To establish a method for estimating dough stickiness, and to clarify the influencing factor on dough stickiness were investigated by using a rheometer. The principle of the test procedure was to measure the adhesive curve obtained when the sample was drawn off from the plunger pressed to the sample beforehand. Parameters of stickiness, adhesive force, stretc hand adhesiveness were obtained from the peak height, peak width and peak area, respectively. Adhesiveness and stretch of dough increased with the added water. Parameters of stickiness increased by addition of 1% NaCl, showed constant to 6% NaCl and decreased over 6% NaCl. All dough stickiness parameters showed maximum values around pH 6. Adhesiveness and stretch of dough reconstituted from isolated gluten protein and commercial wheat starch increased with protein content, but adhesive force decreased inversely. All dough stickiness parameters increased with an increase of mixing time up to 10 minute, and decreased with longer mixing time. Dough stickiness parameter increased with the increasing resting period while stickiness parameter of sheeted dough showed almost constant during resting period. From these results it was suggested that stickiness of dough was related with viscoelasticity of dough and wetting of dough surface.

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In order to understand quantitatively the surface characteristics of cooked noodle, stickiness was evaluated by a rheometer and a sensory test. The parameters of stickiness, adhesiveness, adhesive force and stretch were determined from a peak area, a peak height and a peak width of a rheometer response, respectively. Stickiness of cooked noodle increased with increasing deformation ratio or with increasing compressed stress, while it decreased with an increase in cooking time. Roughness of cooked noodle surface could be evaluated by X-ray mode with SEM. Stickiness of cooked noodle decreased with the NaCl content, and gave a maximum value at 10 minute of mixing time. Adhesiveness and stretch of cooked noodle decreased by dough relaxation, but adhesive force showed a high value at 2hr of dough resting time. Stickiness of cooked noodle increased with increasing standing time after cooking. A significantly high correlation was obtained between adhesiveness and adhesive force, and also between adhesive force and friction force. Slime of cooked noodle showed a relatively high negative correlation between each parameter of stickiness. Highly negative correlations were also obtained between the total sensory value (SV) of surface characteristics of cooked noodle and adhesiveness, between SV and adhesive force and between SV and friction force, respectively.

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The salt contents of pork meat (pork spare ribs) increased from 0.5% of raw meat to 3.1% after one day's salting process at 4% (w/w) NaCl addition, and then the contents was almost constant. By DSC analysis, it became clear that denaturation of the meat mainly occured on myosin by salting. As the denaturation proceeds, the enthalpy change, ΔH, (cal/g of meat) of 1.212 rapidly decreased. to 0.830 for 3 day's salting and then gradually decreased to 0.736 for 27 day's salting. Elastic modulus, viscosity and rupture strength of the meat increased during salting as a whole. The change of dynamic rigidity of the pork meat pastes by heating exhibited the tendency to decrease at the temperature range from 52°C to 58°C after 6 day's salting. The result was considered to come from the structure change of the sample due to thermal denaturation of myosin.

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Inhibitory effects of many species of vegetable and plant extracts (45 species of vegetable, 15 species of fruits, 2 species of nuts, 20 species of grass, 21 species of tree) on the mutagenecity of C-nitro and c-nitroso compounds formed by reaction of sorbic acid with sodium nitrite were investigated by using of Rec-assay method. Extract of persimmon (Diosyros.), knotweed (Polygonum longisetum) and Japanese-aucuba (Aucuba japonica) remarkably inhibited the mutagenecity. The Fraction III separated from persimmon extract by ultracentrifugation inhibited the mutagenecity and moreover its inhibitory effect on the mutagenecity still remained after treatment with some proteases. This facts suggests that the inhibitory factor in the persimmon extract against the mutagenecity may be constituents other than proteins. In another experiment, inhibitory effect of persimmon extract on formation of nitrosomorpholine in the reaction of morpholine with sodium nitrite was investigated using HPLC. Moreover, addition of an excess of sodium nitrite increased the content of nitrosomorpholine formed in the reaction mixture of morpholine with sodium nitrite containing persimmon extract. However, the content did not change by addition of an excess of morpholine. From these results, the inhibitory substance was considered to be kakitannin which can scavenge sodium nitrite.

