Showing papers in "Critical Reviews in Food Science and Nutrition in 1986"

Meat flavor volatiles: A review of the composition, techniques of analysis, and sensory evaluation

Abstract: Flavor is an important quality attribute which relates to the organoleptic characteristics of meat. Although perception of flavor is a complex phenomenon, odor is the most important single factor contributing to the overall characteristics of flavor. A large number of compounds have been identified in the volatile fraction of red meats and poultry. An overview of the chemical constituents present in the volatiles of beef, pork, mutton, and chicken is presented according to species and arranged by chemical class--hydrocarbons, alcohols, acids, aldehydes, ketones, sulfides, heterocyclic compounds, etc. The volatile components of cured and uncured pork are compared. The field of meat flavor is assessed in terms of what has been accomplished and the direction in which it may proceed. Techniques for analysis of these volatiles are briefly described.

Tannin analysis of food products.

Abstract: Phenolic substances occur primarily in fruits and vegetables and in the seeds of certain pigmented cultivars of sorghum, millets, and legumes. One of the major difficulties encountered in polyphenol research is the lack of a standard quantitative method for the analysis of phenolics that would be suitable for a wide range of seeds, forage crops, and food products and under a variety of experimental conditions. Some methods measure "total phenol", which may not be a true index of the nutritional quality of foods and thus does not distinguish polyphenols of nutritional concern from other low-molecular-weight phenols that also occur naturally in these products. Tannic acid (a hydrolyzable gallotannin) is commonly used as a "reference standard", but this may be a questionable practice since its biological properties differ from those of tannins of flavonoid origin. Polyphenols of cereals and legumes are predominantly of the latter type. Also, commercially available tannic acid has been shown to be a mixture of four phenolic compounds, the relative proportions of which vary with the samples. Thus, the choice of a suitable standard for tannin analysis is also important. The quantitative extraction of the condensed tannins from plant tissue is always difficult, since it may be complexed to a carbohydrate or protein matrix which could be quite insoluble due to a high degree of polymerization. The literature on tannin methodology is diverse and at times conflicting. Currently available methods for tannin analysis range from simple colorimetric, UV spectrophotometric, chromatographic, and enzymic to more sophisticated and expensive nuclear magnetic resonance (NMR) techniques. None of these methods of analyses is completely satisfactory nor can it be applied to different food products with the same degree of success. This review covers physical and chemical methods for tannin analysis of different food products, the problems in analysis and interpretation of data, and future research needs in this area.

Capsicum — Production, technology, chemistry, and quality. Part III. Chemistry of the color, aroma, and pungency stimuli

Abstract: The spice capsicum, the fruits of the genus Capsicum (Family Solanaceae), is a very popular food additive in many parts of the world, valued for the important sensory attributes of color, pungency, and aroma. A large number of varieties are widely cultivated and traded. The characteristic carotenoids of the bright red paprika and cayenne-type chillies, the high character impact aroma stimuli, the methoxy pyrazine of green bell capsicum, the esters of ripe tabasco and the highly potent pungency stimuli, and the capsaicinoids of African and other Asian varieties of chillies, have been of great interest to chemists and biochemists. Research workers in other disciplines such as genetics and breeding, agriculture, and technology have been interested in this spice to develop new varieties with combinations of different optimal levels of the stimuli for the sensory attributes and to maximize production of storable products for specific end uses. Physiologists have been intensely studying the action of the highly potent pungency stimuli and social psychologists the curious aspect of growing acceptance and preference for the initially unacceptable pungency sensation. In the sequential review of all these aspects of the fruit spice Capsicum, the earlier two parts covered history, botany, cultivation and primary processing, and processed products, standards, world production, and trade. In Part III, the chemistry, the compositional variations, synthesis and biosynthesis of the functional components, the carotenoids, the volatiles, and the capsaicinoids are comprehensively reviewed.

Water sorption by proteins: Milk and whey proteins

Abstract: The content and physical state of water in foods influence their physical, chemical, quality, safety, and functional behavior. Information concerning the sorption behavior of dairy proteins, in the water activity (Aw) range 0 to 0.9, is collated in this paper. The sorption behavior of proteins in general, the kinetics of absorption, factors affecting water binding, the phenomenon of desorption hysteresis, and the chemical and physical nature of water/protein interactions are reviewed in general terms. This is followed by a discussion of thermodynamic aspects of sorption phenomena and the adequacy of the various equations for describing sorption isotherms of proteins. After a discussion of the methods available for measuring sorption by milk proteins, the sorption behavior of various milk protein preparations, i.e., nonfat dry milk, whey proteins, caseins, and milk powders is summarized. Finally, the water activity of cheese and its relationship to solute mobility and solvent water are discussed. Some of the unique features of protein behavior, i.e., conformational changes, swelling, and solubilization are cited as possible sources of disparities between various reports.

Capsicum--production, technology, chemistry, and quality--Part II. Processed products, standards, world production and trade.

