The pungent and aroma substances of Koreigusu hot sauce from Okinawa made with Awamori and Shimatougarashi (Capsicum frutescens) were analyzed. The major capsaicinoids responsible for pungency in Koreigusu were determined by HPLC. The concentrations of capsaicin (C) and dihydrocapsaicin (DC) were 0.037∼0.058mg/ml and 0.011∼0.026mg/ml, respectively, in 8 of 9 commercial Koreigusu sauces sampled. The DC/C ratio was 0.23∼0.57. In Shimatougarashi, the levels were 4.17 and 2.22mg/g dry weight, respectively, with a ratio of 0.53. This finding of capsaicinoid content in ethanol-extracted Shimatougarashi suggests that the concentrations of capsaicin and dihydrocapsaicin and the DC/C ratio in commercial Koreigusu sauces increases with increasing concentration of ethanol. Aroma substances of Koreigusu were collected by headspace solid-phase microextraction and analyzed by GC, GC-MS and GC-Olfactometry (GC-O). In addition to ethanol as a main component of Awamori, 24 aroma compounds were identified. The important compounds identified by GC-O analysis in the aroma of Koreigusu were found to be 2-isobutyl-3-methoxypyrazine, 3-methyl-1-butanol and esters. The aroma of Koreigusu depends on the both the aroma of Awamori and Shimatougarashi.

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To obtain a highly specific immunoglobulin G (IgG) for wheat nonspecific lipid transfer protein 1 (LTP), a wheat LTP peptide comprising amino acids Nos. 17-27 was designed as the antigen. Rabbit IgG showed high affinity to LTP of wheat and rye, but less or no affinity to water-extracted proteins of barley, oat, rice and maize. The LTP in 1μg of water-extracted wheat and rye protein was detectable by immunoblotting. Purified wheat LTP of over 2ng was detectable by immunoblotting and enzyme linked immunosorbent assay.

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The physicochemical properties (dynamic viscoelastic properties and sensuousness) of water-soluble protein concentrate (WSPC) of fish meat were investigated to improve its utilization with or without β-lactoglobulin (β-LG) and fatty acid salt. The secondary structure of the proteins was also investigated using Fourier transform infrared spectroscopy (FT-IR). Although WSPC is unstable in water and easily precipitates, the stability was increased by the addition of sodium caprate. Whereas β-LG has high gel-forming ability in the presence of fatty acid salt, WSPC itself could not form a fatty acid salt-induced gel. β-LG is a β-sheet protein and changes during the formation of a fatty acid salt-induced β-LG gel were mainly due to a conversion from intramolecular β-sheets to intermolecular β-sheets in β-LG. The secondary structure of WSPC at the sol stage mainly comprised α-helices. The α-helix and intramolecular β-sheet structures in WSPC were slightly changed to intermolecular β-sheet structure by the addition of sodium caprate. The WSPC with sodium caprate affected the rheological properties of β-LG and the β-LG-WSPC mixture formed homogeneous and a high water-holding gel. These results suggest that WSPC could contribute to fatty acid salt-induced β-LG gel as a texture modifier.

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Listeria monocytogenes is a bacterium with wide distribution in natural environments that causes contamination of various food ingredients. L. monocytogenes contamination in ready-to-eat foods such as lightly pickled vegetables creates a risk of foodborne listeriosis outbreaks. To estimate the L. monocytogenes levels in foods, Listeria-selective media such as PALCAM and MOX supplemented with specified antibiotics are usually used. However, when estimating the growth of L. monocytogenes artificially inoculated to lightly pickled cucumber using these media, the high levels of bacteria associated with the cucumbers inhibit the formation of L. monocytogenes colonies and certain bacteria other than L. monocytogenes form colonies with morphology similar to that of L. monocytogenes. In this study, we therefore established a new method to estimate the growth of L. monocytogenes in lightly pickled cucumber by artificially inoculating rifampicin-resistant L. monocytogenes and using PALCAM-Listeria-Selective-Agar-Base supplemented with rifampicin (50μg/ml) and 1/100 of a specified concentration of PALCAM-Listeria-Selective-Supplement. Analyses using this method showed that initial artificial inoculation levels of live L. monocytogenes were maintained during storage for 10 days at 4°C and for 2 days at 10°C, respectively. The addition of 0.05 and 0.1% chitosan significantly decreased the levels of live L. monocytogenes.

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This study was carried out to determine the optimum conditions for dehydrofreezing radish and the suitable thawing method for dehydrofrozen radish. Changes in the physical properties of radish during dehydrofreezing, thawing, and re-hydration were observed and the effects of these processes on the physical properties were evaluated. Consequently, for the dehydration process, vacuum drying under low temperature (20°C) was selected to avoid deterioration. For the freezing process, the time required to pass the zone of maximum ice crystal formation for dehydrating by the brine freezing method was shortened 70-90% compared to the normal freezing method. The amount of drip loss after thawing was the least in the sample dehydrated by brine freezing followed by thawing at 0°C. Electrical properties, which were obtained by measuring the impedance after each process, were used as an index to evaluate product freshness.

