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.     

Hydroxycinnamic acids on gut microbiota and health

Hydroxycinnamic acids (HCAs) are a major class of phenolic acids with the characteristic phenylpropanoid C₆-C₃ backbone. Its typically conjugated status with plant cell wall components and liberation by limited enzymes might be the reason for its neglect by researchers compared to flavonoid-type polyphenols. The polyphenol–gut microbiota interactions and their impact on human health have captured the interest of researchers recently. In addition, there has been a significant progress over the past few years in understanding the gut microbiota-modulating effect of HCA using animal model studies. This review discusses the metabolism of HCA in the digestive tract, HCA–gut microbiota interactions, and its link to colorectal cancer, inflammatory bowel diseases, mental-cognitive impairments, nonalcoholic liver disease, and obesity. The effects of food matrix and processing technologies on HCA bioavailability and HCA–gut microbiota interactions, and HCA safety concerns are also featured in this review. This paper has provided an in-depth insight on HCA–gut microbiota relationship and identified the current literature gaps for future research.     

2013~2014年长春市食品中食源性致病菌检测及分析

目的 了解食源性致病菌在长春市食品中检出情况,为食源性疾病防控工作提供科学的数据。方法 按《2103年国家食品污染和有害因素风险监测工作手册方法》、《 微生物检测方法的标准操作程序 》( 国家食品安全风险评估中心 )和国家标准方法进行食品中的食源性致病菌检测。结果 2013-2014年长春市11类食品433件样本中的食源性致菌的检出率是17.09%,其中蜡样芽胞杆菌、单核细胞增生李斯特氏菌、金黄色葡萄球菌和沙门氏菌的检出率分别是33.87%、12.81%、2.83%和0.58%。2013年和2014年食品中食源性致病菌的检出率无显著性差异(x₂=0.09,P＞0.05)。在乳制品、肉及其制品、婴幼儿食品、水产及其制品、餐饮食品、即食非发酵豆制品和速冻面米制品中食源性致病菌的检出率分别是：73.33%、40%、30.61%、9.52%、7.23%、5%和3.33%。结论 长春市食品存在不同程度上的食源性致病菌污染。乳制品、肉及其制品和婴幼儿食品中的食源性致病菌检出率较高,蜡样芽胞杆菌和单核细胞增生李斯特氏菌对食品污染较严重,需加强对这几类食品的监管。     

益生元、多酚、蛋白质和多不饱和脂肪酸对肠道健康的影响

肠道微生态与人体健康息息相关,肠道菌群失衡会导致人体出现多种疾病。食品功能因子通过调节肠道微生态平衡进行机体防御、疾病防治、健康恢复等。本文在列举肠道微生态失衡诱发的机体疾病基础上,综述了益生元、多酚、蛋白质和多不饱和脂肪酸等部分食品功能因子对肠道微生态的影响,以期为疾病的预防和治疗提供新的思路与方法。      

Effect of ruminal pulse dose of polyunsaturated fatty acids on ruminal microbial populations and duodenal flow and milk profiles of fatty acids

The objective of this study was to examine the effect of ruminal pulse dose of free linoleic acid (LA) and free docosahexaenoic acid (DHA) on microbial populations in the rumen, duodenal fatty acid (FA) flow, milk composition, and milk FA profiles of Chinese Holstein dairy cows. Four rumen- and duodenal-fistulated Chinese Holstein cows in mid lactation (138.5 ± 10 d in milk) were randomly assigned to 3 treatment groups and 1 control group in a 4 × 4 Latin square design over 4 periods (3 wk per period). Diets contained either no LA or 2.7% LA and either no DHA or 0.5% DHA in a 2 × 2 factorial arrangement of treatments. Ruminal pulse dose with DHA increased counts of Megasphaera elsdenii, decreased Fibrobacter succinogenes, but did not affect Butyrivibrio fibrisolvens or Ruminococcus flavefaciens. The pulse dose of LA at 2.7% dry matter had no effect on the population sizes of the 3 major cellulolytic bacterial species or M. elsdenii, and no interaction was observed between LA and DHA. The pulse dose of LA or DHA, either alone or in combination, increased the duodenal flow of vaccenic acid (VA). The milk VA and cis-9,trans-11 conjugated linoleic acid (CLA) contents also increased in response to the fatty acid pulse dose, and the pulse dose of both LA and DHA together had the most profound stimulatory effect. This study indicated that ruminal pulse dose of LA or DHA could be used to increase duodenal flow of VA and the milk contents of potentially health-promoting FA, such as VA and cis-9,trans-11 CLA. These results might be useful in formulating dietary interventions to improve milk cis-9,trans-11 CLA contents.     