Abstract: Capsicums, as a spice, have been known since the beginning of civilization and historically associated with the discovery of the New World. The genus Capsicum (Fam. Solanaceae) provides many varieties and adds color, pungency, and aroma to the cuisines of most of the world. From the pungent chilli, of interest also to pharmaceuticals, to the colorful paprika and the bell capsicums with its remarkable aroma, the genus has been of great interest for its chemistry and physiological action. Pungency as a sensory attribute, its evaluation, structure-activity relationship, and its increasing acceptance and preference by diverse populations of the world are of great interest to many research disciplines. In a comprehensive review of all aspects in four sequential parts, Part I deals with History, Botany, Cultivation, and Primary Processing (CRC Critical Review, Food Science and Nutrition). The Capsicums among the spices are second only to black pepper in trades both in volume and value. The production of the different forms of this spice as ground, specialty seasonings, and as the concentrated oleoresins through technologically advanced processes, proposed newer products, the standard to control quality of the different products, world production, trade, and prospects are reviewed in detail in this, Part II.

Pigeonpea as an important food source.

Abstract: Pigeonpea is an important source of proteins, carbohydrates, B-group vitamins, and certain minerals. India contributes over 90% of the pigeonpea production in the world where it is mostly consumed as dehusked splits or dhal. In African countries and Latin America, it is mainly consumed as canned peas. In this review, world production and distribution, genetic background, and biochemical and nutritional properties, storage and processing of pigeonpea are discussed. Future research needs to improve the utilization of pigeonpea as human food are also addressed.

Effects of temperature on food proteins and its implications on functional properties.

Abstract: This article surveys the knowledge in the area of protein structure and chemistry of denaturation prior to an indepth review of the effects of heat on soy, milk, and egg proteins. It also reviews the methods available to assess denaturation of proteins. Protein denaturation is an ambiguous phenomenon and the consequences of denaturation on the functional properties of proteins is further confounded by this ambiguity. For each of the three food proteins, the known chemistry of individual proteins is reviewed followed by observations made on changes induced by heat in each protein group. Food proteins are not pure entities and purification and physicochemical characterization of various components of the food proteins have not been thoroughly investigated. Further, food is a complex milieu of water, fat, carbohydrate, vitamin, minerals, etc. along with proteins, and processing affects not only each individual component in the food but also the nature and intensity of intercomponent interactions in a food.

Radiation preservation of foods of plant origin. III. Tropical fruits: Bananas, mangoes, and papayas

Abstract: The current status of research on the use of ionizing radiation for shelf life improvement and disinfestation of fresh tropical fruits like bananas, mangoes, and papayas are reviewed. The aspects covered are influence of maturity and physiological state of the fruits on delayed ripening and tolerance to radiation; varietal responses; changes in chemical constituents, volatiles, respiration, and ethylene evolution; biochemical mechanisms of delayed ripening and browning of irradiated fruits; and organoleptic quality. The efficacy of the combination of hot water dip and radiation treatments for control of postharvest fungal diseases are considered. The immediate potential of radiation as a quarantine treatment, in place of the currently used chemical fumigants, for disinfestation of fruit flies and mango seed weevil are discussed. Future prospects for irradiation of tropical fruits are discussed in the light of experience gained from studies conducted in different countries.

Off‐flavors in milk

Abstract: This report is a review of off-flavors encountered in fluid milk. It includes sections on transmitted, microbial, lipolyzed, heated, light-activated, oxidized, and miscellaneous flavors. Finally, the flavor of ultrahigh temperature (UHT) milk is reviewed. Most of the literature cited for different off-flavors covers the period since a comprehensive review was done of milk flavors by Strobel et al. (1953). In addition to causative agents and volatile materials associated with off-flavors, methods for control of each of the off-flavors are presented. This report is designed to serve the dairy production and processing industry, students and faculty of food science curricula, dairy product evaluation students, regulatory people, and fieldmen.

Optimal energy management in grain drying

Abstract: Grain drying is very specific to the geographic location, kind of drying system, and the type of grain. Under a given set of conditions, the optimal system can be selected based on careful evaluation. However, a good choice of drying systems, procedures, and management practices can be made from the information already available. The review of several grain-drying procedures has provided some insight in making a quick evaluation of the process and arriving at the most suitable system for a particular application. Despite extensive research efforts, the present knowledge of grain drying is yet insufficient to optimally design each drying process with respect to capacity, quality, and energy requirement. There is a need for incorporating grain and air parameters more accurately. It is also important to develop comprehensive drying simulation models to encompass agronomic practices, such as planting and harvesting. Recent efforts indicate a strong influence of planting and harvesting strategies on optimal drying and storage system selection. Results of the varietal trials at Ohio State University indicate that it is now possible to select midseason varieties, which dry down rapidly, without sacrificing yield. Also, low moisture at harvest is important to the energy management process because it affects total drying time and energy required. It is also important from a quality standpoint because kernel damage increases rapidly at harvesting moisture levels above 25%. The trend in grain-dryer design has shifted from focusing on drying capacity and operation reliability to energy consumption. The development in design of energy efficient continuous-flow dryers has been significant. Multistage concurrentflow dryers are excellent examples. Various aspects of dryer staging for efficient operation and control are yet to be determined. Recirculation of the exhaust air is a proven method of improving energy efficiency. Likewise, in batch-in-bin systems, stirring and intermittent drying are worth considering. Further research is required to formulate the best procedures for exhaust air recirculation and intermittent drying. Low temperature drying has a great potential in the U.S. corn belt. The suitability of low temperature drying at other places and for grains other than corn has not yet been well established. Energy savings resulting from low temperature drying entail careful planning and management on the part of the operator. Poor design and operation can result in a serious deterioration in grain quality.(ABSTRACT TRUNCATED AT 400 WORDS)

