Showing papers in "Critical Reviews in Food Science and Nutrition in 1992"

Inhibition of enzymatic browning in foods and beverages

Abstract: Enzymatic browning is a major factor contributing to quality loss in foods and beverages. Sulfiting agents are used commonly to control browning; however, several negative attributes associated with sulfites have created the need for functional alternatives. Recent advances in the development of nonsulfite inhibitors of enzymatic browning are reviewed. The review fouses on compositions that are of practical relevance to food use.

Volatiles from interactions of Maillard reactions and lipids

Abstract: This article provides current information on the production of volatile compounds from interactions of Maillard reactions and lipids. It includes a brief introduction outlining the Maillard reactions, the Strecker degradation of amino acids, and the oxidation of lipids. It highlights those compounds derived from these reactions that could interact to form volatile flavor components during the processing or cooking of food. The article discusses results obtained from model systems involving interactions between (1) Maillard reaction products and carbonyl compounds, (2) amino acids and carbonyl compounds, (3) amino acids and derivatives of fatty acids, and (4) Maillard reaction products, triglycerides and phospholipids. The qualitative and quantitative effects that triglycerides and phospholipids have on the formation of volatile Maillard products are also discussed. Particular attention is given to those long-chain alkyl heterocyclic compounds formed during these reactions, proposed methods for their formation, and their aromas. The role that such compounds play in food flavors is discussed with reference to those volatile compounds identified in certain cooked foods, such as meat (beef, lamb, and pork), chicken, potatoes (baked, French-fried, and crisps), and beverages (coffee, tea, and cocoa).

Contributions of heme and nonheme iron to human nutrition

Abstract: Dietary iron is present in food both in inorganic forms as ferrous and ferric compounds, and in organic forms, the most important of these being heme iron. The purpose of this review is to evaluate the contributions of both heme and nonheme iron in establishing and maintaining a healthful iron status. The human requirement for iron, bioavailability of heme and nonheme iron, and amounts of heme and nonheme iron in the diet are individually estimated after reviewing the relevant literature in Sections II, III, and IV, respectively. In Section V, the contribution of heme and nonheme iron to human nutrition, as compared to the human requirement for iron (Section II), is estimated after attenuating the amounts of heme and nonheme iron found in the diet (Section IV) by their bioavailabilities (Section III).

Extrusion of food proteins.

Abstract: Protein extrusion has frustrated earlier predictions regarding its impact in the development of food products. The main reason for this disappointing performance has been its failure to yield fabricated food products with textural quality close enough to that of natural products at competitive prices. Texturized soya protein by extrusion is presently the only commercial success in this area, being incorporated into several convenience products, increasing their protein content and quality and conferring them some desirable sensory properties. Technological and scientific gaps in the extrusion texturization are still to be bridged if this technique is to be applied for upgrading unconventional protein. The precise mechanisms responsible for protein texturization through extrusion are still unclear. Proteins show a very wide range of extrusion behavior that is probably related to large differences in their association properties. New peptide bonds, formed by free amino and carboxylic groups of the protein, were postulated as being responsible for the cross-linking that takes place in protein extrusion. However, disulfide bonds and electrostatic and hydrophobic interactions are regarded presently as the texturization mechanism in this process. The recently suggested suspension (or filled "melt") model for biopolymer extrusion offered a new framework for testing extrusion of novel proteins. According to this view, the large differences between the association properties of proteins produce different types of aggregates. Some of them can be insoluble under extrusion conditions and act as a dispersed phase within the melt phase. The extrusion performance of a protein will thus depend on the amount of insoluble aggregate produced inside the extruder and on protein-protein interactions that occur after the superheated molten mass leaves it.

Singlet oxygen oxidation of foods.

Abstract: (1992). Singlet oxygen oxidation of foods. Critical Reviews in Food Science and Nutrition: Vol. 31, No. 3, pp. 211-236.

On the use of the WLF model in polymers and foods.

Abstract: The validity of the WLF model with fixed "universal" coefficients was tested against that of the model original form with variable coefficients using published coefficients of polymers and amorphous sugars crystallization and viscosity data. The disagreement between the two versions of the model is particularly large at temperature ranges starting about 20 to 30 degrees K above the glass transition or reference temperature, excluding the former from being a model of general applicability. Because the WLF model mathematical structure entails the existence of an almost linear region near the reference temperature, establishment of its validity as a kinetic model and meaningful determination of its constants requires data spread over an extended temperature range, especially when the experimental results have a scatter.