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Soybean oil hydrogenation using hydrogen storage alloys has been studied on purpose to utilize their catalytic activity and hydrogen desorbed from them. Hydrogenation of soybean oil was carried out in a 1l dead-end type reactor. Before starting hydrogenation, hydrogen was absorbed into the alloy in the reactor maintained at 10°C followed by injection of soybean oil into the reactor. Hydrogen storage alloys were evaluated for the catalytic activity and selectivity. Of hydrogen storage alloys employed in this study, LaNi₅ group of which crystal system was hexagonal promoted hydrogenation. Conventional Ni catalyst added to LaNi₅ accelerated the hydrogenation. Pulverization of the alloys by repeating absorption and desorption of hydrogen increased the active sites on them, resulted in their enhanced catalytic activity. Hydrogen storage alloys in soybean oil re-absorbed hydrogen sufficiently to participate subsequent hydrogenation, which indicated that the alloys were feasible for recycling use. Among LaNi₅ group, LaNi_4.0 Al_1.0 promoted significantly non-selective hydrogenation, therefore the prepared oil contained a low level of trans-acid and its solid fat content was less dependent on temperature.

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The heating process of foods, in general, depends on the heat transfer such as heat conduction, heat convection and thermal radiation that are derived by the temperature difference between foods and that sources. The homogeneous and quick heating of foods is not expectable for these heat transfers because of the poor heat transfer coefficient of foods and the avoidance of overcooking on the food surface. On the other hand, the Ohmic heating will depend its heating on the generated heat when the electricity passes through the foods. According to its principle, the homogeneity of foods will result in the homogeneous and quick heating. However, it is often observed that a homogeneous paste food such as "Miso", fermented soybean food, show the bigger temperature deviation than expected between its center and outer surface even under the consideration of its heat diffusion. In this paper, Miso was used and measured its temperature change at 5mm intervals from the center to the surface during the Ohmic heating at 20kHz of alternating current. Finite Element Method (FEM) was examined to the mathematical corresponding model to the obtained temperature changes. The model that the electric conductance of Miso was changeable depending on the temperature and the voltage drop was changeable depending on the electric conductance showed good agreement with the actual result of temperature changes. The model also indicated that the crosswise temperature change of Miso to the applied electrical field, was enhanced and the longwise one was suppressed as its Ohmic heating progressed. The model will be very effective to design the electrode for Ohmic heating to achieve the real homogeneous and quick heating of foods.

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The peptides with average molecular weight 315 were prepared from sardine proteins by Bacillus licheniformis alkaline proteases. The short chain peptides had no bitter taste and little fish flavor. The short chain peptides showed the potent angiotensin I-converting enzyme (ACE) inhibitory activity, which was high resistance to the hydrolysis by any digestive proteases. ACE inhibitory activity of short chain peptides didn't change by the pig intestinal fluid after pepsin digestion. Compared with the long chain peptides in sardine muscle hydrolyzate prepared by digestive proteases, inhibitory activities of various digest were weaker than that of the short chain peptides derived from alkaline proteases hydrolyzate. The short chain peptides were assayed in spontaneously hypertensive rats and found to reduce on blood pressure.

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To elucidate the mechanism of softening of Combu fronds by seasonings during the cooking process, calcium release from calcium alginate (Ca-Alg) immersed in a solution of sodium salt of organic acid was examined. Regardless of concentration of seasonings, calcium release from Ca-Alg reached equilibrium following immersion for a few minutes. The effect of immersion temperature on the rate of calcium release was not so significant. The lower the degree of polymerization of Ca-Alg, the greater the degree of calcium release, but differences were not so significant. Sodium salts from organic acids were classified into four groups according to the degree of calcium release. The most effective group consisted of disodium hydrogen citrate and sodium citrate, followed by sodium malate and sodium tartarate and finally by sodium lactate, sodium succinate, sodium hydrogen tartarate and sodium dihydrogen citrate. The least effective group consisted of sodium acetate. Ion exchange selectivity coefficient for exchanging Ca²⁺ for Na⁺ was significantly larger in the case of sodiumcitrate, sodium hydrogen citrate, sodium malate and sodium tartarate. These results revealed the type of seasonings and the concentration which were most effective for release of calcium from Ca-Alg.

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Volatiles including allylisothiocyanate (AIT) in herbs were examined to evaluate their antimicrobial activities by gaseous contact. Combination effects of volatiles were also examined. AIT suppressed the growth of all microorganisms tested. Salicylaldehyde also showed antimicrobial effects to the all fungi and bacteria tested. Other aldehydes showed inhibitory effects on the growth of fungi and Bacillus subtilis. Hydrocarbons inhibited the growth of B. subtilis. In the case of Staphylococcus aureus, carvacrol was more effective to suppress its growth than AIT. Masking effects of plant volatiles on AIT odor were confirmed with sensory analysis. Citrus oils and vanilla flavor were superior for masking AIT odor. Antimicrobial effects of AIT were not affected by mixing with plant volatiles.

