植物乳杆菌对干腌马鲛鱼降盐增鲜效果的影响

以植物乳杆菌替代部份食盐，制备降盐增鲜风味的干腌马鲛鱼。通过感官评价和呈味物质含量的比较分析可知，以植物乳杆菌代替50%食盐的干腌马鲛鱼样品的咸、鲜和厚味均显著高于对照组1（添加4%食盐腌制的干腌马鲛鱼）、对照组2（添加2%食盐腌制的干腌马鲛鱼）（P＜0.05），说明植物乳杆菌的添加可以产生大量的鲜、厚味物质，同时还可以产生咸味或增咸物质，以代替食盐的使用。而通过鲜味氨基酸和肽分子质量分布的测定可知，添加植物乳杆菌的样品中鲜味氨基酸和＜1?kDa呈味肽的占比均显著高于对照组1与对照组2（P＜0.05），这些物质除了本身具有鲜味、厚味等味感外，还可以增加咸味。此外，添加了植物乳杆菌的样品水分活度、pH值明显低于对照组1、对照组2（P＜0.05），有利于干腌马鲛鱼的保藏，色差与对照组1、对照组2无显著差异（P＞0.05），说明不影响产品的外观品质。结果显示，植物乳杆菌的添加可以降低干腌马鲛鱼中食盐的添加，同时还可以增加其鲜味和厚味等味感。     

SPME-GC-MS结合ROAV分析腌制时间对大河乌猪火腿挥发性风味物质的影响

本研究旨在分析腌制时间对大河乌猪干腌火腿风味品质的影响,揭示干腌火腿的特征风味物质。将172只大河乌猪鲜腿分为4个组,采用传统方法加工后,每组随机抽取4只火腿,采用固相微萃取-气相色谱-质谱（Solid-Phase Microextraction-Gas Chromatography-Mass Spectrometry,SPME-GC-MS）技术并结合相对气味活度值（Relative Odor Activity Value, ROAV）法和主成分分析（Principal Component Analysis,PCA）法对大河乌猪火腿挥发性风味物质进行分析。结果表明:腌制15、18、21、24 d的挥发性成分的种类分别为57、57、54、41种,共鉴定77种同类挥发性成分;聚类分析表明不同腌制时间的大河乌猪火腿挥发性物质的组成及相对含量存在较大的差异;ROAV分析表明醛类和醇类对风味贡献最大;PCA表明1-辛烯-3-醇、异戊醛、正辛醛、双戊烯是不同腌制期火腿中含量变化最明显的挥发性物质。腌制时间对大河乌猪干腌火腿风味品质有一定影响,研究可为火腿品质控制及风味改良提供理论依据。     

真空腌制与传统腌制加工过程中腊肉的品质变化

研究真空腌制和传统腌制加工过程中腊肉质量变化规律。对两种腌制方式腊肉在不同加工阶段的水分和食盐含量、亚硝酸钠残留量、微生物指标、颜色及挥发性风味物质种类及相对含量进行比较。结果表明:腌制完成后,真空腌制和传统干腌样品的水分含量分别下降16.5%和20.5%;食盐含量分别升至5.9%和5.2%;真空腌制的样品与传统干腌法的相比L*值高2.1%,a*值低12.2%,b*值差异不显著,菌落总数较低,球菌成为主要的优势菌种。烘烤烟熏完成后,与传统干腌法相比,真空腌制的腊肉样品水分、食盐和亚硝酸钠的含量更高;L*值高于传统干腌法,a*、b*值较低,使得腊肉色泽更佳,肉质呈愉悦的玫瑰粉红色;真空腌制腊肉中球菌和霉菌的数量高于传统干腌法,成为优势菌种,其他菌种的差异性不显著。加工过程中,同一阶段真空腌制的样品检测出的挥发性风味物质的种类及相对含量均高于传统干腌法。因而真空腌制能起到提高腊肉的保水性、促进腌制剂的吸收及改善腊肉风味和颜色的作用。     