In vivo and in vitro models of the human colonic flora.

Abstract: The study of colonic flora composition and metabolism presents considerable methodological problems. Attempts to circumvent these problems have led to the development of numerous in vitro and in vivo models to simulate the human colon and its microbial population. In terms of in vivo models, conventional laboratory animals have many limitations. Data of greater relevance to man can be obtained by using germ-free rodents associated with human colonic bacteria. The applications of such animals to studies of toxicity of chemicals and gastrointestinal infections are discussed. The advantages and disadvantages of the various in vitro systems for studying gut microflora and its metabolic activity (from simple static cultures to the more sophisticated continuous and semicontinuous flow models) are reviewed. The apparatus involved is described together with practical information on media, running conditions, and sampling. The bacteriological and metabolic criteria for establishing the similarity of the models to the in situ colonic flora are also discussed. The final sections of the review are devoted to the major applications (current and future) of the models, including fermentation studies on dietary fiber, metabolism of nutrients and foreign compounds (including carcinogens) in food, and the investigation of colonization resistance.

Mechanisms of meat batter stabilization: a review.

Abstract: Comminuted meat products are a complex mixture of muscle tissue, solubilized proteins, fat, salt, and water. The two theories that have been presented to explain meat batters stabilization are reviewed. The emulsion theory explains stabilization by the formation of a protein film around fat globules, whereas the physical entrapment theory emphasizes the role of the protein matrix in holding the fat in place during chopping and subsequent heating. However, some aspects of stabilization cannot be explained adequately by either one of these theories. In this article the role of meat proteins, aqueous phase, and lipid phase are examined in light of past and recent research findings.

Food legumes in human nutrition: a personal perspective.

Abstract: Perhaps with the notable exception, and that only in recent years, of red meat, which contributes dietary saturated fats and cholesterol, two well‐known reasons in the etiology of heart‐related disorders, no single group of foods has been portrayed in such negative terms as the food legumes traditionally have been during the last 50 years of research in food science and human nutrition. Even more alarming are the trends of continued research on such aspects as the deficiency of sulfur‐amino acids (both by amino acid analyses as well as rat feeding studies), and the heat lability/stability of proteinase inhibitors and phytohemagglutinins in various legume species. A survey of literature indicates that over 100 research papers were published during the 1981 to 1990 period alone, in just three journals (Journal of Food Science, Journal of Agriculture and Food Chemistry, and Journal of the Science of Food and Agriculture) having the highest citation ratings in food sciences on these three topics, wit...

Tropical oils: Nutritional and scientific issues

Abstract: Individually and in combination with other oils, the tropical oils impart into manufactured foods functional properties that appeal to consumers. The use of and/or labeling in the ingredient lists give the impression that these oils are used extensively in commercially processed foods. The estimated daily intake of tropical oils by adult males is slightly more than one fourth of a tablespoon (3.8 g), 75% of which consists of saturated fatty acids. Dietary fats containing saturated fatty acids at the beta-position tend to raise plasma total and LDL-cholesterol, which, of course, contribute to atherosclerosis and coronary heart disease. Health professionals express concern that consumers who choose foods containing tropical oils unknowingly increase their intake of saturated fatty acids. The saturated fatty acid-rich tropical oils, coconut oil, hydrogenated coconut oil, and palm kernel oil, raise cholesterol levels; studies demonstrating this effect are often confounded by a developing essential fatty acid deficiency. Palm oil, an essential fatty acid-sufficient tropical oil, raises plasma cholesterol only when an excess of cholesterol is presented in the diet. The failure of palm oil to elevate blood cholesterol as predicted by the regression equations developed by Keys et al. and Hegsted et al. might be due to the dominant alpha-position location of its constituent saturated fatty acids. If so, the substitution of interesterified artificial fats for palm oil in food formulations, a recommendation of some health professionals, has the potential of raising cholesterol levels. A second rationale addresses prospective roles minor constituents of palm oil might play in health maintenance. This rationale is founded on the following observations. Dietary palm oil does not raise plasma cholesterol. Single fat studies suggests that oils richer in polyunsaturated fatty acid content tend to decrease thrombus formation. Anomalously, palm oil differs from other of the more saturated fats in tending to decrease thrombus formation. Finally, in studies comparing palm oil with other fats and oils, experimental carcinogenesis is enhanced both by vegetable oils richer in linoleic acid content and by more highly saturated animal fats. The carotenoid constituents of red palm oil are potent dietary anticarcinogens. A second group of antioxidants, the tocotrienols, are present in both palm olein and red palm oil. These vitamin E-active constituents are potent suppressors of cholesterol biosynthesis; emerging data point to their anticarcinogenic and antithrombotic activities. This review does not support claims that foods containing palm oil have no place in a prudent diet.

