The firmness tester originally developed for melons was improved to measure the ripeness of pears. Sampling frequency was increased to measure pears and user interface on a data acquisition program was also improved. In addition, two microphones and a stabilizer rod were arranged to form a tripod for stable measurement on the curved surface of the fruit. The transmission velocity, destructive firmness measurement and sensory evaluation were carried out for 96 La France pears and 85 Le Lectier pears. The transmission velocity calculated from the cross correlation of two acoustic signals showed a high level of correlation (R0.94) with apparent elasticity measured in destructive tests. Measurements with the firmness tester could be used to monitor physiological changes in ripening pears.
Flow property and dispersal state of silkworm (Bombyx mori) blood in a capillary were studied using various bore-sizes of a low shear capillary viscometer combined with photomicroscopy. The viscosity of blood showed the characteristic shear rate dependence and viscosity value influenced by the capillary bore-size. This dependence was affected by the change in dispersal state of particles in the silkworm blood and also affected by the feeding. These effects can be attributed to the formation change of the aggregates of dispersed blood cell particle and particle number distribution in a capillary. The change in flow mechanism of the silkworm blood obtained from the feed of mulberry leaves and artificial feed was elucidated by the blood cell particle distribution in a capillary. From this experimental result, a flow model of the blood was derived and the wall layer was determined to be composed of double layers in the flowing liquid of a capillary.
We examined changes in isoflavone compositions of 4 varieties of soybean (Toyomusume, Tamahomare, Murayutaka, Toyokomachi) during soaking in water, which is one of the important food processing procedures. There were greater amounts of 6″-O-malonylated isoflavone glucosides than those of any other components in all the varieties. This proportion was followed by isoflavone glucosides, whereas the proportions of free isoflavones and 6″-O-acetylated isoflavone glucosides were small. After soaking in water for 20 h at 15°C, the proportion of free isoflavones in all 4 varieties increased significantly, whereas that of isoflavone glucosides decreased. No significant changes were observed in the proportions of 6″-O-malonylated isoflavone glucosides or 6″-O-acetylated isoflavone glucosides. The largest in-crease in free isoflavone was seen in Tamahomare compared to the other 3 varieties. We measured β-glucosidase activities for each variety using p-nitrophenyl-β-D-glucoside as the substrate and found no difference among them. However, the water absorption rate of Tamahomare was significantly higher than that of other varieties at the initial stage of soaking in water, as was the turbidity of the water it was soaked in. The activity of β-glucosidase and ratio of free isoflavones to isoflavone glucosides in the soaking water of Tamahomare were also higher than those of other varieties. Given these findings, we determined that the changes in soybean isoflavones, from isoflavone glucosides to free forms, during the soaking was caused by β-glucosidase present in the soybeans, but that the differences among individual varieties were attributable to differences in water absorption rate and the quantity of eluted components including isoflavones and β-glucosidase.
A Japanese domestic middle-soft flour (Hokusin) was mixed with an extra strong (ES) flour (Wildcat) and examined to evaluate its quality for bread-making. The results were as follows: (1) The properties of the dough of the mixed flour such as the mixing, physical and gas retention properties were similar to the commercial foreign hard flour called Camellia. (2) The baking quality, mainly the specific loaf volume and crumb grain, of the bread from Hokushin-Wildcat blend was similar or superior to Camellia except for the color of the crumb and the staling of the bread. (3) The bread from the 50% Wildcat blend staled a little faster, and the specific loaf volume and crumb grain was better than Camellia. The slightly rapid staling of this bread was attributed to the retrogradation rate of the starch, which was somewhat higher than that in Camellia. (4) The retrogradation of starch in the bread from the 50% Wildcat blend was a little faster than Camellia because of the lower water content of the bread due to the slightly less absorbed water of this flour.
The effect of oxidants on the formation of sodium dodecyl sulfate insoluble gluten (SDS-ISG) during baking process was studied. The amount of the SDS-ISG in mixed dough increased linearly with increasing level of iodate. When the dough was allowed to rest at 30°C, a maximum appeared at around 9 ppm; the maximum shifted to 3 ppm when the dough was heated at 180°C. This result was found to be due to a marked decrease in the amount of SDS-ISG at a higher level of iodate. Similar results were obtained in heated doughs treated with bromate and ascorbic acid. Loaf volume was positively related to the amount of the SDS-ISG in the baked dough, but was unrelated to that in mixing and resting doughs. Polymerization and depolymerization of gluten proteins during the breadmaking process was discussed.
The objective of this study was to develop a partial least squares regression (PLS) calibration method of maximum viscosity determination of Japanese milled rice flours using near-infrared transmittance (NIT) spectroscopy. The diversity of spectra and maximum viscosity of wide ranging of rice subfamilies were much more than those of japonica type rices. The variations of spectra and maximum viscosity were found to influence PLS loading weights. C-H and O-H in ROH and H2O absorbances presented by the loading weights were significant in the 8th loading of the PLS model for japonica type rices. The performance of this PLS calibration model (11 components) for maximum viscosity of a rapid visco analyser (RVA) was the standard error of prediction (SEP) of 17.7, square of regression coefficient (R2) of 0.75 and the ratio of the SEP to the standard deviation of the original data (RPD) of 1.9. This method can be applied to the determination of maximum viscosity of japonica type rices.
