The thermal conductivity of eight kinds of liquid foods of total solid content between 10 and 60wt% was measured by a transient heat flow method using twin probes at temperatures ranging from 10 to 50°C. The effects of temperature and total solid content on the thermal conductivity of sample solutions were investigated. The thermal conductivity of the samples could be represented as a function of both tem-perature and total solid content. The observed values were compared with values calculated from the three typical structural models for thermal conductivity, i.e., series, parallel, and random heat transfer models. A new model to predict the thermal conductivity of liquid foods, defined as a combination of parallel and random models, was developed, and the observed data agreed well with the values calculated from the new model.
The characteristic volatile compounds released during the grinding of roasted coffee beans are as attractive for coffee-flavored products as the aroma of fresh-brewed coffee itself. In this study, the volatile compounds released during the grinding of various roasted robusta coffee beans (originating in Vietnam and Indonesia ; roasting degree L26, L23, and L18) were collected by exposing a solid-phase microextraction (SPME) fiber to nitrogen gas discharged from a glass vessel in which the electronic coffee grinder was enclosed. Identification and characterization of the volatile compounds were achieved using gas chromatography/mass spectrometry (GC/MS) and GC/olfactometry (GC/O), and by applying principal component analysis (PCA) to the GC/O results. The variation in volatile compounds released during grinding, based on origin, roasting degree and species, is described and compared with the results of a previous study on the compounds released during grinding of roasted arabica coffees.
The fatty acid composition, total phenol content and tocopherol content of olive oils from Shodo Island of Japan were analyzed for different varieties, maturation stages and extraction methods. Radical-scavenging activity of olive oils was also determined spectrophotometrically by measuring the disappearance of 1,1-diphenyl-2-picrylhydrazyl radical at 517nm. The differences in fatty acids composition, total phenol and tocopherol content in virgin olive oils were not great among the varieties. The content of oleic acid was in range of 66-78%. Though virgin olive oils contained more phenolic compounds than hexane-extracted olive oils, tocophenol content was not very different. In hexane-extracted olive oils, the total phenol content decreased during olive maturation. The tocopherol content of three types of olive oils also decreased during maturation. Still, large amounts of phenolic compounds remained in the olive residue after hexane extraction. The contribution of tocopherols to radical-scavenging activity was 39-61% in virgin olive oil, which suggests that both tocopherols and phenolic compounds contribute to radical-scavenging activity.
A rapid and sensitive method for evaluation of the radical-scavenging activity, which uses 2,2′-azobis (2-amidinopropane) dihydrochloride (AAPH) as a radical generator in combination with a luminol chemiluminescence (CL) assay, was examined. The radical-scavenging activities of various analytical-grade compounds were measured by monitoring the decrease in CL. In this method (AAPH-CL), compounds that show lower CL values have stronger radical-scavenging activity. These results were compared to those measured using 1,1-diphenyl-2-picrylhydrazyl (DPPH)-colorimetry analysis. They were approximately similar in pattern (r2=0.6043), although there were some discrepancies. The half-inhibition concentration (IC50) values of 11 beverages were also evaluated using AAPH-CL and DPPH-high performance liquid chromatography methods. Data from the two methods showed a correlation (r2) of 0.4786. We conclude that the AAPH-CL method is suitable for the evaluation of radical-scavenging activity in vitro, with the advantages that it is rapid to carry out, has good sensitivity, is not affected by impurities or color in the solution, and bears some similarity to cellular processes.
We examined the effects of extraction conditions on the anti-allergic components, epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3″Me) and strictinin during the manufacture of anti-allergic ‘Benifuuki’ green tea beverage. Ester-type catechins were extracted at a constant ratio to total catechin content and were easy to epimerize. After a long extraction time at above 90°C, large amounts of epimer were rapidly pro-duced. Moreover, the ratio of EGCG3″Me to polyphenol content was nearly constant, indicating that this ratio could be an essential index during the manufacture of tea beverages. EGCG3″Me easily isomerizes at temperatures above 95°C. From the ratios of EGCG3″Me to polyphenol, it was concluded that, at a fixed ex-traction temperature and 20-fold dilution (W/V), similar extraction efficiencies are obtained for extractions from 6 to 15min heated for 9min at 90°C and 95°C showed strong histamine release inhibitory effects. Ex-traction temperature strongly contributed to inhibitory effect volume had a limited effect. We suspect that extraction at high temperature promoted EGCG3″Me extraction efficiency and epimerization to GCG3″Me.
