Prebiotics in foods

A wealth of information has been gathered over the past 15 years on prebiotics through experimental, animal and human studies, with the aim to understand the mechanism of actions and elucidate their beneficial health effects to the human host. Significant amount of evidence exists for their ability to increase the bioavailability of minerals and stimulate the immune system, although there is less clear evidence so far for their prophylactic or therapeutic role in gastrointestinal infections. Moreover, the effect of the food delivery vehicle on the efficacy of prebiotics is an area that has been hardly investigated. Besides their beneficial effects, prebiotics influence the textural and organoleptic properties of the food products, such as dairy and baked products. To do this however, they need to be stable during food processing, in particular under conditions of high temperature and low pH.     

Salmonellae in health foods

Various health food products of different brands were purchased from stores in the metropolitan Atlanta area. These foods were examined for the presence of salmonellae by fluorescent-antibody and cultural methods. Included in the study were tablets of alfalfa, parsley, kelp, wheat bran, enzyme, bone meal, and vitamins. Beef liver powder and tablets and granola cereal were also studied. Salmonella minnesota, Salmonella anatum, and Salmonella derby were isolated from two of three lots of beef liver powder from one manufacturer. All other products were negative.     

Acrylamide in Austrian foods

Acrylamide is known for its potential health hazards. Recently acrylamide was found in starch containing heated foods in high concentrations which lead to the assumption that a cancer risk could be associated with the uptake of foods containing high amounts of acrylamide. This study focuses on the analysis of acrylamide in foods potentially containing this substance which is formed from natural ingredients. The highest concentrations were found in potato crisps with concentrations of above 1500 ng/g (median: 499 ng/g). Other food groups contained lower amounts: cookies with a median of 99 ng/g; crisp bread with a median of 69 ng/g; breakfast cereals with a median of 0 ng/g; popcorn and rice products with a median of 97 ng/g; potato chips with a median of 161 ng/g and coffee with a median of 169 ng/g.     

Salmonellae in health foods.

Various health food products of different brands were purchased from stores in the metropolitan Atlanta area. These foods were examined for the presence of salmonellae by fluorescent-antibody and cultural methods. Included in the study were tablets of alfalfa, parsley, kelp, wheat bran, enzyme, bone meal, and vitamins. Beef liver powder and tablets and granola cereal were also studied. Salmonella minnesota, Salmonella anatum, and Salmonella derby were isolated from two of three lots of beef liver powder from one manufacturer. All other products were negative.     

Genetically modified probiotics in foods

Probiotics have many potential therapeutic uses, but have not been universally accepted because of a lack of understanding of their action. Lactic acid bacteria (LAB) have been modified by traditional and genetic engineering methods to produce new varieties. Modern techniques of molecular biology have facilitated the identification of probiotic LAB strains, but only a few LAB have been modified by recombinant-DNA technology because of consumer resistance to their introduction to markets, especially in Europe.     

食品中桔霉素控制方法的研究进展

桔霉素(Citrinin,CIT)是由青霉、曲霉和红曲霉属产生的一种具有肾毒性的真菌毒素。许多食品和饲料中均含有桔霉素,污染范围十分庞大。桔霉素可与其他真菌毒素发生协同作用,如展青霉素(Patulin,PAT)、赭曲霉毒素(Ochratoxin,OTA)等,从而增强其毒性作用,对人及动物健康造成更大的危害。现阶段常用的控制手段主要有物理、化学和生物方法,均取得了一定的成就。本文简单介绍了桔霉素的毒性及污染状况,对桔霉素控制方法的研究进展进行了综述。     

Traditional fermented foods

For centuries, diverse plant and animal materials have been fermented by various bacteria, yeasts, and fungi to make excellent foods. The kinds of micro organisms used in traditional fermentation are restricted to a relatively few genera, including Aspergillus, Rhizopus, Mucor, Actinomucor, Monascus, Saccharomyces, Neurospora, Acetobacler, Bacillus, and Lactobacillus. The two principal advantages of food fermentations over other processes are to add flavor and to prevent spoilage. Fermented fish is a common food in the Orient and may have been the first product made by fermentation. Flavor is especially important in vegetable diets based on bland foods such as rice. Shoyu is the best, known oriental food fermentation, and it is very widely used as a flavoring agent. Be sides this fermentation, there are a large number of additional ones not so well known outside the Orient, whose products serve as seasoning or flavoring agents. Miso and natto are prepared from soybeans in Japan. Sufu is a cheese like product made from soybean milk in China. Tempeh and ontjom are Indonesian foods prepared from soybeans and peanuts, respectively. These food fermentations are discussed with emphasis on how they are produced and the flavor formed.     

生物技术与食品

现代生物技术是以生命科学为基础,利用生物或其组织部份的特性和功能,设计构建具有预期性状的新物种或新品系,以及与工程原理相结合进行加工生产,为社会提供商品和服务的综合性技术体系。生物技术已经被运用了许多个世纪,传统上它曾被集中地用于生产新种类的食品,如面包、奶酪、啤酒、葡萄酒以及酱油、米酒和发酵的奶制品。食品工业在过去几十年里发生了些什么变化?首先,世界范围的人口结构发生了重要变化,老年社会的形成,65岁以上的人口增加了,这些人需要符合营养结构的及可以立即食用的产品。其次,家庭规模的减小意味着对小包装食品的需求…     

Enterococci from foods

Enterococci have recently emerged as nosocomial pathogens. Their ubiquitous nature determines their frequent finding in foods as contaminants. In addition, the notable resistance of enterococci to adverse environmental conditions explains their ability to colonise different ecological niches and their spreading within the food chain through contaminated animals and foods. Enterococci can also contaminate finished products, such as fermented foods and, for this reason, their presence in many foods (such as cheeses and fermented sausages) can only be limited but not completely eliminated using traditional processing technologies. Enterococci are low grade pathogens but their intrinsic resistance to many antibiotics and their acquisition of resistance to the few antibiotics available for treatment in clinical therapy, such as the glycopeptides, have led to difficulties and a search for new drugs and therapeutic options. Enterococci can cause food intoxication through production of biogenic amines and can be a reservoir for worrisome opportunistic infections and for virulence traits. Clearly, there is no consensus on the acceptance of their presence in foodstuffs and their role as primary pathogens is still a question mark. In this review, the following topics will be covered: (i) emergence of the enterococci as human pathogens due to the presence of virulence factors such as the production of adhesins and aggregation substances, or the production of biogenic amines in fermented foods; (ii) their presence in foods; (iii) their involvement in food-borne illnesses; (iv) the presence, selection and spreading of antibiotic-resistant enterococci as opportunistic pathogens in foods, with particular emphasis on vancomycin-resistant enterococci.     

Chitosan-based dietary foods

Chitosan exhibits anticholesterolemic, antiulcer and antiuricemic properties when orally administered, and is potentially suitable for the prevention of the coeliac disease. This set of properties stems from the capacity to bind specifically fatty acids, bile acids, phospholipids, uric acid and the toxic gliadin fraction. Chitosan does not depress the serum iron and hemoglobin, does not overstimulate the 3-hydroxy-3-methylglutaryl CoA reductase; it does not alter the human intestinal microbiota, but lowers the putrefaction metabolites. Its susceptibility to the hydrolytic action of lipases is discussed. For oral administration, chitosan should be supplied with a proper degree of polymerization and chemical form.