CRC critical reviews in food science and nutrition最新文献

Activated oxygen species which may be important in initiating oxidative changes in foods include singlet oxygen, hydroxyl radical, ozone, superoxide anion (perhydroxyl radical at low pH), and hydrogen peroxide. Chemical and enzymic reactions known to occur in biological materials can generate singlet oxygen, hydroxyl radical, superoxide anion, and hydrogen peroxide. Ozone is primarily a product of photoreactions in polluted air. Reactions involving singlet oxygen, hydroxyl radical, and ozone with food constituents can ultimately yield peroxides which decompose to initiate oxidative chain reactions. Superoxide anion and hydrogen peroxide are relatively inert toward organic molecules but can decompose to produce the more reactive singlet oxygen and hydroxyl radical. Inhibition of reactions initiated by reactive oxygen species in foods should be very important in preserving the oxidative stability of foods. The generation, detection, measurement, reaction, and inhibition of reactions of active oxygen species are surveyed in this review.

The nutritional value of milk as an important source of energy, high-quality protein, calcium, and riboflavin has been recognized for many years. Currently, the widespread use and promotion of milk in the U.S. as well as developing countries has been questioned. This review examines the nutrient composition of dairy products, factors that account for variability in composition of milk, milk processing, preservation, quality control, and contaminants (such as minerals, radionuclides antibiotics, microorganisms and their metabolites, herbicides, and insecticides) in milk. Consumption patterns for milk and evidence for its nutritional value, especially in children, are presented. Milk consumption has been related to disease or conditions such as atherosclerosis, milk allergy, lactose intolerance, anemia, dental problems, and others. Recent recommendations for dietary changes for individuals in the U.S. and other developed countries could affect the use of milk. In addition, the use of feeding programs in the U.S. and developing countries which are based primarily on milk has been criticized. The preparation of new types of milk designed to offset certain difficulties encountered with cow's milk are now being evaluated in humans.

Since the food supply is dependent upon an effective packaging system, threats to packaging represent implied threats to food processing and distribution. Enacted and potential legislation and regulation are retarding technological and commercial progress in food packaging and have already restricted some food packaging/processins systems. The results of these external influences is not simply the sum of the individual acts, but is a cascading self-imposed arresting of food packaging/processing advancement. The technological bases for the enacted and proposed legislation and regulation are presented in the enumeration of the external influences on food packaging. Economic and sociological arguments and facts surrounding the issues are also presented. Among the external influences on food packaging detailed are indirect additives, nutritional labeling, benefit:risk, solid waste and litter, environmental pollution, universal product code, and food industry productivity. The magnitude of the total impact of these external influences upon the food supply is so large that assertive action must be taken to channel these influences into more productive awareness. An objective and comprehensive public communications program supported by the technological community appears mandatory.

Toxicants are widely distributed in plants and plant products, including intentionally added, incidentally added, and naturally occurring food toxicants. This review covers the toxicity of some food additives: the distribution, residues, toxicity, and methods of removal of some pesticides and toxic metals; and the presence of naturally occurring toxicants in plants and plant products. Extensive review has been done, particularly on natural toxicants. However, there are still extensive gaps in our knowledge pertaining to effect upon the health of many of the substances known to be present in natural plant food products, as well as even the identity of many natural chemical components of plant foods and their potential toxicological significance. An understanding of their presence, formation, and toxicity is important as far as public health is concerned.

A renewed interest in lipoxygenase has led to detailed studies of its isoenzymes, substrate specificity, and the nature of its reaction products. Lipoxygenase is highly specific for cis,cis-1,4-pentadiene systems such as linoleic, linolenic, and arachidonic acid (or ester) and catalyzes the formation of the corresponding hydroperoxides with a cis,-trans-conjugated diene system. The hydroperoxides can then undergo enzymic or spontaneous degradation, producing a range of carbonyl compounds. This review will discuss the biochemical properties of this enzyme and its contribution to the quality of raw and processed food products. An attempt has been made to discuss both the desirable and undesirable effects associated with the action of lipoxygenase, citing specific food examples where appropriate.

Sensory evaluation has recently utilized the methods developed by psychophysicists and psychometricians, who week to represent data in terms of various scales and mathematical formulations. This review covers the development of ratio scaling to develop relations between sensory and instrumental measures of food, the use of multivariate psychophysical procedures which relate a variety of physical variables to a single sensory response, and the use of multidimensional scaling to relate different sensory percepts to each other. Each of these approaches is nascent in applications to sensory evaluation, although the mathematics and formulations are very developed. Each approach gives the experimenter insights into subjective and objective correlations and the manner in which the panelist perceives relations among stimuli. The treatment of the reported literature for each approach follows the same course: necessary conditions for its application to sensory evaluation, experiences with model systems and real foods, and potential uses and limitations in sensory evaluation.