Heat-based drying methods often produce undesirable changes in the physical and chemical properties of materials. This paper describes the non-thermal drying capability of a relatively new technique using electrohydrodynamic (EHD) principles. The EHD system consisted of a DC power supply with a single overhead point electrode and an aluminum dish filled with 1% agar gel which acted as the grounded plate electrode. The EHD drying kinetics was highly linear (R2=0.999) and showed about three times faster drying rate than the ambient air-drying control. The relationship between the water vapor flux and the electric field strength was governed by a power law (R2=0.90), whereas the former varied logarithmically with the variation of the electrode gap (R2=0.91). The EHD-induced electric wind was considered to be the principal driving force which accelerated the drying rate through turbulence and vortex motions. Enhanced EHD sublimation occurred from the frozen gel at −14°C.
The effect of sucrose on water activity, the fraction of freezable water, and viscoelastic properties of alginate dispersed aqueous systems was investigated. Water activity and the fraction of freezable water were almost independent of the examined alginate concentration but decreased with increasing sucrose concentration, indicating that colligative properties of those systems were mainly determined by the sucrose content. The specific viscosity values were represented by a single master curve for all the systems containing a concentration of alginate lower than 0.5%(w/w). For the systems containing a concentration of alginate higher than 0.5%(w/w), the ratio of the loss modulus, G", to the storage modulus, G'; G"/G' (=tan δ) was almost independent of alginate concentration in the systems without sucrose, but the G"/G' values decreased with increasing alginate concentration in the systems containing sucrose. These results suggest that interactions between sucrose and alginate were negligible at a low alginate concentration, but that the elastic nature of the systems was enhanced due to sucrose-alginate interactions at a high alginate concentration.
Lipase from Candida antarctica immobilized on a macroporous acrylic resin, Novozym®435, could catalyze the condensation of L-ascorbic acid and medium-chain fatty acids with chain lengths of 6 to 12 in acetonitrile. The chain length did not significantly affect the progress of the condensation. The water content of acetonitrile significantly affected the equilibrium conversion of the condensation of L-ascorbic acid and lauric acid. A higher conversion was achieved at a lower water content. The equilibrium constant for the condensation was determined to be about 1.6 at 60°C.
A new phase inversion method was developed by modifying the membrane emulsification method with preliminary emulsification. A phase-inverted O/W emulsion of which the volume fraction of dispersed phase, φ, was higher than 0.5 was prepared by passing a pre-emulsified low concentration W/O emulsion (φ<0.5) through a hydrophilic polytetrafluoroethylene (PTFE) membrane. A hydrophobic PTFE membrane was used to prepare the phase-inverted W/O emulsion from the pre-emulsified O/W emulsion. The highest dispersed phase volume fraction, φmax, of the phase-inverted emulsions obtained in this study was 0.90 and 0.84 for the O/W and for the W/O type emulsions respectively. The phase-inverted high concentration emulsions showed high stability. The values of φmax as well as the stability of the phase-inverted emulsions depended on the kind and concentration of emulsifying agents used.
The oxidation of shrimp cracker by the influence of water activity (Aw) at 30°C was determined by peroxide value (POV) and free radical concentrations. Although POV at 0 Aw increased rapidly from the initial value of 8.6 to 30 meq/kg of lipid during 105 days of the storage period, at 0.11-0.32 Aw it increased gradually and at 0.42-0.67 Aw it remained almost unchanged from the initial value of 8.6 meq/kg of lipid throughout this period. The free radical concentration measured by electron spin resonance spectrometer changed complicatedly with the increase in storage period at various water activities. Lower activity caused higher level of free radical concentration throughout the period. At 0-0.23 Aw, the gradual increase in free radical concentration was observed during the storage period between 60 and 105th days but no distinct changes of free radical value were observed at 0.32-0.67 Aw for this period. A peak of free radical concentration was observed in each water activity (except 0.67 Aw) at the 15th day of the storage period.
Aspergillus awamori possesses the ability to digest raw starches. For the effective utilization of starchy crops in South-Asian countries, it is important to digest raw starches without cooking for the industrial fermentation process. In this study, mutant strains of Aspergillus awamori IFO4033 with increased activity of α-amylase were isolated from freeze dried spores irradiated with C5+ ion-beams. The frequency of the mutation and the activity were higher for C5+-irradiated samples than those for gamma-irradiated ones. Compared to the digestibility of raw starches from cassava, sago and sukun by the parent strain, it increased two- to threefold by some mutant strains obtained from C5+ ion-beam irradiated spores.
