Annual Review of Food Science and Technology - Volume 1, 2010
Volume 1, 2010
- Preface
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A Promise Kept
Vol. 1 (2010), pp. 1–18More LessThis article is largely biographical and relates to my experiences of the past 67 years in research and teaching, both of equal importance in my life. I was fortunate to start at the beginning of the development of instrumental methods of analysis and have eagerly embraced each new methodology as it became available. This paper is dedicated to all those students and colleagues who taught me much and whose efforts are mainly responsible for what has been accomplished in our work with food science and technology. The research focused primarily on trying to find out the “why” behind the problems that food, and especially the dairy products area, encountered over the past 65 years. The teaching has tried to foster thinking and problem solving.
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Whole Grains: Benefits and Challenges
Vol. 1 (2010), pp. 19–40More LessInclusion of whole grains (WG) in the diet is recommended in dietary guidance around the world because of their associations with increased health and reduced risk of chronic disease. WGs are linked to reduced risk of obesity or weight gain; reduced risk of cardiovascular disease (CVD), including coronary heart disease (CHD), hypertension, and stroke; improved gut health and decreased risk of cancers of the upper gut; perhaps reduced risk of colorectal cancer; and lower mortality rate. The 2005 United States Dietary Guidelines Advisory Committee has recommended that consumers make “half their grains whole.” Yet, whole grains are puzzling both consumers and scientists. Scientists are trying to determine whether their health benefits are due to the synergy of WG components, individual WG components, or the fact that WG eaters make many of the recommended diet and lifestyle choices.
Consumers need to understand the WG benefits and how to identify WG foods to have incentive to purchase and use such foods. Industry needs to develop great-tasting, clearly-labeled products. With both these factors working together, it will be possible to change WG consumption habits among consumers.
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Water-Solids Interactions: Deliquescence
Vol. 1 (2010), pp. 41–63More LessDeliquescence is a first order phase transition from solid to solution that occurs at a relative humidity (RH) that is characteristic to the solid ingredient. In blends containing more than one component with deliquescent behavior, the RH of the solid-solution transition will be lowered, leading to some level of dissolution at relatively low RH conditions. Dissolution arising as a result of deliquescence will impact the chemical and physical stability of complex food systems. Because chemical reactions occur much more readily in solution, deliquescence will enhance the degradation of labile food ingredients. RH fluctuations will lead to cycles of deliquescence and efflorescence (crystallization), which will contribute to particle agglomeration and caking. This review addresses the phenomenon of deliquescence, the significance of deliquescence to the food industry, measurement techniques, the kinetics and thermodynamics of deliquescence, the behavior of mixtures of deliquescent salts (including phase diagrams and thermodynamics of binary systems), and consequences of deliquescence on chemical and physical stability of powdered food and nutritional ingredient blends.
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Food Formats for Effective Delivery of Probiotics
Vol. 1 (2010), pp. 65–85More LessProbiotic bacteria are increasingly incorporated into food products intended to confer health benefits in the human gut and beyond. Little is known about how the food matrix and product formulation impacts probiotic functionality, even though such information is essential to scientific understanding and regulatory substantiation of health benefits. The food format has the potential to affect probiotic survival, physiology, and potentially efficacy, but few comparative studies in humans have been conducted. Human studies should account for the effects of the food base on human health and the bioactive components present in the foods that may augment or diminish interactions of the probiotic with the human host. Some studies show that food ingredients such as prebiotics and milk components can improve probiotic survival during the shelf life of foods, which may enhance probiotic efficacy through increased dose effects. Furthermore, there are indications that synbiotic products are more effective than either probiotics or prebiotics alone. Identification of probiotic adaptations to the food and gut environments holds promise for determining the specific cell components and potential bacterial-food interactions necessary for health benefits and determining how these factors are affected by changes in food formulation and host diet. These studies, combined with controlled human studies, are important future research activities for advancing this field.
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Fate of Starch in Food Processing: From Raw Materials to Final Food Products
Vol. 1 (2010), pp. 87–111More LessStarch, an essential component of an equilibrated diet, is present in cereals such as common and durum wheat, maize, rice, and rye, in roots and tubers such as potato and cassava, and in legumes such as peas. During food processing, starch mainly undergoes nonchemical transformations. Here, we focus on the occurrence of starch in food raw materials, its composition and properties, and its transformations from raw material to final products. We therefore describe a number of predominant food processes and identify research needs. Nonchemical transformations that are dealt with include physical damage to starch, gelatinization, amylose-lipid complex formation, amylose crystallization, and amylopectin retrogradation. A main focus is on wheat-based processes. (Bio)chemical modifications of starch by amylolytic enzymes are dealt with only in the context of understanding the starch component in bread making.