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In this paper, effects of humidity on the physiological responses and the ripening characteristics of the Philippine bananas (Musa AAA group, Cavendish subgroup cv. Giant Cavendish) were studied at 95%, 80% and 60% relative humidity for the fundamental consideration of postharvest handling in bananas. Though almost no effect of humidity on the time of onset of respiration climacteric and ethylene emanation was observed, high respiration rates and elevated ethylene productions occurred during subsequent ripening at low humidity. Yellowing of peel color and softening of pulp were also accelerated at low humidity. Furthermore, changes in citric and malic acid contents of pulp which increased during ripening following decrease prior to climacteric peak of respiration rate, were hastened at low humidity. From the results above, it may be concluded that the ripening processes of bananas are promoted by the increased water deficiency at low humidity.

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The development in taste and texture of Tofu-misozuke, soybean curd fermented in miso (soybean paste) in Fukuoka prefecture, was studied. It was revealed from sensory tests that cheeselike taste developed in Tofu-misozuke during ripening. A decrease of rheometric hardness was also observed during ripening. The ratio of water-soluble nitrogen to the total nitrogen was 13% before ripening and it increased to 41% after 2 days ripening, and then reached 46% after 8 days ripening. The amount of free amino acids in TCA soluble fractions increased during ripening, and arginine, glutamic acid, lysine and leucine were mainly detected in them. We also observed by electrophoresis that proteolysis took place with the constituent proteins of tofu during ripening. Some polypeptide bands such as β-conglycinin subunit and acid subunit of glycinin disappeared and bands of less than 20kd increased. Scanning electron microscopic analysis showed a gradual disintegration of the network structure of tofu protein.

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The reason of more fading color of fall chum salmon (Oncorhynchus keta) muscle than that of sockeye salmon (Oncorhynchus nerka) by heat processing was investigated. Fading was attributed to the following phenomenons:(1) Decrease in Hunter's chromatic a as well as b values was more pronounced in chum salmon than in sockeye salmon against the same decrease in carotenoid content. (2) Hunter a value as well as b value of salt-soluble protein+stroma protein fractions of fall chum salmon muscle decreased more than that of the sockeye salmon by the heating process.(3) Sensitivity of human eyes to color changes are differed by difference of a value. Thus, chum salmon muscle whose a value is originally less than sockeye salmon tends to exhibit an apparent fading compared to sockeye salmon.

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The effects of lyophilization on the rheological properties of gluten prepared from wheat flour by washing with or without N-ethylmaleimide (NEMI) were studied. The extensibility of the gluten prepared with NEMI (NEMI-gluten) decreased by lyophilization, but recovered in the presence of cysteine. These phenomena were more noticeable on the gluten prepared without NEMI (control-gluten). The lyophilization or freezing of control-gluten caused the formation of larger amount of SDS-insoluble fraction than NEMI-gluten. The SDS-insoluble fraction will be high molecular weight aggregate containing intermolecular disulfide bonds, as the fraction was solubilized with 2-mercaptoethanol. Gel filtration chromatography on Sepharose 4 B and a viscosity measurement showed that high molecular weight gluten of NEMI-gluten remained in SDS-soluble fraction because of suppression of the formation of an aggregate. These results suggested that the disulfide polymer of gluten proteins formed during lyophilization will be responsible for the decrease in the extensibility of gluten.

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Changes in physical properties of Japanese type noodle during drying and effect of drying on the texture of the cooked noodle were investigated by using a rheometer. Both logarithmic values of bending strength and bending Young's modulus of dry noodle plotted against moisture content increased convexly upward with a drying except of noodles which oxidized with potassium iodate or prepared by the dough with pH above 7. Cutting strength of cooked noodle decreased with a a decrease of moisture content to about 25% and it increased by additional drying. Both bending strength and bending Young's modulus of dry noodle decreased when salt was added. Moisture content of the dry noodle, which gave the minimal cutting strength to the noodle when cooked, shifted to the lower value when added salt was increased. High bending strength was obtained for cooked noodle prepared from dough which added water was 42.5-45.0%. Dough resting did not affect the mechanical properties of dry noodle, but increased cutting strength of cooked noodle. Emulsified oil decreased both mechanical strength of dry cooked noodles. High mechanical strength was obtained for noodle during drying prepared from the dough with high gluten content or with higher pH than 7.

