膳食反式脂肪酸的风险评估研究进展

反式脂肪酸是一类包含一个或多个反式构型双键的不饱和脂类分子。膳食中的反式脂肪酸有2类:微量的天然反式脂肪酸和可观的人造反式脂肪酸。过去的研究认为反式脂肪酸的摄入仅仅是一个营养问题,但越来越多的毒理学和暴露评估的研究结果表明反式脂肪酸对人体健康有诸多不良影响。因此,反式脂肪酸的摄入已成为一个食品安全问题。目前,许多国家已经对反式脂肪酸的摄入量做了规定。本文主要围绕膳食反式脂肪酸的来源、对人体产生的生理效应和病理影响、产生这些效应的细胞或分子机制,以及如何有效控制反式脂肪酸的摄入等进行综述,并讨论了反式脂肪酸的风险评估现状和未来展望。     

焙烤食品反式脂肪酸标注情况及消费者态度调查

目的:调查反式脂肪酸(TFAs)在焙烤食品中的存在和标注情况,研究消费者对TFAs的认知和态度,以及在告知TFAs害处之后购买意向的变化。方法:对北京海淀区4家大型超市的焙烤类食品的标签进行了调查;以问卷的形式调查了在相应超市购物的500名消费者。结果:标注TFAs的产品仅占总被调查产品数的1.6%。原料中使用的油脂名称混乱,标注不规范。含有TFAs的油脂在饼干类产品中排名最为靠前。消费者普遍消费含有TFAs的食品,其中14%的消费者经常购买这类食品,女性消费频次高于男性。消费者对TFAs的危害及来源缺乏了解,但99.6%的消费者支持对其进行标注。在告知TFAs的危害之后,94.2%的消费者表示会减少相关食品的消费,对标签上原料信息的关注度也显著提高。结论:在焙烤类食品标签上增加反式脂肪酸的标注,有助于消费者选择健康食物。     

Impact of trans fatty acids of ruminant origin compared with those from partially hydrogenated vegetable oils on CHD risk

There is a considerable overlap of trans fatty acid (TFA) isomers in fats of ruminant origin and partially hydrogenated vegetable oils (PHVOs), with many isomers in common. However, there is a considerable difference in the amount of individual TFAs in both sources. At present it is uncertain as to which component(s) of TFAs created by chemical hydrogenation are responsible for their negative metabolic effects. There is evidence of unfavourable effects of TFAs from hydrogenated vegetable oils on LDL and other risk factors of atherosclerosis. There is no evidence that the predominant TFA in milk, vaccenic acid, exerts these unfavourable effects. Prospective studies addressing the effect of TFA intake on coronary heart disease risk, whose estimate of TFA intake was based on dietary protocols, were mostly carried out in populations with a relatively low intake of dairy or ruminant TFAs. Nevertheless, several of them showed a significantly or non-significantly decreased risk with increasing intake of animal TFAs, or at least no increased risk. Up to now there is no human study available that investigates the effect of different TFAs under “Ceteris paribus” conditions (isoenergetic diets with otherwise identical fatty acid profile). By now the production of milk fat samples differing mainly in TFA content is feasible and would allow such controlled intervention studies.     

上海地区部分市售食品中反式脂肪酸含量与组成分析

目的了解上海地区部分市售食品中的反式脂肪酸(trans-fatty acids,TFAs)含量以及异构体组成,为开展TFAs的风险评估和食品选择提供参考。方法于2011年1～6月在上海市超市、面包店或快餐店中抽取具有代表性的9大类共106种市售食品,包括植物油、乳及乳制品、休闲食品、方便食品、快餐食品、饮料、小吃甜饼、调味品和畜禽肉及制品,采用银离子固相萃取(Ag+-SPE)结合气相色谱方法检测TFAs含量。结果抽检样品中的TFAs以反式油酸(t C18∶1)为主,反式多不饱和脂肪酸含量较少。除黑咖啡外,其余105种食品均检测到TFAs,其中,巧克力派的TFAs含量最高(1 711.58 mg/100 g)。反刍动物食品和含乳及乳制品的食品中11t C18∶1异构体含量较高(占总TFAs的53.9%～100.0%)。富含氢化油的休闲食品中9t C18∶1异构体含量较高(占总TFAs的14.3%～87.7%)。猪肉和牛肉经加工后TFAs含量有不同程度降低。结论市售食品中普遍检测到TFAs,食物成分和加工过程不同总TFAs含量及异构体组成存在较大差异,预包装休闲食品和西式甜饼店食品含有较多的TFAs。     

