Diverse food-based applications of nuclear magnetic resonance (NMR) technology

Nuclear magnetic resonance (NMR) spectroscopy is one of the most common investigative techniques used by both chemists and biochemists to identify molecular structures as well as to study the progress of chemical reactions. Magnetic resonance imaging (MRI), another type of NMR technology, has extensively been used in medical radiology to obtain soft tissue images for diagnostic purposes in medicine. Food scientists have also explored the use of both NMR and MRI and continue to develop a wide range of applications for food analysis and food processing. This review begins with a brief introduction to NMR and then focuses on current diverse NMR applications in food research and manufacturing. Topics covered include chemical compositional analysis and structural identification of functional components in foods, determination of composition and formulation of packaging materials, detection of food authentication, optimization of food processing parameters, and inspection of microbiological, physical and chemical quality of foods. This review also emphasizes the pros and cons of specific NMR applications in the analysis of representative foods such as wine, cheese, fruits, vegetables, meat, fish, beverages (i.e. tomato juice and pulp, green tea, coffee) and edible oils, as well as discussing both the challenges and future opportunities in NMR applications in food science.     

2,5-diketopiperazines in food and beverages: Taste and bioactivity

2,5-Diketopiperazines (2,5-DKPs) have been found to occur in a wide range of food and beverages, and display an array of chemesthetic effects (bitter, astringent, metallic, and umami) that can contribute to the taste of a variety of foods. These smallest cyclic peptides also occur as natural products and have been found to display a variety of bioactivities from antibacterial, antifungal, to anthroprotective effects and have the potential to be used in the development of new functional foods. An overview of the synthesis of these small chiral molecules and their molecular properties is presented. The occurrence, taste, and bioactivity of all simple naturally occurring 2,5-DKPs to date have been reviewed and those found in food from yeasts, fungi, and bacteria that have been used in food preparation or contamination, as well as metabolites of sweeteners and antibiotics added to food are also reviewed.     

食品中农兽药残留检测新技术研究进展

农兽药残留是造成食品安全问题的一个重要方面,已经引起了社会的广泛关注。针对食品中农兽药残留开发检测的新技术、新方法及相关应用研究工作近几年来取得了较大进展。本文对农兽药残留检测常用方法和技术及近年相关研究进展作了详细的综述,并对其未来的发展方向做了展望,以期为相关检测技术的进一步发展提供参考与借鉴。     

Encapsulation of probiotic living cells: From laboratory scale to industrial applications

In the recent past, there has been a rising interest in producing functional foods containing encapsulated probiotic bacteria. According to their perceived health benefits, probiotics have been incorporated into a range of dairy products but the major current challenge is to market new probiotic foods. In the research sector, many studies have been reported using dairy products like cheese, yogurt and ice cream as food carrier, and non-dairy products like meat, fruits, cereals, chocolate, etc. However, in the commercial sector only few products containing encapsulated probiotic cells can be found. Nutraceuticals are another important vector for probiotics already developed by several companies in a capsule or a tablet form. The review compiles the technologies used to encapsulate the cells in order to keep them alive and the food matrices used in the research and commercial sector for delivery to the consumer.     

食品和药品接触材料聚丙烯中添加剂及 物质迁移的液相色谱分析

聚丙烯(PP)塑料被广泛用在食品及药品的包装上,PP中有害物质的迁移现已成为食品及药品安全隐患的重要组成部分,当食品与包装材料直接接触时,残留在PP包装材料里的抗氧剂及分解产物可以迁移到食品中污染食品。由于食品的多样性,因此常用几种食品模拟液来代替食品在实验室各种控制条件下进行迁移试验,因为迁移到模拟液里的添加剂浓度非常小,其浓度的测定常使用灵敏度较高的高效液相色谱法。迁移受到很多因素的影响,比如:接触的时间温度、接触的方式、包装材料的类型、迁移物的性质等。本文综述了聚丙烯包装材料有害物质迁移的研究现状,为我国食品包装行业标准化体系的建立提供一定的理论依据。     

乳酸菌合成共轭亚油酸及其应用研究进展

共轭亚油酸(conjugated linoleic acid,CLA)是一种具有多种生理活性的功能性脂肪酸,在食品、保健品中具有广阔的应用前景。然而,天然来源的CLA含量很低,不能满足人类需求。乳酸菌可以合成CLA,且广泛用于食品加工领域,利用乳酸菌开发富含CLA的功能食品是当今的研究热点。为推动CLA功能食品的研究开发,该文对合成共轭亚油酸乳酸菌的研究进展、合成共轭亚油酸乳酸菌的益生性研究以及将产CLA乳酸菌应用到食品和饲料中的研究现状进行综述,并对利用乳酸菌合成CLA进而应用于功能食品进行展望。     