With the aim of finding an effective way of utilizing shrimp waste, the suppression of freeze-induced denaturation of lizardfish myofibril by proteolytic shrimp head protein hydrolysates (SHPH) during frozen storage at -25°C was investigated by determining the amount of unfrozen water and Ca-ATPase activity in myofibrillar samples containing SHPH from three different species of shrimp at various concentrations (2.5-10% dried matter). The amount of unfrozen water increased markedly after freezing and decreased gradually during frozen storage in the samples containing SHPH, regardless of shrimp species. Over 120 days of storage, the Ca-ATPase activity of myofibril containing SHPH slowly decreased, whereas that of the control fell drastically after the initial freezing. These results suggest that the interactions between myofibrillar protein and the active components of SHPH, such as hydrophilic amino acids and peptides, may retard freeze-induced denaturation in fish myofibril during frozen storage. SHPH exhibited optimum suppression of freeze-induced denaturation at concentrations of 5-7.5%, regardless of species differences.
Ready-to-drink Philippine orange juice (POJ) prototypes were developed as iron-fortified beverages for evaluation of Filipino women from 4 representative communities in Quezon City, Philippines. Different formulations containing ferrous sulfate (FeSO4) fortificant were produced such that 0, 10, 20 and 30% of the Philippine recommended intake for iron per serving were met. The respondents (n=72) were interviewed about their citrus fruit and citrus fruit-based beverage consumption and were asked to evaluate the acceptability of the different POJ formulations. Results of the consumption studies showed that citrus fruit-based beverages were more often consumed by the respondents than the unprocessed citrus fruits. Further, the fortification of POJ with FeSO4 did not significantly alter the physicochemical and sensory characteristics of the juice drinks. The familiarity of the respondents with Philippine orange as well as the high acceptance scores of the fortified beverages makes the commodity a suitable vehicle for iron fortification using FeSO4 fortificant.
To examine the influence of preparation method (white or brown roux prepared by heating to 130°C and 170°C, respectively) and fat/oil ingredients (butter fat, corn oil and salad oil), the flavors of roux prepared from wheat flour were studied by sensory analysis and chemical analyses of the aroma compounds with gas chromatography (GC) and GC-MS, followed by GC-Olfactometry. Sensory evaluation of roux flavors in butter roux, corn oil roux and salad oil roux showed that the butter roux had a strong sweet odor and both the butter roux and the corn oil roux had generally preferable flavor. Then, the various types of roux were subjected to chemical analyses. Through comparisons of each component for the butter roux and the corn oil roux, it was found that the difference in flavor was especially apparent in the amount of carbonyl compounds and Maillard reaction products. That is, the butter roux was composed of largely aliphatic methyl ketones (C7-C11) in both the white roux (heated to 130°C) and the brown roux (heated to 170°C), and mostly furans and somewhat cyclic ketoenols such as maltol in the brown roux, while the corn oil roux included more benzaldehyde in the white roux, and phenylacetaldehyde and (E, E)-2, 4-decadienal in the brown roux. Furthermore, GC-O analysis showed that butanoic acid, which confers a rancid odor, δ-decalactone, which confers a floral odor, and furfuryl alcohol and 2-nonanone with a floral odor, respectively might contribute to the flavor of the butter roux, while (E, E) 2, 4-decadienal with a pungent odor and benzaldehyde with an almond-like odor might affect the flavor of the corn oil roux. Therefore, the difference of flavor of the two roux may originate in the composition of the fatty acids of fat/oil. Mixing various fat/oil in the form of butter and corn oil showed the effect of using proportions of ingredients for aroma of the cooked product, especially in the white roux.