Phages and engineered lysins as an effective tool to combat Gram-negative foodborne pathogens

One of the biggest challenges faced by food producers is ensuring microbiological safety. Despite strict criteria for food products, foodborne diseases are a global problem and pose a real risk to consumers. Therefore, it is necessary to identify new and more effective methods for eliminating pathogens from food and the food processing environment. According to the European Food Safety Authority (EFSA), the most common foodborne diseases are caused by Campylobacter, Salmonella, Yersinia, Escherichia coli, and Listeria. Out of the five listed, four are Gram-negative bacteria. Our review focuses on the use of bacteriophages, which are ubiquitous bacterial viruses, and bacteriophage endolysins to eliminate Gram-negative pathogens. Endolysins cleave specific bonds within the peptidoglycan (PG) of the bacterial cell, causing the cell to burst. Single phages or phage cocktails, which are, in some instances, commercially available products, eliminate pathogenic bacteria in livestock and various food matrices. Endolysins have matured as the most advanced class of antibacterial agents in the clinical sector, but their use in food protection is highly unexplored. Advanced molecular engineering techniques, different formulations, protein encapsulation, and the addition of outer membrane (OM) permeabilization agents enhance the activity of lysins against Gram-negative pathogens. This creates space for groundbreaking research on the use of lysins in the food sector.     

n-3 polyunsaturated fish fatty acids in a fish-oil-supplemented bread

White bread enriched in n-3 fatty acids in the form of gelatine-coated fish oil and marketed in Denmark since 1990 under the name of ‘Omega Bread’, was found to be a reliable and significant source of higher n-3 polyunsaturated fatty acids (with 20 and 22 C atoms). The bread from six bakeries contained 40-55 mg per 100 g more n-3 fatty acids. By eating 200 g daily of this bread one gets some 25-30% of the amount of higher n-3 polyunsaturated fatty acids present in 30 g of mixed fish. The daily ingestion of this amount of fish over a period of 20 years is known to reduce mortality from coronary heart disease by more than 50%. The supplement of n-3 polyunsaturated fatty acids obtained by eating Omega Bread daily in place of other types of white bread is expected to reduce coronary heart disease. In addition, such an increased daily ingestion of n-3 polyunsaturated fatty acids over a long-term period may possibly have other beneficial health effects. It is recommended that the intake of higher n-3 fatty acids in industrialised Western societies should be increased by more than can be obtained by a daily ration of Omega Bread. It is therefore advisable that consumption of Omega Bread is combined with an increased intake of fish and/or fish oil capsules and/or fish-oil-enriched substitutes for butter and margarine.     

Omega-3多不饱和脂肪酸在高脂血症中的作用机制研究进展

高脂血症是一种代谢紊乱疾病,直接引起或导致一些严重危害人体健康的疾病,如动脉粥样硬化、冠心病等。Omega-3多不饱和脂肪酸能够显著降低大鼠及人体血清中总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白(LDL)、极低密度脂蛋白(VLDL)的含量,同时增加高密度脂蛋白(HDL)的含量,其作用机制主要为增加外源性胆固醇代谢,减少内源性胆固醇合成,抑制肝脏胆固醇转运相关基因的表达,抑制肝脏载脂蛋白的产生,在高脂血症及其相关代谢性疾病的防治中发挥重要作用。基于国内外研究Omega-3多不饱和脂肪酸对血脂水平的调节作用,对Omega-3多不饱和脂肪酸在高脂血症中的作用机制进行综述,以期为深入研究Omega-3多不饱和脂肪酸对于血脂和脂质代谢调节的相关机制和后续相关药物的研发提供参考。     

Enhancement of dairy sheep cheese eating quality with increased n-3 long-chain polyunsaturated fatty acids

