腊肉加工过程中游离脂肪酸的变化研究

分别对腊肉加工过程中肥肉和瘦肉的游离脂肪酸(FFA)的变化进行了测定,结果表明:肥肉中主要的FFA为油酸(C18∶1)、硬脂酸(C18∶0)、棕榈酸(C16∶0)和亚麻酸(C18∶3),且总FFA不断积累,81h达到最大值;脂肪酸在肥肉中的释放速率为亚油酸>亚麻酸>硬脂酸>油酸>棕榈酸。瘦肉中主要的FFA为硬脂酸、棕榈酸、亚油酸(C18∶2)和油酸,总FFA也不断积累,43h达到最大值;脂肪酸在瘦肉中的释放速率为硬脂酸>亚油酸>棕榈酸>油酸。腊肉加工过程中,脂质发生的降解和氧化对形成腊肉特有的风味发挥了重要作用。     

两种辐照方式对贵州腊肉中脂肪酸成分的影响

目的 研究了不同辐照处理对贵州腊肉中脂肪酸的影响。 方法 通过气象色谱法(GC)对贵州腊肉样品中脂肪酸的种类和含量进行了分析,并研究了_⁶⁰Co-γ 射线辐照和高能电子辐照两种辐照方法在0-5 kGy不同辐照剂量对腊肉中脂肪酸成分的影响。 结果 贵州腊肉样品中共检测出24种不同的脂肪酸,包括14种饱和脂肪酸(SFA),10种不饱和脂肪酸(UFA),未检测出反式脂肪酸(TFA)。辐照处理会导致腊肉中饱和脂肪酸含量上升,不饱和脂肪酸含量下降,产生了新的饱和脂肪酸C8:0和C10:0。高能电子辐照在3 kGy以下剂量时对样品影响更大,而剂量大于3 kGy时则_⁶⁰Co-γ辐照对样品中脂肪酸影响更大。 结论 辐照处理会影响腊肉中脂肪酸的含量和种类,但未产生有害的反式脂肪酸。两种辐照方式的能量大小和穿透能力存在一定差异,但对样品脂肪酸影响趋势基本一致。     

Sensory odour profiling and lipid oxidation status of fish oil and microencapsulated fish oil

The aim of the present study was to evaluate the suitability of defined odour attributes for the sensory evaluation of bulk fish oil and reconstituted microencapsulated fish oil as well as the active modification of the sensory profile during storage. Common attributes previously described for bulk fish oil (fishy, metallic, pungent, green notes) proved to be suitable for the sensory evaluation of reconstituted microencapsulated fish oil. Additional attributes were identified in dependence on the bulk fish oil processing (sweet/biscuit-like) and of constituents of the microcapsule carrier matrix (seasoning-like). Reconstituted sodium caseinate-based microcapsules exhibited a lower fishy odour during storage than did n-octenylsuccinate-derivatised starch-based microcapsules, probably due to the oxidative status. Flavour binding of caseinate may be of minor importance in reconstituted microencapsulated fish oil. Improvement of the sensory profile was achieved by the addition of an odour-masking compound (β-cyclodextrin) or flavouring (vanillin and apple flavour).     

Effect of cooking method on the fatty acid profile of New Zealand King Salmon (Oncorhynchus tshawytscha)

Farmed New Zealand King Salmon (Oncorhynchus tshawytscha) was prepared according to common consumer techniques; raw, poached, steamed, microwaved, pan fried (no added oil), oven baked (no added oil) and deep fried (in sunflower oil). The fatty acid profile was investigated to determine the optimal preparation techniques to achieve both optimal sensory and nutritional qualities, in particular the levels of long chain polyunsaturated omega-3 fatty acids. The modified Bligh and Dyer method was used for lipid extraction and the Hartman and Lago method for FAMES preparation. Fatty acid composition was determined by gas chromatography. There were moisture and lipid losses during cooking amongst the different methods. The fatty acid profile showed only minor differences between the methods apart from an increase in PUFA in the deep fried salmon due to linoleic acid uptake from the frying oil. In all the cooking methods the omega-3 fatty acids were well preserved. However, deep fried showed the lowest amounts of omega-3 fatty acids. As the results showed good preservation of omega-3 fatty acids regardless of cooking method, there may be possible “internal protection” of omega-3 fatty acids in King Salmon that warrants future research.     