不同鲜味物质对干腌马鲛鱼鲜味的贡献与比较分析

以8?种市售干腌马鲛鱼为研究对象,通过比较不同产品中鲜味物质成分和含量差异,并结合其滋味强度值和味精当量的分析计算,以确定对干腌马鲛鱼鲜味贡献最大的物质。结果表明：干腌马鲛鱼具有突出的咸、鲜味和浓厚味感,而其鲜味主要是由谷氨酸、鲜味肽等鲜味物质和乳酸等增鲜物质赋予。在其鲜味物质中,谷氨酸的滋味强度值大于1（除3、5、7号样品）,显示出它对干腌马鲛鱼鲜味的突出贡献,超滤组分的感官分析和肽分子质量分布测定结果表明,分子质量小于1?000?Da的小分子肽对样品的鲜味具有重要贡献。此外,长时间的风干可能会促进乳酸和鲜味肽的生成,但随着水分的流失,其苦味和咸味也增高;而辅料蔗糖和白酒的添加将抑制乳酸的产生,且蔗糖能在一定程度上促进谷氨酸的生成。值得强调的是,8?种样品的核苷酸均已降解为肌苷（inosine,HxR）和次黄嘌呤（hypoxanthine,Hx）等苦味物质,且长时间的风干可能会促进HxR和Hx的积累。     

比利时科学家研究抗坏血酸钠和亚硝酸钠对干腌香肠的蛋白氧化和脂肪氧化的影响

正腌制、微生物、干制和烟熏是影响干腌香肠品质稳定的主要因素。亚硝酸盐和抗坏血酸是发酵肉制品中使用的基础物质,腌制过程中需要添加食盐、硝酸盐或者亚硝酸盐、抗坏血酸钠,亚硝酸盐也能经过微生物的作用从硝酸盐转化。总之,这些物质的添加可以使得肉制品形成特定的目标颜色,同时,亚硝酸盐也能够限制微生物的生长。比利时科学家在干腌香肠成熟过程中,研究了亚硝酸盐和抗坏血酸钠对脂肪和蛋白质氧化的影响。实验分别在香肠成熟的0、2、8、14、     

发酵方式对黄山臭鳜鱼菌群组成及挥发性物质的影响

腌制发酵是获得黄山臭鳜鱼制品的唯一途径。采用干法腌制、湿法腌制及香辛料辅助湿法腌制方式制作臭鳜鱼,以原料鳜鱼作为对照,研究不同发酵方式对黄山臭鳜鱼微生物菌群组成和挥发性物质的影响,并对鱼肉进行感官评价。结果表明：不同发酵方式对黄山臭鳜鱼微生物菌群组成及挥发性物质组分有不同影响;干腌臭鳜鱼中的优势微生物菌群组成与原料鳜鱼基本一致;在湿腌发酵体系下,臭鳜鱼中的优势微生物菌群组成与原料鳜鱼则明显不同,但原料鳜鱼中的优势乳酸菌清酒乳杆菌仍然存在于湿腌体系中;湿腌发酵比干腌发酵产生更多的挥发性物质,在湿腌发酵体系中添加香辛料辅助发酵能够增加更多香气物质,且臭鳜鱼感官品质最好。     

腌制剂不同影响中式发酵香肠挥发性成分的组成

利用固相微萃取-气相色谱-质谱联用提取并分析发酵香肠中的挥发性物质,并探讨3 种不同的腌制剂（硝酸钠、亚硝酸钠、亚硝酸钠和抗坏血酸钠）对香肠风味物质,尤其是来源于支链氨基酸的风味成分的影响。结果表明腌制剂确实会对香肠中的风味物质含量产生一定的影响,且硝酸钠作为腌制剂更有利于乙酸乙酯、丁酸、2-丁酮、2-戊酮、2-庚酮、正己醇、正戊醇等风味物质的形成。     

脉冲减压腌制低盐风味咸蛋及黑圈抑制剂开发

以新鲜鸡蛋为原料，运用真空脉冲减压水腌法，探究腌制液配比、腌制时间等对咸蛋品质的影响，采用抗氧化剂茶多酚与金属螯合剂葡萄糖酸钠作为防黑圈剂，探究在真空脉冲减压水腌法下两者抑制咸蛋黑圈的可行性及抑制效果，结果发现在42℃的腌制环境下，将鸡蛋放入盐度为24%的五香腌制液中腌制5 d，再放入盐度16%的五香腌制环境中腌制2 d，腌制成熟时间最短为7 d，极大缩短了腌制时间，咸蛋蛋黄出油率为（64.73±1.98）%，蛋清的盐含量为（4.05±0.06）%，蛋黄盐含量为（1.36±0.02）%，风味物质含有醇类、烃类、酮类、酸类和酯类，酯类物质种类及含量增加，产品为低盐风味咸蛋。复配的腌制助剂（1%茶多酚+4%葡萄糖酸钠）较单一腌制助剂预防黑圈的效果较好，在质构分析与感官评价表现也较好。     