This study investigated the effect of different plant oil-infused and rumen-protected wheat-based pellets containing eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) on n-3 long-chain (≥C₂₀) polyunsaturated fatty acid (LC-PUFA) content, fatty acid recovery, and sensory attributes of ripened cheese from dairy sheep. During a 10-wk supplementary feeding trial, 60 dairy ewes balanced by live weight, milk yield, parity, and sire breed were randomly divided into 6 groups that were (1) supplemented with on-farm existing commercial wheat-based pellets without oil inclusion (control) or supplemented with wheat-based pellets infused with 50 mL/kg dry matter of oils from (2) canola, (3) rice bran, (4) flaxseed, (5) safflower, and (6) rumen-protected EPA + DHA. Milk samples from each treatment were collected separately by sire breed during the experimental period for cheese processing at the end of the experiment. Twelve batches of cheese (2 batches per treatment) were processed and ripened for 120 d. Three cheese samples were collected and analyzed for each cheese making session (total of 36 cheese samples) at d 120 of ripening. Processed cheese of rumen-protected EPA + DHA had the most efficiency at elevating total n-3 LC-PUFA [total EPA + DHA + docosapentaenoic acid (DPA, 22:5n-3] content compared with the control (0.49 vs. 0.28%). Flaxseed elicited the greatest enhancement of α-linolenic acid (ALA, 18:3n-3), whereas safflower was the most effective diet in enhancing the level of linoleic acid (18:2n-6) in cheese (1.29 vs. 0.71% and 4.8 vs. 3.3%, respectively). Parallel recoveries of n-3 and n-6 LC-PUFA were observed across all treatments except for α-linolenic acid and EPA. Cheese eating sensory traits were also highly affected by oil supplementation, with the highest score of 7.5 in cheese from the rice bran and flaxseed treatments. These results provide new insights into the biological mechanisms and processes that determine dairy ewe milk productivity by underpinning the vital biological role of n-3 LC-PUFA in not only enhancing the healthy composition of cheese from ewes but also translating it into consumer acceptability.     

烟台市部分即食食品中反式脂肪酸含量的调查

目的采用GC-MS/MS方法对烟台市部分在售即食食品中反式脂肪酸的含量进行定量分析,为市民的饮食结构提供参考。方法食品中提取的脂肪经氢氧化钾-甲醇溶液水解、甲酯化后转变为脂肪酸甲酯,进样GC-MS/MS系统分析,外标法定量。结果通过对烟台市主要市场、超市含油脂食品的调查发现,含油脂的食品中广泛存在着不同含量的反式脂肪酸。结论烟台市部分在售即食食品中所用油脂质量参差不齐,反式脂肪酸含量差别很大,市民要仔细查看食品标签上的配料成分,谨慎购买。     

气相色谱法检测食品中脂肪酸的研究进展

脂肪酸是食品的重要组成成分,也是机体能量的主要来源之一。了解脂肪酸的含量,对于合理规划饮食有很大帮助。近年来,食品安全事件频频发生,食品中脂肪酸的检测已成为食品检测领域重点工作。在食品中脂肪酸众多的检测手段中,气相色谱法依然是最常用的检测方法。本文汇总了目前食品中脂肪酸的国家标准检测方法,针对鱼油、植物油和婴幼儿食品等不同食品基质有不同的标准;综述了近年来国内外对食品中脂肪酸的气相色谱检测方法的研究进展,包括气相色谱法在不同食品中的检测应用、气相色谱前处理方法的优化以及串联质谱检测方法的拓展。对前处理条件的优化,从脂肪提取、甲酯化处理和色谱条件的改变等各方面分别进行概述。最后也对其发展趋势作出展望。     

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。     

Short‐term feeding of fermentable dietary fibres influences the gut microbiota composition and metabolic activity in rats

This study investigated the effects of dietary fibres on gut bacterial abundance and metabolic activity in rats fed short‐term. Faecal samples from rats fed for 7 days showed differences in the effects of dietary fibres on gut bacterial populations. Broccoli fibre, inulin, potato fibre and potato resistant starch significantly increased the faecal Bacteroides‐Prevotella‐Porphyromonas group compared with cellulose. Growth of pathogenic bacteria such as Clostridium perfringens, Escherichia coli and Enterococcus spp. was decreased significantly in rats fed barley β‐glucan, citrus pectin, inulin and broccoli fibre diets. An increase in Bifidobacterium spp. and butyric acid levels, the so‐called bifidogenic and butyrogenic effects, was observed in rats fed inulin and potato fibre diets. Organic acid concentrations and polysaccharide contents in the rat faeces confirm the fermentability of dietary fibres in the gut. This study demonstrates the positive effects of plant‐sourced dietary fibres on gut microbiota composition and metabolic activity.     

