An allergenic peptide responsible for atopic dermatitis was isolated from the chymotryptic hydrolysate of gluten. The primary structure of the peptide was determined as (Ser-Gln-Gln-Gln-(Gln-)Pro-Pro-Phe)4. The epitope in the allergenic peptide was Gln-Gln-Gln-Pro-Pro. The N-terminal glutamine and the two proline residues were essential for epitopic function. Based on this epitope structure, a practical method is proposed to produce hypoallergenic flour using food-processing enzyme. Soft flour was mixed with water dissolving actinase and then incubated at 37°C for 1 h. The product was determined to be negative allergenicity by ELISA (enzyme-linked immunosorbent assay). Hypoallergenic wheat products in the form of bread and pasta-like noodles were fabricated.
In the presence of glucose, Mycelia sterilia strain M1 decolorized wastewater from a molasses alcohol distillery. Treatment of diluted wastewater 50 times over 7 days achieved a decolorization yield of more than 90%. Two-day treatment resulted in an increase of color unit and pH. This browning was caused by compounds like melanin (CLM) generated by the oxidation of polyphenolic compounds (PP). In diluted wastewater 500 mg/l of PP was detected by the Folin-Denis method. In treatment without glucose, 30% of PP was eliminated by the browning. In treatment of L-dihydroxyphenylalanine (DOPA) solution, the same change in color and pH as in treatment of wastewater was confirmed. Melanin generated in the oxidation of DOPA was decolorized with M1.
Oil-in-water (O/W) microspheres (MS) were produced using microchannels (MC) of different channel size and type formed on a single-crystal silicon substrate, and the fundamental properties for the MS generation were studied. Sunflower oil containing sorbitan monolaurate as surfactant was used. MC of 5.3 μm in equivalent diameter gave an average 20 μm diameter of the produced O/W-MS. The coefficient of variation of the MS was below 2% with the surfactant concentration less than 0.5 wt%. The average diameter and the coefficient of variation of the MS changed little over 60 days, indicating high stability against coalescence. Horizontally setting the MC of 8.5 μm similar to that of 5.3 μm, the monodispersed MS were difficult to produce because of their coalescence and expansion near the channels. Changing MC from horizontal to vertical type, the monodispersed MS could be produced continuously by utilizing the buoyancy.
Percolated and centrifuged virgin olive oils obtained from different olive varieties by the continuous combined enzyme-aided percolation-centrifugation extraction system have been characterized. The percolation extractor gave, under the selected conditions used, oils showing the following: (i) higher contents of pleasant volatiles (with higher values of the characteristic ratios between naturally occurring flavor and aroma compounds), phenols, o-diphenols, hydroxytyrosol, tyrosol- and hydroxytyrosol-aglycons, α-tocopherol, and waxes; (ii) tendentially lower contents of β-carotene, major xanthophylls (lutein, violaxanthin, and neoxanthin), chlorophylls, and pheophytins; (iii) lower values of chroma and turbidity; (iv) lower alcoholic index and integral color index; (v) lower contents of superior aliphatic and triterpene alcohols, triterpene dialcohols, sterols, and hexanal; (vi) higher sensory score, oxidative stability, overall quality indices, and 1, 2-diglycerides/1, 3-diglycerides ratio; and (vii) similar UV (ultraviolet) spectrophotometric indices, carbonyl index, free acidity degree, fatty acid composition, campesterol/stigmasterol ratio, triacylglycerol and diacylglycerol percentage, and hue values.
Chemiluminescence (CL) analysis was used to evaluate the thermal deterioration of hard milk fat two pressurization periods. Hard milk fat was heated at 200°C for 1 h, 2 h or 3 h after high-pressure treatment (400MPa) at 45°C for 1 h or 4 h. The CL intensity of hard milk fat was then measured at 45°C, 50°C and 55°C and increased with heating time at each temperature. When the intensity was measured at 50°C or 55°C, the effect of pressurization time was difficult to discern, because the intensity varied widely during measurement. In contrast, at 45°C, the CL intensity of heated hard milk fat that had been pressurized for 4 h was significantly lower than those measured at other temperatures for each heating period. The intensity of non-pressurized hard milk fat was observed to be significantly higher than that measured at other temperatures for each heating period, indicating that pressurization for 4 h yields the highest suppression of the thermal deterioration of hard milk fat.
Yam is often added to kamaboko, such as Hanpen and Shinjo. We investigated the presence of endopeptidase in powdered yam and the effect of its addition on the texture of kamaboko. Hydrolyzing activities of casein and myofibrillar protein were observed in a crude extract of powdered yam. In addition, the optimum temperature and pH against casein and myofibrillar protein were approximately 70°C and 7.4, and 60°C and 6.8, respectively. Approximately 60% of the endopeptidase activity remained even with 3% NaCl. In the kamaboko to which powdered yam had been added degradation of the myosine heavy chain and decrease of the elasticity were observed.