Fabrication of Reduced Fat Products by Controlled Heteroaggregation of Oppositely Charged Lipid Droplets

Abstract: This study describes how the rheological properties of colloidal dispersions formed by heteroaggregation of oppositely charged protein‐coated lipid droplets depend on total particle concentration. Mixed‐particle emulsions were formed by mixing single‐particle emulsions containing either β‐lactoglobulin‐coated lipid droplets (ζ≈?42 mV, d₄₃≈ 0.35 μm) or lactoferrin (LF)‐coated lipid droplets (ζ≈+26 mV, d₄₃≈ 0.32 μm). A series of single‐particle and mixed‐particle emulsions with different total fat contents (5% to 40%) were prepared, and their mean particle size, apparent viscosity, and shear modulus were measured. Mixed‐particle emulsions (40% LF: 60%β‐Lg) containing relatively high fat contents (>10%) had high viscosities and paste‐like properties. These rheological characteristics were attributed to extensive particle aggregation and network formation due to electrostatic attraction between oppositely charged droplets. The viscosities of mixed‐particle emulsions were much higher than those of single‐particle emulsions with equivalent fat contents. Measurements of the color coordinates (L*, a*, b*) of mixed‐particle emulsions with low fat contents showed that they had similar appearances as single‐particle emulsions with high fat contents. This study has important implications for the creation of reduced fat foods with similar sensory qualities as higher fat foods. Practical Application: This study describes how novel food materials can be created by mixing together negatively charged and positively charged lipid droplets. These mixed emulsions may be suitable for the creation of reduced fat products, since they have high viscosities and paste‐like properties at relatively low fat contents.     

A quick method for identifying radiolytic hydrocarbons in low‐fat‐containing food

BACKGROUND: As radiation‐induced alterations of the lipid fraction of foods are related to their initial fat content, concentrations of fat degradation products used as irradiation markers are expected to be lower when irradiating low‐fat‐containing foods. Thus the sensitivity required when applying analytical methods for identifying irradiation markers in foods eventually depends on their respective amounts of fat. The aim of this study was to perform the qualitative analysis of characteristic hydrocarbons resulting from irradiation of samples with a fat content as low as 25 g kg^?1. RESULTS: A rapid extraction using a small amount of ethyl acetate was the unique sample pretreatment required to accomplish the analysis of radiolytic markers by using on‐line coupling of reverse phase liquid chromatography and gas chromatography with mass spectrometry detection (RPLC/GC/MS). Efficient elimination of the large volumes (up to 2170 µL) directly transferred from LC to GC was achieved by optimising the operation mode of the through‐oven transfer adsorption/desorption system used as interface. CONCLUSION: The reported procedure allowed confirmation, in less than 65 min, of the occurrence of up to five irradiation markers, namely n‐pentadecane, 1‐hexadecene, 1,7‐hexadecadiene, n‐heptadecane and 8‐heptadecene, in cooked ham irradiated at doses as low as 2 kGy. © 2012 Society of Chemical Industry     

Composition and Structure of the Bovine Milk Fat Globule Membrane—Some Nutritional and Technological Implications

Milk fat is dispersed in milk as small, spherical globules, stabilized in the form of emulsion by its surrounding membrane. This membrane, called the milk fat globule membrane (MFGM), is created in the secretory cells of the mammary gland, and represents an ordered and unique biophysical system. This review characterizes the main milk fat globule components, their structure, and intracellular origin. The milk fat globule membrane has many potentially bioactive components. These are discussed in terms of their health effects for the native and processed globules. Because of their functional and nutritional properties, MFGM components can be used as valuable ingredients in the manufacture of new functional foods.     

