Absorption, metabolism and antioxidative effects of tea catechin in humans

Green tea is consumed as a popular beverage in Japan and throughout the world. During the past decade, epidemiological studies have shown that tea catechin intake is associated with lower risk of cardiovascular disease. In vitro biochemical studies have reported that catechins, particularly epigallocatechin-3-gallate (EGCg), help to prevent oxidation of plasma low-density lipoprotein (LDL). LDL oxidation has been recognized to be an important step in the formation of atherosclerotic plaques and subsequent cardiovascular disease. Metabolic studies have shown that EGCg supplement is incorporated into human plasma at a maximum concentration of 4400 pmol/mL. Such concentrations would be enough to exert antioxidative activity in the blood stream. The potent antioxidant property of tea catechin may be beneficial in preventing the oxidation of LDL. It is of interest to examine the effect of green tea catechin supplementation on antioxidant capacity of plasma in humans by measuring plasma phosphatidylcholine hydroperoxide (PCOOH) as a marker of oxidized lipoproteins.     

High-pressure processing – effects on microbial food safety and food quality

High-pressure processing (HPP) is a nonthermal process capable of inactivating and eliminating pathogenic and food spoilage microorganisms. This novel technology has enormous potential in the food industry, controlling food spoilage, improving food safety and extending product shelf life while retaining the characteristics of fresh, preservative-free, minimally processed foods. As with other food processing methods, such as thermal processing, HPP has somewhat limited applications as it cannot be universally applied to all food types, such as some dairy and animal products and shelf-stable low-acid foods. Herein, we discuss the effects of high-pressure processing on microbial food safety and, to a lesser degree, food quality.     

Biofluid 1H NMR-based metabonomic techniques in nutrition research - metabolic effects of dietary isoflavones in humans

A metabonomic approach to nutrition research may provide an insight into in vivo mechanisms of action following nutritional intervention. This approach was applied to investigate changes in the (1)H NMR spectral profile of urine collected from controlled dietary intervention studies conducted in premenopausal women before and following soy or miso consumption. The aim of the study was to identify the biochemical effects of a diet rich in soy isoflavones, phytochemicals which are receiving significant attention because of their potential importance to human health and wide bioactivity in vitro. By applying various chemometric techniques to the data the biochemical effects of conjugated and unconjugated isoflavones were determined. The biochemical changes observed suggest that soy isoflavone ingestion had significant effects on several metabolic pathways associated with osmolyte fluctuation and energy metabolism. These biochemical changes were more significant following ingestion of the unconjugated soy isoflavone (miso) diet suggesting that the chemical composition of the isoflavones present in soy-based foods may have an effect on their biological efficacy in vivo. This study describes a novel application for (1)H NMR analysis by determining subtle differences in biochemical profiles following dietary intervention and providing further insight into the mechanisms of action of phytochemicals in vivo.     

Polysaccharides and food processing

The rôle of polysaccharides during processing and for the quality of foods is discussed. Starch is the most important energy source for man. Most other polysaccharides are not metabolized for energy, but play an important rôle as dietary fibres. Pectins, alginates, carrageenans, and galactomannans are discussed as functional food additives in relation to their structure and their rheological behaviour, stability and interactions. Endogenous polysaccharides of fruits and vegetables and in products derived from them are responsible for such phenomena as texture (changes), press yields, ease of filtration and clarification, cloud stability, and mouth feel. To achieve desirable properties, the action of endogenous enzymes on polysaccharides must be inactivated and/or exogenous enzymes added as processing aids. This is also true for overcoming haze phenomena in clear juices or to break down undesirable microbial polysaccharides. Dough properties for bread baking can be improved by enzymic breakdown of a restrictive pentoglycan network. Network formation may come about by oxidative coupling of phenol rings of ferulic acid bound to hemicelluloses by ester links. Gels may be made by inducing oxidative coupling in natural or synthetic systems. Stagnation in development of new polysaccharide food additives is ascribed to difficulties in obtaining government approval for food use.     