Naoto SHIMIZU, Jyunji KATSURA, Takashi YANAGISAWA, Shigeru INOUE, Robin P. WITHEY, Ian A. COWE, Colin G. EDDISON, Anthony B. BLAKENEY, Toshinori KIMURA, Shigeru YOSHIZAKI, Hiroshi OKADOME, Hidechika TOYOSHIMA, Ken’ichi OHTSUBO
The objective of the present study was to develop a method to analyze apparent amylose content (AAC) of Japanese milled rices using near-infrared transmittance spectroscopy (NIT). Samples (n=110, varieties=37), harvested in 1996, were collected at various sites throughout Japan. Whole-grain milled rice was scanned using a near-infrared range (833-1050 nm with 8 nm steps and 27 wavelengths) transmittance filter type spectrometer. The AACs of samples were in the range of 13.1% to 20.7% (SD: 1.53). The wide range AAC (0-35.3%) partial least squares (PLS) model was found to be inadequate for accurate prediction of the narrow AAC range (13.2-20.7%) of the rice samples. The statistical performance of PLS modeling (11 factors) for narrow range AAC analyses gave a standard error of cross-validation (SECv) of 0.78 and square of regression coefficient (R2) of 0.74. The AAC model was applied to 20 unknown samples of products from different crop year (1997), and gave a standard error of prediction (SEP) of 1.25, R2 of 0.49 on the validation set. These results suggested that this model based on NIT spectroscopy could be applied for rapid and nondestructive measurement of narrow range AAC of Japanese milled rices.
Information on antioxidative constituents from fermented sardine with rice-bran (FSR, “Iwashinukazuke”) was obtained by fractionating the hot water soluble fraction of fish meat in FSR. Antioxidative activity of each fraction was measured in the model system for linoleic acid oxidation. Chemical composition of the fraction showing the strongest oxidative activity was analyzed and separated by size exclusion chromatograpy. Antioxidative activities of hot water soluble fraction of FSR increased with ripening. The strongest antioxidative fraction from FSR was estimated to be about 3900 Da and was composed of peptides consisting of mainly Asp, Glu, Gly, and Lys. It is suggested that the increase of antioxidative activity during the ripening of FSR is attributable to the production of the antioxidative peptides from the meat.
The effects of purified lipase and α-amylase were tested for the retrogradation of starch in bread and their impact on some rheological properties. The combined addition of lipase and α-amylase increased significantly the loaf volume compared with the control, and the farinograph data showed that combined addition shortened the arrival time and slightly increased the stability time of dough. The addition of lipase alone increased the gelatinization enthalpy of starch (Δh1) of dough and the starch-lipid complexes (Δh2) of dough and bread by DSC. After 5 days storage, the retrogradation rate of bread which was estimated by the change of Δh1 was slowed to 1.73 fold that of control by addition of 1000 units lipase alone, while the combined addition of lipase and α-amylase (100 units) slowed the retrogradation rate to 2.65 fold. The changes of firmness and moisture content in bread crumbs seemed to correlate with these DSC data. These results suggest that lipase alone retards retrogradation of bread during storage, whereas the combined addition of lipase and α-amylase affects it greatly. The addition of lipase increased the amount of Δh2, suggesting a retardation effect of retrogradation, but Δh1 decreased during storage, which suggests that lipase could retard the retrogradation of bread.
A mixture of soybean oil and glycine was heated at different temperatures for different periods. The volatile compounds produced were extracted by solid phase microextraction (SPME) and then analyzed by GC and GC-MS. 2-Pentylpyridine was the highest heterocyclic volatile compound found in the mixture. Effect of sucrose on the volatile compounds produced from heated glycine and soybean oil was also studied, furfurals, pyrroles and oxidative thermal degradation products of fatty acids (OTDPFA) were found, but no pyridines. Factors affecting the producing of 2-pentylpyridine were investigated by two sources of chemicals: one was furfural which is one of the major thermal degradation products of sucrose, and the other was OTDPFA which remains from soybean oil after heating. The results indicated that 2, 4-heptadienal induced the production of 2-ethylpyridine, but no 2-pentyl-pyridine; 2, 4-decadienal enhanced the production of 2-pentylpyridine; while all other chemicals tested in this study decreased pyridines. This suggested that oxidation-reduction potential and availability of 2, 4-decadienal affected the production of 2-pentylpyridine.
Antibodies against an antitumor β-glucan purified from Grifola frondosa (GGF) were raised in the rabbit by subcutaneous immunization. Our antibodies reacted significantly with GGF by an ELISA inhibition assay. The antibodies did not recognize other polysaccharides such as laminarin and pustulan, but reacted somewhat with lentinan, whose structure is similar to GGF. It was demonstrated that GGF could be measured by ELISA using antibodies. In addition, the effects of the storage temperature on GGF content during storage were measured using our antibody. GGF content was 24.7 μg/g fresh weight (f.w.) at zero time storage, and little change occurred during storage of the mushroom for 7 days at 5°C. However, a drastic decrease to 11.4 μg/g f.w. occurred after 7 days of storage at 20°C. These results suggest that storage at low temperatures is desirable to maintain the quality of GGF.
