The influences of saccharides on hardening and water mobility of wheat starch gels stored at 2°C have been investigated. Hardening process of saccharides-supplemented gels could be separated into the four regions similarly to the control gel. In the region I, the creep compliance of the gels decreased exponentially with increasing storage period from the beginning of storage to several hours. In the following several hours, the compliance showed approximately a flat or slow increasing or decreasing change (region II). In the region III, the value decreased exponentially on the trend which was assumed the initial value extended. Finally, the compliance continued with decreasing more slowly (region IV). Except for D-ribose-added gel, no great differences were recognized among the initial creep compliance (J01) of saccharides-supplemented gels in the region I, and the compliances were smaller than the value of the control gel. However, D-ribose-added gel showed the same strain with the stress of which was about 60% in the other gels. Hardening rate constants (kI for the region I, kIII for the region III) of gels added with D-ribose, maltose, trehalose, sucrose, maltose, and malto-oligosaccharides (major components were maltose and maltotriose, or maltotriose) were smaller than the control gel. On the other hand, 13-fructose, D-galactose, melibiose increased the hardening rate compared to the control gel. Gel-stabilizing effect of disaccharides and oligosaccharides would be dependent on both constituent monosaccharides and glucosidic linkages in these molecules. The mobility of water in starch gels was inferred from measurements of apparent transverse relaxation time T2 using 17O-NMR techniques. The decreasing ratio of T2 to the initial T2 with storage was larger in order of maltose-added gel≤trehalose-added gel < sucrose-added gel <control gel < melibiose-added gel. The saccharides which reduced the hardening rate, resulted in adecrease in water mobility in the non-stored gel, and in a inhibition of progressive decrease in watermobility with the elapse of storage period.

View full abstract

The distribution and the properties of components of rice grain were investigated to optimize the processing of rice under consideration of the characteristics for utilization. The gelatinization properties of the starch in the layers to be polished and the underlying physicochemical properties were investigated on rice grains of three varieties, Habataki, Ohchikara and Kinuhikari and following results were obtained. (1) The components and their properties were varied among the layers for all the three varieties. The contents of moisture, minerals (Mg, K, Fe) and protein were higher in the outer layer, whereas the contents of starch which is the major component was high in the inner layer, and the apparent amylose content was apt to be high. Regards as tone, the brightness (L) was high and the degrees of redness (a) and yellowness (b) were low in the inner layer. The differences in the length variation of chain length distributions of amylopectin were small among layers and varieties. (2) Viscograph of the respective layers revealed that the viscosity was high in the inner layer and the values of characteristics of gelatinization, such as maximum and minimum viscosities, the final viscosity, breakdown, consistency were generally high. The viscosity changed stepwisely and the changes were different among the varieties and the lowering of viscosity was marked in the outer layer. The viscosities changed by four steps for Habataki, by two steps for Ohchikara, and by three steps for Kinuhikari. (3) By analyzing the relationships between the gelatinization properties (viscosity) and the physicochemical properties, it was found that the former properties for each layer were closely correlated to the contents of amylose and protein, and the tone. These results suggested that the contents of starch including the apparent amylose and protein were the important factors affecting the gelatinization characteristics of each layer.

View full abstract

The differences of flavor components found in green tea drinks made from tea leaves plucked on different matured stage were investigated. Catechins and amino acids were abundant in tea drinks made from younger leaves. The contents of those compounds in tea drinks made from matured leaves decreased. In the drinks of Sencha, the concentrations of catechin and amino acids were higher than those in the drink of Kamairicha. These differences are induced from the differences of the degrees of rolling the manufacturing process found among Sencha and Kamairicha. By the sterilization process, the specific off-flavor, called retort-smell is induced. The retort-smell was stronger in the drinks of Sencha made from young leaves and weaker in Sencha drinks made from matured leaves and Kamairicha drink. The off-flavor (retort-smell) in tea drinks is induced by hydrolysis of precursor of volatile compound (such terpen-alcohols). Generally, the contents of precursors in tea leaves are higher in young leaves than that in matured leaves. Farthermore, the precursors in tea leaves are easily hydrolyzed during firing process of Kamairicha at 200-250°C. Therefore, the content of precursors of volatile compounds in Kamairicha is low. So, the off-flavor become weaker in the drinks of Sencha made from matured leaves and the drink of Kamairicha.