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A combination of double fluorescence-labeled probes was applied to multiplex discrimination of Thunnus thynnus orientalis (Pacific bluefin) and T. thynnus thynnus (Atlantic bluefin) in the fluorogenic ribonuclease protection (FRIP) assay. The FRIP assay provides information about the absence or presence of known single nucleotide polymorphisms (SNPs). It requires only one pair of fluorescence donor- and acceptor probes for discriminating one species, and allows rapid and sensitive analysis. DNA was extracted from individuals of six Thunnus species and subjected to PCR with primers targeting the T7 RNA polymerase promoter region, and then in vitro transcribed RNA was produced. Both an FITC-labeled probe targeting Pacific bluefin tuna and a TAMRA-labeled probe targeting Atlantic bluefin tuna were simultaneously hybridized to individual RNA samples in hybridization buffer solution. Fluorescence emissions were temporary quenched via FRET, but fluorescence intensity recovered in the response to the presence of mismatches in DNA- RNA hybridridization following RNase A digestion. Similar results were also observed in visualization of FRIP reaction mixtures under UV light excitation. The FRIP assay, which is a simple, rapid, sensitive and economic analytical method, can be employed in a variety of food inspection and authentication applications.

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A soft-type cooked squid muscle (mantle of Todarodes pacificus) was prepared by vacuum cooking, and its sensory and rheological properties and changes in muscle proteins were investigated to determine the softening mechanism. The soft-type sample was prepared by heating for one hour at 60°C and was compared with the sample prepared by heating for one hour at 80°C. The intramuscular collagen of both samples was assumed to be solubilized since the outer skin comprising the third and forth layers disappeared. The rupture stress of the former sample measured by breaking both perpendicular and parallel to the muscle fibers encircling the mantle was smaller than that of the latter sample and the difference of the values between the samples was remarkably large for the breaking parallel to the muscle fibers. SDS-PAGE analysis demonstrated that heating of squid muscle induced irreversible liberation of actin from myofibrils. Such reactions proceeded more prominently at 60°C than at 80°C with most of the liberated actin being soluble even after two hours of cooking at 60°C. All results suggested that the extensive liberation and solubilization of actin from myofibrils induced by a lower temperature heating as well as the solubilization of intramuscular collagen was responsible for softening of the vacuum-cooked squid muscle.

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Excitation-emission matrix (EEM) fluorescence spectroscopy was used to detect deoxynivalenol (DON), which is a mycotoxin and is the most frequent contaminant occurring in toxicologically relevant concentrations in wheat and other cereal grains. Concentration gradients of DON aqueous solution samples with 7 levels were prepared as follows : 0, 4, 8, 125, 250, 500 and 1000ppm. EEM was measured using a spectrofluorometer. DON could be characterized by some fluorescence peaks in EEM, especially those with the following specific excitation (Ex) and emission (Em) wavelength ranges : Ex 200∼240nm/Em 300nm and Ex 250∼300nm/Em 250∼350nm. Through discriminant analysis of EEM, two groups of DON and pure water can be discriminated with the following three wavelength conditions : Ex 210nm/Em 270nm, Ex 240nm/Em 620nm and Ex 280nm/Em 330nm. For these conditions, a linear discriminant model was able to identify DON solutions with a classification accuracy of 100%.

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The antihypertensive effect of water extracts from leaves of Moringa oleifera Lam. was studied in spontaneously hypertensive rats (SHR). Extracts (10g of the dried leaves with 100ml of water) were given to SHR by a single oral administration at 3ml/kg body weight or by repeated oral administrations at 3ml/kg body weight/day for 6 weeks. The water extracts contained 0.3mg/ml of γ-aminobutyric acid (GABA). Although the single oral administration of the water extract could not reduce systolic blood pressure in SHR, repeated oral administration for 6 weeks resulted in significant decreases compared with the control. These results suggest that the daily intake of Moringa oleifera Lam. was effective for prevention against hypertension.

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A variety of dishes prepared from bitter gourd are often served with Katsuobushi. Based on the use of this combination, we investigated the debittering effect of Katsuobushi. Addition of Katsuobushi reduced the bitterness of both raw and cooked bitter gourd ; however, significant debittering effect was not achieved by using the extract.Katsuobushi was shown to bound the bitter substances in bitter gourd. Based on this finding, it was concluded that Katsuobushi scavenges the bitter substances in bitter gourd, thereby the reducing bitter taste.

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In the present study, carbon, nitrogen, and oxygen isotope ratios of beef from Japan, Australia, and the USA, were examined as potential tools for verifying the geographical origin of beef commercially distributed in Japan. Beef from the USA is characterized by a higher carbon isotope ratio (-12.6±1.0‰, mean±sd), than beef from Japan (-19.3±0.5‰) and Australia (-22.1±1.5‰). Furthermore, beef from Australia is characterized as having a higher oxygen isotope ratio (+17.2±1.1‰) than beef from Japan (+10.4±1.0‰) and the USA (+10.8±1.1‰). The present results suggest that carbon and oxygen stable isotope analysis is applicable as a tool for determining the geographical origin of beef.

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[in Japanese]

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