/L和7.70 g/L、单宁含量为1.02 g/L和1.13 g/L、游离氨基酸总量为102.97 mg/L和493.17 mg/L,均显著高于发酵荔枝酒(p0.05),其中发酵-浓缩荔枝酒的醇酯比为0.50,酒香增加,但由于酸度及不良风味物质偏高,口感欠佳,而浓缩-发酵荔枝酒的醇酯比为0.26,果香浓郁,口感甜润饱满,酒体醇厚。荔枝汁先冷冻浓缩再发酵的工艺可以生产更高品质的荔枝酒。     

荔枝酒的制作工艺

荔枝酒的制作是采用新鲜荔枝进行去皮去核、打浆等预处理后得到荔枝果浆,通过不同荔枝品种的选择,荔枝原料配比、发酵配方、发酵工艺参数的研究,确定了荔枝酒的发酵工艺为采用黑叶荔枝,在荔枝发酵液中添加2‰的果胶酶、0.4‰酵母、调整糖度为22Brix、pH为4,发酵温度控制在24℃下发酵7d后。采用全铜精馏器带果渣蒸馏到72%vol,得到72%vol荔枝蒸馏酒。     

全低温酿制优质荔枝全汁酒的工业化生产工艺

研究了以冻藏荔枝果实为原料制备的澄清荔枝汁在低温条件下的发酵工艺。利用冻藏的荔枝果实制备的澄清荔枝全汁 ,以活性干酵母QA2 3和DV1 0在 1 0～ 1 5℃条件下均能生产出优质的具有类似干白葡萄酒风格的荔枝酒。     

荔枝酒生产工艺研究

以"黑叶"荔枝原汁为原料,研究了不同活性干酵母菌种、不同发酵工艺对荔枝酒发酵的影响,研究了荔枝酒的澄清工艺,分析了荔枝酒发酵前后的糖酸变化.结果显示,荔枝酒的较优发酵菌种为DV10,较适发酵温度为20℃,添加偏重亚硫酸钾对防止褐变无效果,采用50mg/L壳聚糖可获得较好的澄清效果.发酵后残余的糖为果糖,含量小于4 g/L,发酵结束后苹果酸有所下降而乳酸有所增加,发酵过程可能存在苹果酸乳酸发酵.     

低醇荔枝酒酿造菌种的筛选

通过研究6株产香酵母和2株酿酒酵母的酿造特性及其对荔枝酒感官品质的影响,筛选出2株产乙醇较低、发酵荔枝酒感官特性较好且有良好应用性能的产香酵母;其中异常汉逊氏酵母Y4产乙醇低,酿造的荔枝酒果香、酒香良好,香气协调悦人,是酿造低醇荔枝酒的优良菌种.     

影响干白荔枝酒发酵的因素及控制方法

干白荔枝酒发酵的主要环节是酵母将糖转化为酒精和CO2.影响干白荔枝酒发酵的主要因素是酵母菌种、适宜酵母发酵的果汁成分、SO2含量以及发酵温度、发酵条件及贮藏条件等.研究结果表明,酵母菌种采用葡萄酒酵母(S.ellipsoideus),果汁含糖量为15～17 Bx°,SO2含量为60 mg/L,发酵温度控制在16～18℃为佳.     

发酵温度对荔枝酒香气成分的影响

采用顶空固相微萃取(HS-SPME)结合气相色谱-质谱(GC-MS)方法,探讨13℃与18℃两种发酵温度对荔枝酒香气成分的影响。结果表明,两种发酵温度下从荔枝酒中分别检测出14和15种香气成分,其中酯类含量最高,其次是醇类。从两种荔枝酒中共同检出辛酸乙酯、己酸乙酯、癸酸乙酯、3-甲基-1-丁醇醋酸酯、2-甲基-1-丁醇醋酸酯、乙酸乙酯、3-甲基-1-丁醇、2-甲基-1-丁醇8种特征香气成分。两种荔枝酒的香气成分表现出种类的一致性,但平均含量存在较大的差异。这种差异为研究不同发酵温度对荔枝酒香气成分的影响提供了理论依据。     

荔枝酒酿造过程中氨基酸的变化

利用高效液相色谱法(HPLC)对不同发酵温度的荔枝酒酿造过程中氨基酸含量的动态变化进行了分析研究。结果表明,荔枝汁和荔枝酒中均含有丙氨酸、苏氨酸、缬氨酸、谷氨酸、丝氨酸等14种氨基酸,其中,丙氨酸是荔枝汁和荔枝酒中的主体氨基酸,含量分别达1 139.682 mg/L、341.049～412.161 mg/L。不同发酵温度的荔枝酒酿造动态过程中,其游离氨基酸的种类和含量变化较大,且变化趋势各异。不同贮藏方式对荔枝酒中氨基酸含量和种类影响也不同。通过比较,发酵温度12℃优于15℃,发酵温度为15℃的荔枝酒中氨基酸含量在贮藏过程中变化幅度较大,不稳定,且影响风味的氨基酸较多。     

葡萄冰酒干酵母R2发酵冰荔枝酒工艺条件的优化

以冻藏荔枝经低温榨取或低温浓缩后的荔枝汁为原料,利用葡萄冰酒干酵母R2发酵酿制冰荔枝酒,研究了发酵温度、接种量、SO2添加量、起始糖和酸含量、硫酸铵添加量等因素对发酵的影响。通过正交试验确定了冰荔枝酒最佳的发酵条件为发酵温度10℃、SO2添加量100mg／L、起始糖度330g／L、硫酸铵添加量600mg／L、起始酸含量为7．7g／L、接种量为375mg／L。可生产酒精体积分数为10％-12％的冰荔枝酒,产品呈金黄色,清亮透明,果香浓郁,丰满醇厚,甜润爽口,具有较好的类似于葡萄冰酒的品质。     

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.     

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.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

Tests of potential functional barriers for laminated multilayer food packages. Part II: Medium molecular weight permeants

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

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.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status