To research wider uses of the low temperature steam heating process, blade vegetables were heated by steam of temperature adjusted from 55°C to 80°C for 5-30 min. The treated vegetables were used for analysis of various ingredients, measurement of color tone and texture, and evaluation of taste. To determine possible sterilizing effect of the process on E. coli, broccoli soaked in nutrient broth with the germ was treated at 60 and 65°C. The breaking stress of Chinese cabbage leaf stalk increased when treated for 30 min at 60°C. The color tone of leaves heated for 10 min at 65°C scarcely changed during storage for 48h at 5°C. The E. coli adhering to broccoli declined from 10 CFU/g to <30 CFU/g after steaming for 5 min at 60°C. The desirability of cabbage steamed for this same period and temperature showed little difference from the fresh sample. Total vitamin C in both Chinese cabbage and cabbage steamed for 5 min at 60°C remained over 90%, while there was augmentation of the γ-amino butyric acid in the samples at this temperature. The water soluble pectin in Chinese cabbage at 60°C decreased and NaOH soluble pectin increased. Consequently, we would like to propose that the low temperature steam heating process is a very useful way to prepare blade vegetables, because the color tone and taste of the treated samples were almost the same as those of the fresh sample, and E. coli was sterilized if condition of treatment were adequate.
The protective effects of hot water extracts from safflower petals (Ex) against paraquat (PQ)-induced oxidative were examined in rats. Ex significantly relieved decreases in food intake and body weight gain, and increase in lung weight which were induced by the administration of the paraquat diet. Ex also relieved increases in liver TBARS, and decreases both in the catalase activity in liver mitochondrial fraction and the level of liver triacylglycerol in the PQ-fed rats. These results indicate the possibility that Ex acts preventively against oxidative stress.
The enzymatic hydrolysis of soybean protein isolate (SPI) was investigated using commercially available Bacillus sp. proteases for reduction of soybean allergenicity. An alkaline protease, Proleather FG-F, was found to be useful for degradation of the major soybean allergens (Gly m Bd 30 K, Gly m Bd 28 K and α-subunit of β-conglycinin), whereas all proteases tested so far preferentially degrade β-conglycinin in native SPI at 70°C. The hydrolysate prepared using Proleather FG-F retained gel-forming ability, while the reactivity with IgE in serum of soybean-sensitive patients was markedly reduced. Thus, this hydrolysate may be especially useful as an ingredient in hypoallergenic foods.
Abilities of 31 kinds of raw fruits, 33 kinds of raw vegetables, and 2 kinds of raw mushrooms to remove the odor of methylmercaptan were examined. Apple, pear, loquat, peach, plum, prune, apricot, cherry, grape, lettuce, chicory, udo, perilla, peppermint, basil, burdock, potato, eggplant, and mushroom (Agaricus bisporus) showed high deodorizing activity. Highest activities were obtained with burdock and unripe fruits (apple and pear). These green foods are believed to contain large amounts of both polyphenolic compounds and their specific polyphenol oxidases, by which oxidation reaction causes addition reaction of the resulting quinone radicals with SH-compounds such as methylmercaptan. The sequential reactions can be called enzymatic deodorization. Sensory examination or measurement with an odor sensor indicated that eating apple, unripe pear and prune significantly removed bad breath caused by eating garlic. The enzymatic deodorization method has great potential for eliminating bad odors from the environment including bad breath.
A total of 45 Japanese and Bangladeshi water fish and fishery products were investigated for radical-scavenging activity using a 1,1-diphenyl-2-picrylhydrazyl-HPLC method. Among the 35 Japanese fish and fishery products (37 items), cutlassfish showed the highest activity (565.7 mg Trolox eq/100 g) and seaweed showed the lowest (24.9 mg Trolox eq/100 g) on a fresh weight basis. Dried bonito, crab (abdomen), Pacific saury, horse mackerel, skipjack, halfbeak, tuna, sand borer, Pacific mackerel, barracuda and anglerfish showed activities of over 100 mg Trolox eq/100 g. The radical-scavenging activities of 10 Bangladeshi fish and fishery products varied from 37.9 to 202.1 mg Trolox eq/100 g. The stronger activity of cutlassfish was attributed to its silver colored skin. The active component was suggested to be uric acid, the metabolic end-product of guanine.