Preservation and fermentation: past,present and future

Preservation of food and beverages resulting from fermentation has been an effective form of extending the shelf-life of foods for millennia. Traditionally, foods were preserved through naturally occurring fermentations, however, modern large scale production generally now exploits the use of defined strain starter systems to ensure consistency and quality in the final product. This review will mainly focus on the use of lactic acid bacteria (LAB) for food improvement, given their extensive application in a wide range of fermented foods. These microorganisms can produce a wide variety of antagonistic primary and secondary metabolites including organic acids, diacetyl, CO2 and even antibiotics such as reuterocyclin produced by Lactobacillus reuteri. In addition, members of the group can also produce a wide range of bacteriocins, some of which have activity against food pathogens such as Listeria monocytogenes and Clostridium botulinum. Indeed, the bacteriocin nisin has been used as an effective biopreservative in some dairy products for decades, while a number of more recently discovered bacteriocins, such as lacticin 3147, demonstrate increasing potential in a number of food applications. Both of these lactococcal bacteriocins belong to the lantibiotic family of posttranslationally modified bacteriocins that contain lanthionine, beta-methyllanthionine and dehydrated amino acids. The exploitation of such naturally produced antagonists holds tremendous potential for extension of shelf-life and improvement of safety of a variety of foods.     

浅析婴幼儿食品中食品添加剂的使用管理问题

婴幼儿食品安全是食品安全工作的重点领域。目前,婴幼儿食品中违规使用非食用物质和滥用食品添加剂的现象依然存在。为建立合理的添加原则,保障产品的质量,减少因滥用食品添加剂所致的健康危害,国际组织和我国均制定了相应的法规和标准。本文全面系统地介绍了国际和国内涉及婴幼儿食品中食品添加剂使用的相关法规和标准概况,并对我国婴幼儿食品中食品添加剂的使用安全问题进行了分析,旨在对我国婴幼儿食品中食品添加剂的使用管理提供参考和借鉴。     

Hydrocolloids in fried foods. A review

Many food ingredients and additives can be used to improve fried food, but hydrocolloids are the principal category of functional agents that have been used for the past forty years. Hydrocolloids play two main roles in fried food development. One is to form a fine ‘invisible’ coating, practically on their own, when their main purpose is to avoid excessive oil absorption during the pre-frying and frying processes. In the other, when they are added to the batter among its other ingredients, they are used to avoid oil absorption too, but they also act as viscosity control agents, improve adhesion, pick-up control and freeze-thaw stability or help to retain the crispness of the battered/breaded fried foods. This article reviews the wide range of functions that hydrocolloids perform in fried foods.     

磁性固相萃取技术在食品真菌毒素分析中的应用

真菌毒素常见于食品和各种粮食作物中，具有致癌性、诱变性、致畸性等危害，严重威胁人类和动物的健康。由于真菌毒素在食品基质中存在种类多、浓度低、极性范围广等特点，因此建立快速高效的食品样品前处理方法对真菌毒素的痕量分析十分重要。磁性固相萃取（magnetic solid-phase extraction，MSPE）是一种基于磁相互作用的样品前处理技术，凭借简单快速、绿色安全、高效经济等特点，已广泛应用于食品样品真菌毒素分析的前处理中。本文介绍了MSPE的萃取过程和磁性纳米材料的制备和修饰，综述了以无机材料（氧化硅基和碳基）、有机材料（印迹型、有机高分子、表面活性剂和有机小分子）和其他材料（离子液体和单克隆抗体）为代表的MSPE吸附剂在食品样品真菌毒素检测中的应用，并对MSPE技术的发展趋势进行了展望。     

Bacteriocins of lactic acid bacteria: Their potentials as food biopreservative

Abstract

Numerous strains of lactic acid bacteria used in the fermentation of foods are known to produce bacteriocins. In general, bacteriocins are a group of proteinaceous antimicrobial substances that inhibit the growth of closely related bacteria. However, some bacteriocins produced by lactic acid bacteria (LAB) exhibit a relatively broad antimicrobial spectrum and are active against several food‐spoilage and health‐threatening microorganisms. Many investigators have reported on the use of bacteriocins as food preservative to extend the shelflife of various foods. This review decribes the research that has been conducted on bacteriocinogenic lactic acid bacteria— isolated from a wide variety of foods and in some instances of animal origin—and the characteristics of bacteriocins. Special emphasis is placed on their potentials for use as food preservative and on their physicochemical nature, antibacterial spectrum, and genetic behavior.     

