Showing papers in "Critical Reviews in Food Science and Nutrition in 1976"

Functional properties of proteins in foods: A survey

Abstract: Proteins for foods, in addition to providing nutrition, should also possess specific functional properties that facilitate processing and serve as the basis of product performance. Functional properties of proteins for foods connote the physicochemical properties which govern the behavior of protein in foods. This general article collates the published information concerning the major functional properties of food proteins, e.g., solubility, binding properties, surfactant properties, viscogenic texturizing characteristics, etc. The effects of extraction and processing on functional properties and possible correlations between structure and function are discussed, in relation to practical performance in food systems. Modification of proteins to improve functional characteristics is briefly mentioned.

Lipid Peroxidation and atherosclerosis

Abstract: Atherosclerosis and its clinical sequelae are among the most important of human cardiovascular diseases. Abnormal amounts of lipid are usually present in the thickened intima of atherosclerotic arteries. The notion that lipid peroxidation and polymerization occur in these lipid deposits is based largely on the fact that ceroid pigments have been demonstrated in atherosclerotic plaques. The detection of cholesteryl hydroxyoctadecadienoic acids in lipids of atheromas is suggestive evidence of lipoperoxidation; detection of lipoperoxides as such is technically difficult and the results to date are inconclusive. Studies of arteries from man and animals indicate that ceroid pigments occur late in the disease process and are not likely to be initiators of atherosclerosis. It is possible that hydroperoxides or intermediate free radiclals participate in the early stages of atherogenesis, but this theory is without conclusive support. Ceroid has been implicated as an inflammatory or sclerosing agent in arteries, p...

Effect of acidification of canned tomatoes on quality and shelf life

Abstract: The review included a discussion of the reasons why acidification of canned tomatoes is sometimes desirable from a microbiological point of view, the possible Changes in the pH of tomatoes as a result of the breeding of new varieties, and the methods and suitable acids for acidification. Acidification does cause some minor differences in the chemical components of the canned product, but the differences appear to be inconsequential. Although can corrosion may be accelerated slightly, this again does not seem to be of practical importance. The can manufacturers recommend the same type of can whether or not tomatoes are acidified. Flavor studies almost invariably have indicated that tomatoes are as acceptable as nonacidified tomatoes at least down to pH 4.1 to 4.0. In fact, most studies show that acidified tomatoes are somewhat more acceptable. Reasons are suggested as to why outbreaks of botulism have occurred from home‐canned tomatoes, although the pH appears to have been below 4.5, and as to why outbreak...

Anthocyanins in foods

Abstract: The colors of fruits and vegetables, particularly pink, red, mauve, blue, and violet, are caused by the combination of the glycosides of the six basic anthocyanidins. The amounts and chemical nature of the anthocyanins themselves have a strong influence on the color and storage stability in foods. This review describes the existing analytical methods and suggests some improvements in such techniques to provide information about anthocyanin composition and their degradation in foods. Being electron deficient, the flavylium nuclei of anthocyanins are highly susceptible to attack by nucleophylic reagents. The instability of anthocyanins in food products can pose problems of considerable economic importance. Condensation of anthocyanins with other polyphenols produces polymeric compounds which may or may not distort the typical color of the product. This review integrates several aspects and focuses attention on certain unanswered areas of research. The potential use of naturally occurring anthocyanins as foo...

Microwave heating of foods ‐ changes in nutrient and chemical composition

Abstract: Industrial microwave applications have increased considerably over the years and so has the number of microwave ovens in American homes. Remarkable characteristics have been attributed at times to microwaves without sound scientific information to back up these claims. Heating foods in a conventional and a microwave oven to comparable internal temperatures will generally result in greater moisture losses in the microwave heated products. The effects of microwaves on proteins and lipids are minor and due to heat, rather than the radiation in a microwave oven. Data of the effects on carbohydrates are virtually nonexistent. The degree of destruction of vitamins and pigments during microwave processing is not greater than that observed in conventionally heated foods. There are differences in flavor and taste in certain food products prepared in a conventional and a microwave oven. Data from different laboratories are not always in complete agreement, which is understandable considering the great variability i...

Polychlorinated biphenyls (Pcbs) in food

Abstract: The universal presence and toxicity of polychlorinated biphenyls (PCBs) poses a threat to the environment and human health. They are disturbingly widespread in the ecosystem, including human adipose tissue, human milk, and even brain and liver of small children. Paradoxically, although they have been in commercial use since the last 40 years, they were reported in environmental samples only very recently. It is interesting to note that the properties which make them industrially indispensable are the same properties which cause them to persist in the environment. Their enormous commercial uses include incorporation in adhesives, paints, varnishes, printing inks, elastomeres, lubricants, hydraulic fluids, liquid seals, flexible packaging, heat transfer fluids, fire retardants, carbonless reproducing papers, and many others. This also indicates the numerous ways by which they can gain access to the environment and marine food chains, as well as food products. Mass‐scale poisoning and contamination resulted ...

Effects of environmental factors and agronomic and storage practices on quality of sugarbeet

Abstract: The sugarbeet is an herbaceous dicotyledon. The annual world production of sugarbeet exceeds 200 million tons. It supplies 40% of the world's sugar. The sugarbeet, a biennial, normally completes its vegetative cycle in 2 years. During the first year it develops a large succulent root, in which reserve food sugar is stored. During the second year it produces flowers and seeds. Favorable environmental conditions and proper agronomic practices (such as temperatures, climate, day length, fertilization, disease control, control of late growth) are essential for producing high sugar and less impure sugarbeet. Proper nitrogen fertilization increases the yield, but decreases the sugar percentage and juice purity of sugarbeet. Nitrate is the principle source of nitrogen used by sugarbeets. Nitrate uptake and metabolism require energy which is derived at the expense of sugar accumulation. Glutamine in sugarbeet is synthesized mainly in the roots and is transported to the leaves. Estimation and application of the op...