Characteristics of antisweet substances, sweet proteins, and sweetness‐inducing proteins

Abstract: Recent studies on structures and functions of sweetness‐inhibiting substances (gymnemic acid, ziziphin, and gurmarin); sweet proteins (monellin, thaumatin and mabinlin); and taste‐modifying proteins (miraculin and curculin) were reviewed. Several gymnemic acid homologues and gurmarin were purified from the leaves of Gymnema sylvestre and their structures were determined. Ziziphin was also purified from leaves of Ziziphus jujuba. Gymnemic acid and ziziphin are glycoside of triterpenes that suppress sweetness in human, while gurmarin is a peptide having antisweet activity in rat. Mabinlin is a heat‐stable sweet protein. The whole amino acid sequence and the position of disulfide bridges of mabinlin were determined. Miraculin has the unusual property of modifying a sour taste into a sweet taste. Curculin elicits a sweet taste. In addition, water and sour substance elicit a sweet taste after curculin. Their amino acid sequences and subunit structures were determined. These proteins are expected to be...

Is copper an antioxidant nutrient

Abstract: Reactions radicalaires, effet du cuivre sur ces reactions. Proprietes antioxydantes du cuivre : fonctions physiologiques, distribution dans l'organisme, intervention du cuivre dans la superoxyde dismutase, ceruleoplasmine, fer et glutathion, glutathion peroxydase. Implications du cuivre dans la sante et les desequilibres physiologiques : systeme ardiovasculaire, cancer, vieillissement, poumons, globules rouges, tissu neural, foie et reins

Carotenoids and retinoids in human nutrition

Abstract: Since the discovery of vitamin A as a fat-soluble growth factor in the early part of the century, research into carotenoids and retinoids has attracted the attention of many scientists. These two groups of compounds are still being actively studied all over the world since many gaps in knowledge exist and new frontiers are being pursued. Recent developments in studies into the possible roles of carotenoids and retinoids beyond their classical functions in vision have created a great deal of excitement in the biomedical community. This review covers a wide range of topics pertaining to these two closely related compounds. Particular emphasis is given to the functions of these compounds and their roles in human nutrition. Various aspects of vitamin A deficiency and studies on carotenoids and retinoids in cancer development and prevention are reviewed in some detail.

Macromolecule replacers in food products.

Abstract: Traditional macromolecules and other recently synthesized materials have been accepted by consumers for use as low-calorie replacements for fats and sugars in food products. These include carbohydrates such as polydextrose, maltodextrins, modified starches, gums, and fibers. Protein and lipid-based replacements, including fat analogs and emulsifiers, are also available and some have been approved for use in food products. This article presents the properties of each of the macromolecule replacers, some uses that have been reported in food products, and speculative thoughts regarding functionality. Because control of water in the food product, added solids, and the mouthfeel characteristics associated with microparticles are three of the critical functions that must be provided by replacers, effectiveness of usage from a sensory perspective is also considered.

The effect of dairy products on iron availability.

Abstract: Many researchers report substantial reductions in iron availability when dairy products are consumed with solutions of iron. Yet other studies indicate that dairy products have little effect on iron availability when added to complex meals. The conflicting data may be due to differences in the technique used to measure availability, species of animal used, form of iron in the diet, and meal composition. Human studies show superior bioavailability of iron in human milk when compared with cow's milk. Definitive causes for the differences between human and cow's milk have not been identified. Human milk contains lower amounts of casein, phosphate, and calcium, components thought to inhibit iron absorption. More work is needed to identify the factors that influence iron-dairy interactions. The nutritional benefits provided by dairy products outweigh the slight inhibitory effect they may have on iron availability.