食品感官科学研究：挑战与可能

食品感官科学作为食品科学属下的一门独立学科,已有半个多世纪的发展历史,取得了许多标志性成果,形成了比较系统的理论体系。传统的食品感官科学研究主要以材料科学的方法为研究手段,关注食品的结构和组成成分,而忽视了消费者个体的生理学和心理学行为对食品感官的重要影响。本文从食品感官的基本概念切入,从不同视角剖析食品感官科学的一些本质性问题,进而讨论当代食品感官研究的挑战和可能突破的领域方向,以期引发我国食品感官科学工作者的更多思考和争论,共同推动食品感官科学事业的发展。     

Nutrition-based health: cell-based bioassays for food antioxidant activity evaluation

Food science has progressively evolved and now there are wide evidences that foods have biological activities that are beyond their classical nutritional value. In this field, the antioxidant activity of pure compounds, food, feed, and dietary supplements has been extensively studied and numerous analytical approaches and assay models have been developed, involving various systems from simple chemical assays to animal models and human studies. This article is an overview of different cell-based models that have been used for testing the antioxidant properties of food, feed, and dietary supplements. Advantages, drawbacks, and technical problems to develop and validate suitable, robust, and high-throughput cell-based bioassays for screening food antioxidant activity will be discussed.     

Galactooligosaccharides: novel components of designer foods

Since introduction of functional foods, commercialization of the traditionally used probiotics has ushered in more followers into the new fraternity of sophisticated, health-conscious consumers. In 1995, this was followed by the first introduction of prebiotics. Prebiotics are defined as "a non-digestible feed supplement, beneficially affecting the host by selectively stimulating growth and/or activity in one or a limited number of bacteria in the colon." The number of new product introductions with prebiotics has steeply increased over the last few years. Paradoxically, probiotics have limited applications as these cannot be used in wide range of food products because of their viability issue. Fortunately, prebiotics do not suffer from any such constraint and can be used in a wide range of food products. Probiotics do not have a long shelf life in their active form. In most cases, refrigeration is required to maintain the shelf life. While probiotics are predominantly used in fermented dairy products, the use of prebiotics has expanded into other food categories. Prebiotics have successfully been incorporated in a wide variety of human food products such as baked goods, sweeteners, yoghurts, nutrition bars, and meal replacement shakes. For instance, the introduction of galacto-oligosaccharides (GOS) into baby foods has been very successful. GOS, which are identical to the human milk oligosaccharides, has emerged with strong clinical support for both digestive and immune health. Various aspects related to GOS such as types and functions of functional food constituents with special reference to GOS, their role as prebiotics, and enhanced industrial production through microbial intervention are dealt in this review.     

不溶性膳食纤维的提取、表征及改性研究进展

合理摄入膳食纤维对机体健康至关重要。为了开发兼顾营养、感官与健康的膳食纤维强化食品,不溶性膳食纤维的分离提取与改性研究广受关注。大量研究运用物理作用力、化学反应或酶解等手段,对样品组成、结构以及性质进行改造,以强化其在食品加工与营养健康方面功能特性。改性产物作为添加成分对于食品的加工过程、产品品质及健康功效方面具有积极影响,有利于各类膳食纤维强化产品的开发。本文对近年来国内外文献报道的不溶性膳食纤维的提取、改性及应用相关研究成果进行梳理总结,以期为调控膳食纤维功能特性、开发高品质健康功能食品提供参考。     

New Perspectives on Dietary-derived Treatments and Food Safety—Antinomy in a New Era

Despite the advances in science and technology and wide use of chemical drugs, dietary intervention (or food therapy) remains useful in preventing or treating many human diseases. A huge body of evidence shows that the dietary pattern or habit is also an important contributing factor to the development of chronic diseases such as hypertension, type 2 diabetes, hyperlipidemia, and cancers. In recent years, over-the-counter health foods, nutraceuticals, and plant-derived medicinal products have been gaining popularity all over the world, particularly in developed countries. Unfortunately, owing to the contamination with various harmful substances in foods and the presence of toxic food components, food-borne diseases have also become increasingly problematic. Incidents of food poisonings or tainted food have been increasing worldwide, particularly in China and other developing countries. Therefore, the government should put in a greater effort in enforcing food safety by improving the surveillance mechanism and exerting highest standards of quality control for foods.     