油炸食品含油率研究

油炸食品是一种传统方便食品,由于其特殊风味倍受人们喜爱,而含油率已被认定为影响其安全性重要因素。该文探讨油炸食品含油机理,分析原料性质对含油率影响,并提出降低含油率措施及其检测技术。     

7类食品中反式脂肪酸含量的调查

对采集的7类76种食品中的反式脂肪酸(TFAS)异构体构成及其含量进行调查。采用气相色谱内标法测定反式脂肪酸(TFAS)含量。结果表明:68%样品中的TFAS含量≤0.3 g/100 g,29%样品的TFAS含量在0.3～2.0 g/100 g,只有3%样品的TFAS含量>2 g/100 g。除锅巴和膨化食品外,被检食品中的TFAS异构体的组成主要是以C18∶1t为主,其C18∶1 t总量占总TFAS含量的60%～96%,说明反式脂肪酸(TFAS)广泛存在于被检的各类食品中,除含人造奶油、代可可脂高的少数食品外,绝大多数食品中的TFAS含量水平不高。     

Sensory perception of fat in common foods using two scaling methods

Seventy-three subjects evaluated fat content and preference for six different foods using a ranking task and a line scale, and the results from the two methods were compared. The foods included milk, pudding, mashed potatoes, and chicken spread (0–30% added fat), scrambled eggs (0–50% added fat) and a savory snack (low-high in added fat). Samples within a series were formulated to minimize appearance and flavor differences. The perception of fat in these foods appeared to be system-specific. Subjects effectively judged increasing fat content in the milk, pudding, potato, and snack samples, but could not reliably judge fat content in the chicken spreads and scrambled eggs. The hedonic ratings were unrelated to the ability to perceive fat in these foods. Both scaling techniques were effective in scaling these perceptions.     

Too good to be true: Dose insensitivity and stereotypical thinking of foods’ capacity to promote weight gain

It has been well documented that the general public holds many mistaken beliefs about foods and their roles in weight gain and health/disease. For example, foods that are perceived as bad for health (e.g., 3 slices of bacon; 109 calories) are typically judged to promote significantly more weight gain than more reputable foods (e.g., a large raisin bran muffin; 460 calories), even if the “bad” food contains far fewer calories than the “good” food. The current study was unique in that participants were provided not only names of snacks but also their caloric amounts and then asked to judge each snack’s capacity to promote weight gain. Results indicated that, despite the caloric information presented, respondents rated “bad” foods as weight promoters (compared to “good” foods) and only fat content (not energy density or fiber and sugar content) primarily predicted which foods would be judged to promote weight gain. It appears that “high fat” may be a synonymous with “bad” for many people or that dietary fat is perceived to have a far greater impact on body weight than is justified by the nutrient’s caloric content. In either case, it appears that a potentially harmful message has been assimilated by the general public.     

大豆及其加工食品转基因成分检测技术研究进展

随着基因工程技术在食用农产品领域的应用发展,形形色色的转基因食品应运而生。目前包括我国在内的许多国家为保护消费者的知情权和选择权,都建立了转基因食品标识管理制度。科学有效的转基因食品检测技术是实现我国转基因产品标识管理的前提。我国食品成分多样且基质复杂,针对初级农产品的转基因成分检测技术并不完全适用于工业加工食品尤其是深加工食品。这对食品监管及技术检测部门提出了新的要求。本文根据技术原理的不同分类介绍了目前几种主要的食品中转基因成分检测技术,除介绍现在已经成熟应用的技术方法外,本文还重点介绍了国内学者新近研发出的几种新技术,为研究人员进一步研发新技术提供重要参考。     