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Alginic acid has a physiological function to promote the excretion of sodium ion. As the chemical structure is known to affect the function of alginic acid as a dietary fibre and also the affinity for ions to a great extent, it is necessary to clarify the effect of the chemical properties on the sodium ion binding capacity in order to establish the extraction conditions and origins of alginic acid having higher binding capacity. In the present investigation, alginic acid (H-Alg) and potassium alginate (K-Alg) were extracted from Laminaria japonica Areschoung, Ecklonia cava Kjellman and Sargassum hemiphyllum under different acid hydrolysis conditions, and the relationship between the sodium ion binding capacity in vitro and the chemical properties such as the composition and sequence of uronic acid and the molecular weight were examined. The ratio of D-mannuronic acid to L-guluronic acid (M/G ratio) and the molecular weight of K-Alg prepared in this study were in the range of 0.3 to 1.2 and 1.5×10⁴ to more than 15×10⁴ depending on the species of brown algae and the extraction conditions, respectively. In spite of such a large variation of the chemical properties, no significant difference was observed in the sodium ion binding capacity, suggesting that the sodium ion binding capacity does not depend on those chemical properties. It was noteworthy that K-Alg from S. hemiphyllum had a much lower M/G ratio (0.3-0.4) and a higher percentage of homopolymeric blocks of L-guluronic acid than that from the others, while the yield and the sodium ion binding capacity were equivalent. As the homopolymeric blocks of L-guluronic acid were less susceptible to enter- obacteria than the homopolymeric blocks of D-mannuronic acid, S. hemiphyllum may be a promising bioresourse for the extraction of alginate that can have higher capacity to excrete sodium ion.

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Alkaline-pyrophosphate leaching under reduced pressure is a method devised for removing fat and preventing protein denaturation effectively from fatty pelagic fish (so-called red-meat fish) meat in surimi processing. In this study, an attempt was made to improve the quality of minced sardine meat by a modified vacuum-alkaline leaching. Minced sardine meat was briefly washed once with a small quantity of cold sodium bicarbonate solution containing pyrophosphate in vacuo (at about 10mmHg for 20min) to liberate an excess amount of fat, and to retain as much tasty substances as possible. The free fat and excess aqueous layer were removed by centrifugation. It was found that by this treatment, more than one third of fat in the original minced meat was removed, and that the solubility of myofibrillar protein in the minced meat and its gel-forming ability increased. The hamburger prepared from vacuum treated minced meat was somewhat sticky and elastic compared with ordinary meat hamburger (such as beef hamburger), and had a bland taste with little fishy smell.

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"Shibazuke" is a traditional Japanese salted and fermented pickles, made of vegetables (eggplant etc.) and leaves of perilla. The quality of Shibazuke is characterized by sour taste, magenta color and typical flavour. In this paper, we studied the function of lactic acid bacteria in the quality of Shibazuke. Lactic acid bacteria, cultivated in GYP agar medium, were isolated from Shibazuke fermented in five different stages. Five kinds of lactic acid bacteria were identified on the basis of morphological observation and physiological properties. We found it obviously important that L. plantarum grew sufficiently during twenty day's fermentation for producing the typical magenta color and good sour taste of Shibazuke especially.

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Decomposition of added phloxine (Food red No. 104) and β-carotene in oils (olive, soybean and whale oils), and its extent in oils with different degrees (peroxide value 2, 98, 292 and 695 meq/kg) of oxidative deterioration were investigated. Oils containing 0.01% phloxine and 0.1% β-carotene were placed in a beaker (4×5.5cm, oil: 10g) and oxidized at a window (room temperature: 25±2°C). Oxidative deterioration of oils and the decomposition of phloxine and β-carotene in oils during storage were determined by Oven test (at the window) and a Lovibond colorimeter, respectively. Phloxine and β-carotene with oxidative products (oxidized fatty acids [OFA]; fatty substances insoluble in petroleum ether) separated from oxidized soybean oil in ethanol were placed in a test tube (10ml), and decomposition of phloxine and β-carotene during storage at the window were determined by absorption spectrometry at 548.5 and 470nm, respectively. The degree of decomposition of β-carotene in oils was observed to be much higher in whale oil than in soybean and olive oils during storage, and it depended on the degree of oxidative deterioration of oils. On the other hand, no significant large difference could be found in the decomposition of phloxine among the three kinds of oils. The decomposition of phloxine and β-carotene in an ethanol solution was apparently promoted by OFA, and it increased with increasing concentration of OFA.