The relationship between lipid oxidation in pulverized niboshi which occurred during freezing and further oxidation, free amino acid loss, and browning which took place after the sample had been thawed was investigated. Lipid oxidation occurred in the samples which were kept frozen at −20°C, however, browning and free amino acid loss did not. This oxidation affected the rate of lipid oxidation, the browning, and the decrease of free amino acids in the niboshi once it had been thawed and stored at 25°C. It was apparent that the longer the niboshi was stored in a frozen state, the faster was the rate of browning, lipid oxidation, and loss of free amino acids after thawing. The free amino acids which decreased were methionine, histidine, ornithine, and lysine. When the same sample was packed with nitrogen gas, browning, lipid oxidation, and amino acid loss were almost eliminated. It was also found that if the thawed sample was left for five days at 25°C and then packed in nitrogen gas, the lipid oxidation and decrease in free amino acid levels could be controlled, although the browning process could not, and the sample color changed to reddish-brown. The results suggested a correlation between the lipid oxidation which occurs during freezing and the browning, decrease in free amino acids, and further progression of lipid oxidation which takes place after thawing. This deterioration in quality can be prevented by using the nitrogen gas packing immediately after processing of the food product.
An intracellular cysteine protease inhibitor (ICPI) from Chlorella sp. was purified to homogeneity judging from polyacrylamide gel electrophoresis. The purified inhibitor had a molecular mass of 410kDa and a pI of 5.3. ICPI retained 100% of the original activity even after heating at 100°C for 5 min. It exhibited an inhibitory activity against the proteolytic activity of papain, ficin, chymopapain, calcium dependent neutral protease and bromelain, but not against cathepsin B, pepsin, trypsin, or α-chymotrypsin. The inhibitory activity was inactivated by α-chymotrypsin. ICPI contained 76% carbohydrate residues by weight and inhibited papain at a ratio of 1:3. From these results, we assume that ICPI is a novel type of cysteine protease inhibitor.
The enzymatic transglycosylation to monoacylglycerol (MG) to synthesize a more hydrophilic emulsifier was investigated using various α-glucosidases. Among the α-glucosidases examined, rice α-glucosidase had the highest transglucosylating activity to MG. The formation of the glucosylated MG was more effective in the presence of acetone because of higher solubility of MG. The structure of the purified glucosylated MG was identified as a mixture of (2R)-1-monoacyl-3-O-α-D-glucopyranosyl-sn-glycerol and (2S)-1-monoacyl-3-O-α-D-glucopyranosyl-sn-glycerol by FAB-MS, 1H-, 13C-NMR analyses and α-, β-glucosidase treatments. The solubilities of monocaprylin [MG(C8:0)], monocaprin [MG(C10:0)] and monolaurin [MG(C12:0)] were increased by glucosylation. The surface tensions of the aqueous monocaprylin monoglucoside [MG(C8:0)-G], monocaprin monoglucoside [MG(C10:0)-G] and monolaurin monoglucoside [MG(C12:0)-G] solutions significantly decreased with up to 0.01% concentration of emulsifiers, and then decreased slightly at concentrations above that. The foamability increased with the MG(C8:0)-G, MG(C10:0)-G and MG(C12:0)-G contents. The foamability and the foaming stability of MG(C8:0)-G, MG(C10:0)-G and MG(C12:0)-G were superior to those of the original MG and the other commercial emulsifiers.
Two types of ume fruit (Japanese apricot) products, hardened fruit and salted and sun-dried fruit, were prepared using calcium gluconate, a calcium compound which has attracted interest recently because of the proliferation of Lactobacillus bifidus, as a substitute for calcium hydroxide; the properties of the products were compared with conventional products prepared using calcium hydroxide. Calcium gluconate acted as a hardener similar to conventional calcium hydroxide in hardened ume fruit products. The color of the product lost some of its redness and turned more yellowish. Since calcium hydroxide made the surface of the hardened ume fruit product redder, which is not preferred by consumers, calcium gluconate had a favorable effect on the surface color. Another problem regarding taste was also solved by using calcium gluconate. The product prepared using calcium hydroxide tasted bitter, while calcium gluconate did not leave a bitter taste in the hardened ume fruit product, and the difference was significant (p<0.01). The bitterness threshold in the solution was also lower with calcium gluconate compared with the case of calcium hydroxide. The effect of calcium gluconate on the salted and sun-dried ume fruit product was the same as calcium hydroxide and it was apparent that calcium gluconate prevented damage to the skin.