Trans fatty acids content and fatty acid profiles in the selected food products from Korea between 2005 and 2008

Since a high intake of trans fatty acids (TFA) has been associated with the increased risk of developing cardiovascular disease, food regulation worldwide has been amended with respect to nutrition labeling and health claims on TFA. In the present study, the TFA levels of Korean food products were investigated to assess the regulation effect of TFA labeling. Same Korean food products within 7 different categories were purchased in years 2005 and 2008, and the contents of TFA and lipid and fatty acid composition were investigated. Lipid and TFA contents decreased in all food products manufactured in 2008. TFA levels were 0.01 to 6.88 g/100 g food in 2005, but the levels remarkably decreased to nondetectable level or up to 0.5 g TFA/100 g food in 2008. The foods from 2005 contained a various level of TFA ranging 0.6% to 44.6% of total fatty acids; however, the TFA level significantly decreased in most foods up to 3.8% from year 2008. For TFAs, trans C18:1 levels were greater than trans isomers of C18:2, and the levels in 2005 were significantly reduced in 2008 (P < 0.05). TFA levels at the sn-2 position were up to 48.3% of total fatty acids in 2005, but the level considerably decreased up to 5.4% in 2008. The considerably decreased content of TFA in 2008 suggested that food manufacturers recognized the adverse effect of TFA on human health and followed the compulsory trans fat labeling rule by Korean Food and Drug Administration (KFDA), which started December 2007.     

油脂加工减控反式脂肪酸技术研究进展

该文简介反式脂肪酸性质、来源、分类、对人体健康主要危害及世界各国管理规定,分析油脂加工过程中反式脂肪酸生成机理、途径及影响其生成工艺技术参数,重点综述阻断或减少油脂加工过程中反式脂肪酸生成途径与方法,并提出减控反式脂肪酸生成技术研究、反式脂肪酸安全风险分析与控制、监督管理措施等方面建议。     

火麻油总脂肪酸及sn-2位脂肪酸组成分析

采用气相色谱法测定火麻油中总脂肪酸和sn-2位脂肪酸的组成和含量,并与其他9种常见植物油进行对比,旨在为火麻油的营养价值研究提供基础数据。结果表明,3种不同品牌火麻油主要由软脂酸（C16∶ 0）、硬脂酸（C18∶ 0）、油酸（C18∶ 1n9c）、亚油酸（C18∶ 2n6c）、α-亚麻酸（C18∶ 3n3）组成,其中多不饱和脂肪酸含量为70.57%~78.73%,sn-2位多不饱和脂肪酸含量为77.61%~83.74%,说明以亚油酸和α-亚麻酸为主的多不饱和脂肪酸更易连接在甘三酯结构的sn-2位上。另外,对比其他9种常见植物油,火麻油总脂肪酸和sn-2位脂肪酸中油酸含量均最低,亚油酸和亚麻酸含量较高;多不饱和脂肪酸含量均最高,分别为77.90%和83.74%;n-6系脂肪酸与n-3系脂肪酸比例分别为3.7∶ 1和4.2∶ 1。研究结果表明,火麻油是一种不饱和脂肪酸含量较高且易于被人体吸收代谢的植物油。     

Physico‐enzymatic production of monoacylglycerols enriched with very‐long‐chain polyunsaturated fatty acids