View full abstract

Continuous production by a complete cell-concentration culture using hollow fiber module was conducted to enhance productivity of vinegar containing 10% (w/v) acetic acid. By preventing the discharge of acetic acid bacteria from the fermentor during the culture with the use of the hollow fiber module, cell concentration at 973 hours was increased to 11.27 g-dry cell/l. During the cultivation, acetic acid and ethanol concentrations could be maintained at ca. 10% (w/v) and 1% (v/v), respectively using an ethanol controller. Acetic acid production rate could be enhanced to 13.0 g-acetic acid/ (l. h) on an average for 708 hours. The production of acetic acid can be divided into two stages: one accompanying the growth of acetic acid bacteria and another accompanying the maintenance, the former contributes to the acetic acid production more than the latter. After 200 hours, the relative ratio of the former and the latter was estimated to be 0.69:0.31. Within the period of from 108 to 708 hours, cell concentrations capable of producing acetic acid accompanying growth and maintenance were estimated to be 0.35 and 1.23 g-dry cell/l, respectively. It has been proved that, in the complete cell-concentration culture, cells making no contribution to the production of acetic acid are accumulated in a large amount in the fermentor with the passage of time.

View full abstract

Continuous production by a partial discharging of cell-concentration broth using hollow fiber module was conducted to enhance productivity of vinegar containing 10% (w/v) of acetic acid and to suppress the excessive increase in the cell concentration. By discharging of some portion of cells from the fermentor, the cell concentration C. (g-dry cell/l) in it was expressed as the function of discharged ratio θ(=F_x/F;F_x and F are the discharging rate of cell-concentration broth and the feeding rate of medium, respectively.), which indicated that the cell concentration could be regulated by controlling the discharged ratio.
C_x=0.117(1/θ)+0.0551
The maximum acetic acid production rate of 16.6 g-acetic acid/l·h) could be attained at the dilution rate of 0.163 h-1 and the discharged ratio of 0.1. The high growth rate contributed to the achievement of high production rate of acetic acid. Continuous fermentation was conducted at a dilution rate of 0.077 h-1 and a discharged ratio of 0.2 for 80 days. Thus a vinegar, which contained 105.1 g-acetic acid/l and 4.5 g-ethanol/l could be constantly produced at an average acetic acid production rate of 8.1 g-acetic acid/(l·h) and at a yield of 0.95 g-acetic acid/1.304 g-consumed ethanol.

View full abstract

The contents of proximate composition, minerals and vitamins of firefly squids which were caught at offshore of 6 prefectures from January to July in 1988 were analyzed. Seasonal changes in the contents of lipid, copper (Cu), manganese (Mn) and vitamins of firefly squids were observed. The lipid contents reached the maximum value in April or May. The change in lipid contents of firefly squids was coincided with that in their liver lipid. The contents of Cu and Mn increased from March to July. Especially the Cu contents in July were about twice as much as those in March. It was assumed that the increase of Cu contents of the whole body was dependent on those of the liver. The vitamin B1 contents also increased from March to May and were almost unchanged thereafter. The increase of the vitamin B1 contents was in good accordance with the change of thiamin contents, while the contents of 2-(1-hydroxyethyl) thiamin (HET) didn't change through the sampling period. On the other hand, the retinol contents reached the maximum value in April or May, and the tocopherol contents increased with the sampling period. The mantle length and the body weight of firefly squids increased through the sampling period, and firefly squid spawns from March to June. It was, therefore, suggested that the changes in the nutritive components described above were related with the growth and the spawning of firefly squid.

View full abstract

Effect of hot water extracts of lo han kuo (Rakanka) fruits on blood pressure and lipid peroxides in tissues of spontaneous hypertensive rat (SHR) was investigated. The results were as follows: (1) SHRs were fed with a commercial diet (MF, Oriental Yeast Co. Ltd., the control group) or MF supplemented lo han kuo extracts (the lo han kuo group). NaCl was added to drinking water at a 1% level. Feeding with the lo han kuo extracts retarded the increase of blood pressure compared with the control ones, however no significant difference was observed between the two groups. The weight of heart was significantly lower in the lo han kuo group than that in the control group. (2) Lipid peroxide levels in liver and kidney were similar in both groups. The lipid peroxide content in heart of the lo han kuo group was significantly greater than that in the control, while the lipid peroxide level in plasma of the lo han kuo was significantly lower than that in the control one. Antioxidant activity of lo han kuo was suggested to be dependent on individual tissues.

View full abstract

Tocopherol contents of germinating Adzuki bean seed and sprout were determined in con-nection with the antioxidative activity, and changes in its activity of chloroform-methanol (2:1) extracts were also studied. The anti-oxidative activity measured by an iodometric method decreased rapidly after 10 days immer-sion although slight changes in its activity were observed within 7 days. The antioxidative ac-tivity of non-polar lipid (NRL) fraction was detected until 3 days after immersion, but δ-tocopherol decreased rapidly after immersion. Although the antioxidative activity of polar lipid (PL) fraction in seeds was hardly detected, an increase in its activity was found within 7 days after immersion. These results suggest that some effective antioxidants are present both in NPL fraction and PL fraction of the chloroform-methanol (2:1) extracts, in additionto δ-tocopherol.

