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Xanthone compounds in mangosteen (Garcinia mangostana Linn.) fruit have been reported to have biological activities including antioxidative and anti-inflammatory effects, and the major xanthone compounds in mangosteen are α-mangostin and γ-mangostin. The objectives of this research were to quantify and qualify the major xanthones in each part of the mangosteen fruit with and without yellow gum from the point of view of effective utilization of agricultural product. Quantitative evaluation revealed that yellow gum had extremely high amounts of α-mangostin and γ-mangostin (382.2 and 144.9 mg/g on a wet basis, respectively) followed by pericarp and aril. In mangosteen fruit with yellow gum inside, xanthones seemed to have shifted from the pericarp and to have concentrated in a gum on the surface of aril, and there was almost no difference between the amounts of α-mangostin and γ-mangostin in whole fruits with and without yellow gum. Pericarp and yellow gum showed much higher radical-scavenging activity and ferric reducing antioxidant potential than the aril.

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Blending non-starch polysaccharides with starch is expected to change the rate and extent of starch digestion and has a potential effect on glucose response. The objective of this study was to investigate the effects of four water-soluble non-starch polysaccharides: xanthan gum, guar gum, pectin, and konjac-glucomannan, on in vitro starch digestibility and in vivo glucose response of gelatinized potato starch. Gelatinized potato starch was digested rapidly, and the added polysaccharides significantly reduced the digestion of gelatinized potato starch even over a short reaction time. Postprandial blood glucose response in rats was reduced by the addition of polysaccharides to gelatinized potato starch. The effects on the blood glucose level after ingestion were dependent on the type of polysaccharide. The addition of xanthan gum significantly reduced the blood glucose levels at 30 min, whereas guar gum and pectin reduced the levels at 60 min. The interaction between gelatinized potato amylopectin and polysaccharides was investigated using a quartz crystal microbalance. Xanthan gum was found to be immobilized on the layer of gelatinized amylopectin, suggesting that interaction between starch and xanthan gum is one of the major factors in starch hydrolysis inhibition.

Milling method and particle size affect some properties of rice flour. To prepare ultra‐fine rice flour of <30 μm, hammer and dry jet grinding methods were examined and the effect of particle size on starch damage and pasting properties of the flour were elucidated. A jet mill could make finer flour (<10 μm mean size) with a narrower particle size distribution than a hammer mill could. Starch damage increased dramatically at a mean size of <10 μm. Particles of a similar size (<60 μm) had different levels of starch damage between mills. Not only the particle size, but also the milling method affected the level of damaged starch. Flour samples of ≥45 μm mean size had similar viscosity curves, but samples of <20 μm had different curves. Peak viscosity and final viscosity decreased sharply at <10 μm. Setback viscosity for particles of 3 μm from both brown rice and white rice were higher than the peak viscosity. Stability to heat and shearing stress were decreased for <20 μm flours as the breakdown viscosities decreased. Starch damage and pasting properties of flour ground from the nonwaxy japonica cultivar Koshihikari changed dramatically at a mean size of <10 μm.

The effect of particle size reduction on the pasting properties of rice, wheat, corn (maize), potato, sweet potato, and cassava starches was elucidated. Before pulverizing, the mean particle size and the pasting properties of the starches differed by crop. With increased pulverizing, the mean particle size decreased in all flours (to＜10 μm) and the pasting properties converged. Commercial flours containing the larger starch granules have the higher starch damage after pulverization.

The objective of the present study was to develop a mathematical model of pathogenic bacterial inactivation kinetics in a gastric environment in order to further understand a part of the infectious dose-response mechanism. The major bacterial pathogens Listeria monocytogenes, Escherichia coli O157: H7, and Salmonella spp. were examined by using simulated gastric fluid adjusted to various pH values. To correspond to the various pHs in a stomach during digestion, a modified logistic differential equation model and the Weibull differential equation model were examined. The specific inactivation rate for each pathogen was successfully described by a square-root model as a function of pH. The square-root models were combined with the modified logistic differential equation to obtain a complete inactivation curve. Both the modified logistic and Weibull models provided a highly accurate fitting of the static pH conditions for every pathogen. However, while the residuals plots of the modified logistic model indicated no systematic bias and/or regional prediction problems, the residuals plots of the Weibull model showed a systematic bias. The modified logistic model appropriately predicted the pathogen behavior in the simulated gastric digestion process with actual food, including cut lettuce, minced tuna, hamburger, and scrambled egg. Although the developed model enabled us to predict pathogen inactivation during gastric digestion, its results also suggested that the ingested bacteria in the stomach would barely be inactivated in the real digestion process. The results of this study will provide important information on a part of the dose-response mechanism of bacterial pathogens.Dose-response models play an important role in characterizing the risk in quantitative microbial risk assessments (15). The currently available dose-response models of microbial risk assessment are derived from the following different source data: human-feeding volunteer tests (14), extrapolation of the results of animal experiments to humans (44, 51), and estimations from epidemiological studies of outbreaks of food-borne illness (8). However, these approaches to dose-response modeling of low-dose exposures to pathogens rely on multiple assumptions and extrapolations, which reflect the current lack of knowledge regarding the fundamental mechanisms underlying the responses to a dose (10).Recently, a new concept, called the key-events dose-response framework (KEDRF), has been introduced as an alternative approach for the development of dose-response models (10). In the KEDRF approach, the following five major and necessary steps, termed key events, are proposed: (i) survival of pathogens in the upper gastrointestinal tract, (ii) establishment in the intestine and attachment to and uptake into epithelial cells, (iii) survival and escape from phagosomes in enterocytes and transfer of pathogen to phagocytes, (iv) transfer of pathogens across placenta, and (v) pathogen growth leading to fetal morbidity and mortality.At each step, the ranges of facto...