The effects of soy isoflavones on obesity

Over the last decades, the prevalence of obesity and related diseases has increased rapidly in the Western world. Obesity is a disorder of energy balance and is associated with hyper-insulinemia, insulin resistance, and abnormalities in lipid metabolism, and it is one of the most important risk factors in the development of Type II diabetes, cardiovascular disease, atherosclerosis, and certain cancers. Because of the lower frequency of these diseases in Asian countries, attention has been turned toward the Asian diet, which consists highly of soy and soy-based products. The health benefits associated with soy consumption have been linked to the content of isoflavones, the main class of the phytoestrogens. As a result of their structural similarities to endogenous estrogens, isoflavones elicit weak estrogenic effects by competing with 17beta-estradiol (E2) for binding to the intranuclear estrogen receptors (ERs) and exert estrogenic or antiestrogenic effects in various tissues. The estrogenic activities of soy isoflavones are thought to play an important role in their health-enhancing properties. Additionally, the isoflavones have been proved to exert non-ER-mediated effects through numerous other pathways. Genistein, daidzein, and glycitein are the principal isoflavones in soy. Genistein is the most thoroughly examined of these, because it is the most prevalent isoflavone in soy and the most active of these compounds, because of its higher binding affinity for the ER. Genistein and daidzein can be obtained in high levels in humans under certain nutritional conditions, and epidemiologic and laboratory data suggest that these compounds could have health benefits in human obesity. This review will focus on the latest results of research on isoflavones and their effect on obesity in cell cultures, rodents, and humans.     

Neural processing of imminent collision in humans

Detecting a looming object and its imminent collision is imperative to survival. For most humans, it is a fundamental aspect of daily activities such as driving, road crossing and participating in sport, yet little is known about how the brain both detects and responds to such stimuli. Here we use functional magnetic resonance imaging to assess neural response to looming stimuli in comparison with receding stimuli and motion-controlled static stimuli. We demonstrate for the first time that, in the human, the superior colliculus and the pulvinar nucleus of the thalamus respond to looming in addition to cortical regions associated with motor preparation. We also implicate the anterior insula in making timing computations for collision events.     

Microbes in food processing technology

Abstract: There is an increasing understanding that the microbial quality of a certain food is the result of a chain of events. It is clear that the microbial safety of food can only be guaranteed when the overall processing, including the production of raw materials, distribution and handling by the consumer are taken into consideration. Therefore, the microbiological quality assurance of foods is not only a matter of control, but also of a careful design of the total process chain. Food industry has now generally adapted quality assurance systems and is implementing the Hazard Analysis Critical Control Point (HACCP) concept. Rapid microbiological monitoring systems should be used in these cases. There is a need for rapid and simple microbiological tests which can be adapted to the technology and logistics of specific production processes. Traditional microbiological methods generally do not meet these high requirements. This paper discusses the tests, based on molecular biological principles, to detect and identify microbes in food-processing chains. Tests based on DNA technology are discussed, including in vitro DNA amplification like the polymerase chain reaction (PCR) method and identifications based on RFLP, RAPD and DNA fingerprinting analysis. PCR-haled methodology can be used for the rapid detection of microbes in food manufacturing environments. In addition, DNA fingerprinting methods are suitable for investigating sources and routes of microbial contamination in the food cycle.     

Hierarchical processing of auditory objects in humans

This work examines the computational architecture used by the brain during the analysis of the spectral envelope of sounds, an important acoustic feature for defining auditory objects. Dynamic causal modelling and Bayesian model selection were used to evaluate a family of 16 network models explaining functional magnetic resonance imaging responses in the right temporal lobe during spectral envelope analysis. The models encode different hypotheses about the effective connectivity between Heschl's Gyrus (HG), containing the primary auditory cortex, planum temporale (PT), and superior temporal sulcus (STS), and the modulation of that coupling during spectral envelope analysis. In particular, we aimed to determine whether information processing during spectral envelope analysis takes place in a serial or parallel fashion. The analysis provides strong support for a serial architecture with connections from HG to PT and from PT to STS and an increase of the HG to PT connection during spectral envelope analysis. The work supports a computational model of auditory object processing, based on the abstraction of spectro-temporal “templates” in the PT before further analysis of the abstracted form in anterior temporal lobe areas.     