气相色谱法测定食品中反式脂肪酸的研究进展

气相色谱法(GC)是测定食品中反式脂肪酸(TFAs)的常用方法,该方法灵敏度高、准确度好。然而,由于来源于反刍动物的天然TFAs(n-TFAs)与部分氢化油的工业TFAs(IP-TFAs)的组成不同,以及不同食品中不饱和脂肪酸的组成差异,无法利用一种固定操作程序完全分离并准确分析各类食品中的TFAs组成。本文通过分析食品中TFAs的来源与组成,系统综述了GC法分析TFAs的原理和操作步骤,包括样品前处理方法、甲酯化衍生方法、Ag+预分离法,色谱条件(如色谱柱、柱长、柱温、进样口温度和检测器温度等)的选择和优化,以及常见的定性、定量分析方法。同时介绍了目前国内外标准方法的适用范围和特点,以便帮助分析人员依据实际样品以及所在实验室条件选择适合的分析方法。     

Weissella cibaria short-fermented liquid sourdoughs based on quinoa or amaranth flours as fat replacer in focaccia bread formulation

Production of the traditional Italian Focaccia bread (FcBread) requires reformulation to meet the new rules for healthier foods. We tested the applicability of a short-fermented (15 h) liquid sourdough (LS) (dough yield, DY, 250), obtained using quinoa (Q) or amaranth (Am) flour fermented with a Weissella cibaria strain (C43-11) producing exopolysaccharides (EPS) as fat replacer in yeast-leavened FcBread. The LSs were applied during the FcBread-making process at industrial pilot plant, reducing the added fat amount by 20% (FcBread-QLS and FcBread-AmLS) and products were compared with reference samples not containing EPS. All the products were analysed for physico-chemical properties (pH, TTA, organic acids, protein content and profile, instrumental colour), textural properties, sensory quality and glycemic index. The application of both pseudo-cereal-based W. cibaria LSs in FcBread allowed obtaining products with a reduced amount of fat, increased protein amount, mainly due to the albumin and glutenin/glutelin fractions, reduced glycemic index, improved texture and preserved in the traditional sensory profile of ‘focaccia’.     

The Influence of Herbs,Spices, and Regular Sausage and Chicken Consumption on Liking of Reduced Fat Breakfast and Lunch Items

Adults often consume more fat than is recommended. We examined factors that may improve liking of reduced fat and reduced saturated fat foods, including the addition of herbs and spices and habitual consumption of different high‐fat and low‐fat food items. We randomized adults to taste 3 different conditions: full fat (FF), reduced fat with no added spice (RF), and reduced fat plus spice (RFS). Subjects rated their liking of French toast, sausage and the overall meal, or chicken, vegetables, pasta, and the overall meal on a 9‐point hedonic Likert scale. Overall liking of the RF breakfast and lunch meals were lower than the FF and RFS versions (breakfast: 6.50 RF compared with 6.84 FF, P = 0.0061; 6.50 RF compared with 6.82 RFS, P = 0.0030; lunch: 6.35 RF compared with 6.94 FF, P < 0.0001; 6.35 RF compared with 6.71 RFS, P = 0.0061). RFS and FF breakfast and lunch meals, French toast, chicken, and vegetable likings were similar. FF and RFS conditions were liked more than RF for the breakfast and lunch meals, French toast, chicken entrée, and vegetables. Liking of all 3 sausage conditions was similar. FF pasta was liked more than RFS and RF (7.47 FF compared with 6.42 RFS, P < 0.0001; 7.47 FF compared with 6.47 RF, P < 0.0001). Habitual consumption of roasted chicken was associated with reduced liking of FF chicken (r = ?0.23, P = 0.004) and FF pasta (r = ?0.23, P = 0.005). Herbs and spices may be useful for improving the liking of lower fat foods and helping Americans maintain a diet consistent with the U.S. Dietary Guidelines.     