Lipid interactions in breadmaking.

Abstract: Both the natural lipids of flour and added fats are known to play an important role during the production of bread In this review, the chemical and physical interactions of fat have been assessed in an attempt to explain these technological functions Particular emphasis has been placed on the “binding” or complexing of lipid by flour proteins during the development of dough While publications in this field have frequently been contradictory, evidence now indicates that observed lipid binding may involve lipid mesophase transformation and the nonspecific occlusion of lipid phases within the gluten network The significance of these suggested events has been compared with current theories of lipid function in the breadmaking process

Vitamin C and plasma cholesterol.

Abstract: There has been some inconsistency in data on the effect of vitamin C on human plasma cholesterol levels. The purpose of this review is to analyze the published intervention studies in order to identify the factors that may have caused conflicting results. It discusses cholesterol and triglyceride metabolism, physiological studies, intervention studies, epidemiological studies, and conclusions

Application of immunochemical assays to food analysis

Abstract: Immunochemical assays are powerful bioanalytical techniques with application to several areas in food science, including food analysis, microbiology, nutrition, food safety, food quality, and process control. In principle, immunochemical techniques can be applied to the analysis of any compound, with only one specific antibody needed that can be obtained either from laboratory animals or, when available, from commercial sources. A well‐designed immunochemical assay can detect targeted compounds at levels as low as 10−12 M. Immunochemical techniques require little or no sample pretreatment, making these analytical procedures relatively rapid. The initial cost of developing an immunoanalytical assay may be high, but when the procedure is well established, the cost per test is often a fraction of that for other analytical methods. For these reasons, immunoanalytical assays provide an attractive alternative for the food analyst who requires either inexpensive qualitative screening tests or reliable q...

Safety evaluation of olestra, a nonabsorbed, fatlike fat replacement

Abstract: Olestra is the mixture of the hexa-, hepta-, and octa-esters of sucrose with long-chain fatty acids from any edible oil Its physical properties are comparable to those of triglycerides, but it is not digested by lipolytic enzymes or absorbed and therefore is noncaloric Technically, it can replace fat in a wide variety of foods and can be used to make cooked, baked, and fried foods lower in fat and calories A Food Additive Petition is under review by the FDA, which is comprised of results of extensive testing in animals and humans The major areas of investigation are metabolism and absorption, chronic toxicity, mutagenicity, carcinogenicity, reproductive and developmental toxicity, safety for gastrointestinal tract, nutrition, and the potential for olestra to affect absorption of drugs This testing involved studies in five different species of animals and over 30 clinical investigations The results of this research support the safety of olestra for use in foods

Testing guidelines for evaluation of the immunotoxic potential of direct food additives

Abstract: Immunotoxicity testing is a new addition to the safety assessment guidelines for direct food and color additives. The approaches and philosophy for this area of specialized testing are consistent with the case‐by‐case strategy applied in the regulatory approval process, which is based on structure‐activity relationships, preexisting knowledge, and projected exposure estimates. Specialized testing such as immunotoxicity is not part of the basic testing requirements, but would be applied when indicators are positive. Concepts for immunotoxicity testing have evolved, in part, from research for evaluating various testing methods as well as specific study designs. This research, conducted over the last decade, has focused mainly on the rat as the rodent species of choice. The miniature swine was evaluated as a nonrodent model. Testing is defined by type 1 and type 2 tests, which differ in that type 1 tests are performed on the same animals used in the core study design. Sets of type 1 and type 2 tests...

Pesticide residue controls to ensure food safety.

Abstract: (1992). Pesticide residue controls to ensure food safety. Critical Reviews in Food Science and Nutrition: Vol. 31, No. 3, pp. 191-203.

Perspectives on toxicological risk--an example: foodborne carcinogenic risk.