The effect of vinegar produced from the boiled extract of black soybeans on apoptosis induction in human monoblastic leukemia U937 cells was investigated. The boiled extract of black soybeans obtained from a natto (traditional Japanese fermented soybean product) factory was employed as a novel raw material for vinegar production. An ethyl acetate-soluble fraction of this vinegar (EBV fraction) was shown to strongly suppress cell proliferation of U937 cells. Fragmentation of DNA and morphological changes showing apoptotic bodies, which are characteristic of apoptotic cell death, were observed in U937 cells treated with 10mg/ml of the EBV fraction. Flow cytometry analysis using an Annexin-V-FLUOS Staining Kit confirmed that cell death was due to apoptosis. On the other hand, the cell viability of lymphocytes separated from human blood was less affected by the EBV fraction, and fragmentation of DNA was not induced. These results suggest that the EBV fraction exerted cell toxicity via apoptosis in U937 cells but not in normal lymphocytes.
A human exposure estimation to bacterial pathogens in drinking water of Philippine inter-island passenger vessels was done. The calculation of estimated microbial intake per person per voyage was based on the voyage travel time, average water consumption per voyage and estimated microbial contamination level of water consumed. A model that detailed ship drinking water flow diagram and order of change in microbial concentration was used in the estimation of microbial contamination level. Results of the study indicated that possibility of infection relative to established infective doses of Vibrio cholerae, Salmonella typhi and pathogenic strains of Shigella spp. and Eschericia coli exist when raw water is loaded to the ship reservoir specially during extended travel time. Review of policy and implementing guidelines related to drinking water management for Philippine inter-island passenger vessels was recommended.
Application of a real-time PCR system for the detection of blending and the quantification of the blending ratio of rice was investigated. Quantitative measurement by real-time PCR was performed using two types of primer sets ; one was an improved rice cultivar identification kit, while the other was newly developed for the determination of total amount of rice DNA. Calculation formulae for blending ratios were developed based on standard curves of both primer sets. These formulae were verified using DNA solutions extracted from the Koshihikari containing 5% or 25% of another rice sample. Calibration errors were less than 30% of the expected values.
The quality of squid deteriorates very rapidly after catch. To maintain the quality of squid for a longer period, we carried out super-chilling storage. Live swordtip squids Loligo edulis were killed and stored at -2°C (super-chilling) and 5°C (refrigeration). At selected time intervals, their external color, texture, and K-values were evaluated. Additionally, the levels of free amino acid, water-soluble and water-insoluble proteins, and viable cell counts were determined. In the samples stored using the super-chilling method, whitening of the exterior, elevation of K-values, and the increase of viable cell counts were suppressed. Regarding the meat structure, free amino acids, texture, and content of water-soluble and water-insoluble proteins, no differences were observed between the two different storage temperatures. These results suggest that super-chilling storage can prolong the period for which squid can be preserved and maintains a higher quality than refrigeration.
In the present study, the production of a novel feruloyl esterase (FAE) from a typical human intestinal bacterium Lactobacillus acidophilus using various carbon sources was investigated. The results showed that FAE activity was strongly induced by hemicellulosic substances, with the highest activity detected when de-starched wheat bran (DSWB) was used as a carbon source. Moreover, the production was stimulated by the monosaccharides xylose and arabinose, suggesting its particular secretion mechanism. With increasing levels of free ferulic acid (FA) added, the production of FAE increased, reached a peak and declined. Further, on addition of either xylanase or α-L-arabinofuranosidase, the amount of FA released from DSWB by the purified FAE from L. acidophilus increased from 0 to 12.4nmol and 3.64nmol, respectively. When the three enzymes existed together, 15.7nmol of FA was detected. These results indicated that xylanase is predominant and arabinofuranosidase subordinate in their synergistic effect on FA release by FAE.
γ-Oryzanol extracted from brown rice as a free radical scavenger was separated into four constituents, which were identified as cycloartenyl ferulate, 24-methylenecycroartanyl ferulate, β-sitosteryl ferulate and campesteryl ferulate by NMR and MS. All four constituents displayed scavenging activity for 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. The scavenging activities of the four constituents were almost the same as that of ferulic acid. We confirmed that the ferulic acid 4-hydroxyl group was the active unit in γ-oryzanol constituents for DPPH radical scavenging activity.