The aging rate of fungi-inoculated tofu was found to be 34.5% and that of 1-month-old and 3-month-old nyufu fermented milk 56.2% and 71.4%, respectively. The quantity of free amino acids in nyufu increased to approximately 10 times the level in fungi-inoculated tofu. Because solubilization of protein was shown to be associated with the duration of nyufu aging, changes in the molecular weight of the water soluble nitrogen fraction were assessed using HPLC gel filtration chromatography. Almost no peptides with a molecular weight over 5000 were found in the 3-month-old nyufu; approximately 57% had a molecular weight of 1800, and 38% existed at peaks below a molecular weight of 255, indicating a decreased molecular size and a noticeable difference in molecular weight distribution. Water soluble peptides were separated into acidic, basic, and neutral fractions. The neutral fraction had the highest score of sensory evaluation. The concentration of glutamic acid and aspartic acid was high in neutral and acidic fractions, reflecting the palatability. Approximately 50 of the peptide chromatograms were detected in peaks 2 and 3 of the neutral fraction, which was high in the sensory evaluation. This agreement between the sensory evaluation results and chromatographic analysis indicates that peptides influence the taste of nyufu.
The antioxidative flavonols, quercetin and kaempferol in the unused parts of 10 types of food plants commonly consumed in Japan were determined by paper chromatography and ultraviolet spectroscopy. The purpose was to determine a whether these portions might be usable as an antioxidant to protect foodstuffs from oxidation. The leaves of burdock and moroheiya and used tea leaves were found to contain an abundance of quercetin glycosides. These were isolated and identified as quercetin 3-O-ramnoglucoside (substance 1(Tables 1,2))(burdock), quercetin 3-O-ramnoside (substance 5)(moroheiya), and quercetin 3-O-glucoside (substance 4)(used tea leaves). The leaves of persimmon and peach trees contained a large amount of kaempferol glycosides, and these were isolated and identified as kaempferol 3-O-glucoside (substance 2(Tables 1,2))(persimmon), and kaempferol 3,7-O-glycoside-(substance 3)(peach tree). Among the flavonols, quercetin 3-O-glucoside (substance 1) from the leaves of burdock, and kaempferol 3,7-O-glycoside (substances 3 and 10) from the leaves of peach tree and ume (Japanese apricot) tree are the first reported here. Our data will provide a basis for the possible utilization of the leaves of burdock, persimmon and peach trees, and used tea leaves as antioxidants to protect foodstuffs from oxidation.
The physical properties of trout skin gelatin were compared with those of bovine skin gelatin to develop a novel use of fish gelatin. Gelling temperature, melting temperature and jelly strength of trout gelatin were 16.5°C, 16.2°C and 340 g, respectively, which were lower than those of bovine gelatin, while springiness of trout gelatin gel tended to be higher than that of bovine gelatin gel. After the freezing-thawing process, bovine gelatin gel became very fragile, while trout gelatin gel showed little change in jelly strength or springiness. The addition of trout gelatin to soybean curd (“tofu” in Japanese) effectively prevented syneresis by freezing and thawing. These results suggest that trout gelatin could be used as a natural additive with syneresis-preventing ability and springiness.
Seafoods are known to contain many kinds of minerals, and minerals to be bioavailable need to be in a soluble form. Solubility of iron and zinc from seaweeds (nori, red alga; aonori, green alga; and hijiki, brown alga), mollusks (scallop, clam, surf clam and oyster), and crustaceans (prawn and king crab) was determined under simulated gastrointestinal conditions, and mineral contents in the low molecular weight fraction were estimated by ultrafiltration. The solubility of iron was lower than zinc, however, pepsin-pancreatin treatment increased iron solubility. A larger percentage of both soluble minerals existed in the low molecular weight segment except for iron in mollusks and crustaceans. The solubility of zinc at pH 2 was higher than at pH 6, and also after pepsin treatment was higher than after pancreatin treatment in almost all samples.