In our previous publications, we have reported that extract of cocklebur containsan antibacterial substance. This substance was purified using silica gel column chromatography and TLC; it was dissolved in acetone and successively crystallized by adding hexane. The crystal appeared needle-like and white, with a melting point of 60°C and molecular weight of 246. IR, UV and 1H-NMR spectra revealed that the compound was xanthatin. Minimum inhibitory concentrations (MICs) of xanthatin obtained were 12.5-100 μg/ml against Bacillus sp. which usually contaminates koji (qu) used in the preparation of alcoholic beverages. MICs of xanthatin were 25-100 μg/ml against Candida sp., Pichia sp., Saccharomycopsis sp. and Torulaspora sp.. Therefore, the inhibitory effect exhibited by xanthatin from cocklebur leaf extract against Bacillus sp. and some film-forming yeasts would be very useful to prevent contamination in koji and during production of alcoholic beverages.
Accurate values for the absorption coefficients of carotenoids can be obtained by correlation of specific radioactivities in comparison with the known coefficient of a standard substance. Tritium-labelled all-trans-β-carotene of known specific radioactivity was used as the standard. Comparison of absorbance values and specific radioactivity in 6 kinds of solvents (hexane, ethanol, ethyl acetate, acetone, benzene and dichloromethane) allowed the absorption coefficient to be determined in each solvent. After I2-catalysed stereoisomerization, cis and trans isomers of β-carotene were separated by chromatography. Absorption coefficients for each isomer were determined by correlating recorded absorbance values with specific radioactivity, which was unchanged by the isomerization. The same approach can be used to compare the absorption coefficients of other groups of carotenoids that can be interconverted by simple chemical reactions.
Water soluble pectin (WSP) in an alcohol insoluble solid (AIS) of mango “Kaew”, which is exclusively used in processing, increased with maturation. Hydrochloric acid soluble pectin (HSP) decreased. Ammonium oxalate soluble pectin (ASP) did not exhibit a regular pattern. Average molecular weight (MW) of all soluble pectins decreased as the mangoes matured to the overripe stages. Between the half-ripe and ripe stages, average MW decreased significantly in both WSP and ASP. Average MW values for HSP declined gradually as maturation proceeded.
Liquid seasoning was prepared from the wash water produced during cod surimi production, which is normally discarded, using an hydrolysis test plant. This solution had not only a good flavor but also showed inhibitory activity on the angiotensin I-converting enzyme (ACE). Inhibitors in the liquid seasoning showed a molecular weight distribution of about 200 to 500 by gel filtration chromatography. Two inhibitory peptides were isolated from the liquid seasoning using reverse-phase HPLC. The amino acid sequences of inhibitory peptides were Val-Trp and Ile-Trp. Peptide sequences of Val-Trp and Ile-Trp were found in the primary structure of actin. Val-Trp fragment exists also in myoglobin.
Onion bulbs contain quercetin, quercetin 4'-glucoside (Q4'G) and quercetin 3,4'-diglucoside (Q3,4'G), almost all of which are localized in the abaxial epidermis of scales. There is a question of whether these compounds are synthesized in the abaxial epidermis or transported to the epidermis. To elucidate this, activities of enzymes that participate in the formation and degradation of quercetin glucosides were measured in the abaxial epidermis, adaxial epidermis and mesophyll. Activities of glucosyltransferases, which transform quercetin to Q4'G and Q4'G to Q3,4'G, were highest in the abaxial epidermis. Activity of phenylalanine ammonia-lyase was also higher in the abaxial epidermis than in other tissues. These results suggest that the flavonol glucosides are synthesized in the abaxial epidermis. Activities of glucosidases, which transform Q3,4'G to Q4'G and Q4'G to quercetin, were highest in the abaxial epidermis, suggesting that quercetin, which is present in the abaxial epidermis, is formed by deglucosidation of quercetin glucosides in the epidermal cells.
Weak electrolyzed water obtained by electrolysis of tap water has various physicochemical properties. This study investigated the effects of weak electrolyzed water on making bread. Sensory evaluation revealed that when weak electrolyzed anode water was used, the breadcrumb had a higher elasticity than that made with tap water, and when weak electrolyzed cathode water was used, the breadcrumb was softer than that made with tap water. This finding suggests that the use of electrolyzed anode water would produce bread of higher elasticity in the acid soluble large molecular weight gluten sub-unit which participates in the formation of a more soluble gluten-matrix. It was suggested that the use of electrolyzed cathode water would produce soft bread in that the gluten-matrix would become fragile and that the chemical gelatinization of wheat starch would be accelerated by the alkali.
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