不同腌制方式对风干鳊鱼理化指标的影响

为探讨不同腌制方式对风干鳊鱼理化指标的影响,以鳊鱼为原料,分别研究干腌、湿腌、混合腌制三种腌制方式对风干鳊鱼加工过程中鱼肉的含盐量、含水量、TBA、p H、硬度和感官评价的影响。结果表明,三种腌制方式鳊鱼鱼肉的含水量均呈现下降的趋势,其中干腌含水量下降速率最快;含盐量均呈现上升的趋势,腌制结束后各种腌制方式的含盐量差异显著(p0.05),干腌含盐量升高的速率大于其他两种腌制方式,其最终含盐量为7.80%;TBA均呈现上升的趋势,在腌制结束后,干腌TBA显著高于湿腌和混合腌制(p0.05),其最终TBA值达到5.64 mg/kg;硬度均呈现先下降后上升的趋势,但差异不显著(p0.05);p H在加工过程中变化不大;三种腌制方式干腌的感官评分最高,其次是混合腌制、湿腌,三种腌制方式的感官评分分别是91.29、86.24、84.50。综合比较干腌腌制的风干鳊鱼在腌制速度和产品风味方面优于湿腌和混合腌制。     

生姜蛋白酶和猕猴桃蛋白酶对干腌羊火腿微生物菌相变化的影响

研究生姜蛋白酶和猕猴桃蛋白酶对干腌羊火腿微生物菌相变化的影响。采用聚合酶链式反应-变性梯度凝胶电泳技术对鲜羊腿（0 d）、腌制3 d以及对照组、生姜蛋白酶添加量0.05%组（S组）、猕猴桃蛋白酶添加量0.05%组（M组）风干前期（8 d）、风干中期（15 d）、风干后期（23 d）、成熟期（30 d）工艺点的干腌羊火腿微生物菌相变化进行测定。结果表明：腐生葡萄球菌（Staphylococcus saprophyticus）、表皮巨球菌（Macrococcus epidermidis）、土壤葡萄球菌（S. edaphicus）、哈夫尼亚菌（Hafnia paralvei）、明串珠菌（Leuconostoc gelidum）是各组干腌羊火腿的优势菌，其中葡萄球菌属种类较多；2 种蛋白酶可丰富干腌羊火腿微生物的种类；生姜蛋白酶和猕猴桃蛋白酶处理组成熟30 d时均出现木糖葡萄球菌（S. xylosus）；在整个加工过程中，干腌羊火腿微生物菌相变化较稳定，受2 种蛋白酶的影响不大。     

Effects of abomasal infusions of fatty acids and 1-carbon donors on apparent fatty acid digestibility and incorporation into milk fat in cows

Our primary objective was to determine the effects of the abomasal infusion of 16-carbon (16C) and 22-carbon (22C) fatty acids (FA) on apparent FA digestibility, plasma FA concentrations, and their incorporation into milk fat in cows. Our secondary objective was to study the effects of 1-carbon donors choline and l-serine on these variables. Five rumen-cannulated Holstein cows (214 ± 4.9 d in milk; 3.2 ± 1.1 parity) were enrolled in a 5 × 5 Latin square experiment with experimental periods lasting 6 d. Abomasal infusates consisted of (1) palmitic acid (PA; 98% 16:0 of total fat), (2) PA + choline chloride (PA+CC; 50 g/d of choline chloride), (3) PA + l-serine (PA+S; 170 g/d of l-serine), (4) behenic acid (BA; 92% 22:0 of total fat), and (5) docosahexaenoic acid algal oil (DHA; 47.5% DHA of total fat). Emulsions were formulated to provide 301 g/d of total FA and were balanced to provide a minimum of 40 and 19 g/d of 16:0 and glycerol, respectively, to match the content found in the infused algal oil. Apparent digestibility of FA was highest in DHA, intermediate in PA, and lowest in BA. Digestibility of 16C FA was lowest in BA and highest in PA. The digestibility of 22C FA was highest in DHA relative to BA (99 vs. 58%), whereas 1-carbon donors had no effect on 22C FA digestibility. Plasma 16C FA concentrations were greatest with PA treatment, and 22C FA concentrations were ~3-fold greater in DHA-treated cows relative to all other treatments. Milk fat 16:0 content was highest in PA relative to BA and DHA (e.g., 37 vs. 27% in PA and DHA), whereas the milk yield of 16:0 was higher in PA relative to DHA (i.e., 454 vs. 235 g/d). Similarly, milk 22:0 content and yield were ~10-fold higher in BA relative to all other treatments, whereas DHA treatment resulted in higher content and yield of 22:6 in milk fat relative to all other treatments (41- and 38-fold higher, respectively). Consequently, the content of FA >16C (i.e., preformed) was higher in milk fat from cows infused with BA and DHA relative to PA. De novo FA content in milk did not differ between PA, PA+CC, and PA+S (~16% of milk fat) but was higher in BA and DHA treatments (19 and 21%, respectively). We conclude that FA carbon chain length and degree of saturation affected FA digestibility and availability for absorption as well as their incorporation into milk fat. The abomasal infusion of choline chloride and l-serine did not modify these variables relative to infusing palmitic acid alone.     

