Showing papers in "Comprehensive Reviews in Food Science and Food Safety in 2006"

Mechanisms and Factors for Edible Oil Oxidation

Abstract: : Edible oil is oxidized during processing and storage via autoxidation and photosensitized oxidation, in which triplet oxygen (3O2) and singlet oxygen (1O2) react with the oil, respectively. Autoxidation of oils requires radical forms of acylglycerols, whereas photosensitized oxidation does not require lipid radicals since 1O2 reacts directly with double bonds. Lipid hydroperoxides formed by 3O2 are conjugated dienes, whereas 1O2 produces both conjugated and nonconjugated dienes. The hydroperoxides are decomposed to produce off-flavor compounds and the oil quality decreases. Autoxidation of oil is accelerated by the presence of free fatty acids, mono- and diacylglycerols, metals such as iron, and thermally oxidized compounds. Chlorophylls and phenolic compounds decrease the autoxidation of oil in the dark, and carotenoids, tocopherols, and phospholipids demonstrate both antioxidant and prooxidant activity depending on the oil system. In photosensitized oxidation chlorophyll acts as a photosensitizer for the formation of 1O2; however, carotenoids and tocopherols decrease the oxidation through 1O2 quenching. Temperature, light, oxygen concentration, oil processing, and fatty acid composition also affect the oxidative stability of edible oil.

Resistant Starch–A Review

Abstract: The concept of resistant starch (RS) has evoked new interest in the bioavailability of starch and in its use as a source of dietary fiber, particularly in adults. RS is now considered to provide functional properties and find applications in a variety of foods. Types of RS, factors influencing their formation, consequence of such formation, their methods of preparation, their methods of estimation, and health benefits have been briefly discussed in this review.

Low-calorie Sweeteners and Other Sugar Substitutes: A Review of the Safety Issues

Abstract: Sugar-free or reduced-sugar foods and beverages are very popular in the United States and other countries, and the sweeteners that make them possible are among the most conspicuous ingredients in the food supply Extensive scientific research has demonstrated the safety of the 5 low-calorie sweeteners currently approved for use in foods in the United States–acesulfame K, aspartame, neotame, saccharin, and sucralose A controversial animal cancer study of aspartame conducted using unusual methodology is currently being reviewed by regulatory authorities in several countries No other issues about the safety of these 5 sweeteners remain unresolved at the present time Three other low-calorie sweeteners currently used in some other countries–alitame, cyclamate, and steviol glycosides–are not approved as food ingredients in the United States Steviol glycosides may be sold as a dietary supplement, but marketing this product as a food ingredient in the United States is illegal A variety of polyols (sugar alcohols) and other bulk sweeteners are also accepted for use in the United States The only significant health issue pertaining to polyols, most of which are incompletely digested, is the potential for gastrointestinal discomfort with excessive use The availability of a variety of safe sweeteners is of benefit to consumers because it enables food manufacturers to formulate a variety of good-tasting sweet foods and beverages that are safe for the teeth and lower in calorie content than sugar-sweetened foods

A Critical Review of Milk Fouling in Heat Exchangers

Abstract: Fouling of heat exchangers is a problem in the dairy industry and costs billions of dollars every year. It has been studied extensively by researchers around the world, and a large number of studies are reported in the literature. This review focuses on the mechanisms of milk fouling, investigating the role of protein denaturation and aggregation as well as mass transfer. We also endeavor to review the effect of a number of factors which have been classified into 5 categories: (1) milk quality, (2) operating conditions, (3) type and characteristics of heat exchangers, (4) presence of microorganisms, and (5) transfer of location where fouling takes place. Different aspects have been discussed with the view of possible industrial applications and future direction for research. It may not be possible to alter the properties of milk since they are dependent on the source, collection schedule, season, and many other factors. Lowering the surface temperature and increasing the flow velocity tend to reduce fouling. Reducing the heat transfer surface roughness and wettability is likely to lower the tendency of the proteins to adsorb onto the surface. The use of newer technologies like microwave heating and ohmic heating is gaining momentum because these result in lower fouling; however, further research is required to realize their full potential. The presence of microorganisms creates problem. The situation gets worse when the microorganisms get released into the process stream. The location where fouling takes place is of paramount importance because controlling fouling within the heat exchanger may yield little benefit in case fouling starts taking place elsewhere in the plant.

Bioactivity of Resveratrol

Abstract: : Resveratrol (3,5,4′-trihydroxystilbene) is a natural polyphenolic phytochemical with a variety of bioactivities associated with health promotion. Resveratrol is readily absorbed with the other absorbable digestion products of its main human dietary sources (peanuts, peanut butter, grapes, and red wine). The polyphenolic structure of resveratrol confers antioxidant activity and may reduce oxidant-induced apoptosis and low-density lipoprotein (LDL) oxidation. Resveratrol may be responsible, in part, for the correlation between increased wine consumption and decreased risk of coronary heart disease. The cardioprotective activity of resveratrol is associated with the inhibition of platelet aggregation and LDL oxidation and the promotion of artery vasorelaxation. As a chemoprevention agent, resveratrol has been shown to inhibit tumor initiation, promotion, and progression, as well as inhibit the growth of cancerous cells through increased apoptosis and/or cell cycle blockage. Inflammatory processes are associated in the pathogenesis of many chronic diseases including heart disease and cancer. Resveratrol has been shown to reduce inflammation via inhibition of prostaglandin production, cyclooxygenase-2 activity, and nuclear factor-кB activity. In addition, the estrogenic activity of resveratrol may help prevent post-menopausal bone loss. Modulation of cellular signal transduction pathways (such as mitogen-activated protein kinases) may explain, in part, the diverse bioactivities associated with resveratrol. Scientific information summarized in this review supports the many potential health benefits of resveratrol; however, further understanding of the bioavailability, metabolism, and cellular effects of resveratrol is necessary.

