Showing papers in "Critical Reviews in Food Science and Nutrition in 1990"

Antioxidants/antimutagens in food.

Abstract: Oxygen is indispensable for aerobic organisms including, of course, human beings, but it is believed that oxygen also may be responsible for undesired phenomena. In particular, oxygen species such as hydrogen peroxide, superoxide radical anion, and singlet oxygen are proposed as agents attacking polyunsaturated fatty acids in cell membranes, giving rise to lipid peroxidation. Several reports have suggested that lipid peroxidation may result in destabilization and disintegration of cell membranes, leading to liver injury and other diseases, and finally, to aging and susceptibility to cancer (4).

Chemical and nutritional changes in foods during extrusion

Abstract: Revue bibliographique sur les transformations physicochimiques provoquees par la cuisson-extrusion sur l'amidon, les lipides, les proteines, les elements mineraux, les fibres, les vitamines, les contaminants et les facteurs antinutritionnels presents dans les aliments

Dietary fiber and coronary heart disease

Abstract: Facteurs de risques d'atherosclerose (lipides, alimentation, hypertension entre autres). Pathologie: mecanismes proposes de la pathologie de l'atherosclerose. Effets des fibres alimentaires sur les facteurs de risques. Revue des fibres alimentaires: gommes, pectine, fibres de cereales, de fruits, de legumineuse. Mecanismes d'actions des fibres. Applications therapeutiques. Revue bibliographique

Glycolysis and related reactions during cheese manufacture and ripening

Abstract: Fermentation of lactose to lactic acid by lactic acid bacteria is an essential primary reaction in the manufacture of all cheese varieties. The reduced pH of cheese curd, which reaches 4.5 to 5.2, depending on the variety, affects at least the following characteristics of curd and cheese: syneresis (and hence cheese composition), retention of calcium (which affects cheese texture), retention and activity of coagulant (which influences the extent and type of proteolysis during ripening), the growth of contaminating bacteria. Most (98%) of the lactose in milk is removed in the whey during cheesemaking, either as lactose or lactic acid. The residual lactose in cheese curd is metabolized during the early stages of ripening. During ripening lactic acid is also altered, mainly through the action of nonstarter bacteria. The principal changes are (1) conversion of L‐lactate to D‐lactate such that a racemic mixture exists in most cheeses at the end of ripening; (2) in Swiss‐type cheeses, L‐lactate is meta...

Modified atmosphere packaging of seafood.

Abstract: The shelf life of seafood under current icing and refrigerated storage conditions ranges from 2 to 14 d, depending on species, harvest location, and season. Elevated carbon dioxide levels in modified atmosphere packaging (MAP) has been shown to inhibit the normal spoilage flora of seafood and double or triple shelf life. The threat of botulism, due to the presence of non‐proteolytic psychyrotrophic Clostridium botulinum types B, E, and F, has been reason for caution in expanding this technology. This article examines the safety of MAP seafood through analysis and comparison of raw materials, research methodologies, quality indices, treatment, and packaging options.

Chlorophylls in foods

Abstract: Revue bibliographique sur les techniques d'extraction, les proprietes spectroscopiques et l'analyse chromatographique des chlorophylles des fruits et legumes et sur leur alteration au cours de la senescence et des processus de transformation ou de conservation

The formation and properties of wheat flour doughs.

Abstract: Among the cereal flours, only wheat flour will form a viscoelastic dough when mixed with water. The viscoelasticity appears to be because the gluten proteins are water compatible and thus will swell and interact. The gluten protein's large molecular size and low charge density appear to allow them to interact by both hydrogen and hydrophobic bonds. Wheat flour doughs are also unique in their ability to retain gas. This property appears to result from a slow rate of gas diffusion in the dough. The third major unique property of wheat flour doughs is their ability to set in the oven during baking, and thereby to produce a rigid loaf of bread. Although not clearly understood, this appears to be a heat-induced crosslinking of the gluten proteins.