For the production of highly soluble HVP (hydrolysed vegetable protein) by enzymic hydrolysis, wheat gluten suspension (6% w/w, protein) was pretreated with weak acid (0.1 N HCl) at 95\\xa1 C for 1 h to overcome insolubility of the suspension. After treating it for 3 h with alcalase, flavourzyme was added to the wheat gluten hydrolysate and hydrolysis continued for a further 21 h at 50\\xa1 C. α-Amino nitrogen content (AN, mg/ml) and nitrogen solubility index (NSI, %) of the resulting wheat gluten hydrolysate product was 2.87 mg/ml and 94.9%, respectively. The wheat gluten hydrolysate product contained peptides and free amino acids with molecular weights below 300 dalton. Non-acid treated SPI (soy protein isolate) was also adopted as a protein substrate. The AN and NSI of the resulting SPI hydrolysate were 2.02 mg/ml and 70.4%, respectively. SPI hydrolysate contained proteins and peptides with molecular weights above 80 Dalton and below 7300 Dalton.
We examined the properties of frozen dough made with an extra strong (ES) flour called Wildcat to determine the freezing resistance of the flour. The results were as follows: (1) Degradation of the frozen dough, which is evaluated as the decrease in specific loaf volume, was mostly induced by damage to the yeast from freezing. This damage lowers the gas retention of the dough, resulting in a weakness in its physical properties and reduction of its gassing power. (2) Properties of the ES flour as frozen dough were good. Tolerance to degradation when frozen was due largely to its gas retention decrease being less than that of other flours. (3) This lower decrease in gas retention when frozen was mainly a result of a rather high value of the dough’s breaking force when it was thawed, which was attributable to its resistance to glutathione, a reducing agent, that leaked from frozen damaged yeast. This resistance seemed to be related to the particular physical properties of this dough without freezing, which was represented for very high value of breaking force of this dough.
Bovine serum albumin (BSA) was chemically treated in the presence or absence of L-cysteine (Cys) after the cleavage of hydrogen bonds by urea and reduction of disulfide linkages by sodium tetrahydroborate. The reduced BSA was re-oxidized with hydrogen peroxide and Cys treated- or non-Cys treated- BSA was obtained (C-BSA or NC-BSA). The percentage of thiol groups modified in C-BSA was 73.6%. The peptic digestibility of BSA was markedly improved by chemical treatment in the presence of Cys. The pancreatic and tryptic digestibility of BSA was higher in the order of C-BSA>NC-BSA>native BSA. SDS-PAGE confirmed that chemical treatment with Cys improved the digestibility of BSA and facilitated protein fragmentation into small molecular weight peptides by protease. Further, enzyme-linked immunosorbent assay showed that the antigenicity of the tryptic digests of BSA was reduced about one-tenth by the chemical treatment with Cys. This result indicated that the change in conformation of BSA decreased the antigenicity through enhancement of protease susceptibility.
The effect of dietary flavonoids (flavone, isoflavone, flavanone, chalcone, flavonol, and flavonol derivatives) on the differentiation of 3T3-L1 adipocytes was investigated. Glycerol-3-phosphate dehydrogenase (GPDH) activity, which is a hallmark of 3T3-L1 differentiation, was measured. The GPDH activity in the cells treated with quercetin, kaempferol, and isorhamnetin was significantly lower than that in the control cells. A low lipid accumulation in cells stained with Oil-Red O was observed following treatment of these flavonols. The anti-differentiation action of quercetin was more potent than that of its derivatives. Quercetin directly inhibited the activity of GPDH extracted from mature 3T3-L1 adipocytes. The inhibitory action of quercetin on the differentiation of 3T3-L1 cells may involve the direct inhibition of GPDH, which is a key enzyme lipid synthesis.
We examined the effect of edible plant extracts on prevention of obesity. 3T3-L1 cell that differentiated into a mature adipocyte was used as a model for screening in vitro. After the cells had formed a confluent monolayer, they were treated with DEX-MIX and incubated in a medium containing edible plant extract for 12 days. The mioga (Zingiber mioga Rosc.) extract significantly suppressed the increase in glycerol-3-phosphate dehydrogenase activity and triglyceride accumulation in 3T3-L1 cells. The results of Oil-Red O staining supported these findings. We further investigated the effect of mioga extract in prevention of obesity in male ICR mice in vivo. Through oral administration of the extract (10 or 50 mg/mouse), increases in body weight and epididymal fat weight were prevented in the animals. These results indicate that mioga extract may be useful in preventing obesity.