Furan and Methylfurans in Foods: An Update on Occurrence,Mitigation, and Risk Assessment

The acceptance of many foods is related to traditional cooking practices, which create taste and texture and are important to digestibility, preservation, and the reduction of foodborne illnesses. A wide range of compounds are formed during the cooking of foods, a number of these have been shown to lead to adverse effects in classical toxicological models and are known as food processing contaminants (FPC). It is essential that the presence and effects of such compounds alone and in combination within the diet are understood such that proportionate risk management measures can be developed, while taking a holistic view across the whole value chain. Furan and alkylfurans (principally 2‐ and 3‐methylfuran) are highly volatile FPC, which are formed in a wide range of foods at low amounts. The focus of research to‐date has been on those foods, which have been identified to be most consequential in terms of being sources of exposure, namely jarred and canned foods for infants and young children (meals and drinks) and coffee (roast and ground, soluble). This report presents (i) new industry data on the occurrence of furan and methylfurans in selected food categories following previous coffee studies, (ii) the most salient parameters that impact furan formation, and (iii) aspects of importance for the risk assessment.     

Antimicrobial edible films and coatings

Increasing consumer demand for microbiologically safer foods, greater convenience, smaller packages, and longer product shelf life is forcing the industry to develop new food-processing, cooking, handling, and packaging strategies. Nonfluid ready-to-eat foods are frequently exposed to postprocess surface contamination, leading to a reduction in shelf life. The food industry has at its disposal a wide range of nonedible polypropylene- and polyethylene-based packaging materials and various biodegradable protein- and polysaccharide-based edible films that can potentially serve as packaging materials. Research on the use of edible films as packaging materials continues because of the potential for these films to enhance food quality, food safety, and product shelf life. Besides acting as a barrier against mass diffusion (moisture, gases, and volatiles), edible films can serve as carriers for a wide range of food additives, including flavoring agents, antioxidants, vitamins, and colorants. When antimicrobial agents such as benzoic acid, sorbic acid, propionic acid, lactic acid, nisin, and lysozyme have been incorporated into edible films, such films retarded surface growth of bacteria, yeasts, and molds on a wide range of products, including meats and cheeses. Various antimicrobial edible films have been developed to minimize growth of spoilage and pathogenic microorganisms, including Listeria monocytogenes, which may contaminate the surface of cooked ready-to-eat foods after processing. Here, we review the various types of protein-based (wheat gluten, collagen, corn zein, soy, casein, and whey protein), polysaccharide-based (cellulose, chitosan, alginate, starch, pectin, and dextrin), and lipid-based (waxes, acylglycerols, and fatty acids) edible films and a wide range of antimicrobial agents that have been or could potentially be incorporated into such films during manufacture to enhance the safety and shelf life of ready-to-eat foods.     

The chemistry and analysis of annatto food colouring: a review

Annatto food colouring (E160b) has a long history of use in the food industry for the colouring of a wide range of food commodities. The principal colouring component of annatto is the oil-soluble diapo carotenoid bixin, which is the methyl ester of the dicarboxylic acid norbixin and soluble in aqueous alkali. Bixin and norbixin, therefore, exhibit not only physicochemical properties normally associated with carotenoids, but also certain anomalous properties that have an impact on the stability, food colouring applications, and importantly the analysis of annatto. This review summarizes the key aspects of the structural determination of bixin (and norbixin) with special attention to cis-trans isomerization and how this links with its chemical structure, spectroscopic properties, and stability. The oxidative, thermal, and photo-stability of annatto and the subsequent implications for its use in the colouring of foods, food processing, and the analysis of foods and beverages are discussed along with important mechanistic, thermodynamic and kinetic aspects. The main analytical techniques used for the chemical characterization of annatto, i.e. spectrophotometry, nuclear magnetic resonance (NMR), chromatography (particularly high-performance liquid chromatography (HPLC)) and mass spectrometry are reviewed in detail and other methods are discussed. This links in with a review of the methods available for the detection and measurement of annatto in colour formulations and foods and beverages, which highlights the importance of the need for a good understanding and knowledge of the chemistry of bixin and norbixin in order to meet new analytical challenges.     

A sensitive monoclonal-antibody-based test for gluten detection: Studies with cooked or processed foods

A method for detection of wheat, rye, barley and oat proteins in a wide range of foods, including baked goods and processed meats has been developed. The procedure requires immobilisation of food extracts upon nitrocellulose paper followed by treatment with an enzyme-conjugated monoclonal antibody. Upon addition of the appropriate enzyme substrate, gluten-containing foods yield purple spots; a wide range of non-gluten common food proteins did not react. The method has several advantages over other means of detecting cereal protein, such as electrophoresis. It is rapid, requiring little sample preparation, and does not require sophisticated equipment or prior knowledge of electrophoretic patterns of common non-cereal food proteins. Since the method may be used with cooked or baked foods, it should be suitable for food-monitoring applications.