Muscle growth and exercise

Abstract: This paper first reviews muscle growth and then considers the influence of exercise in growth. Knowledge about how muscle cells grow and some factors that may influence the growth pattern are discussed first since these effects must be considered before the influence of exercise becomes clear. Growth of muscle can occur in three ways: (1) by an increase in muscle cell numbers, (2) by an increase in muscle fiber diameter, and (3) by an increase in fiber length. All three of these mechanisms are involved in muscle growth. However, growth in cell numbers is limited to the prenatal and immediately postnatal period, with the animals and man being born with or soon reaching their full complement of muscle cells. Thus, growth occurs by either hypertrophy of the existing muscle fibers by adding additional myofibrils to increase the muscle mass or by adding new sarcomeres to the ends of the existing muscle fibers to increase their length. Both of these mechanisms occur during the growth process. Growth in the girth of the muscle fibers appears to take place by splitting of the myofibrils. This may be stimulated by development of stress creating an unequal pressure with splitting at the Z-band and development of additional SR and T-tubule systems. This adds to the diameter or girth of myofibers without any hyperplasia. The growth in length occurs at either end of the fibers and results in addition of new sarcomeres. In both cases, new myofibrillar protein must be synthesized and deposited in the muscle cells. It is suggested that adaptation by adding or removing sarcomeres is physiologically determined by the degree of force a muscle can generate that is in turn dependent on the degree of overlap of the thick and thin filaments. Thus, the amount of tension would control the number of in-series sarcomeres in a single muscle fiber. Nutrition is also known to play an important role in muscle and was discussed from the standpoint of the effects of nutritional adequacy and restriction. Although a nutritionally balanced and calorically adequate diet is required to achieve optimum muscle growth, it may be less efficient in terms of protein deposition than a moderately restricted diet. Muscle and bone deposition, however, can be limited on severely restricting the dietary intake. Although fat deposition is the first tissue to suffer on a severely restricted diet, muscle and bone follow next with the nervous system, brain and eyes being the last systems to be affected.(ABSTRACT TRUNCATED AT 400 WORDS)

Aeromicrobiology--a review.

Abstract: This article reviews the presence of microorganisms in air and their sources, the relation of airborne dust and endotoxin, the sources of atmospheric microbial contamination in food-processing plants, the mechanisms of airborne particle deposition, the importance of airborne microbes, the survival of microorganisms in air, methods of air sampling, airborne microbial populations in food-processing plants, control of airborne microorganisms in food-processing plants, and the general issue of microorganisms in air and their impact on food safety. The purpose was to bring together scattered information about airborne microorganisms and review their importance in food protection and sanitation.

The applications and future implications of bitterness reduction and inhibition in food products.

Abstract: Numerous food and beverage products, bulking agents, and Pharmaceuticals have pleasant as well as unpleasant bitter‐tasting components in their taste profile. In numerous cases, the bitter taste modality is an undesirable trait of the product. Bitter characteristics found in some food systems have been removed or diminished by various known processes, but no universally applicable bitter inhibitor has ever been recognized. Some indications point to a receptor‐mediated phenomenon for sweetness and bitterness. Research on sweet compounds has led to knowledge of sweetness inhibitors and could ultimately lead to bitterness inhibitors. To facilitate efforts to rationally design a universal bitter inhibitor or cocktail of such, a review of the bitter taste phenomena and known methods of bitterness reduction and inhibition have been compiled.

Volatiles in packaging materials

Abstract: The increasing application of complex natural and/or synthetic polymers to food packaging has required definitive information on the characteristics of the finished products. High temperature encountered during the manufacturing process may induce thermal decomposition products that can migrate into the packaged product and cause undesirable flavor. A general methodology for testing polymer odor and odor contributors is discussed in this article with examples representing the odor of a variety of packaging materials. The precursors and the mechanisms of the major volatile components of each packaging material are presented.

Critical review of isolation, detection, and identification of yeasts from meat products.