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Glycoalkaloids (GAs), e.g. α-chaconine and α-solanine, are found in potatoes. Sometimes, they cause food poisonings. We have developed easy and rapid method to detect GAs in potato using a high performance liquid chromatograph (HPLC). GAs were analysed under the following conditions; column: Inertsil C₈ (250mm×4.6mmI.D.); mobile phase: 20mM phosphate buffer+acetonitrile (67:33, 0.7ml/min); wavelength to detect: 205nm. GAs were extracted with methyl alcohol and analyzed with HPLC. This method was applied to edible and other parts of potato plant.α-Chaconine was found in roots (2520mg/kg), leaves (489mg/kg), periderm tubers (263mg/kg) and stems (62mg/kg).α-Solanine was found in roots (1400mg/kg), leaves (152mg/kg), periderm tubers (109mg/kg)and stems (26mg/kg). In cortex tubers, α-chaconine and α-solanine were not found at the detection limit of 10mg/kg.

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Chinese noodle was manufactured from wheat flour (protein content 11%) in the presence of microbial transglutaminase (MTGase). Effect of MTGase was evaluated by evaluating breaking strength of MTGase-treated noodles with and without pickling in vinegar or retorting. Scanning electron microscopy (SEM) was employed to observe microstructure of the noodles. In both pickled and retorted noodles, breaking strength increased correspondingly with MTGase concentration. After boiling, the breaking strength of MTGase treated noodles was higher than that of the control noodle. SEM investigation indicated that protein network became stronger by the MTGase treatment. These results suggest that physical properties of Chinese noodles could be improved through the formation of ε-(γ-glutamyl) lysine by MTGase.

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The effects of coating oil quantity, drying process and fungi on oxidative deterioration of coating oil on "Tenobesomen" (a kind of handmade vermicelli) were studied during storage at room temperature up to one year. The amount of cottonseed oil coated on vermicelli did not give any effect on its peroxide value (POV), while the acid value (AV) decreased with an increase in the oil quantity. The drying process affected somewhat on the oxidation of coating oil, i.e., POV was higher in the machine-dried vermicelli than that in the sun-dried one, while AV was lower in the machine-dried vermicelli. Application of the mycelium and metabolites of a fungus, Eurotium sp. to vermicelli decreased POV and increased AV during storage.

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Influence of a reduced sodium chloride (NaCl) content and application of potassium chloride (KCl) as its substitute on bread making was studied. Dough and bread with 0.5-2% NaCl or KCl were prepared, and their rheological and bread making properties, sensory evaluation and shelf-life were investigated. The influence of KCl substitution on bread making quality was also studied. Reduction of either NaCl or KCl affected more on resistance to extension (R) than on extensibility (E) in rheological properties. When NaCl was reduced to below 1%, R was extremely decreased. Both R and E of dough with 2% KCl were almost the same as those with 1% NaCl. Total carbon dioxide production of the non-sugar bread dough decreased with an increase in NaCl or KCl level. It is considered that addition of at least 1.25-1.5% of NaCl is required for making bread with satisfactory quality and shelf-life. The use of KCl alone gave undesirable effect on bread quality due to its better taste. A sensory evaluation test did not exhibit a significant difference between bread with 1% NaCl and that with 2% NaCl. Bread making property and bread quality in the case of using both 1% NaCl and 0.25-0.5% KCl were as good as those when only NaCl was used, and sensory evaluation also indicated the taste of NaCl-KCl bread was as good as that of regular NaCl bread. From these results, it is considered that the amount of NaCl can be cut down to 1.25% and if 0.25-0.5% NaCl is substituted for KCl, the NaCl level could be reduced to 1% in white bread formula.

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The composition of pigments in two different colored okra cultivars was studied. The carotenoids were separated by column, thin layer and high performance liquid chromatography and identified by order of absorption affinities on the column and by their absorption spectra. The contents and kinds of pigments were as follows: (1) The green colored okra cultivar' Better five' contained chlorophyll a (470μg/g) and chlorophyll b (190μg/g) as the major pigment; a small amount of α-carotene (0.2μg/g), β-carotene (11.4μg/g) and xanthophylls (43.2μg/g) were also present. (2) The reddish purple colored okra cultivar' Benney' contained chlorophyll a (120μg/g) and chlorophyll b (60μg/g) as the major pigment: a small amount of α-carotene (tr.), β-carotene (4.2μg/g) and xanthophylls (27.6μg/g) were present, and anthocyanins were detected. (3) From the above results, it was found that the 'Better five' of high chlor phyll contents paralleled with high carotenoid contents and the 'Benney' of low chlorophyll contents paralleled with low carotenoid contents. (4) Xanthophylls were consisted neoxanthin, violaxanthin, lutein epoxide and lutein.

