Effects of Storage and Roasting Condition on the Antioxidant Activity of Soybeans with Different Colors of Seed Coat.

The DPPH radical scavenging activity and ORAC value of soybeans (yellow soybean, blue soybean, and black soybean) were increased by roasting at above 190 °C. Concerning raw beans, black soybeans with the darkest seed coat color had the strongest antioxidant activity, indicating the effect of the coat pigment. However, the degree of increased antioxidant activity by roasting was almost similar regardless of seed coat color, suggesting that coat color is independent of the increased antioxidant activity. Concerning aged beans stored at 37 °C/75% RH for 60 days, the antioxidant activity increased in yellow soybean and decreased in blue and black soybean compared to before storage. Conversely, when roasted at 190 °C for 20 min, the DPPH values of all the aged beans were significantly increased. Other analyses of roasted beans with and without seed coat showed that changes in the components of cotyledons during storage may have contributed to the increased antioxidant activity of aged beans, regardless of seed coat color. These results revealed that roasting effectively improves the antioxidant activity of aged soybeans, regardless of seed coat color. We concluded that roasting is recommended for antioxidant properties, particularly regarding the effective use of aged beans.

Structural changes in cell wall of Japanese radish accompanied by release of rhamnogalacturonan during pressure cooker heating.

Changes in the cell wall of Japanese radish due to heating at 100 °C or 117 °C for 3 h were examined. Signals in 13C cross polarization magic angle spinning solid-state NMR (which detects rigid components) showed no differences between heating temperatures. 13C pulse saturation transfer magic angle spinning NMR (which detects flexible components) showed clear temperature-dependent changes in the rhamnose side chains of rhamnogalacturonan. Alcohol-insoluble solids isolated from raw samples were heated in water at 100 °C or 117 °C for 3 h. The concentrations of dissolved sugars and metal ions measured after heating in water at 117 °C were greater than in samples heated at 100 °C, indicating that loosening of cell wall structures increased with temperature, likely via degradation and elution of rhamnogalacturonan followed by ß-elimination of homogalacturonan, and fewer interactions between cell wall components, including divalent metal ions. Vegetable shape was retained despite fewer interactions.

Influences of Soaking Temperature and Storage Conditions on Hardening of Soybeans (Glycine max) and Red Kidney Beans (Phaseolus vulgaris).

The influences of soaking treatment and storage conditions on the softening of cooked beans, namely, soybeans and red kidney beans, were investigated. It was revealed that the softening of fresh soybeans and fresh red kidney beans was suppressed during subsequent boiling after soaking treatment at 50 and 60 °C. Furthermore, in treated aged soybeans and red kidney beans that were subjected to storage at 30 °C/75% relative humidity for 6 mo and soaking treatment at 50 to 60 °C, the hardness during cooking was further amplified. This suggested that the mechanism of softening suppression differs depending on the influences of soaking and storage. Analysis of the pectin fraction in alcohol insoluble solid showed insolubilization of metal ions upon storage at high temperature and high humidity in both soybeans and red kidney beans, which suggests interaction between Ca ions and hemicellulose or cellulose as cell wall polysaccharides. The results of differential scanning calorimetry (DSC) showed that aged soybeans exhibited a shift in the thermal transition temperature of glycinin-based protein to a higher temperature compared with fresh soybeans. From the results of DSC and scanning electron microscopy for aged red kidney beans, damaged starch is not conspicuous in the raw state after storage but is abundant upon soaking treatment. As for the influence of soaking at 60 °C, it can be suggested that its influence on cell wall crosslinking was large in soybeans and red kidney beans in both a fresh state and an aged state.

Effects of dried bonito (katsuobushi) and captopril, an angiotensin I-converting enzyme inhibitor, on rat isolated aorta: a possible mechanism of antihypertensive action.

In order to elucidate the mechanism of the antihypertensive action of dried bonito (katsuobushi), we compared the effects of dried bonito extracts with those of captopril, an angiotensin I-converting enzyme (ACE) inhibitor, on aorta preparations isolated from rats. Dried bonito extracts (3 x 10(-4) to 3 x 10(-3) g/ml) more potently relaxed contractions induced by norepinephrine (10(-7) M) than contractions induced by KCl (55.9 mM). Dried bonito extracts (3 x 10(-3) g/ml) slightly inhibited 10(-7) M angiotensin I-induced contractions. In contrast, captopril (10(-8) to 10(-7) M) did not affect 10(-7) M norepinephrine- or 55.9 mM KCl-induced contractions, but a higher concentration of captopril (10(-6) M) very slightly relaxed it. Captopril (10(-8) to 10(-6) M) markedly inhibited 10(-7) M angiotensin I-induced contractions in a concentration-dependent manner. These results suggest that antihypertensive mechanism of action induced by dried bonito involves direct action on vascular smooth muscle in addition to ACE-inhibitory activity.

Effect of acetic acid added to cooking water on the dissolution of proteins and activation of protease in rice.

The effect of acetic acid on the dissolution of proteins in rice was studied to elucidate the mechanism for the textural change induced by the acid by chemical and SDS-PAGE analyses of the rice proteins in the soaking solution. More proteins were extracted with 0.2 M acetic acid (pH 2.7) than with water (pH 6.8). The effect of acetic acid on the protein dissolution increased with increasing temperature. Immunoblotting confirmed that, when rice was soaked in acetic acid, glutelin was dissolved into the soaking solution and degraded by aspartic proteinase. Aspartic proteinase degraded glutelin much more than it did albumin and globulin. It was found that the combined amount of albumin and globulin dissolved into the acetic acid solution was much larger than that of glutelin, despite the smaller amounts present of albumin and globulin than of glutelin. Metal ions were extracted more with acetic acid than with water. In addition, carboxypeptidase was activated under the acidic condition and resulted in an increase in the amount of free amino acids. The main effect of acetic acid on the dissolution of rice proteins was enhancement of the solubility of albumin, globulin, and glutelin, the effect of proteases being minor.

Detection of giant myofibrillar proteins connectin and nebulin in fish meat by electrophoresis in 3-5 gradient sodium dodecyl sulfate polyacrylamide slab gels.

An improved method was investigated for sodium dodecyl sulfate polyacrylamide slab gel electrophoresis (SDS-PAGE) to facilitate the analysis of the giant myofibrillar proteins, connectin and nebulin, in fish meat by using jack mackerel (Trachurus japonicus) as the sample fish. It was established that separation of the alpha-connectin band from the beta-connectin band by SDS-PAGE could be achieved by using 3-5% gradient gels with glycerol to facilitate the formation of a gradient with polymerization at 35 degrees C. SDS-PAGE samples of white dorsal muscle from the jack mackerel were homogenized with a 2% SDS solution containing an inhibitor mixture (1 microg/mL of phenylmethanesulfonyl fluoride, 1 microg/mL of leupeptin, and 1 microg/mL of E-64) and heated at 50 degrees C for 20 min. Heating these samples at 100 degrees C for 2 min resulted in the disintegration of connectin but did not affect nebulin. A purified myofibril sample and a whole muscle sample showed similar changes in the overall rate of degradation of whole connectin and nebulin during the postmortem storage period, but it was clear that beta-connectin was cleaved from alpha-connectin during the preparation of myofibrils at the early stage postmortem. Storage of the SDS-PAGE samples at -85 degrees C was preferable to storage at -18 degrees C for a long period.