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Crosslinking Food Proteins for Improved Functionality
Vol. 1 (2010), pp. 113–138More LessDifferent possibilities for protein crosslinking are examined in this review, with special emphasis on enzymatic crosslinking and its impact on food structure. Among potential enzymes for protein crosslinking are transglutaminase (TG) and various oxidative enzymes. Crosslinking enzymes can be applied in cereal, dairy, meat, and fish processing to improve the texture of the product. Most of the current commercial applications are based on TG. The reaction mechanisms of the crosslinking enzymes differ, which in turn results in different technological properties.
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Genetics of Yeast Impacting Wine Quality
Vol. 1 (2010), pp. 139–162More LessThe availability of the sequence of the Saccharomyces genome in combination with the development of chemical analytical technologies with dynamic ranges sensitive enough to detect volatile aromatic compounds has generated a renewed interest in defining the role of yeast in the generation of wine aroma and flavor. Genetic differences among wine strains are well documented and aroma profiles also appear to vary, implying that specific allelic alterations may exist and impact the production of compounds associated with flavor. Partial or complete sequencing data on several wine strains are available and reveal underlying genetic differences across strains in key genes implicated in flavor formation. This review discusses the current understanding of the roles of Saccharomyces in wine flavor with an emphasis on positive contributions to flavor and highlights the discoveries of the underlying enzymatic and metabolic mechanisms responsible for the yeast contribution to wine quality.
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Anthocyanins: Natural Colorants with Health-Promoting Properties
Jian He, and M. Monica GiustiVol. 1 (2010), pp. 163–187More LessAnthocyanins are flavonoids in fruits and vegetables that render them vivid red to blue. To date, there have been more than 635 anthocyanins identified in nature, featuring six common aglycones and various types of glycosylations and acylations. Dietary consumption of anthocyanins is high compared to other flavonoids, owing to their wide distribution in plant materials. Based upon many cell-line studies, animal models, and human clinical trials, it has been suggested that anthocyanins possess anti-inflammatory and anti-carcinogenic activity, cardiovascular disease prevention, obesity control, and diabetes alleviation properties, all of which are more or less associated with their potent antioxidant property. Evidence suggests that absorption of anthocyanins occurs in the stomach and small intestine. Epithelial tissue uptake seems to be highly efficient, yet transportation into circulation, tissue distribution, and urine excretion are very limited. The bioactivity of bioavailable anthocyanins should be a focus of future research regarding their putative health-promoting effects.
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An Update on the Health Effects of Tomato Lycopene
Vol. 1 (2010), pp. 189–210More LessLycopene is a non-provitamin A carotenoid that is responsible for the red to pink colors seen in tomatoes, pink grapefruit, and other foods. Processed tomato products are the primary dietary lycopene source in the United States. Unlike many other natural compounds, lycopene is generally stable to processing when present in the plant tissue matrix. Recently, lycopene has also been studied in relation to its potential health effects. Although promising data from epidemiological, as well as cell culture and animal, studies suggest that lycopene and the consumption of lycopene containing foods may affect cancer or cardiovascular disease risk, more clinical trial data is needed to support this hypothesis. In addition, future studies are required to understand the mechanism(s) whereby lycopene or its metabolites are proven to possess biological activity in humans.
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Food Powders Flowability Characterization: Theory, Methods, and Applications
Vol. 1 (2010), pp. 211–239More LessCharacterization of food powders flowability is required for predicting powder flow from hoppers in small-scale systems such as vending machines or at the industrial scale from storage silos or bins dispensing into powder mixing systems or packaging machines. This review covers conventional and new methods used to measure flowability in food powders. The method developed by Jenike (1964) for determining hopper outlet diameter and hopper angle has become a standard for the design of bins and is regarded as a standard method to characterize flowability. Moreover, there are a number of shear cells that can be used to determine failure properties defined by Jenike's theory. Other classic methods (compression, angle of repose) and nonconventional methods (Hall flowmeter, Johanson Indicizer, Hosokawa powder tester, tensile strength tester, powder rheometer), used mainly for the characterization of food powder cohesiveness, are described. The effect of some factors preventing flow, such as water content, temperature, time consolidation, particle composition and size distribution, is summarized for the characterization of specific food powders with conventional and other methods. Whereas time-consuming standard methods established for hopper design provide flow properties, there is yet little comparative evidence demonstrating that other rapid methods may provide similar flow prediction.