Know your place: neural processing of social hierarchy in humans

Social hierarchies guide behavior in many species, including humans, where status also has an enormous impact on motivation and health. However, little is known about the underlying neural representation of social hierarchies in humans. In the present study, we identify dissociable neural responses to perceived social rank using functional magnetic resonance imaging (fMRI) in an interactive, simulated social context. In both stable and unstable social hierarchies, viewing a superior individual differentially engaged perceptual-attentional, saliency, and cognitive systems, notably dorsolateral prefrontal cortex. In the unstable hierarchy setting, additional regions related to emotional processing (amygdala), social cognition (medial prefrontal cortex), and behavioral readiness were recruited. Furthermore, social hierarchical consequences of performance were neurally dissociable and of comparable salience to monetary reward, providing a neural basis for the high motivational value of status. Our results identify neural mechanisms that may mediate the enormous influence of social status on human behavior and health.     

Bacterial desorption from food container and food processing surfaces

The desorption ofStaphylococcus aureus, Acinetobacter calcoaceticus, and a coryneform from the surfaces of materials used for manufacturing food containers (glass, tin plate, and polypropylene) or postprocess canning factory conveyor belts (stainless steel and nylon) was investigated. The effect of time, pH, temperature, and adsorbed organic layers on desorption was studied.S. aureus did not detach from the substrata at any pH investigated (between pH 5 and 9).A. calcoaceticus and the coryneform in some cases detached, depending upon pH and substratum composition. The degree of bacterial detachment from the substrata was not related to bacterial respiration at experimental pH values. Bacterial desorption was not affected by temperature (4–30°C) nor by an adsorbed layer of peptone and yeast extract on the substrata. The results indicate that bacterial desorption, hence bacterial removal during cleaning or their transfer via liquids flowing over colonized surfaces, is likely to vary with the surface composition and the bacterial species colonizing the surfaces.     

Indirect effects of predatory trout on organic matter processing in detritus-based stream food webs

Indirect effects of predators on basal resources in allochthonous-based food webs are poorly understood. We investigated indirect effects of predatory brown trout ( Salmo trutta ) on detritus dynamics in southern beech ( Nothofagus spp.) forest streams in New Zealand through predation on the obligate detritivore, Zelandopsyche ingens (Trichoptera, Oeconesidae). Trout presence/absence and Z. ingens density were manipulated in flow-through tanks to investigate the lethal and sub-lethal effects of trout on litter processing by Z. ingens . An experiment that allowed trout access to Z. ingens showed trout predation reduced densities of Z. ingens resulting in slower breakdown of coarse particulate organic matter (CPOM) and reduced production of fine particulate organic matter (FPOM). A second experiment that prevented trout access to Z. ingens , but allowed the transmission of trout cues, resulted in no change in litter processing rates in the presence of trout. Litter processing rates were higher in high Z. ingens density treatments compared to low density treatments. Thus, trout effects on litter processing were due to reduced Z. ingens densities, not trout-induced modifications to Z. ingens feeding behaviour. Field assays of litter processing rates using artificial leaf packs in natural streams showed significant reductions in CPOM loss in trout streams compared to fishless streams. Z. ingens dominated biomass in fishless stream leaf packs, but a facultative shredder, Olinga feredayi , dominated trout stream leaf packs. Thus, the absence of Z. ingens drove differences in processing rates between trout and fishless streams and the indirect effects of trout on litter processing observed in mesocosms were evident in complex, natural food webs. Overall our study provides evidence that predators can influence resource dynamics in donor-controlled food webs through their effects on consumers.     