Radiation preservation of foods of plant origin. Part V. Temperate fruits: Pome fruits, stone fruits, and berries

Abstract: The current status of research on the application of ionizing radiation for improving the storage of temperate fruits, i.e., apple, pear, peach, nectarine, apricot, cherry, plum, strawberry, bilberry, cranberry, raspberry, and black currant, is reviewed. Changes in fruit metabolism, chemical composition, texture, and organoleptic quality attributes are discussed with reference to the irradiation dose. The feasibility of using radiation either alone or in conjunction with heat treatment, refrigeration, and controlled atmospheres (CA) for the control of storage decay caused by fungal pathogens is considered. Areas of further research are suggested before irradiation could be considered for practical application in some of these temperate fruits. The recent trends in the possible use of irradiation for disinfestation of certain pome and stone fruits and the prospects for the commercial utilization of irradiation for improving the market life of strawberries are discussed.

Chemistry and technology of green gram (Vigna radiata [L.] Wilczek)

Abstract: Green gram or mung bean (Vigna radiata [L.] Wilczek) is an important food legume grown under tropical and subtropical conditions. It is an excellent source of protein and is almost free from flatulence‐causing factors. Because of this, green gram seeds are preferred for feeding babies and those convalescing. The seeds contain a higher proportion of lysine than any other legume seeds. The seeds are processed and consumed as cooked whole beans or splits (dhals), sprouts, immature seeds, and flour and are used in various recipes. The proposed work will incorporate available information on nutritional composition, processing, and utilization of green gram. The results reported in the literature on the above aspects of green gram will be analyzed critically, and future research needs will be defined to improve the utilization of green gram as human food.

Food applications and the toxicological and nutritional implications of amorphous silicon dioxide

Abstract: The chemical and physical characteristics of the different types of amorphous silicon dioxide contribute to the versatility of these compounds in a variety of commercial applications. Traditionally, silicas have had a broad spectra of product usage including such areas as viscosity control agents in inks, paints, corrosion‐resistant coatings, etc. and as excipients in Pharmaceuticals and cosmetics. In the food industry, the most important application has been as an anticaking agent in powdered mixes, seasonings, and coffee whiteners. However, amorphous silica has multifunctional properties that would allow it to act as a viscosity control agent, emulsion stabilizer, suspension and dispersion agent, desiccant, etc. The utilization of silicas in these potential applications, however, has not been undertaken, partially because of the limited knowledge of their physicochemical interactions with other food components and partially due to their controversial status from a toxicological point of view. The main g...

Radiation preservation of foods of plant origin. Part IV. Subtropical fruits: Citrus, grapes, and avocados

Abstract: Current information on the use of ionizing radiation for improving the storage of subtropical fruits like citrus, grapes, and avocados is reviewed The feasibility of applying radiation either alone or in combination with other physical or chemical treatments for the control of postharvest fungal diseases is considered Irradiation effects on the physiology of the fruits as related to respiration, ethylene evolution, changes in major chemical constituents, and quality are discussed The recent trends in the possible use of irradiation as an alternative treatment to chemical fumigants for disinfestation of citrus and avocados and the prospects for the future application of irradiation for preservation of some of these fruits are outlined

A review of basic concepts in rice-drying research.

Abstract: Rice-drying research is international, diffuse, important, and deceptively difficult. This review presents current thinking, background, entrance citations to the literature, and critical analysis for each of the most significant problems in rice-drying research, as well as an overview summary and general recommendations. Discussion is limited to mechanical drying with hot air. The literature examples are divided into four groups by research approach: within-kernel experimental, small-sample experimental, theoretical, and dryer design. While all areas have contributed and are expected to continue to do so, the small-sample experimental approach is cited as appearing to have an untapped potential for bringing about a quantum advance. Problems discussed include: uniformity, fissuring sequence, stress and plastic flow, diffusion mechanisms, temperature and other environmental factors, kernel vs. husk, controlled drying rate, chemical changes, dryer design, timing of harvest, trade-offs, reliability of data, and experimental design or approach.