Measurement method and values of thermal conductivity and permeability of water vapor were presented for the dried layer of food materials undergoing freeze-drying. Some structural models were developed for predicting the permeability of water vapor flowing through the dried layer. In a cellular food model, the resistance of a cell membrane to the molecular transfer of water vapor was determined from both value of permeability and microscopic observation of average diameter of cells. The model was considered to play an important role in predicting optimum heating program for the surface temperature of materials. A micro-slicer image processing system (MSIPS) has been developed for measuring the three-dimensional (3-D) structure and distribution of ice crystals formed in frozen food materials. The system has functions to reconstruct the 3-D image based on the image data of exposed cross sections obtained by multi-slicing of a frozen sample with the minimum thickness of 1 μm and to display the internal structure as well as an arbitrary cross section of the sample choosing observation angles. The effects of freezing conditions on the morphology and distribution of ice crystals were demonstrated quantitatively from the observations of raw beef stained by fluorescent indicator of muscle fibers. The scale-up procedures were described for optimizing the design and operation of industrial freeze-dryer to produce dried-egg soups.

抄録全体を表示

Corn-zein is a protein polymer promising as a biodegradable food packaging film to overcome environmental pollution caused by the use of non-degradable petroleum-derived plastics. However, the brittleness of pure zein film requires that plasticizers be added. The effects of the proportion of polyethylene glycol (PEG) and lauric acid (LA) used as composite plasticizer on mechanical and barrier properties of zein-based film were observed. Flexibility of plasticized-zein films increased as the portion of PEG was increased, as shown by the trend of decreasing elastic modulus (EM) and increasing elongation to break (ETB). Tensile and puncture strength values were also affected by in-crease in the PEG portion, although they were not as consistent as EM and ETB values. Water vapor permeability values rose with PEG while values for oxygen permeability were more erratic.

抄録全体を表示

Ten different Japanese wheat flours with protein contents ranging between 9.86 and 11.5% were treated with gaseous acetic acid, then used for breadmaking. Gaseous acetic acid treatment at a concentration of 0.5–1.5 ml acetic acid per kg of the flour improved breadmaking properties of bread height and specific volume. It is known that the level of these breadmaking properties is related to the protein content of the wheat flour. The slight acetic acid flavor in the breadcrumbs was masked by adding butter flavor or butter to the bread dough.

抄録全体を表示

The effects of increase in α-amylase and endo-protease activities during germination on the deterioration of the breadmaking quality of hard wheat were examined using three varieties with different strengths of gluten: VictoriaINTA, Harunoakebono, and Leader. The results are summarized as follows: (1) The degradation of the breadmaking quality of flour damaged in germination differed greatly according to the gluten strength of each variety. VictoriaINTA, which has extra-strong gluten, was more tolerant of the germination damage than the other varieties with strong gluten. (2) The degradation of specific loaf volume, which is caused by lowering the gas retention of the dough, was the result of the softening of the dough that was observed as a decrease in the mixing peak time and the breaking force of the dough. (3) The α-amylase and endo-protease activities of flours did not seemed to influence the breadmaking quality, although there was a considerably high correlation between endo-protease activity of whole wheat flour and breadmaking quality. From these results, it would seem that the main reason that flour damaged during germination degrades breadmaking quality is the endo-protease in the wheat grain, which already causes partial gluten decomposition. Accordingly, it might be better to examine the endo-protease activity of whole wheat flour at harvest ripeness in order to estimate the value of breadmaking quality within the hard-wheat breeding system.

抄録全体を表示

To determine a useful method for evaluating the quality of fresh-cut Welsh onions (Allium fistulosum L.), the onions were examined and electrical conductivity (EC), potassium and ammonia contents of electrolyte solution extracted from them were compared. The quality of cut onions stored at 0, 5 and 10°C was stable for 6 days, while the quality of those stored at 15 or 20°C showed slight deterioration after 4 and 3 days of storage, respectively, with mashed deterioration occurring thereafter. EC of onions stored at 15 or 20°C decreased for the first 4 and 3 days of storage, respectively, and thereafter began to increase, although that of onions stored at 0, 5 or 10°C decreased throughout the storage period. The changes in potassium content extracted by homogenization were steady during storage, although the changes in potassium extracted by leakage were similar to those in EC stored at 15 or 20°C. The relationships between EC or potassium content and quality of cut onions suggested that electrolyte leakage occurred when the tissue collapsed due to decay. In cut onions stored at 15 or 20°C, ammonia was first detected after 4 or 3 days, respectively, with high levels of ammonia detected thereafter. This indicated that ammonia is formed in the cellular tissue. The first day on which ammonia was detected corresponded approximately with the day on which an unpleasant odor was detected. Chlorophyll content of cut onions decreased with decay. However, in the case of EC, potassium and chlorophyll, the quality of the onions could not be known without continuous measurement. On the contrary, if ammonia was measured once, the quality of the onions could be evaluated; therefore, ammonia was a good parameter with which to evaluate onion decay.