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Emulsion Design to Improve the Delivery of Functional Lipophilic Components
Vol. 1 (2010), pp. 241–269More LessThe food industry has used emulsion science and technology for many years to create a diverse range of food products, such as milk, cream, soft drinks, nutritional beverages, dressings, mayonnaise, sauces, dips, deserts, ice cream, margarine, and butter. The majority of these food products are conventional oil-in-water (O/W) or water-in-oil (W/O) type emulsions. Recently, there has been increasing interest within the food industry in either improving or extending the functional performance of foods using novel structured emulsions. This article reviews recent developments in the creation of structured emulsions that could be used by the food and other industries, including nanoemulsions, multiple emulsions, multilayer emulsions, solid lipid particles, and filled hydrogel particles. These structured emulsions can be produced from food-grade [generally recognized as safe (GRAS)] ingredients (e.g., lipids, proteins, polysaccharides, surfactants, and minerals), using simple processing operations (e.g., mixing, homogenizing, and thermal processing). The structure, production, performance, and potential applications of each type of structured emulsion system are discussed.
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Biochemistry and Genetics of Starch Synthesis
Vol. 1 (2010), pp. 271–303More LessEnormous progress has been made in understanding the genetics and biochemistry of starch synthesis in crop plants. Furthermore, starch remains at the very epicenter of the world's food and feed chains and has even now become one of the world's most important sources of biorenewable energy (biofuel). Yet, despite this remarkable progress and the obvious economic importance, very little has been achieved in terms of adding value to starch or increasing starch yield, particularly in cereal crops. Here, we review the genetics and biochemistry of starch synthesis in crop plants, particularly maize. With all this know-how in place and a chasm of opportunity ahead, the time is right to see science deliver progress into a new frontier. Thus, in our view the stage is set for a new era of changes in starch synthesis, delivering enhancements in functionality and yield.
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Functional Oligosaccharides: Application and Manufacture
Vol. 1 (2010), pp. 305–339More LessOligosaccharides are attracting increasing interest as prebiotic functional food ingredients. They can be extracted or obtained by enzymatic hydrolysis from a variety of biomass sources or synthesized from simple oligosaccharides by enzymatic transfer reactions. The major prebiotic oligosaccharides on the market are inulin, fructo-oligosaccharides, and galacto-oligosaccharides. They have been evaluated using a range of in vitro and in vivo methods, although there is a need for more large-scale human trials using modern microbiological methods. Prebiotics are being studied for their effects on gut health and well being and specific clinical conditions, including colon cancer, inflammatory bowel disease (IBD), acute infections, and mineral absorption. Developing understanding of the functional ecology of the human gut is influencing current thinking on what a prebiotic might achieve and is providing new targets for prebiotic intervention.
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Food Safety: What Can We Learn From Genomics?
M áire Begley, and Colin HillVol. 1 (2010), pp. 341–361More LessThe entire genome sequences of numerous foodborne pathogens have been determined, and genome sequencing projects of many others are currently underway. The resulting sequence information will permit detailed bioinformatic analyses and provide direction for subsequent functional analyses. Genomics-driven studies will have many applications in food safety, such as assisting with the development of tools for the rapid detection and identification of pathogens and helping to provide insights into their evolution, biology, and ecological fitness. These studies will also aid in elucidating the mechanisms employed by pathogens as they adapt to the variety of conditions encountered throughout their life cycle, from the food-processing environment to in vivo during infection. It is anticipated that genomics will aid in the development of novel preventative and control strategies, which in turn will ultimately lead to a safer food supply.