Abstract: Developpement des methodes rapides d'identification des levures dans les produits alimentaires, notamment dans les produits carnes, basees sur l'emploi de milieux selectifs a colorant de type triarylmethane et sur un systeme d'identification informatise, utilisant 23 tests physiologiques, elabore pour 84 especes de levures

Delayed light emission as a means of quality evaluation of fruits and vegetables

Abstract: DLE is probably produced by all fruits, vegetables, and plant materials undergoing photosynthesis. However, the intensity and duration of the emitted light vary widely depending upon many factors. Because of the strong dependence of DLE on the chlorophyll content, variation in the DLE can be expected among different varieties of the same product. Therefore, quality evaluation based on DLE measurements require careful selection of measuring criteria such as duration and intensity of illumination, dark period, and temperature. It is necessary to obtain precise values of DLE for a particular product under a set condition; and the measurement conditions should be carefully validated to establish a standard measuring criteria. In general, the quality evaluation of fruits and vegetables is based on three major aspects: maturity and/or ripeness evaluation, composition analysis, and internal and external defect detection. DLE measurements so far have focused mainly on maturity evaluation because of the definite relationship between the emitted light and chlorophyll concentration, which changes with maturity. It should be noted that chlorophyll alone is not sufficient; it is the complex of in situ chlorophyll and related compounds in plant materials that jointly contribute to the DLE. Composition of fruits such as sugar content has been related to DLE. Recently, DLE measurements have been applied to detect certain physiological stress responses and defects such as chilling injuries. However, these areas of research have not yet been fully explored. Further investigation relating to compositional quality and internal and external defects of fruits and vegetables with DLE measurement may offer solutions to certain complex quality evaluation problems. The duration of DLE after excitation involves a matter of at least several seconds. From a mechanical standpoint, this extended period of light emission offers a convenient time in which to separate excitation and measurement. However, the exponential decay necessitates very precise control of time between illumination and measurement. The broad activation spectrum permits wide choice and simple design of excitation sources. However, size, shape, and varietal variations of plant materials make uniform DLE measurements difficult. It is suggested that DLE measuring instruments be designed to make several measurements over the entire surface of the specimen. An average of such measurements would reduce the effect of surface nature and shape of the product. Reporting the DLE intensity per unit surface area of the product will eliminate the dependence of area of excitation on DLE.(ABSTRACT TRUNCATED AT 400 WORDS)

Food analysis on silica-bound HPLC phases.

Abstract: HPLC analysis of food on various silica bonded phases has been described. Technical and theoretical aspects of the materials such as normal‐, reverse‐, ion‐exchange‐, affinity‐, chiral‐, size‐exclusion‐, and ion‐phases have been discussed. Special problems such as mobile phase or solvent‐selection, selectivity and mechanisms of resolution on these bonded phases have been mentioned. Application of various bonded materials such as amino, cyano, diol, amino‐cyano, C‐18, C‐8, anion‐exchangers, strong and weak‐cation exchangers, chiral and enzyme bound affinity phases to analyze and determine food components such as carbohydrates, food colors and pigments, flavors, proteins, vitamins and toxins has been described.

Integrity of small data bases in computer analysis of dietary data.

Abstract: The integrity of data bases to support microcomputer-based dietary analysis programs has become increasingly important to developers and users of nutritional analysis software. This paper reviews critical issues in maintaining data integrity during development of small nutritional data bases. Because a limited number of large, source data bases provides the data for smaller, special-purpose data bases, this review initially focuses on factors that affect the quality and precision of methodologies used in establishing large data bases. Issues discussed are accuracy of source data as determined by analytical methodology and imputation procedures, and methods for insuring representativeness of data. The effect of data transfer procedures on small data base integrity are discussed, including use of multiple sources and standardization of naming and coding conventions. Also reviewed are procedures for selecting reduced numbers of foods and nutrients without sacrificing accuracy of analysis, and methods currently in use for validating small data bases.