奶粉脂肪酸与乳制品风味关系研究

用气质（GC—MS）联用色谱分析了11个商业奶粉样品的脂肪酸组成以及含量,每个样品均检测到了28种脂肪酸,在表现奶粉风味的4个呈味脂肪酸,也即辛酸、己酸、壬酸和葵酸中只检测到了辛酸和葵酸。辛酸和葵酸含量在进口奶粉中普遍高于国产奶粉。国产奶粉中辛酸和葵酸的含量以2号最好,3号其次。亚油酸含量在国产奶粉中普遍高于进口奶粉。     

气相色谱法同时测定保健食品中的5种 不饱和脂肪酸

目的建立气相色谱法同时测定保健食品中亚油酸、α-亚麻酸、二十碳五烯酸(eicosapentaenoic acid,EPA)、二十二碳六烯酸(docosahexaenoic acid,DHA)和二十二碳五烯酸(docosapentaenoic acid,DPA)的含量。方法样品先采用氢氧化钾甲醇溶液进行皂化处理,再用三氟化硼甲醇溶液甲酯化,经HP-FFAP色谱柱(30m×0.53 mm,1.0μm)分离测定。结果 EPA甲酯、DHA甲酯、DPA甲酯、亚油酸甲酯、α-亚麻酸甲酯分别在0.03927~1.178、0.04200~1.260、0.03449~1.035、0.08368~1.255、0.08482~4.241 mg/mL的浓度范围内线性关系良好,相关系数r均大于0.999;检出限分别为0.0039、0.0042、0.0034、0.0042、0.0042 mg/mL;加标回收率在91.1%~109.3%之间,相对标准偏差均小于5%。结论该方法操作简单快捷,适用于保健食品中亚油酸、α-亚麻酸、EPA、DPA和DHA的测定。     

Determination of ethanol,volatile fatty acids,lactic and succinic acids in fermentation liquids by gas chromatography

A rapid and simple quantitative method was developed to determine, by gas chromatography, the concentrations in fermentation liquids of ethanol, the C₂-C₆ volatile fatty acids, and lactic and succinic acids. Aqueous samples were acidified with 250μlml^?1 metaphosphoric acid (5:1 ratio), centrifuged, and injected directly on to a column containing a porous aromatic polymer (Chromosorb 101) maintained at 200°C in a gas chromatograph fitted with a flame ionisation detector. It was unnecessary to purify samples further before injection, although distillation and ion-exchange methods were examined. Derivatisation of lactic and succinic acids before injection was not necessary, but the lowest level of detection of these two relatively non-volatile acids was about four times greater than that for the volatile fatty acids. The method described was suitable for the analysis of rumen fluid, methane digester fluid, silage extracts and other anaerobic fermentation fluids. The relative retention times are given for 23 organic acids and six other fermentation end-products.     

磁化处理对脂肪酸精馏过程的影响

在不同磁感应强度的磁场中,研究了磁化处理对脂肪酸精馏过程的影响。研究结果表明,磁场对脂肪酸的精馏过程有一定的影响,脂肪酸经磁化处理后,油酸的含量提高0.41%～0.64%,收率提高0.30%～0.47%;亚油酸的含量提高0.46%～0.69%,收率提高0.37%～0.54%;硬脂酸的含量提高0.44%～0.62%,收率提高0.34%～0.48%。由此可见,磁化处理有利于脂肪酸精馏过程的进行。     

