The greater part of peroxidase was distributed in core of Kiwifruit and was extracted by Tris-HC1 buffer (pH 8.0) containing 5% NaCl. The amount of extractable peroxidase activity was decreased during fruit ripening. Polyacrylamide gel electrophoretic analysis showed that the three peroxidase isozymes were contained in core of Kiwifruit and the zymogram pattern of isozyme was not changed during fruit ripening. Peroxidase was partially purified about 22 folds from core of fruits by means of ammonium sulfate fractionation, ion-exchange chromatography on CM-52 cellulose column and gel filtration on Toyopearl HW-55 F. Zymogram of partially purified peroxidase on polyacryramide gel showed one active band. This enzyme preparation had a pH optimum of 7.5, K_m value for pyrogallol of 10 mM, and was strongly inhibited by KCN.

View full abstract

Ge1atinization properties of Australian standard white (Western Australia) (ASW) and wheats representing the three major varieties grown in Japan were compared with respect to their suitability for Japanese-type noodle. Quality factors which affect on the starchge1atinization properties were studied using the Brabender Amylograph. The addit ion of NaCl caused a pronounced difference in the area under the sticking out portion of the amylogram during cooling stage (maximum viscosity during coo1ing stage) for flou rs milled from ASW and Japanese wheats. ASW, which possessed favorable characteristics for noodle making, showed a large area, whereas none or little area was observed for Japane se wheats This may relate to noodle quality, especially to noodle staling. Starches recove red from flours by wet-fractionation procedure contained soluble proteins. ASW starch sho wed a distinct high protein solubilities on the extraction with 1% sodium dodecyl sulf ate (SDS). Treatment of starches with 1% SDS resulted in a minimized variance of gelatiniza tion properties between ASW and Japanese wheats. On the basis of reconstitution studi es of SDS treated starches and their-solubles, somewhat unfavorable gelatinization propert ies of Japanese wheat were considered to be caused by SDS-solubles. Proteins of SDS-sol ubles were further analyzed by RP-HPLC, which showed somewhat different protein charac teristics

View full abstract

As a new continuous and time-saving method of production of rice cake doughs, weexamined the extrusion cooking of the rice flour by use of a twin screw extnder. The results are as follows: (1) The extrudates are almost the same quality as the products by an electric home use rice cake maker. (2) In case of extrusion cooking, the products made from the mixture of glutinous and non-glutinous rice flour (half-and-half) was more similar to the commercial cut rice cake than those made from the only glutinous rice flour on the results of sensory test. (3) The measurement of degree of gelatinization (BAP me thod) and carbon-13 nuclear magnetic resonance spectra revealed that the products by extrusion cooking are slower in retrogradation speed during storage period of one month than those by thee electric home use rice cake maker.

View full abstract

The fatty acid composition of nonglutinous brown rice was investigated on 15 Japonicatype and 14 Indica-Japonica hybrid type cultivars in Korea. The Indica-Japonica hybridtype, as compared with the Japonica type, gave significantly higher myristic, palmitic, palmitoleic, stearic, oleic and arachidic acid contents and lower linoleic and eicosenoic acidcontents. As to the relationship between fatty acid contents, there were the highest andnegative correlations between oleic and linoleic acids in both types. The scatter diagrambetween both fatty acid contents could be divided into Japonica type and Indica-Japonicahybrid type. The Indica-Japonica hybrid type in Korea, therefore, might inherit its fattyacid composition from Indica type.

View full abstract

The deterioration of oils and the degradation of antioxidants in croÛton fried with sesame or corn oils were examined. The amounts of antioxidants (sesamol, sesaminol and tocopherol) and the oxidative stability during storage were determined by HPLC or PV and TBA methods. After storage at 60°C for one month, the PV (meq/kg) of each oil extracted from croûton was 613.0 (corn oil), 80.0 (unroasted sesame oil) and 6.0 (roasted sesame oil), respectively. Tocopherol in croûton fried with corn oil was diminished after one month storage, whereas that fried with unroasted sesame oil remained about 70%, and that fried with roasted seed oil almost unchanged. About 40% of sesaminol (unroasted sesame oil) or 66% of sesamol (roasted sesame oil) was remained. Consequently, in spite of larger amounts of tocopherol in corn oil than in sesame oils, excellent oxidative stability of croÛton fried with both sesame oils was observed. This fact indicated the stronger antioxidative activity of sesaminol or sesamol rather than tocopherol. Furthermore, excellent oxidative stability in roasted oil than in unroasted oil indicated the presence of unknown antioxidative substances.

View full abstract

Fresh cheese curds partly melted and stretched at 52°C were subjected to chilled water to manufacture fiber structured, so-called "string" cheese which is now available in the market. Both compression and yielding tests by using a spherical indenter and sensory evaluation applied to these cheese samples during ripening for 9 weeks at 10°C indicated that the modulus of Deformability is of great value in predicting consumer's acceptability to cheese texture. In addition, the evaluation suggested that the significant effect of me chanical relaxation in the cheese structure is responsible for sensory firmness of the cheese in the first stage of ripening, while the significant effect of enzymatic decomposition contributes to the texture formation in the last stage.

View full abstract

Physical properties of the pastes of glutinous and non-glutinous rice flours prepared under different heating conditions were studied by using the multi-biting test. Changes in the physical properties of 4.3 or 8.5% pastes of the rice flours which had been heated for 5-60minutes at different temperatures could be analysed by the parameters of multi-biting test. Ratio of the parameters of apparent viscosity characteristics vs the parameters of apparent springiness characteristics of the 4.3% pastes of the glutinous and non-glutinous rice flours heated for different heating conditions well indicated the differences of the physical properties of the pastes of glutinous and non-glutinous rice flours. In general, changes in the parameters of the multi-biting test of the 4.3% pastes of glutinous and non-glutinous rice flours heated for 5-60minutes at different four temperature levels (70, 80, 90 and 98°C) well showed the rheological differences due to the swelling and gelatinization characteristics of glutinous and non-glutinous rice flours.

View full abstract

An absorptiometric method was applied for the analysis of food dyes, sorbic acid(SOA), dehydroacetic acid (DHA) and phydroxy benzoic acid butglester (POBB), by measuring the absorbances of the polyamide films (film) on which these food additives were adsorped from their solutions in the presence of hydrochloric acid and sodium sulfate. The procedure for adsorption was as follows. A flask in which the solution and the film were placed was heated on a plate heater for l5min, followed by washing the film by running water and by air-drying. This procedure was suggested to be useful for the analysis of food additives as they were easily adsorbed in to the fi1ms.

View full abstract