The rheological properties of ι-carrageenan isolated from Togekirinsai (Eucheuma serra) were measured with a rheogoniometer. The flow curves of a Ca-salt of ι-carrageenan solution showed plastic behavior and the yield value was estimated to be 0.4, 1.7 and 7.7 Pa at 0.1, 0.2 and 0.3% (w/v) concentration, respectively. The dynamic modulus of Ca-salt of ι-carrageenan increased with increase in concentration and gelation occurred at a concentration of 0.3% (w/v) at room temperature. The Ca-salt showed larger values than did of Na- and K-salts of ι-carrageenan in dynamic viscoelasticity. The Na- and K-salts of ι-carrageenan had very large values in the presence of CaCl2 (6.8 mM) in dynamic modulus which maintained a constant value as the temperature increased to 40°C. A transition temperature, at which dynamic modulus decreased rapidly, was observed at 40°C. The Ca-salt of ι-carrageenan decreased with the addition of urea (4.0 M). The gel formation of the ι-carrageenan isolated from Togekirinsai might be essentially attributed to intra- and intermolecular associations, contributed by sulfate groups of adjacent D-galactose and 3,6-anhydro-D-galactose residues through Ca2 bridges with ionic bonding and attractive electrostatic forces within and between molecules.
The relationship between wheat flour protein and the expansion of yakifu, one of the traditional foods in Japan, was studied. Wheat flour proteins were fractionated by their solubility in various solvents. The protein fraction (PF) and wheat starch were blended into reconstructed flours (RFs). In RF 1, the protein content was equal to that of hard wheat flour, while in RF 2 part (10%, 20%, or 30%) of the protein originally included in soft or hard wheat flour was replaced with a PF extracted from each flour. Among RF 1, those blended with water-soluble and NaCl-soluble fractions did not produce substantial gluten doughs and therefore failed to form well expanded structures when baked. A smooth and well homogenized gluten dough was prepared with 70% ethyl alcohol-soluble and HCl-soluble fractions although the acetic acid-soluble, acetic acid-insoluble, and HCl-insoluble fractions produced a tough and coarse gluten dough. The specific volume of yakifu was greater when smooth and well homogenized gluten doughs were baked than when tough and coarse ones were. In RF 2, the specific volume gradually increased with the increase of the HCl-soluble fraction ratio, while it remained almost constant with the increase of the HCl-insoluble fraction ratio. These results demonstrated the primary role of the 70% ethyl alcohol-soluble fraction and HCl-soluble fraction, that is, the gliadin-rich fraction, in the expansion of yakifu.
We have investigated the effect of extract prepared from skin of red grape (Vitris vinifera) on the growth of human lymphoid leukemia Molt 4B cells. It was found that the extract obtained by extraction with butanol suppressed the growth of Molt 4B cells. Fraction IV obtained by separation with HPLC inhibited the growth of the Molt 4B cells by 86% at the concentration of 600 μM. We determined the structure of compound contained in Fraction IV and identified it as enin, a kind of anthocyanin, by 1H- and 13C-NMR. The enin-treated cells clearly exhibited morphological changes, indicating the blebbing and chromatin condensation which are characteristic of apoptosis. Characteristic oligonucleosomal-sized DNA fragments were observed in the enin-treated cells. These findings suggest that the suppression by enin of growth of Molt 4B cells results from the induction of apoptosis by this compound.
The antioxidant activity, expressed in mM Trolox equivalent antioxidant capacity (TEAC), of some edible Yemeni plants belonging to different families was evaluated using the ferrylmyoglobin/ABTS·+ method. Methanolic (80%) extracts of tested plants exhibited higher (p<0.05) TEAC than extracts of other solvents. Extracts of coffee beans (Coffea arabica), sweet basil (Ocimum basilicum), wild thyme (Thymus serpyllum) and sorrel (Rumex acetosa) had antioxidant activities equivalent to 8.7–47.1 mM Trolox or 7.9–42.8 mM BHA per g dry weight of plant. The TEAC of methanolic extracts for sorrel was not significantly different (p>0.05) from extracts of Leucaena leucocephala (Thailand) and Japanese green tea (Camellia sinensis). A good correlation (R2=0.937) was observed between TEAC and total phenol contents in 80% methanol extracts of tested plants.
Endoinulinase was partially purified from the culture filtrate of a filamentous fungus Aspergillus niger mutant 817. The enzyme preparation was immobilized covalently onto a porous cellulose derivative, Amino-Cellulofine. A 5% (w/v) solution (pH 5.0) of pure dahlia inulin was fed continuously into a packed-bed column reactor containing the immobilized enzyme. The operating conditions were studied to produce a mixture of oligomers with a degree of polymerization of 3 to 5 by partial hydrolysis of inulin. Inulotriose (F3) and -tetraose (F4) were purified from the hydrolysis products by preparative high-performance liquid chromatography. In vitro studies indicated that both the F3 and F4 were preferentially utilized by Bifidobacterium spp., but not by Escherichia coli or Clostridium perfringens.