抄録全体を表示

Odor detection thresholds of optically active compounds and other volatile compounds found in the oil of yellow Keaw mangoes were determined. Odor intensity of individual components was evaluated by Lod (limited odor unit) based on data of the odor detection threshold and the concentration of individual components at the recognition threshold level of the volatile oils. β-Damascenone and terpinolene were found to have Lod values greater than one and were identified as the components most responsible for the characteristic aroma. Odor recognition threshold of a mixture of 15 chemicals having larger Lod values against natural Keaw mango oils was 1.8 ppm, which exceeded that of Keaw mango oils (0.62 ppm) against Ok-rong mango oils. The mixture of fifteen compounds comprising β-damascenone, terpinolene, ethyl hexanoate, (E,Z)-(2,6)-nonadienal, 2,5-dimethyl-4-methoxy-3(2H)-furanone, (3R)-(2)-linalool, ethyl butyrate, ethyl octanoate, ethanol, (1S)-(1)-δ-3-carene, (1S,5S)-(2)-α-pinene, trans-linalool oxide, (3S)-(1)-linalool, butyric acid, and p-methylacetophenone was judged to possess an aroma very similar to that of the natural Keaw mango. Thus, these fifteen compounds were the key contributors to the aroma of Keaw mango.

抄録全体を表示

Mango fruits ‘Chiin Hwang No. 1’ produced on 7-year-old trees cultivated in a plastic greenhouse {inside temp.: in winter, min. 5.8°C (room) and 12.7°C (soil); in summer, max. 42.5°C (room) and 26.8°C (soil)} were used for this study. Fruits were harvested approximately 13 (Sample I), 15 (Sample II) and 17 (Sample III) weeks after flowering in 1999. Sample III was ripened at 25°C, 58–84% RH for 12 days. Brix value, respiratory rate, and free sugar content increased during maturation. These values increased markedly when the fruits of Sample III were ripened. The surface color remained practically unchanged during maturation, but with ripening Hunter b and a values began to increase at a late stage. The b value of flesh color, particularly in the apex portion, increased gradually, and with ripening the L value decreased, while the a and b values increased. The flesh firmness remained almost constant during maturation, but decreased markedly during ripening. Citric acid, an abundant organic acid, decreased gradually as maturity progressed. Though fructose content was nearly constant throughout maturation and ripening, sucrose content increased rapidly with storage at 25°C. AIS (alcohol insoluble solid), starch and total pectin reached maximum levels in Sample II and decreased in Sample III. Furthermore, the contents of these substances decreased significantly with ripening, and the decrease in starch was marked. Changes in the activities of amylase, polygalacturonase, and pectin esterase during maturation and ripening suggested correlations with the changes in content of starch and pectins. The results in the changes of Brix value, flesh firmness, and chemical composition suggest that the optimal time for harvesting ‘Chiin Hwang No. 1’ mango fruit is 17 weeks after flowering.

抄録全体を表示

Suppressive effects of hot water extract of safflower leaves (Ex) and its major component luteolin-7-O-glucoside (LuGlc) on oxidative stress were determined in rats in which oxidative stress had been induced by paraquat (PQ). Both Ex and LuGlc suppressed lowering of food intake, and body weight gain, increases in lung weight, liver thiobarbituric acid reactive substances (TBARS), and a decrease in the liver triacylglycerol concentration were all induced by PQ-feeding. Rises in the liver total glutathione and oxidized glutathione concentrations in the PQ-fed rats were suppressed by adding Ex and LuGlc to the PQ diet. Moreover, Ex and LuGlc tended to suppress decreases in catalase activity in the liver mitochondrial fraction and liver α-tocopherol concentration which were induced by PQ-feeding. These results showed that both Ex and LuGlc, which is a major component of Ex, may be available to suppress oxidative stress in vivo.

抄録全体を表示

It has been reported that consuming food which contains flavonols is related to the decrease in risks to arteriosclerosis and cancer. One objective of this study was to elucidate the metabolism of quercetin and the glucosides (quercetin 3,4′-diglucoside and quercetin 4′-glucoside) present in onion soup, in the oral cavity. Not only quercetin glucosides but also quercetin were found in whole saliva which was collected 15 min after eating onion soup. Quercetin seemed to be formed by deglucosidation of the glucosides. The concentrations of the flavonols were much higher in sediments than in supernatants of the saliva suggesting that the flavonols bound to components of the sediments like detached epithelial cells. Concentrations of quercetin and the glucosides in the oral cavity decreased as a function of time after the intake. The decreases were mainly due to the washing away from this cavity by saliva. In addition, deglucosidation of quercetin glucosides to quercetin was also assumed to contribute to the decrease in the glucosides and oxidation of quercetin by peroxidase (POX) in saliva to the decrease in quercetin. Based on the data that quercetin was oxidized by POX in saliva in the presence and absence of thiocyanate, it is suggested that quercetin as well as thiocyanate can be a substrate for POX in saliva to scavenge H₂O₂ in oral cavity.