View full abstract

We aimed to investigate the content and the fatty acid composition of total lipids in the central part of dorsal muscles of pink salmon caught in the coast of the Sea of Okhotsk. The sex differences and their changes depending on the date of fishing were studied. The lipid was extracted from the central part of dorsal muscles by FOLCH method and the fatty acids were analyzed by GLC method. The lipid contents were within the range from 1.52 to 2.62%, however, no significant differences in contents were found between sexes and fishing date. The dorsal muscles of the heavy subjects showed a tendency of higher contents of lipid. In addition, the fatty acid compositions were compared among the subjects in respect of the fishing date and sex, there was no noticeable difference in fatty acid constituents of dorsal muscles in each fishing date. The major fatty acids of the samples were C14 : 0, C16 : 0, C18 : 0, C16 : 1, C18 : 1, C20 : 1, C18 : 2, C20 : 5 and C22 : 6. The sum of these acids was more than 85% of the total acids in each samples. The male pink salmon revealed higher contents of C18 : 0, C18 : 1, total saturated fatty acids and total polyenoic fatty acids, although there were more higher contents of C20 : 1, C24 : 1 and total monoenoic acids in the female. The content of total saturated fatty acids was 25.41±13.09%. On the other hand the contents of total monoenoic and polyenoic acids were 48.90±6.93 and 21.88± 5.325%, respectively.

View full abstract

We have developed a simple quantitative measurement method of glycogen in pearl oyster ligament using the disposable blood glucose sensor developed in the medical field. Ligament samples were directly heated in HC1 solution, and the glucose concentration of the supernatant after neutralization was measured by glucose sensor. When this method was compared to conventional accurate method, the output of glucose sensor was linearly correlated with the glycogen content by conventional method at correlation coefficient of 0.99. Then, the coefficient of variation was 2.8% (n=10) for the ligament sample of 2.0% glycogen content.

View full abstract

The influence of several water-insoluble alcohols on the enzymatic activity and stability of rutin-degrading enzymes (RDEs) I and II from tartary buckwheat (Fagopyrum tataricum Gaertner) seeds was investigated. The RDEs' original activity was maintained in the presence of 20% (v/v) long chain alcohols such as 1-hexanol, 1-heptanol and 1-decanol. The longer the chain length of alcohol in the reaction mixture, the lower the relative activity of RDE. Unknown products obtained by rutin decomposition with RDE in the presence of 10% (v/v) water-insoluble alcohols were analyzed with HPLC using an Asahipak NH2 column. In HPLC analysis, unknown products tended to eluate earlier than rutinose with an increase in alcohol chain length. Unknown products formed in the presence of 1-pentanol, 1-heptanol and 1-decanol were identified by 13C NMR analysis as pentyl β-D-rutinoside, heptyl β-D-rutinoside and decyl β-D-rutinoside, respectively.

View full abstract

Cluster-dextrin, with a weight-average degree of polymerization of 900 (molecular weight, about 146 000), is composed of a cluster unit of amylopectin and has a cyclic structure at the reducing-end. The cluster-dextrin was mixed with the suspension of potato starch or wheat starch and gelatinized by heating. The viscosi- ties of both gelatinized starch pastes mixed with the cluster-dextrin were significantly lower and their transparencies were much higher than the gelatinized starch pastes without the cluster- dextrin. These phenomena were observed even when the cluster-dextrin was added after the gelatinization of each starch suspension. It is therefore concluded that the cluster-dextrin de- creases viscosity of gelatinized starch paste and increases its transparency. We could not find these phenomena by addition of maltose.

View full abstract

Batch production of gluconic acid using free and co-immobilized glucose oxidase and catalase under increased oxygen pressure was investigated to enhance productivity of gluconic acid and to produce mild and pleasant sour pure carrot juice acidified with gluconic acid produced in it. During the first 10-minute reaction gluconic acid of 30g was produced in buffer containing 100 g/l glucose by reaction with the crude enzyme solution containing 17.4mg protein under 2-atm oxygen pressure and 1 VVM oxygen aeration. The gluconic acid productivity increased with an increase in oxygen pressure, and after 6 hours reaction gluconic acid of 52 g/l in concentration was produced in concentrated carrot juice under 3-atm oxygen pressure. Repeated batch production of gluconic acid using the co-immobilized enzyme was carried out in buffer and concentrated carrot juice under 2-atm oxygen pressure. The productivity of gluconic acid gradually decreased with time of repetition and fell to half after repetition of more than 6 (buffer) and 4 (concentrated carrot juice) times. When the concentrated carrot juice processed by the enzymes was adjusted with water and unprocessed concentrated carrot juice, pure carrot juice tasted with mildness and pleasant sourness of gluconic acid was produced.

View full abstract