脂肪酸营养与功能的最新研究

概述了脂肪酸的种类以及与胆固醇和动脉硬化的相关研究,同时综述了各类脂肪酸营养与功能的最新研究,包括有n-6系多价不饱和脂肪酸、n-3系多不饱和脂肪酸、饱和脂肪酸、一价不饱和脂肪酸,以及一些微量脂肪酸如共轭脂肪酸、中短边脂肪酸等等。     

鱼制品腥味产生机制及调控措施研究进展

为开发一种天然来源的脱腥剂,研究姜、蒜、香菜提取液对罗非鱼片腥味的影响。以罗非鱼片为原料,通过单因素实验研究了不同浓度（2、4、6、8、10 g/L）姜、蒜、香菜提取液对罗非鱼片腥味值、脂肪氧化及菌落总数的影响,再通过响应面试验优化三种提取液的浓度。结果表明,姜、蒜、香菜提取液在浓度为6~8 g/L时能有效减轻新鲜罗非鱼片的腥味值,并抑制冷藏过程中腥味物质的产生;三种提取液对硫代巴比妥酸值的最佳抑制浓度皆为8 g/L,蒜提取液处理组的抑制效果较好;姜、蒜、香菜提取液最适的抑菌浓度为8、8、10 g/L,蒜提取液处理组的抑菌效果较好。通过响应面优化得到的三种提取液复合脱腥的配方为：姜提取液8.9 g/L、蒜提取液7.5 g/L、香菜提取液5.8 g/L,在此条件下新鲜罗非鱼片腥味值为0.42。姜、蒜、香菜提取液复配对去除罗非鱼片的腥味具有较好的效果。     

基于气相色谱-离子迁移谱分析镇巴腊肉贮藏过程中挥发性风味成分变化

目的 基于气相离子迁移谱(gas chromatography-ion mobility spectroscopy, GC-IMS)分析镇巴腊肉储藏过程挥发性风味成分变化。方法 采用GC-IMS对现代工艺和传统工艺加工的镇巴腊肉在储藏过程中挥发性风味物质变化进行分析。分别取储藏1、6、12、24个月的现代工艺生产腊肉样品及储藏6、12、24个月的传统工艺生产腊肉样品,通过直观可视的三维图、二维图谱、指纹图谱及主成分分析(principal component analysis, PCA)的方式分析腊肉加工过程中挥发性风味物质种类及变化规律。结果 两种工艺腊肉样品都含有相同的43种已定性的挥发性物质,主要为酯类、酮类、醛类化合物,且每一个储藏阶段都有特征标记物产生;指纹图谱及PCA分析均可以看出现代工艺加工的样品中的挥发的风味成分储藏12个月到24个月的种类一致、含量没有明显变化,反映腊肉品质在该过程逐渐趋于稳定;而传统手工作坊腊肉储藏过程挥发性风味物质含量有着显著的差异,反映腊肉品质不一。结论 挥发性风味成分是腊肉储藏过程中非常重要指标,可用于腊肉样品的监测和品质评价。     

牛肉酶解物对牛肉特征香味形成的影响研究

以五种不同水解度牛肉酶解物分别制备得到5种热反应牛肉香精。利用定量感官分析和GCMS-O分析考察了5种热反应牛肉香精香气成分的变化。结果显示,添加DH29.13%酶解液的牛肉香精样品其牛肉味、肉香味和仿真度相比于其它样品是最强的。GC-O分析也发现DH29.13%的牛肉酶解液赋予形成了种类较多的香气活性化合物,而没有添加牛肉酶解物的肉味香精缺失了这些特征化合物。利用PLSR进行了香气活性化合物、感官评价和牛肉酶解液的肽分子量分布之间的相关性分析,进一步解释了DH为29.13%的牛肉酶解液是赋予热加工牛肉风味的最合适风味前体。     

The effects of the organic acids in cocoa on the flavour of chocolate

Samples (54) of dried fermented cocoa beans from different world regions were analysed for levels of organic acids, pH and titratable acidity. The effects of the organic acids on the flavour characteristics of cocoa were examined by sensory evaluation of chocolate made from samples of cocoa beans. Concentrations (g kg^?1) of acids ranged from 1.3 to 11.8 for acetic, 1-6 to 9-9 for citric, 0.6 to 11.1 for lactic and 2.1 to 6.5 for oxalic. pH values ranged from 4.6 to 5.8, while titratable acidity ranged from 0.08 to 0.31 equivalents of sodium hydroxide per kg sample. Cocoas from South East Asia and the South Pacific tended to be more acidic than West African beans in terms of both chemical and sensory characteristics. Lactic and acetic acids were found to be in greater concentrations in cocoas from the former regions and were considered to be largely responsible for higher acid flavour scores. In contrast, citric and oxalic acids were generally lower in these beans. Flavour assessments of cocoas with and without added organic acids indicated that oxalic acid played an important role in chocolate flavour. These results suggest that a reduction in the levels of acetic and lactic acids only, may not be sufficient to produce a desirable flavour balance.     