Analysis of pomegranate seed oil for the presence of jacaric acid

BACKGROUND: Pomegranate seed oil is predominantly composed of triglycerides containing unsaturated fatty acids, including high levels of conjugated linolenic acids (CLnAs). The major CLnA component, punicic acid, is known to possess biological activity. Consequently, it is desirable to obtain a detailed characterisation of pomegranate seed oil fatty acid profiles, including molecules potentially co‐eluting with punicic acid, such as jacaric acid. RESULTS: Conjugated fatty acid profiles of a commercial sample of cold pressed pomegranate seed oil were characterised in detail by both gas chromatography of methyl esters and by ¹³C NMR spectroscopy. The methylation procedures were found to be critical for determination of accurate fatty acid profiles. GC analysis was unable to resolve jacaric acid from punicic acid, the major fatty acid present in pomegranate seed oil. To establish the presence or absence of jacaric acid, ¹³C NMR was employed. CONCLUSION: This is the first study to investigate pomegranate seed oil for the presence of jacaric acid. Punicic acid, eleostearic acid, and catalpic acid were confirmed by ¹³C NMR, but jacaric acid was not found. Thus, we have shown that punicic acid levels may be accurately measured by gas chromatography alone in pomegranate seed oil. Copyright © 2009 Society of Chemical Industry     

Effects of addition of malic or citric acids on fermentation quality and chemical characteristics of alfalfa silage

We studied the effects on alfalfa preservation and chemical composition of the addition of different levels of malic acid and citric acid at ensiling as well as the utilization efficiency of these 2 organic acids after fermentation. Alfalfa was harvested at early bloom stage. After wilting to a dry matter content of approximately 40%, the alfalfa was chopped into 1- to 2-cm pieces for ensiling. Four levels (0, 0.1, 0.5, and 1% of fresh weight) of malic acid or citric acid were applied to chopped alfalfa at ensiling with 4 replicates for each treatment, and the treated alfalfa forages were ensiled for 60 d in vacuum-sealed polyethylene bags (dimensions: 200 mm × 300 mm) packed with 200 to 230 g of fresh alfalfa per mini silo and an initial density of 0.534 g/cm³. The application of malic or citric acids at ensiling for 60 d led to lower silage pH than was observed in the control silage (0% of malic or citric acids). Application of the 2 organic acids led to higher lactic acid concentration in alfalfa silage than in the control silage except with the application rate of 1% of fresh weight. Silages treated with both organic acids had lower nonprotein nitrogen concentrations than the control silages, and the nonprotein nitrogen concentrations in ensiled forages decreased with the increase in malic or citric acid application rates. The application of the 2 organic acid additives led to lower saturated fatty acid proportions and higher polyunsaturated fatty acid proportions in ensiled alfalfa than in the control silage. The amount of malic and citric acids degraded during ensiling of alfalfa was 1.45 and 0.63 g, respectively. At the application rate of 0.5% of fresh weight, residues of malic acid and citric acid in alfalfa silage were 11.1 and 13.6 g/kg of dry matter. These results indicate that including malic or citric acids at the ensiling of alfalfa effectively improved silage fermentation quality, limited proteolysis, improved fatty acid composition of the ensiled forage, and could provide animals with additional feed additives proven to promote animal performance. However, when the application rate of both organic acids reached 1%, the concentration of lactic acid in silages decreased notably. Additionally, 0.5 and 1% application rates also increased the yeast count in ensiled alfalfa.     

过氧乙酸灭菌效果及酸残留的实验研究

目的 研究过氧乙酸灭菌的效果及酸的残留量对pH值的影响。方法 用微生物学无菌检测法和pH值测定法。结果 满载,少量装载,重复灭菌时达到无菌效果,△pH均在0.3～0.4之间。结论 经过氧乙酸灭菌的塑料瓶能达到无菌要求,酸的残留量对pH值的影响不显著,生产上可用过氧乙酸灭菌法对不耐热的内包材进行灭菌。     

杂多酸催化合成辛酸蔗糖酯

以蔗糖、辛酸为原料,杂多酸为催化剂合成辛酸蔗糖酯。用L16(45)正交设计优化实验,高效液相色谱法分析反应液组成。考察了催化剂种类和用量、反应温度、原料配比、反应时间等因素对辛酸蔗糖酯产率的影响,发现以二甲基亚砜为溶剂、蔗糖与辛酸摩尔比1∶9、磷钨酸用量为蔗糖质量的2.0%、110℃反应时间6h,蔗糖转化率达60%,产物产要是二酯。动力学研究发现,蔗糖反应级数为一级,反应表观速率常数为0.0059min-1(90℃)、0.0117min-1(110℃),反应表观活化能Ea=39.57kJ/mol。     

酸味酿造产品中三酸比例评析

酸味酿造产品中乳酸、醋酸、丁酸共存,但比例不同形成的酸味特征也不同。控制不同的环境条件,创造出不同的微生物区系,形成不同的三酸比例,才能形成不同的产品风格。该文对常见的酸味酿造产品中微生物区系的变化及三酸含量进行了分析。