Contents Digest

Contents Digest Effect of pulsed electric field processing on the functional properties of bovine milk Thermal pasteurization ensures safety and enhances the shelf life of milk. Exposure to heat can modify labile milk components and alter the functional properties of milk proteins. This has driven the development of nonthermal food preservation techniques such as pulsed electric field (PEF) processing, primarily for the inactivation of spoilage microorganisms. Milk components, in particular fat and protein, affect the functionality, yield and quality of dairy products, requiring a clear understanding of the structural and chemical changes occurring due to PEF processing. On page 87, Pankaj Sharma and co-workers review current knowledge of the impact of PEF treatment on the functional properties of milk, namely, the physicochemical changes of milk components, changes in technological properties, shelf life, and sensory and nutritional properties. PEF treatment in combination with other hurdles (such as heat) has the potential to increase the preservation of milk while retaining sensory attributes. Intense PEF treatment conditions (electric field intensity, treatment temperature and square wave pulses), higher flow rates, and the mode of operation (batch or continuous) can induce changes to proteins that may affect the functional properties of milk; however, these changes after PEF treatment are often less compared to thermal treatments. Variability in equipment design and differences in treatment conditions and medium used will impact upon functional properties. Further studies on PEF-treated whole milk should be considered to provide more understanding of the changes that take place in more complex dairy products containing fat. The mechanism of volatile compound formation

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and partitioning between the fat and aqueous phases in PEF-treated milk is not well studied. This will have an impact on the flavor of dairy products. The direct equivalence of PEF processing to thermal pasteurization of milk with defined quality assurance indices is necessary before up scaling and commercialization. Preservation of the integrity of labile milk components and associated functional properties can be addressed by stepwise intermediate cooling between PEF treatment zones. Uniform pumping systems with minimized generation of shear forces should be implemented to reduce the impact of shear-induced structural changes. Mathematical models, similar to those developed for microorganism count reductions and enzyme inactivation, need to be developed as tools to predict the effect of PEF treatment on the structural changes of the MFGM. These structural changes will have a profound impact upon the development of texture and flavor in dairy products.

Analytical techniques for the elucidation of wheat bran constituents and their structural features Wheat bran is a by-product of white flour production available in abundance. It consists of nutritionally and technologically valuable constituents, above all around 50% of dietary fiber. Numerous applications ranging from functional dietary fiber to fine chemicals are currently being developed in order to valorize wheat bran beyond animal feed. This shift in utilization necessitates an adequate set of analytical tools. On page 102, Stefan B€ohmdorfer and co-workers review the analysis of wheat bran constituents in general and

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dietary fiber in particular with a focus on instrumental methods. The analysis of non-carbohydrate constituents of wheat bran is largely dominated by standardized AOAC methods and therefore leaves little demand for discussion. On top of that, the focus of this work is on the analysis of wheat bran carbohydrates. The authors present non-carbohydrates together with the respective analytical method and a reference, preferably a standardized method. Where no standardized method was available, suitable literature citations are given. The multitude of analytical techniques available makes for a handy toolbox in the analysis of wheat bran. Of course, acquisition costs for analytical instruments are often the limiting factor, but since many instruments essentially generate the same information and only differ in their drawbacks and advantages, a sound selection is sufficient to describe wheat bran in large parts. Even though the starting material has already been thoroughly characterized, structural analysis is far from being concluded. Advances in processing and ensuing health-related issues as well as physicochemical changes, especially regarding dietary fiber, can be expected to make structural analysis even more indispensable. With sample workup mostly being cumbersome and coherent information having to be put together manually from fragments collected in different analyses, there is still plenty of room to advance state-of-the-art technology in both instrumental capabilities and data evaluation. It is, however, rather unlikely that these techniques will be incorporated into official AOAC methods in the near future, since they are largely tailored to a specific matrix whereas AOAC methods are required to be more widely applicable. Either way, the strict divide between market-oriented quantification of dietary fiber according to AOAC methods and research-oriented structural elucidation, as it stands now, will have to give.