抄録全体を表示

A rapid and convenient spectrophotometric method for determination of amino group was developed using the bifunctional reagent glutaraldehyde and water-soluble tetrazolium XTT. The method is based on the formation of XTT formazan by the reduction with dihydropyridine that generates in the reaction of glutaraldehyde with amino group. Only 5 min was required for an assay. The detection limit of lysine was 1 nmol/assay. When the method was applied to the determination of protein, the detection limit was 1.1 μg/assay for BSA. Satisfactory recovery data were obtained when casein was added to commercial milk (99–101%).

抄録全体を表示

The radical-scavenging activity of vegetables was measured using the 1,1-diphenyl-2-picrylhydrazyl-HPLC method, and the effect of cooking on this activity was determined. The content of ascorbic acid having radical-scavenging activity was highest in burdock among the 18 fresh vegetables tested. In some vegetables, the activity increased in spite of the loss of ascorbic acid content after boiling, while in other vegetables, the activity had decreased after boiling. This decrease may be due to release of the activity from cooked tissue into the cooking water during boiling. Both activity and ascorbic acid content of the vegetables cooked in a microwave were generally higher than in those cooked by boiling.

抄録全体を表示

L-Ascorbic acid (AsA) plays an important role in food, especially in the rheological properties of bread dough. So in this study, we estimated the effect of AsA on the polymerization of proteins using ovalbumin (OVA). OVA was separated into 4 fractions by size-exclusion high-performance liquid chromatography (SE-HPLC) on the basis of molecular weight. When the OVA was incubated at 55°C, the relative areas of fraction 1 (molecular weight of more than 350,000) increased. The relative area of fraction 1 of OVA added with AsA, and of the OVA with superoxide anion radical (O₂⁻) generating system was increased. Furthermore, the remaining sulfhydryl group content in OVA with the O₂⁻ generating systems showed a significant decrease from control. Thus, it was suggested that the O₂⁻ produced during the autoxidation of AsA might react with the sulfhydryl groups, and consequently affect the polymerization of OVA.

抄録全体を表示

The color stability of a dried food model added with carotenoids, represented by β-carotene and lutein, and the effects of these carotenoids on lipid oxidation were studied. Addition of both β-carotene and lutein gave a yellow color to the dried food model. During incubation, the changes in the remaining amounts of carotenoids, and also in the color of the dried food model showed that the carotenoids degraded quickly when their initial concentration was high. Also, the higher the concentration of added carotenoids, the higher was the level of lipid oxidation of the samples produced. However, the color change and the oxidative promotion of carotenoids could be lowered by the addition of tocopherols.

抄録全体を表示

Heat-induced gels of charcoal-treated, freeze-dried porcine serum fortified by chicken myosin solution (2.5%, w/w), as well as pork sausage fortified by the serum, were analyzed in terms of their rheological properties by creep measurements at different protein concentrations. The creep curves of gels and sausages conformed to a six-element mechanical model consisting of one Hookean, two Voigt and one Newtonian component. The mixture of the serum and chicken myosin (5.6% total protein concentration) formed a harder gel upon heating than 6% serum alone. This indicated that interactions between porcine serum protein and myosin occurred with heating. The viscoelastic values of pork sausage increased with the addition of the serum. Moreover, pork sausage fortified by the serum had higher viscoelastic values than sausage fortified by egg white protein (p<0.05). The serum may be a useful functional ingredient in meat products.

抄録全体を表示

The antimicrobial action of dietary polysaccharides on eight food-borne pathogenic bacteria were examined. Among the polysaccharides, the carrageenans showed the most pronounced inhibitory effect, the growth of all the bacterial strains except Listeria monocytogenes being significantly inhibited by them, particularly by ι-carrageenan. A growth-inhibition experiment using Salmonella enteritidis showed that the inhibitory effect of the carrageenans was not bactericidal but bacteriostatic. The removal of sulfate residues eliminated the bacteriostatic effect of ι-carrageenan, suggesting that the sulfate residue(s) in carrageenan played an essential role in this effect. The results of the present study suggest that dietary polysaccharides, and particularly carrageenans, may act as effective preservatives in various types of processed food.

抄録全体を表示