Seasonal patterns of food limitation in Daphnia galeata: separating food quantity and food quality effects

Food limitation for the cladoceran Daphnia galeta was measuredgrowing them with natural lake seston for one growing seasonunder standardized conditions in the laboratory. Growth rateswere related to several measures of food quantity. Particulateorganic carbon (POC) <30 µm was the best predictorof total food availability measured. It was better than chlorophyll-a(Chl-a) of the same size fraction, algal volume calculated fromcell counts or total particle volume from Coulter Counter measurements.Daphnids were also grown with Scenedesmus acutus under the sameconditions and their growth rates were compared. Sestonic carbonconcentrations were related to Scenedesmus carbon concentrations,that provided equal growth rates. The ratio of the carbon concentrationsof both food types (seston, Scenedesmus) represented the foodquality of seston. Thus, the nutritional quality of naturallake seston relative to a standard alga was determined overone growing season. Growth rates of seston fed animals revealedthat they were food limited during long periods of the year.This was also ascertained by standard clutch sizes of fieldanimals. However, the causes of food limitation varied withinthe duration of the studied period. Whereas during the clear-waterphase the food quantity was limiting (while the quality washigh: 100% Scenedesmus), shortly after on 10 June and 17 Junefood conditions were close to threshold concentrations due tolow food quality. For the remainder of the summer, a POC of0.3–0.6 mg C I^–1 with a quality of     

Antioxidant mechanisms of isoflavones in lipid systems: paradoxical effects of peroxyl radical scavenging

Oxidation of lipids has been implicated in the pathophysiology of atherosclerosis. It has been suggested that scavenging of lipid peroxyl radicals contribute to the antiatherosclerotic effects of naturally occurring compounds such as the isoflavones. This group of polyphenolics includes genistein and is present in relatively high concentrations in food products containing soy. Soy isoflavones are capable of inhibiting lipoprotein oxidation in vitro and suppressing formation of plasma lipid oxidation products in vivo. However, key aspects of the antioxidant mechanisms remain unknown. In this study the antioxidant effects of genistein and other soy isoflavones on lipid peroxidation initiated by mechanistically diverse oxidants was investigated. Although isoflavones inhibited lipid peroxidation stimulated by both metal-dependent and independent processes, the concentration required for these effects were relatively high compared to those found in vivo. Interestingly, however, isoflavones were not consumed and remained in the native state over the time during which inhibition of lipid peroxidation was observed. This was also the case under conditions where synergistic inhibition of LDL oxidation was observed with ascorbate. Furthermore, in an oxidation system driven solely by peroxyl radicals, isoflavones were found to be relatively poor peroxyl radical scavengers. Consistent with the apparent lack of reactivity with lipid-derived oxidants, isoflavones were also relatively resistant to oxidation mediated by the potent oxidant peroxynitrite. The potential antioxidant mechanisms of isoflavones are discussed in the context of possible reactivities of isoflavone-derived phenoxyl radicals.     

Determination of isoflavones in soybean food and human urine using liquid chromatography with electrochemical detection

A highly sensitive high-performance liquid chromatographic method with electrochemical detection (HPLC-ED) was developed for the determination of isoflavones. Electrochemical behaviour of daidzein and genistein was studied on carbon paste electrode (CPE) by adsorptive transfer stripping square wave voltammetry. The obtained electrochemical results were used for the development of HPLC-ED method. Furthermore, isoflavones were separated on an Atlantis dC18 column using a mobile phase consisting of acetonitrile (solvent A) and 0.15M acetate buffer of pH 5.5 (solvent B) at a flow rate 0.4 mL/min. A linear gradient profile (solvent B) was at 0-2 min 87%; 22 min 60%; 27 min 50%; 31 min 45%; 47 min 87%. Full scan of multi-channel coulometric detection was tested and optimal potential at 450 mV was chosen for our purposes. Calibration curves were linear (daidzein R(2) = 0.9993 and genistein R(2) = 0.9987). The detection limit for daidzein/genistein was 480/394 pg/mL (1.8/1.5 nM) and per column 2.4/1.9 pg. Isoflavones extracted from soybean products (farina, meat, milk) by the accelerated solvent extraction (ASE) procedure and isoflavones present in human urine were determined by the HPLC-ED method.