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Functional foods against metabolic syndrome Metabolic syndrome is a condition of at least three of the cardiovascular risk factors: obesity, excessive visceral fat storage, dyslipidemia, hypertension and hyperglycaemia or Type 2 diabetes. It is a state of insulin resistance, oxidative stress and chronic inflammation. Cardiovascular disease is the highest cause of death globally. Certain dietary components and over 800 plants help prevent or moderate metabolic syndrome by assisting the body homeostasis mechanisms. On page 114, Suhaila Mohamed reviews the most current studies on foods that help fight metabolic syndrome and the scientific evidences to support their use. This includes functional fats, digestive enzymes inhibitors, various beverages, different fruits, specific vegetables, grains, legumes, herbs and spices that can reduce cardiovascular disease risk, through several cellular mechanisms. Plant polyphenols have antioxidant, vasodilatory, anti-inflammatory, antifibrosis and antiapoptosis properties that activate prosurvival cellular pathways. They mediate by modulating metabolic intermediates, microRNAs, sirtuins and reperfusion injury salvage kinases and survivor activating factor enhancement pathways. The polyphenols effect blood vessels, endothelial cells and increase the vasoprotective factors including nitric oxide (NO) and endothelium-derived hyperpolarizing factor, to reduce vascular oxidative stress and hypertension. Regular dietary polyphenols consumptions are negatively related to cardiovascular and degenerative disease risk in epidemiological studies. Non-pharmacologic therapies against metabolic syndrome include good optimal nutrition, ideal body weight maintenance, exercise programs and scientifically proven dietary supplements. Polyphenols like flavonoids, resveratrol, quercetin, epi-gallocathechin-3-gallate and curcumin, help retard elevated fat storage, blood pressure, blood glucose, lipid levels,

hemoglobin-A1c and insulin resistance in mammals. Oxidative stress induces mitochondrial increase and arrest preadipocytes proliferation. Preconditioning preadipocytes with some dietary polyphenols totally or partially protects them against mitochondrial changes, obesity-associated diabetes and cardiovascular diseases. Polyphenols present in green tea, grape seeds, orange and grapefruit combat adipogenesis at the molecular level and also induce lipolysis.

Measuring sensory and marketing influences on consumers’ choices among food and beverage product brands Advance in food science depends on measuring the factors in human perception that influence eaters’ activities with branded products. Assessed samples must include at least two levels of a sensed material characteristic (e.g. sucrose) or conceptual marketing attribute (e.g. “low fat”), minimally confounded by other features. Each feature needs to be measured for its effect on the individual’s objective achievement of choosing among the samples for a familiar context of use. These influences interact, consciously and unconsciously. This theory of how a mind works has generated a wide range of scientifically illuminating and commercially practical examples, illustrated in this review. On page 129, David Booth reviews the fundamental requirements of psychological food science, and a variety of examples are given of the calibration of two or more factors in human perception and choice of a food. It is fairly straightforward to measure the influence of any sensed characteristic or conceptual attribute of an item of food on a person’s perception of the item and on

the act of accepting or rejecting it in the context of use. The measurements rely on the basic mental mechanism of discriminating between the level of a feature of the present situation and its peak level in a norm learnt from past situations. The trained or untrained assessor’s response to a test is proportional to these conscious or unconscious disparities between the present and the past, as they are configured in the personal norm. Hence, when the levels of any sensory or symbolic factor have been monitored across the test samples, an assessor’s peak point of that factor in the personal ideal or a familiar target product or brand follows directly from the observations, together with tolerance for disparities from “just right”. Aggregation of peak points and discriminative tolerances across a representative panel gives an equally direct estimate of the market for each variant of the product in the uses that are simulated by the testing. All acquisition and analysis of human data needs to include peak-referenced responses and hypothesis-testing designs. Because everybody’s mind operates in this way, such questions and answers are easier to operate on malls, over the internet or in the laboratory than tick boxes on series of vague and puzzling phrases, or unnecessarily difficult tasks such as ranking, voting or identifying the odd one out. Sufficient for most purposes are two precise anchor phrases, such as “just right” and “just wrong” (with “worse” beyond), on an array of otherwise unlabeled boxes, or of integers from a zero on one of the two anchor phrases. What matters for the science, technology and marketing are the causal relations of those scores to the peak points and limits of tolerance for each of the factors that are varied among sets of realistic food samples. Statistical modeling of response numbers cannot mea- sure optimum levels of the real factors that are under the control of production and marketing. Indeed, sensory profiling scores are not even necessary to measure the effects of sensed factors on consumers’ choices. Attitude models, like/dislike

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category ranks, pleasantness line ratings and hall preference votes, also fail to make contact with actual influences from purchased products. It is irrelevant whether or not the consumer experiences a sensation or a pleasure when rating intensity or preference. She/he might instead be using the sensory vocabulary or the term “like” or “pleasant” to categorize the test item on a series of familiar foods having greater or less intensity or likelihood of being chosen. An eater or a shopper may be following a habit or an impulse without any awareness of what is influencing the choice of item. Each of these psychological hypotheses can be refuted or confirmed by the calling of discrimination distances from the personal norm being used during the tests. A psychological science and technology of food has long been accessible within the facilities and costs already dedicated to the collection of human responses. In psychology at least, the most basic scientific findings about familiar situations are also the most practically relevant.

