We have observed acid fog in Mr. Oyama adjacent to the Kanto Plains in Japan, where acid fog unde... more We have observed acid fog in Mr. Oyama adjacent to the Kanto Plains in Japan, where acid fog under pH 3 has been frequently observed and natural fir forest (Abiesfirma) has been declining. We applied the simulated acid fog to the needles of fir twigs and the treatment removed calcium, boron, and cell-wall acidic sugars from the needles. We also observed high contents of calcium, boron, and acidic sugars in throughfall collected under the declining forest canopy. Ca + + and Mg + + ion leach via ion-exchange with major cations of fog-water and the amount of leached boron increased with the increase in the concentration of leached Ca + +. The deficiency of calcium and boron by leaching could be one of the main causes of decline of the fir forest.
A ^-D-glucanase activity hydrolyzing 1,3:1,4-/7-Dglucan was released from the cell walls of barle... more A ^-D-glucanase activity hydrolyzing 1,3:1,4-/7-Dglucan was released from the cell walls of barley by 3 M LiCl treatment. It was purified by sequential cation-exchange, gel-filtration and hydrophobic chromatography. The molecular mass of the glucanase was 66 kDa as determined by SDS-polyacrylamide gel electrophoresis. Sequence determination of the first thirty amino acids of the N-terminus revealed a high homology of this enzyme to the Pseudomonas l,4-/7-D-glucosidase (56.5%). The purified fio-glucanase has a pH optimum at 5.0, and hydrolyzes oligosaccharides containing /?-D-1,3 or /?-D-1,4 linkage. The glucanase showed maximum hydrolytic activity toward laminaritetraose, the rate being about two times that of cellotetraose and about four times that of gentiobiose. Polysaccharides such as lichenan, l,3:l,4-/*-D-glucan (from barley), laminarin and pustulan are also hydrolyzed, but not carboxylmethyl-curdlan, carboxymethyl-cellulose, xyloglucan and maltose. The purified /?-D-glucanase yielded monomeric glucose from laminarihexaose, and exhibited characteristics of an exo-l,3-/?-D-glucanase (EC 3.2.1.58). The activity and biochemical characteristics of this enzyme suggest that it is an exo-l,3-/£-D-g!ucanase involved in the rapid turnover of l,3:l,4-y9-D-glucan in barley cell walls during seedling growth.
Journal of the Japanese Society for Horticultural Science, 2008
The acoustic vibration signals of 9 cultivars in 3 groups (Kaga, Senju and Kujo) of bunching onio... more The acoustic vibration signals of 9 cultivars in 3 groups (Kaga, Senju and Kujo) of bunching onion were acquired using a device for acoustic measurement of food texture. To imitate biting bunching onion with an incisor, a stainless steel wedge-type head was introduced to fresh tissue perpendicularly and parallel to the longitudinal axis. A half-octave multifilter was developed to analyze the obtained signals in the frequency domain, and then the root-mean-square amplitude in each frequency band was computed and defined as a texture index. The results showed that the signals obtained with the perpendicular insertion were larger than those obtained with the parallel insertion. The total texture index, which is the summation of texture indices in 18 frequency bands, of each cultivar was grouped together as the same cultivar group, except for 'Shimonita' cultivar of the Kaga-group. Principal components analysis (PCA) also clustered successfully each cultivar group in the space of the first two principal components (PCs), also excluding 'Shimonita'. Furthermore, the ratios of the texture index of perpendicular to parallel penetration clearly distinguished each group. These results suggested that the device could detect textural differences among cultivar groups of bunching onion.
We examined the effects of ripening stage, temperature, film wrapping, and storage period on the ... more We examined the effects of ripening stage, temperature, film wrapping, and storage period on the elasticity index (EI) and fruit quality of 'Irwin' mangos to develop a storage technique for improving the storage life of this fruit and to determine whether flesh firmness can be estimated using the EI. The second resonant frequency measured between the two sides of the fruit was nearly equal to measurements between the dorsal and ventral surfaces of the fruit. The EI declined as fruit ripening progressed and was not influenced by fruit size. Fruits harvested at the pre-natural fruit drop stage (pre-NFDS; 2 to 3 days before fruit drop) and the post-natural fruit drop stage (post-NFDS) were kept at 25 8C for 10 days. No significant differences were detected between fruits at these two stages in terms of the EI and flesh firmness, except that both variables at the pre-NFDS were higher than those at the post-NFDS after 0 and 4 days and after 0 day of storage, respectively. Similarly, no significant differences were found between fruits at these two stages in terms of total sugar and organic acid contents, regardless of the length of the storage period. Fruits harvested at pre-NFDS were individually wrapped in low-density polyethylene film (11 mm thick) and stored at 10, 15, 20, and 25 8C for 10 days. The EI of fruits kept at 10 8C was higher than that of fruits stored at 15 to 25 8C regardless of the presence of film wrapping. At 10 8C storage, the EI of film-wrapped fruits was higher than that of non-film-wrapped fruits. Film-wrapped fruits harvested at pre-NFDS were stored at 10 8C for 30 days. After 15 days in storage, relatively rapid and then gradual declines in both the EI and flesh firmness were observed. Sugar content was unaffected by the storage period, but organic acid content decreased after 30 days in storage. A strong positive correlation was found between the EI and flesh firmness. When the data set was limited to fruits less than 20 N • cm L2 in flesh firmness and more than 350 g in weight, the correlation coefficient was higher compared with a data set with all fruit combined. The results of this study indicate that flesh firmness in 'Irwin' mangos can be estimated by measuring the EI. Moreover, the ripening stage, storage temperature, and film wrapping affected the retention of fruit quality.