The effects on blood coagulation of dipicolinic acid (DPA, 2,6-pyridinedicarboxylic acid), an antibacterial substance known to be produced by Bacillus subtilis natto and contained in natto, a traditional Japanese fermented soybean food, were studied. It was found that addition of DPA with a final concentration of 5×10-3M results in substantial inhibition of platelet aggregation. DPA inhibition was found to be far stronger than that resulting from addition of aspirin. Furthermore, the clotting reaction of thrombin-fibrinogen was also found to be inhibited by DPA. It was confirmed by examination of thromboelastogram patterns that the coagulation of whole rat blood was completely inhibited by addition of 5×10-3M DPA. From the point of view of the blood coagulation system, these results show that DPA contained in natto may be effective in the prevention of thrombosis.
Bacillus subtilis spores were pressurized at 60MPa at 40°C for 0∼24 hours in phosphate buffer or GAM broth. After 24 hours, viable counts and spore counts decreased by about 5 log cycles in the broth and by only 1.6 log cycles in the phosphate buffer. Most of the spores in the broth changed from bright to dark after 4 hours, after which some of them began to bud, as observed by phase contrast microscopy. These results show that the spores germinated due to pressure and the presence of germination-inducing components in the broth, and that the germinated spores were then inactivated before changing into vegetative cells. We conclude that it is possible to inactivate B. subtilis spores by pressure-holding in non-thermal conditions. The same phenomenon was observed for B. licheniformis, B. cereus and B. coagulans, but the viable counts for these bacilli did not decrease as much as that of B. subtilis.
A number of fermented milk products containing Lactobacillus acidophilus and Lactobacillus gasseri are now available as probiotic products. The proteolytic, lipolytic and autolytic properties of human-derived L. acidophilus (5 strains) and L. gasseri (7 strains) were evaluated, as these factors are closely related to cell viability and flavor development in the products. All L. gasseri strains showed higher intracellular protease activities than the L. acidophilus strains ; in contrast, lipase activities in L. gasseri were mostly lower than those of L. acidophilus. The many strains of L. gasseri were shown to have a greater tendency than L. acidophilus to autolyze in dispersed solution ; this liability was more distinct at lower pH values. These properties should be taken into account when bacteria are selected for production of probiotic products.
The effects of cooking methods on antihypertensive properties and inhibitory action on angiotensin converting enzyme (ACE) of Hatakeshimeji mushroom (Lyophyllum decastes Sing.) were investigated. The molecular mass of proteins in the fruit body of Hatakeshimeji was lowered by deep-frying with cooking oil, as the free amino groups of the hot-water extractable fraction of Hatakeshimeji were increased. However, there was no change in IC50 for ACE activity. The effect on blood pressure for untreated and fried Hatakeshimeji was investigated by oral administration to spontaneously hypertensive rats (SHR). At 6 hours after administration, systolic blood pressure (SBP) of the fried Hatakeshimeji group was significantly lower than that before administration. At 5 hours after administration, ACE activity in the lungs of the fried Hatakeshimeji group was decreased as was that in the untreated Hatakeshmeji group, and the level was significantly decreased when compared to the control group. These results show that the antihypertension effect of Hatakeshimeji peptide was not lost by deep-frying.
The ability to determine the total reductant capacity (i.e. the total amount of electron-donating antioxidants) in dietary foodstuffs would be useful, because foods contain a number of different components with reducing activity. We assessed reducing activity in a variety of edible plants, including various fruits, vegetables, roots, and tubers. The reductive effect was assessed by measuring the ability of each sample to inhibit the oxidation of oxymyoglobin (MbO2) to metmyoglobin (metMb). We found that several types of plant, such as Chinese cabbage, lemon, paprika, and radish, show marked inhibitory effects on MbO2 oxidation. Using the MbO2 assay, it was determined that L-ascorbic acid (AsA) was the main reductive substance in these active plants. However, the majority of the plants tested, including herbs that are regarded as being abundant in antioxidants, were found to promote MbO2 oxidation. The results of the present study may be useful in the identification of beneficial dietary foodstuffs.