川味腊肉脂肪氧化控制研究进展

拥有悠久的历史和文化背景的川味腊肉是我国优良传统肉制品代表之一,它具有色泽鲜艳、皮黄肉红、麻辣鲜香等特点。脂肪氧化是川味腊肉特征风味产生的主要途径,而过度的氧化又会产生令人不愉快的滋味和气味,使川味腊肉失去食用价值。本文阐述了肉制品脂肪氧化的机理和川味腊肉脂肪氧化的特点。综述了通过原料肉的选择、低温处理、隔氧控制、添加抗氧化剂等控制技术的应用从而控制川味腊肉脂肪氧化的研究进展。并对川味腊肉未来的发展进行了展望。     

Extractable oil in microcapsules prepared by spray-drying: Localisation,determination and impact on oxidative stability

Aim of the present study was to investigate the localisation of the extractable oil in spray-dried microencapsulated fish oil prepared under different spray-drying conditions and to investigate the impact on lipid oxidation upon storage. Confocal laser scanning microscopy, scanning electron microscopy and different extraction procedures revealed that the extractable oil in microencapsulated fish oil is mainly located on the surface and in oil droplets close to the surface. Consequently, different methods for determination of the different fractions are proposed. Lipid oxidation as determined by hydroperoxide content or anisidine value was higher in microcapsules with 50% oil load spray-dried at 210/90 °C, propanal content was increased in samples with 30% oil load spray-dried at 210/90 °C. The differences in stability could only partly be explained by the varying amount of extractable oil. It is concluded that the surface oil protects other fractions of the extractable oil and that the extractable oil cannot be used to predict shelf-life of microencapsulated oils.     

Effects of nitrogen catabolite repression‐related amino acids on the flavour of rice wine

The quality of rice wine is highly dependent on the content of the flavour compounds produced by the budding yeast Saccharomyces cerevisiae. In this study, the effects of three amino acids (arginine, glutamate and glutamine) related to nitrogen catabolite repression on the formation of flavour compounds were investigated. Each of these amino acids could promote the growth of S. cerevisiae, and a total of 83 flavour compounds were found in a model system of rice wine production. The effects of arginine, glutamate and glutamine on the content of the higher alcohols, amino acids and esters were significant, whereas the effects on the aldehydes and organic acids were slight. The results of this study could facilitate the development of new strategies to control the flavour pattern and improve the quality of rice wine. Copyright © 2015 The Institute of Brewing & Distilling     

微生物PUFA微囊粉剂的免疫调节作用

考察了微生物多不饱和脂肪酸(PUFA)微囊粉剂对小鼠的体重、淋巴器官/体重比值、ConA诱导的脾淋巴细胞转化、二硝基氟苯(DNFB)诱导的迟发型变态反应、血清溶血素水平、腹腔巨噬细胞吞噬功能、碳廓清指数、抗体生成细胞等指标的影响。结果表明,该制剂对小鼠体重和淋巴器官/体重比值没有明显影响,而该制剂的中、高剂量可显著增强小鼠脾淋巴细胞的增值能力(P<0.05)、加剧ConA诱导的迟发型变态反应(P<0.05)、提高溶血素水平(P<0.05)、增强巨噬细胞吞噬功能(P<0.05)、增强碳廓清能力及抗体生成细胞的能力(P<0.05),因此微生物PUFA微囊粉制剂具有调节小鼠免疫功能的作用。     

Long chain polyunsaturated fatty acids in smoked Atlantic mackerel and Baltic sprats