Stress Response of Escherichia coli

Abstract: : Escherichia coli encounter numerous different stresses during their growth, survival, and infection. These stresses are relevant to survival in foods and food processing environments. E. coli and other bacteria respond to stress conditions by activating small or large groups of genes under the control of common regulator proteins. Stress conditions result in the accumulation of these regulator proteins and subsequent transcription of many genes allows cells to cope with specific stress situations, conferring stress tolerance and survival. In addition, induced stress tolerance of cells is attributed to enhanced virulence and enhanced tolerance to other stresses (cross-protection). In this review, regulation of stress and the stress tolerance response of E. coli to heat, acid, starvation, and cold stresses that are commonly used in food preservation and food production will be addressed. The effect of different stress on survival, adaptation, and cross-protection of E. coli studied using laboratory media, and real foods will be briefly summarized. Finally, the relationship of stress response and subsequent virulence and cross-protection will also be discussed.

Use of Volatiles as Indicators of Lipid Oxidation in Muscle Foods

Abstract: Lipid oxidation has long been recognized as a leading cause of quality deterioration in muscle foods and is often the decisive factor in determining food product storage life. Lipid oxidation generates a number of products, including volatile compounds, which are the major contributors to the development of rancid off-flavors and odors. Over the years, methodologies have been developed to quantify lipid oxidation products in muscle foods. This article reviews the analytical methods that have been used to quantify volatile compounds as indicators of lipid oxidation in muscle foods. The sampling methodologies of distillation/solvent extraction and headspace analysis, and isolation methods associated with gas chromatographic (GC) and high-performance liquid chromatography (HPLC) analyses are discussed. Within gas chromatographic methodologies, headspace (HS) sampling (static HS, dynamic purge-and-trap HS techniques, and solid-phase microextraction [SPME]) are addressed.

Addition of Carbon Dioxide to Dairy Products to Improve Quality: A Comprehensive Review

Abstract: : Changes in distribution patterns and demand for increased food quality have resulted in a desire to improve the shelf life of nonsterile dairy products. Refrigerated shelf life extension typically requires, at a minimum, reductions in the growth rate of spoilage microorganisms and subsequent product deterioration. Reducing initial bacterial loads, increasing pasteurization regimes, and reducing postprocessing contamination have all been employed with measured success. The use of antimicrobial additives has been discouraged primarily due to labeling requirements and perceived toxicity risks. Carbon dioxide (CO2) is a naturally occurring milk component and inhibitory toward select dairy spoilage microorganisms; however, the precise mechanism is not fully understood. CO2 addition through modified atmosphere packaging or direct injection as a cost-effective shelf life extension strategy is used commercially worldwide for some dairy products and is being considered for others as well. New CO2 technologies are being developed for improvements in the shelf life, quality, and yield of a diversity of dairy products, including raw and pasteurized milk, cheeses, cottage cheese, yogurt, and fermented dairy beverages. Here we present a comprehensive review of past and present research related to quality improvement of such dairy products using CO2.

Analysis and evaluation of food manufacturing practices used to address allergen concerns

Abstract: Introduction According to the National Institutes of Health (NIH), 6 to 8% of children and up to 2% of adults in America suffer from food-related allergic reactions, which can range from mild itching to the more severe and sometimes fatal condition of anaphylaxis (NIH 2004). In August 2004 Congress responded to this significant public health concern by enacting the “Food Allergen Labeling and Consumer Protection Act” (FALCPA) (Pub. L. 108-282). The goal of this law is to ensure that foods that contain a major food allergen (defined by the law as milk, egg, finfish, crustacean shellfish, tree nuts, peanuts, wheat, and soybeans), or a derivative of these allergens (with certain exceptions) disclose the presence of the allergen on the product label using the “common or usual name” of the allergen source, so as to make it recognizable to the consumer. FALCPA further required that the Secretary of Health and Human Services provide a comprehensive report on the problem of unintended residues of food allergens in processed foods. The report included findings on the manufacturing conditions and practices associated with foods becoming unintentionally contaminated with undeclared allergens. The report also addresses pre-FALCPA (which took effect Jan. 1, 2006) use of advisory labeling (such as “may contain”) by food manufacturers, consumer preference for food product labeling and the effectiveness of the food industry’s efforts to address cross-contact issues. FDA’s report was sent to Congress in July 2006. On September 23, 2004, the Food and Drug Administration (FDA) of the U.S. Dept. of Health and Human Services signed a 5year contract with the Institute of Food Technologists (IFT) to provide scientific review and analysis of issues in food safety, food security, food processing, and human health. In February of 2005 FDA tasked IFT with assessing the state of manufacturing and labeling practices used by food manufacturers to address allergen concerns. IFT assembled a group (Scientific & Technical Panel) to develop a strategy for accomplishing this task. The panel was comprised of experts in food allergens and/or food manufacturing and labeling practices. Subsequently, IFT implemented an allergen-related information acquisition strategy, obtaining a wealth of data and information from numerous manufacturers of a wide variety of food commodities. This report summarizes IFT’s response to the manufacturing portion of Task Order #2.