Seasonal change of volatile components in Citrus sudachi was monitored by headspace gas-chromatographic analyses. The limonene content increased sharply from 50.87% (unripe sudachi) to 87.23% (over-ripe sudachi) in accordance with maturation of the fruit, while α-thujene, sabinene, α-phellandrene, β-ocimene and γ-terpinene decreased. Linalool decreased particularly sharply during maturation from 5.20% to 0.55%. Other oxygenated compounds such as cis- and trans-limonen-1,2-oxide, citronellal, decanal, terpinen-4-ol and carvone were not detected in unripe sudachi but appeared in the volatiles during the ripening progress. These oxygenated terpenes had larger log Uo values (>1). Furthermore, as limonene, α-pinene, decanal, citronellal, linalool are the characteristic odor chemicals in sudachi, these increase and decrease of odor active terpenes during maturation are determined to contribute to the change of the characteristic aroma and the generation of sudachi-like aroma.
Amylase activity of 42 kinds of spices was assayed. Capsicum pepper, Cumin seed, Chinese pepper, Fennel seed, Paprika, and Ajowan had a high amylase activity. That of Capsicum pepper and Cumin seed was particularly high due to the starch degrading enzymes α- and β-amylase, as determined from the results of viscosity measurements, reducing sugar assays and TLC-analysis of the hydrolysate. We also examined temperature and pH optima for the amylase activity of Capsicum pepper and Cumin seed.
To more fully utilize defatted soybeans (DSB) as a food, various defatted soybean ontjoms (DSB ontjoms, fermented DSB with Neurospora intermedia) were prepared. The taste of DSB ontjoms was remarkably improved by adding 10% peanuts or 20% glandless cottonseeds (GLCS) to DSB. In the 20% GLCS-DSB ontjom, gossypol, the toxin of cotton seed, was not detected. The 10% peanut-DSB ontjom and the 20% GLCS-DSB ontjom contained about 50% crude proteins, about 25% soluble proteins, and a limited amount of undigesitible oligosaccharides related to flatulence. These DSB ontjoms to which oilseeds are added are expected to become popular as a digestible protein-rich wholesome and healty food.
We have investigated the effect of crude extract prepared from leaves of Japanese aucuba (Aucuba japonica Thunb) on the growth of human lymphoid leukemia Molt 4B cells. The extract suppressed the growth of these cells by 60% at the concentration of 200 μg/ml. Fraction III obtained by separation with HW40S gel chromatography inhibited the growth of the cells by 95% at the same concentration. We analyzed the structure of the compound contained in Fraction III, and identified it as eucommiol by NMR and MS. The antiproliferative effect of eucommiol on the growth of Molt 4B cells was examined, and it was found to moderately suppress the proliferation of Molt 4B cells by 41% at the concentration of 200 μg/ml.
Antibodies capable of binding two different antigens are termed bispecific antibodies. In this study, we prepared a bispecific antibody reactive to ovomucoid and horseradish peroxidase by a chemical recombination method. Using the resulting F(ab')2 type bispecific antibody, we obtained a good standard curve of ovomucoid by a competitive ELISA.
The effects of salt and pH on the reduction of interfacial tension and the emulsifying property of monolaurin monoglucoside [MG(C12:0)-G] were investigated. MG(C12:0)-G made an emulsion of an oil in water(O/W) type. The creaming stability of the emulsion prepared with 0.05% MG(C12:0)-G did not change up to 0.2 M salt and at various pHs, and under these conditions the medium droplet size in the emulsion was constant. The ratio of oil phase weight to total weight separated by centrifuging the MG(C12:0)-G emulsion was constant up to 0.2 M salt, and at various pHs. Its emulsifying property was superior to that of sucrose esters of fatty acids.
An ethanol sensor using two chloride ion-selective polymeric membrane electrodes (Cl-ISEs) was developed. Two different polymeric membranes were used, one with o-nitro-phenyloctyl ether (NPOE) and the other with n-decylalcohol (DA) as the plasticizer. The electrical potential of the Cl-ISE fell linearly with increasing ethanol concentration at a given concentration of Cl-. The electrical potential equation is viewed as a function of the concentration of ethanol and Cl-. The responses to ethanol and Cl- differed between plasticizers. The two Cl-ISEs showed nearly Nernstean slopes for Cl- in ethanol solution (0-20%). In addition, each electrode had good linearity for ethanol with a slope of −2.51 mV/ethanol % (NPOE) and −1.01 mV/ethanol% (DA), respectively. The concentration of ethanol and Cl- can be estimated by solving the simultaneous equations derived from the electrical potentials of the two different Cl-ISEs. To decrease the interference from co-existing components, KCl solution was added to the sample until the total concentration was 30 mM. The ethanol sensor using the two Cl-ISEs showed good accuracy in the measurement of ethanol in sake and shochu.
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