反式脂肪酸的研究进展

本文对反式脂肪酸的结构、来源、摄入量、生理作用和检测方法等进行综述。研究表明日常食用的人造奶油、起酥油和焙烤食品中存在大量反式脂肪酸,它们主要是在油脂的氢化过程中产生的。天然的反式脂肪酸主要是在反刍动物的瘤胃菌作用下产生的,存在于乳制品中,含量较低;乳制品中主要的反式脂肪酸—18∶111t,已证实可在体内转化为对人体有益的18∶29c11t。反式脂肪酸能提高冠心病和Ⅱ型糖尿病的发病率,并且干扰不饱和脂肪酸代谢、影响婴儿的生长。人们对不同来源的反式脂肪酸的生理作用还存在争议,反式脂肪酸的作用可能与其异构体种类有关。     

Antioxidant and Antimicrobial Activities of (‐)‐Epigallocatechin‐3‐gallate (EGCG) and its Potential to Preserve the Quality and Safety of Foods

Quality deterioration of fresh or processed foods is a major challenge for the food industry not only due to economic losses but also due to the risks associated with spoiled foods resulting, for example, from toxic compounds. On the other hand, there are increasing limitations on the application of synthetic preservatives such as antioxidants in foods because of their potential links to human health risks. With the new concept of functional ingredients and the development of the functional foods market, and the desire for a “clean” label, recent research has focused on finding safe additives with multifunctional effects to ensure food safety and quality. (‐)‐Epigallocatechin‐3‐gallate (EGCG), a biologically active compound in green tea, has received considerable attention in recent years and is considered a potential alternative to synthetic food additives. EGCG has been shown to prevent the growth of different Gram‐positive and Gram‐negative bacteria responsible for food spoilage while showing antioxidant activity in food systems. This review focuses on recent findings related to EGCG separation techniques, modification of its structure, mechanisms of antioxidant and antimicrobial activities, and applications in preserving the quality and safety of foods.     

美国食品所标示的有关膳食脂肪与冠心病关系的健康声明及对中国出口食品的指导意义

介绍了ＦＤＡ关于食品健康声明的定义,膳食脂肪与冠心病关系,可以标示健康声明的食品要求以及ＦＤＡ在最终通过健康声明之前须考虑的安全性问题,为国内的食品界提供一些参考信息。     

Effect of increasing the protein-to-fat ratio and reducing fat content on the chemical and physical properties of processed cheese product

Scientific studies indicate that the intake of dietary fat and saturated fats in the modern Western diet is excessive and contributes adversely to health, lifestyle, and longevity. In response, manufacturers of cheese and processed cheese products (PCP) are pursuing the development of products with reduced fat contents. The present study investigated the effect of altering the fat level (13.8, 18.2, 22.7, 27.9, and 32.5 g/100 g) in PCP on their chemical and physical properties. The PCP were formulated in triplicate to different fat levels using Cheddar cheese, skim milk cheese, anhydrous milk fat, emulsifying salt (ES), NaCl, and water. The formulations were designed to give fixed moisture (~53 g/100 g) and ES:protein ratio (0.105). The resultant PCP, and their water-soluble extracts (WSE), prepared from a macerated blend of PCP and water at a weight ratio of 1:2, were analyzed at 4 d. Reducing the fat content significantly increased the firmness of the unheated PCP and reduced the flowability and maximum loss tangent (fluidity) of the melted PCP. These changes coincided with increases in the levels of total protein, water-soluble protein, water-insoluble protein, and water-soluble Ca, and a decrease in the molar ratio of water-soluble Ca to soluble P. However, both water-soluble Ca and water-soluble protein decreased when expressed as percentages of total protein and total Ca, respectively, in the PCP. The high level of protein was a major factor contributing to the deterioration in physical properties as the fat content of PCP was reduced. Diluting the protein content or reducing the potential of the protein to aggregate, and thereby form structures that contribute to rigidity, may provide a means for improving quality of reduced-fat PCP by using natural cheese with lower intact casein content and lower calcium:casein ratio, for example, or by decreasing the ratio of sodium phosphate to sodium citrate-based ES.