Quantitative evaluation of mechanical damage to fresh fruits Fresh fruits are very susceptible to mechanical damage during harvesting, packaging and transport, which can result in a substantial reduction in quality. Ideally, such damage would be minimized through improved understanding of the mechanisms. If damage occurs, grading affected fruits might minimize economic losses, based on the severity of damage, into those that need more than minimal further processing and those that do not. In either case, an objective and quantitative evaluation of the degree of mechanical damage is required. However, this is still far from being realized and remains an important challenge of past

and proposed research in food safety. On page 138, Zhiguo Li and Colin Thomas review concerns the quantitative evaluation of mechanical damage to fresh fruits including the sources of damage to fresh fruits during mechanical handling, the mechanisms, existing quantitative assessments characterizing surface and internal mechanical damage and its prediction and lastly future research directions are discussed. The main challenge in evaluating mechanical damage to fresh fruit objectively is to develop a method to assess accurately the extent of internal damage to fruits caused by excessive external forces. Improvements in methods to assess internal damage of fruits after mechanical handling has not been achieved so far because such damage cannot be visualized non-destructively and because different tissues in different fruits have different extents of browning. NMR can distinguish intact and damaged tissues and is a method for assessing internal damage volume of fruit objectively, at least in the laboratory. This approach is worth further investigation, although transfer of these high technology methods to the supply chain may be problematic. Studies on the relationship between surface and internal mechanical damage can be evaluated as the area of damaged exocarp and predictions of associated internal damage could be validated using existing experimental methods. Should any relationships exist between surface and internal damage, it would be possible to predict internal damage from surface damage and allow future research using absorbed energy or peak contact force as a surrogate measure of damage. Combining it with NMR, hyperspectral imaging, X-rays or ultrasonic techniques could enhance logistic regression modeling of damage. Existing sensory evaluation methods are somewhat subjective and the use of new, more objective, technologies could lead to a better understanding of how handling causes bruising. There seems to be little consistency in regression models linking bruising and mechanical parameters from

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compression and impact tests. Fewer and better understood, correlations would be preferable. This will require multiscale mathematical modeling using nonlinear finite element methods to interpret test results. Furthermore, high quality models will strengthen the accuracy of predictions of damage to fruits from mechanical handling. Investigation of the food safety and quality implications of structural damage to fruits has largely focused on bruising but many fruits such as tomato are inhomogeneous bodies and may suffer structural damage as well as cell and tissue damage. The former has been neglected although it may lead to increased decay during storage.

Alpha-cyclodextrin: enzymatic production and food applications Cyclodextrins are a family of cyclic oligosaccharides typically containing six (a-cyclodextrin), seven (b-cyclodextrin), or eight (g-cyclodextrin) 1,4linked D-glucose units. Because the glucose units adopt the chair conformation, the cyclodextrins are shaped like a hollow truncated cone with a hydrophilic outer surface, which makes them water-soluble. On page 151, Jing Wu review the unique properties, enzymatic production, and food applications of a-cyclodextrin, as well as its differences with b- and g-cyclodextrins. The fermentative production of a-cyclodextrin glycosyltransferase (a-CGTase) is also discussed. More efficient processes for the production for a-cyclodextrin have been developed, including the use of a-CGTases with improved a-cyclodextrin specificity, the addition of appropriate complexing agents, and the simultaneous use of an a-CGTase with another amylase. Compared with other cyclodextrins, a-cyclodextrin has the smallest internal cavity and highest

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resistance to enzymatic hydrolysis, so it has special applications in food industry, especially as a natural, soluble dietary fiber. Its high water solubility, ability to form complexes, and relatively high resistance to enzymatic

hydrolysis have led to an increase in potential applications of a-cyclodextrin in many fields, especially in the food industry. However, its application is still significantly limited due to its low yield and high price. It is expected

that advancements in biotechnology will dramatically improve the production process of highly pure a-cyclodextrin and expand its industrial applications.