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The effects of non-dialyzable extracts of some edible plants on the inhibition of melanogenesis of B 16 mouse melanoma cells, the immunoglobulin secretion of HB 4 C 5 human-human hybridoma cells, and the differentiation of U-937 human myeloid leukemia cells were examined. The non-dialyz-able extracts of green tea, eggplant, kiwi fruit, carrot and spinach inhibited melanogenesis of B 16 cells. The highest activity on inhibition of melanogenesis was shown by the non-dialyzable extract of green tea, and the extract decreased melanin production by 46% compared with the control. The IgM secretion of HB 4 C 5 cells was promoted by the non-dialyzable extracts of green tea. The processed spinach extract induced the adhesion and morphological change of U-937 on the culture plate, and the expression of cell surface antigens of CD 11 b of U-937 cells was also induced by this extract.

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The quality of food is greatly influenced by freezing rate and temperature history during freezing process. We applied unsteady-state heat conduction theory for analyzing the fruit and vegetable juices freezing process, and a cylindrical heat transfer model including phase change is developed to predict the freezing curve and changes in temperature profiles for fruit and vegetable juices, apple, orange and tomato, during freezing period. The collocation method was applied to solve the fundamental equation assuming that thermal properties of juices depended on temperature. Predicted temperature of juices was closely matched with observed data. Compared with the paper in Nippon Shokuhin Kagaku Kougaku Kaishi, 42 (12), 977 (1995) by TANAKA et al., this model could express the both freezing and thawing process. It is expected that this result would be useful for frozen food freezing operations.

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Physicochemical properties of a new polysaccharide produced by Bacillus circulans were investigated by comparing with those of xanthan gum, locust bean gum, guar gum, sodium alginate and carboxymethylcellulose (CMC). The polysaccharide produced by B. circulans (BPS) showed a high water-holding capacity at 0.1% concentration together with a good emulsifying effect of oil next to xanthan gum. The viscosity of 1% BPS solution was about 900cP, the value being nearly equal to that of xanthan gum. The viscosity of BPS solution was almost unchanged at a pH range between 5 and 9, and the heat treatment of BPS at 100°C for 30min brought about a 25% decrease in viscosity. The addition of 30% glucose to BPS solution enhanced the viscosity by 20%, but the addition of 1% citric acid lowered the viscosity to about 30%. A synergistic effect of BPS on the increase in the viscosity of locust bean gum or guar gum solution was observed. A maximum viscosity of a mixed solution of BPS and locust bean gum or guar gum was obtained at a ratio of about 2:8(v/v). A Young's modulus of a film prepared from BPS was apparently higher than that of CMC and guar gum.

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The contents of flavonol glucosides in yellow, red and white onions harvested in Hokkaido were measured. Seven varieties of yellow onion averaged 16.8mg/100g of quercetin-3, 4'-di-O-β-glucoside, 18.5mg/100g of quercetin-4'-O-β-glucoside, 0.8mg/100g of quercetin-3-O-β-glucoside and 2.9mg/100g of isorhamnetin-4'-O-β-glucoside. The red onion contained about 3-fold the amount of these glucosides while the white onion contained no detectable amounts of flavonols. The content of each flavonoid was higher in the outer scales than in the inner ones. Flavonol glucosidases and UDPG: flavonol glucosyltransferases were detected in the onions. The optimum pH of quercetin-3-O-β-glucosyltransferase, 4'-O-β-glucosyltransferase, 3-O-β-glucosidase and 4'-O-β-glucosidase was 6.0, 8.0, 4.5 and 7.0, respectively. In all the onion varieties, the activity of quercetin-4'-β-glucosyltransferase was higher than that of 4'-O-β-glucosidase, but the activity of 3-O-β-glucosyltransferase was lower than that of 3-O-β-glucosidase. Since quercetin-4'-O-β-glucosyl-transferase was not able to transglucosylate quercetin-3-O-β-glucoside and rutin, the precursor of quercetin-3, 4'-di-O-β-glucoside is estimate to be the 4'-O-β-glucoside and not the 3-O-β-glucoside.

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