We have observed acid fog in Mr. Oyama adjacent to the Kanto Plains in Japan, where acid fog unde... more We have observed acid fog in Mr. Oyama adjacent to the Kanto Plains in Japan, where acid fog under pH 3 has been frequently observed and natural fir forest (Abiesfirma) has been declining. We applied the simulated acid fog to the needles of fir twigs and the treatment removed calcium, boron, and cell-wall acidic sugars from the needles. We also observed high contents of calcium, boron, and acidic sugars in throughfall collected under the declining forest canopy. Ca + + and Mg + + ion leach via ion-exchange with major cations of fog-water and the amount of leached boron increased with the increase in the concentration of leached Ca + +. The deficiency of calcium and boron by leaching could be one of the main causes of decline of the fir forest.
A ^-D-glucanase activity hydrolyzing 1,3:1,4-/7-Dglucan was released from the cell walls of barle... more A ^-D-glucanase activity hydrolyzing 1,3:1,4-/7-Dglucan was released from the cell walls of barley by 3 M LiCl treatment. It was purified by sequential cation-exchange, gel-filtration and hydrophobic chromatography. The molecular mass of the glucanase was 66 kDa as determined by SDS-polyacrylamide gel electrophoresis. Sequence determination of the first thirty amino acids of the N-terminus revealed a high homology of this enzyme to the Pseudomonas l,4-/7-D-glucosidase (56.5%). The purified fio-glucanase has a pH optimum at 5.0, and hydrolyzes oligosaccharides containing /?-D-1,3 or /?-D-1,4 linkage. The glucanase showed maximum hydrolytic activity toward laminaritetraose, the rate being about two times that of cellotetraose and about four times that of gentiobiose. Polysaccharides such as lichenan, l,3:l,4-/*-D-glucan (from barley), laminarin and pustulan are also hydrolyzed, but not carboxylmethyl-curdlan, carboxymethyl-cellulose, xyloglucan and maltose. The purified /?-D-glucanase yielded monomeric glucose from laminarihexaose, and exhibited characteristics of an exo-l,3-/?-D-glucanase (EC 3.2.1.58). The activity and biochemical characteristics of this enzyme suggest that it is an exo-l,3-/£-D-g!ucanase involved in the rapid turnover of l,3:l,4-y9-D-glucan in barley cell walls during seedling growth.
Journal of the Japanese Society for Horticultural Science, 2008
The acoustic vibration signals of 9 cultivars in 3 groups (Kaga, Senju and Kujo) of bunching onio... more The acoustic vibration signals of 9 cultivars in 3 groups (Kaga, Senju and Kujo) of bunching onion were acquired using a device for acoustic measurement of food texture. To imitate biting bunching onion with an incisor, a stainless steel wedge-type head was introduced to fresh tissue perpendicularly and parallel to the longitudinal axis. A half-octave multifilter was developed to analyze the obtained signals in the frequency domain, and then the root-mean-square amplitude in each frequency band was computed and defined as a texture index. The results showed that the signals obtained with the perpendicular insertion were larger than those obtained with the parallel insertion. The total texture index, which is the summation of texture indices in 18 frequency bands, of each cultivar was grouped together as the same cultivar group, except for 'Shimonita' cultivar of the Kaga-group. Principal components analysis (PCA) also clustered successfully each cultivar group in the space of the first two principal components (PCs), also excluding 'Shimonita'. Furthermore, the ratios of the texture index of perpendicular to parallel penetration clearly distinguished each group. These results suggested that the device could detect textural differences among cultivar groups of bunching onion.
We examined the effects of ripening stage, temperature, film wrapping, and storage period on the ... more We examined the effects of ripening stage, temperature, film wrapping, and storage period on the elasticity index (EI) and fruit quality of 'Irwin' mangos to develop a storage technique for improving the storage life of this fruit and to determine whether flesh firmness can be estimated using the EI. The second resonant frequency measured between the two sides of the fruit was nearly equal to measurements between the dorsal and ventral surfaces of the fruit. The EI declined as fruit ripening progressed and was not influenced by fruit size. Fruits harvested at the pre-natural fruit drop stage (pre-NFDS; 2 to 3 days before fruit drop) and the post-natural fruit drop stage (post-NFDS) were kept at 25 8C for 10 days. No significant differences were detected between fruits at these two stages in terms of the EI and flesh firmness, except that both variables at the pre-NFDS were higher than those at the post-NFDS after 0 and 4 days and after 0 day of storage, respectively. Similarly, no significant differences were found between fruits at these two stages in terms of total sugar and organic acid contents, regardless of the length of the storage period. Fruits harvested at pre-NFDS were individually wrapped in low-density polyethylene film (11 mm thick) and stored at 10, 15, 20, and 25 8C for 10 days. The EI of fruits kept at 10 8C was higher than that of fruits stored at 15 to 25 8C regardless of the presence of film wrapping. At 10 8C storage, the EI of film-wrapped fruits was higher than that of non-film-wrapped fruits. Film-wrapped fruits harvested at pre-NFDS were stored at 10 8C for 30 days. After 15 days in storage, relatively rapid and then gradual declines in both the EI and flesh firmness were observed. Sugar content was unaffected by the storage period, but organic acid content decreased after 30 days in storage. A strong positive correlation was found between the EI and flesh firmness. When the data set was limited to fruits less than 20 N • cm L2 in flesh firmness and more than 350 g in weight, the correlation coefficient was higher compared with a data set with all fruit combined. The results of this study indicate that flesh firmness in 'Irwin' mangos can be estimated by measuring the EI. Moreover, the ripening stage, storage temperature, and film wrapping affected the retention of fruit quality.
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Papers by Naoki Sakurai