Atlantic mackerel and Baltic sprats are rich sources of n − 3 long chain polyunsaturated fatty acids (LC PUFA). Literature data point to an influence of the properties of the raw material, storage conditions, and processing parameters of hot- and cold-smoking on the stability of these acids. The effects of industrial smoking in an automatic smokehouse in controlled, mild conditions at core temperature below 60 °C, as well as of cold storage, on the fatty acids (FA) in mackerel and sprats have been investigated. The FA were determined by gas chromatography (GC) according to the AOCS Ce 1b-89 method, in lipids extracted from the meat of several batches of defrosted and smoked fish early after smoking and during storage at 2 °C for up to 2 weeks. The contents of eicosapentaenoic acid C20:5 n − 3 (EPA) and docosahexaenoic acid C22:6 n − 3 (DHA) in different assortments of smoked mackerel meat were from 50 to 55 and from 67 to 100 mg/g of lipids, respectively while, in hot-smoked sprats, they were from 48 to 68 and from 73 to 128 mg/g of lipids. The results show that the variability of the FA composition of the frozen raw material was larger than the changes induced by smoking or by storage within the period of high quality life of the smoked product.     

促进微生物生产多不饱和脂肪酸的研究

多不饱和脂肪酸(PUFAs)作为功能性油脂已被广泛应用于食品工业领域。随着对纯PUFAs脂质的需求量越来越多,来自于动植物和深海洋鱼的PUFAs远远不能满足市场需求,且动植物含油量及不饱和脂肪酸类型、比例均受到一定的限制。一系列的研究表明,微生物特别是藻类、真菌能合成几乎所有的PUFAs,并能在工业规模上培育有开发价值的可替代生物资源。作者在近年来国内外有关研究的基础上,从培养条件、菌种选育、基因工程、代谢调控等方面对促进微生物产PUFAs的研究进行了综述,为相关的研究提供参考。     

Impact of trace element addition on degradation efficiency of volatile fatty acids, oleic acid and phenyl acetate and on microbial populations in a biogas digester

The effect of trace element addition on anaerobic digestion of food industry- and household waste was studied using two semi-continuous lab-scale reactors, one (R30+) was supplied with Fe, Co and Ni, while the other (R30) acted as a control. Tracer analysis illustrated that methane production from acetate proceeded through syntrophic acetate oxidation (SAO) in both digesters. The effect of the trace elements was also evaluated in batch assays to determine the capacity of the microorganisms of the two digesters to degrade acetate, phenyl acetate, oleic acid or propionate, butyrate and valerate provided as a cocktail. The trace elements addition improved the performance of the process giving higher methane yields during start-up and early operation and lower levels of mainly acetate and propionate in the R30+ reactor. The batch assay showed that material from R30+ gave effects on methane production from all substrates tested. Phenyl acetate was observed to inhibit methane formation in the R30 but not in the R30+ assay. A real-time PCR analysis targeting methanogens on the order level as well as three SAO bacteria showed an increase in Methanosarcinales in the R30+ reactor over time, even though SAO continuously was the dominating pathway for methane production. Possibly, this increase explains the low VFA-levels and higher degradation rates observed in the R30+ batch incubations. These results show that the added trace elements affected the ability of the microflora to degrade VFAs as well as oleic acid and phenyl acetate in a community, where acetate utilization is dominated by SAO.     

Fillet proximate composition,lipid quality,yields, and organoleptic quality of Mediterranean-farmed marine fish: A review with emphasis on new species

Species diversification in Mediterranean mariculture involves various important fish that contribute to the diet of many human populations. These include meagres (Sciaenidae), flatfishes, mullets, and various sparids. Their quality aspects (yields, fillet proximate composition, and lipid quality) are discussed in this review. Their filleting yield is mostly 40–45%. The viscerosomatic index ranges from 1.5% to 14%, depending on species. Low muscle fat contents of flatfishes and meagres differentiate them from the rest of the farmed species. Farmed fish contain high n-3 polyunsaturates fatty acids (PUFA; 12.3–36.3% vs. 5.48–37.2% in the wild) and have higher muscle fat and n-6 PUFA contents (mainly 18:2 n-6) than their wild counterparts. The aquaculture management, diet, and season can affect fillet composition and fatty acids, while season (i.e. food availability and maturation) largely affects lipid quality in wild fish. Data on the sensory quality of Mediterranean-farmed species are mainly limited to whether specific management differentiates the sensory quality; thus, further development of tools for sensory analysis is required. Observations on the quality features in farmed Mediterranean fish indicate that species diversification can also provide product diversification based on different commercial weights and fillet quality specifications.