Abstract: Epidemiologists estimate that approximately one third of all cancer deaths can be attributed to diet. It is instructive to attempt to apportion this dietary carcinogenic risk to the specific classes of foodstuffs and food additives, pesticides, etc., that are typically regulated. When this is done it is evident that virtually all the calculated risk can be attributed to naturally occurring carcinogens in the diet. This article indicates that both epidemiological data and the simplest kind of risk assessment agree that foodborne carcinogenic risk probably overwhelmingly originates from the food itself and not from additives, pesticides, or contaminants.

A review of sweet taste potentiation brought about by divalent oxygen and sulfur incorporation

Abstract: The plethora of high‐potency sweetener research has allowed the construction of important structure‐taste relationships. In light of new structure‐taste relationships, it is instructive to review sweet taste potentiation brought about by divalent oxygen and sulfur incorporation. The taste of sulfur‐containing organic compounds was reviewed in Japanese by Yasuo Ariyoshi in 1977.5 Several new representative examples of sweet taste potentiation and taste dichotomy (sweet and bitter) found within similar classes of oxygen‐ and sulfur‐containing organic compounds: amides, dipeptides, ureas, sulfamates, sulfonamides, oximes, sugars, dihydroisocoumarins, and others are reviewed. Special attention is given to the thioethers and thioureas in sulfamates, dipeptides, aryl ureas, and hybrid dipeptide ureas. The most notable contributions have arisen from the work of Nofre and Tinti at Universite Claude Bernard in Lyons, France.” A common trend emerges with certain sweeteners when a carbon atom is strategical...

Revisions to the FDA's Redbook guidelines for toxicity testing: neurotoxicity.

Abstract: In 1982, the Food and Drug Administration issued a publication, known as the Redbook, that described the current toxicological principles used for the safety assessment of regulated food and color additives. However, this document contained only minimum reference to neurotoxicity as a specific toxicological concern and only general mention of the types of data that should be collected to detect and assess adverse changes to the nervous system. The general nature of the toxicological information typically derived from studies based on the original Redbook has had only limited use as a guide for comprehensive assessment of neurotoxic hazard. This limitation is one of the issues being addressed in the current efforts to update the information provided in the Redbook. In the revised Redbook, neurotoxicity, encompassing adverse structural and functional changes to the nervous system, is explicitly identified as an important criterion in the assessment of food chemical safety. The proposed strategy for evaluating neurotoxic hazard has a tiered testing approach. Accordingly, testing would initially involve the identification of chemicals presumptively associated with neurotoxic effects. As appropriate, subsequent testing would be carried out to confirm and delineate the scope of the neurotoxicity, to determine the dose response kinetics, and to define the no-adverse-effect levels.

Overview of FDA's redbook guidelines

Abstract: As part of its responsibility, the Food and Drug Administration provides guidance to industry and the public concerning the procedures and methods for safety assessment of food and color additives. The FDA published its guidelines in 1982 as the so-called "Redbook" ("Toxicological Principles for the Safety Assessment of Direct Food Additives and Color Additives Used in Food"). The Center for Food Safety and Applied Nutrition of the FDA is now in the process of revising and updating the Redbook in light of developments in toxicological testing methods and comments from the scientific community and the public. The effort involves a number of center scientists who have special expertise in various areas of toxicology and food safety assessment. The goal is to make the revised Redbook more useful and practical and to address areas of safety assessment not covered in the 1982 edition. The several papers that follow deal with chapters that will be new to the Redbook.

The problem of obesity: fundamental concepts of energy metabolism gone awry.

Abstract: The growing prevalence and complex issues related to obesity continue to draw the interest and concern of health researchers and practitioners. This review summarizes pertinent background information on the multiple factors involved in the causes of obesity. Factors such as percentage of body fat, upper- vs. lower-body obesity, family history, past dieting history, and underlying medical conditions should be assessed on an individual basis and applied in the development of successful weight-reducing strategies. The recommended approach to nonpharmacologic intervention for weight loss is to first educate individuals about fat storage and energy balance and then focus on the development of positive behavioral skills such as wise food selections, favorable eating patterns, and regular physical activity. Although preventive measures such as positive eating patterns and exercise habits are ideally acquired in childhood and adolescence, successful weight management can still be achieved in adulthood. The information presented in the following sections provides clinicians with essential material to assist individuals in developing realistic goals at the outset of a weight-control program.