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Mechanisms of Microbial Hydrogen Disposal in the Human Colon and Implications for Health and Disease
Vol. 1 (2010), pp. 363–395More LessIn the human gastrointestinal tract, dietary components, including fiber, that reach the colon are fermented principally to short-chain fatty acids, hydrogen, and carbon dioxide. Microbial disposal of the hydrogen generated during anaerobic fermentation in the human colon is critical to optimal functioning of this ecosystem. However, our understanding of microbial hydrogenotrophy is fragmented and, at least as it occurs in the colon, is mostly theoretical in nature. Thorough investigation and integration of knowledge on the diversity of hydrogenotrophic microbes, their metabolic variation and activities as a functional group, as well as the nature of their interactions with fermentative bacteria, are necessary to understand hydrogen metabolism in the human colon. Here, we review the limited data available on the three major groups of H2-consuming microorganisms found in the human colon [methanogens, sulfate-reducing bacteria (SRB), and acetogens] as well as evidence that end products of their metabolism have an important impact on colonic health.
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Genomic Evolution of Domesticated Microorganisms
Vol. 1 (2010), pp. 397–414More LessStrains of lactic acid bacteria, yeasts, and molds have been selected over thousands of years based on the unique sensory attributes they provide to food fermentations. Over the centuries they have evolved to their domesticated roles, leading to genome decay, loss of pathways, acquisition of genomic elements, and beneficial mutations that provide an advantage in their nutrient-rich food environments. This review highlights the evolutionary traits influenced by the domestication process as these microbes adapted to nutrient-rich foods developed by humans.
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Edible Packaging Materials
Vol. 1 (2010), pp. 415–448More LessResearch groups and the food and pharmaceutical industries recognize edible packaging as a useful alternative or addition to conventional packaging to reduce waste and to create novel applications for improving product stability, quality, safety, variety, and convenience for consumers. Recent studies have explored the ability of biopolymer-based food packaging materials to carry and control-release active compounds. As diverse edible packaging materials derived from various by-products or waste from food industry are being developed, the dry thermoplastic process is advancing rapidly as a feasible commercial edible packaging manufacturing process. The employment of nanocomposite concepts to edible packaging materials promises to improve barrier and mechanical properties and facilitate effective incorporation of bioactive ingredients and other designed functions. In addition to the need for a more fundamental understanding to enable design to desired specifications, edible packaging has to overcome challenges such as regulatory requirements, consumer acceptance, and scaling-up research concepts to commercial applications.
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Phage and Their Lysins as Biocontrol Agents for Food Safety Applications
Vol. 1 (2010), pp. 449–468More LessBacteriophage (phage) are bacterial viruses and are considered to be the most widely distributed and diverse natural biological entities. Soon after their discovery, bacteriophage were found to have antimicrobial properties that were exploited in many early anti-infection trials. However, the subsequent discovery of antibiotics led to a decline in the popularity of bacteriophage in much of the Western world, although work continued in the former Soviet Union and Eastern Europe. As a result of the emergence of antibiotic resistance in a number of bacterial pathogens, focus has been redirected back to bacteriophage and bacteriophage lysins as a means of pathogen control. Although bacteriophage have certain limitations, significant progress has been made toward their applications in food and has resulted in the U.S. Food and Drug Administration approving the use of a bacteriophage-based additive for the control of Listeria monocytogenes contamination. Furthermore, a number of animal studies have revealed the potential of bacteriophage for the control of various foodborne pathogens within the animal gastrointestinal tract and to subsequently decrease the likelihood of foodborne outbreaks. From a biopreservative perspective, phage have a number of key properties, including relative stability during storage, an ability to self-replicate, and a nontoxic nature. The purpose of this review is to highlight the recent developments in the use of phages and their lysins for biocontrol and to address their potential future applications.
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Glass Transition Temperature and Its Relevance in Food Processing
Vol. 1 (2010), pp. 469–496More LessAmorphous, noncrystalline solids are typical of low water content and frozen foods. Solids in these foods, e.g., confectionary, dehydrated foods, cereal foods, and frozen foods, often form nonequilibrium glass-like structures. The glassy state of the solids forms during food processing in a reversible glass transition. Vitrification can occur in numerous glassy states that exhibit various relaxations around the glass transition. The success of freeze drying, spray drying, and extrusion and the stability of dehydrated foods against flow, collapse, and crystallization is based on the control of the glassy state during the dehydration process and storage. Encapsulation processes often use glass-forming materials to entrap dispersed components or improve retention of volatiles. Plasticization of the noncrystalline structures by temperature or water reduce relaxation times exponentially above the glass transition, which results in rapid deterioration. Critical values for water activity and water content express the level of water plasticization leading to glass transition in food storage.
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