BACKGROUND: Monoacylglycerols (MAG) containing polyunsaturated fatty acids (PUFA), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have interesting applications. The enzymatic processing of such MAG directly from fish oils is highly interesting, integrating the processing of MAG and concentration of EPA and DHA. The aim of this study was to develop an efficient enzymatic glycerolysis system together with physical fractionation for the production of PUFA‐MAG from tuna oil. RESULTS: Novozym 435 was eventually selected after evaluation together with immobilized lipase AK in a tertiary alcohol‐based system. A further evaluation of solvent mixtures involving tertiary alcohols was made, taking ease of operation into consideration. It turned out that a number of mixtures gave a similar performance to that of tert‐butanol (TB). Basic reaction parameters were thoroughly evaluated. In the batch reaction system with TB as solvent, the recommended conditions were: glycerol/tuna oil 4:1 (mol/mol), TB/tuna oil 2:1 (wt/wt), 15 wt% Novozym 435, and temperature 40 °C. Under these conditions, the yield of MAG was up to 90% after 3 h incubation. Crude MAG from the production was fractionated to produce MAG with higher EPA and DHA content. Using acetone as solvent at 0 °C led to ca 50% yield of MAG but contained EPA and DHA up to 71% in comparison with ca 30% in tuna oil. CONCLUSION: Potentially practical process steps have been developed for the production of MAG containing a high content of EPA and DHA from natural fish oils with high efficiency and simplicity. Copyright © 2007 Society of Chemical Industry     

Short communication: effects of nonesterified fatty acids on lymphocyte function in dairy heifers

This in vitro study was performed to assess the effects of various concentrations of nonesterified fatty acids (NEFA) on lymphocyte function of heifers. Nine Holstein heifers were studied. Peripheral blood mononuclear cells were incubated with various concentrations of NEFA (0, 0.0625, 0.125, 0.25, 0.5, 1, and 2 mmol/L). The mixture of NEFA was represented by C16:0 (30%), C16:1 (5%), C18:0 (15%), C18:1 (45%), and C18:2 (5%). The DNA synthesis was diminished at concentrations of NEFA of 2, 1, and 0.5 mmol/L. The IgM secretion was inhibited at concentrations of NEFA of 2, 1, 0.5, and 0.25 mmol/L. Secretion of IFN-gamma was depressed at concentrations of NEFA of 2, 1, 0.5, 0.25, and 0.125 mmol/L. Increases of plasma NEFA might contribute to explain the higher incidence of infections observed in cows suffering from energy deficit.     

Culture‐Independent Rapid Detection Methods for Bacterial Pathogens and Toxins in Food Matrices

Rapid detection of bacterial pathogens and toxins in foods is necessary to provide real‐time results to mitigate foodborne illness outbreaks. Cultural enrichment methods, although the most widely used, are time‐consuming and therefore inadequate for rapid pathogen detection from food samples. The development of novel “rapid” detection methods has decreased detection time dramatically. This review presents an overview of detection methods for various foodborne pathogens, including Listeria monocytogenes, Salmonella enterica, and shiga toxin‐producing Escherichia coli, and bacterial toxins in food matrices, with emphasis on those methods which do not require cultural enrichment. Discussed methods include nucleic acid‐, immunological‐, and biosensor‐based techniques. A summary of each type of detection method is given, including referenced methods from the literature. Since these discussed methods do not require cultural enrichment, there is a higher probability of interference from the food matrices. Therefore, the review also discusses the potential interference of food components on detection methods and addresses preprocessing strategies to overcome matrix associated inhibition and to concentrate low quantities of pathogens and toxins in food. Development of rapid and sensitive detection technologies advances and ensures public health safety and security.     

植物油脂多不饱和脂肪酸的分离与富集研究

利用低温冷冻结晶和尿素包合法在同一工艺条件下考察了五种植物油脂中多不饱和脂肪酸的分离和富集效果。低温冷冻结晶初步分离得到的脂肪酸Ⅰ中,仅含少量饱和脂肪酸,总不饱和脂肪酸含量达到95%以上,达到PUFAs的预浓缩目的。尿素包合法富集PUFAs实验中,光皮油、棕榈油脂中PUFAs的分离效果最好,亚油酸纯度达到96.67%和97.18%;小桐子油和大豆油脂中亚油酸含量分别为81.74%和91.75%;桐油中PUFAs的富集效果不明显,总PUFAs纯度仅由原来的85.36%提高到91.62%。