In this review nutritional characteristics and the health benefits of dietary diacylglycerol are summarized. The global obesity epidemic and our knowledge of its relation to human health have increased research on dietary fat control. Among several approaches, we have focused on the structure of acylglycerols and have studied nutritional functions of diacylglycerol oil in comparison with conventional triacylglycerol oil with the same fatty acid composition. A cooking oil product containing 80% (w/w) or more diacylglycerol has been used in Japan since 1999 as a “Food for Specified Health Use” approved by the Ministry of Health, Labour and Welfare. The approved claims are: (i) Less increase in postprandial triacylglycerol concentrations in the blood and (ii) Less likelihood of being stored as body fat. These effects are probably the result of the unique metabolic characteristics of diacylglycerol because its bioavailability is practically the same as that of triacylglycerol oil. Although studies of its digestion, absorption and metabolic processes are yet to be completed, the ingestion of diacylglycerol oil has been shown to be beneficial in reducing risk factors for life-style related diseases.
The cooking process was studied under soaking and no-soaking conditions with an automatic electric rice cooker to determine if the cooking energy can be conserved. The rice was cooked after 0, 30 and 60 min of soaking in different amounts of water (water-rice ratio: 1.5, 2.0 and 2.5) and the moisture content and hardness of cooked rice were measured. The hydration characteristic of rice was also measured at different soaking intervals (0, 30 and 60 min). The hydration increased with an increase in soaking time and was higher for parboiled rice than for the raw rice. The moisture content and the hardness of cooked rice were found to be 66 to 69% and 8 to 10 N (for a single kernel), respectively, which consumes 1.02 to 1.2 MJ/kg of energy under different soaking time before cooking and with a water-rice ratio of 2.5. The parboiled rice required a longer cooking time and consumed a greater amount of energy compared to the raw rice. The energy consumption was reduced with an increase in soaking time for all types of rice. This study reveals that for 66% MC of cooked rice, 60 min of presoaking helps to conserve about 6 to 11% and 4% of cooking energy in the case of parboiled and raw rice, respectively, which would be helpful in reducing environmental pollution.
Poly-γ-glutamic acid (γ-PGA) from Bacillus subtilis (natto) with a high molecular weight (Av. M.W.=350,000) effectively inhibited the formation of insoluble calcium phosphate at Ca/P=0.5 (12.5 mM/25 mM) under the condition of 37°C and pH 7.4. Since decrease in inhibitory activity in γ-PGA was observed after the treatment by simulated gastric fluid (pH 1.2, 0.5% pepsin), γ-PGA was encapsulated by egg lecithin liposome to keep the inhibitory activity under gastric conditions. Encapsulation was done by dehydration-rehydration (DR) and reverse-phase-vesicle (REV) methods. Higher encapsulation efficiency (57.0%) was achieved by DR method. Turbidity measurement at 450 nm indicated the high stability of DR microcapsule, prepared with trehalose, against gastric juice. Encapsulated γ-PGA by DR method showed 93.3% residual inhibitory activity after the gastric juice treatment.
We have reported that O-methylated EGCGs (epigallocatechin-3-O-(3-O-methyl) gallate (EGCG3″Me) and epigallocatechin-3-O-(4-O-methyl) gallate) and strictinin had anti-allergic action, and that the tea (Camellia sinensis L.) cultivar ‘Benifuki’ was rich in EGCG3″Me. However, changes in the content of anti-allergic components in tea leaves during growth are unclear. Therefore, here we determined the contents of EGCG3″Me and strictinin at various points of maturity and in the leaf order of ‘Benifuki’ tea in the first and second crop seasons. The EGCG3″Me content was high and caffeine content decreased in fully-matured tea leaves late in the first crop season or under the third leaf during the second crop season. The amount of EGCG3″Me contained in the stem was low. A higher concentration of strictinin was found in younger new shoots in the first crop, and the content greatly decreased during the second crop season. Thus, to obtain the anti-allergic benefits of EGCG3″Me, green tea should be made from fully-matured ‘Benifuki’ leaves under the fourth shoot late in the first crop or under the third shoot in the second crop, refined by removing stems. This green tea is lower in caffeine as compared with that made from younger shoots. On the contrary, to utilize strictinin, green tea should be made using younger new shoots of ‘Benifuki.’
The relationship between physical dough properties and bread-making quality during flour aging was investigated for two Japanese domestic bread-making spring wheat cultivars (Haruyutaka, Haruyokoi) and the winter wheat cultivar (Kitanokaori). The specific loaf volume increased for 4 weeks after milling in all cultivars. The decrease in the breaking deformation of dough continued for 8 weeks in all cultivars and showed a higher negative correlation coefficient to the specific loaf volume. In addition, a greater increase of specific loaf volume was observed by decreasing the breaking deformation in a cultivar with less breaking deformation immediately after milling. Farinograph stability increased for 2 weeks after milling and also showed higher correlation coefficients to specific loaf volume. Water absorption showed higher correlation coefficients to the breaking deformation in Haruyutaka and Haruyokoi but a negative correlation in Kitanokaori. The breaking force, gassing power, and vacuum expansion volume of dough showed lower correlation coefficients to the specific loaf volume in all cultivars. Overall, a higher correlation coefficient was observed among breaking deformation decrease, farinograph stability, and specific loaf volume during flour storage. The relationship between the breaking deformation immediately after milling and the increasing rate of specific loaf volume would be a useful indicator of flour aging maturity.
A trial production was conducted of Tsukudani with strong scavenging activity against active oxygen species by acceleration of the Maillard reaction and addition of sub materials with the activity. As the activity of caramel, POLYPHENONE®, Japanese pepper and perilla adopted as sub materials was stable for heat, the activity was expected to be retained after the production. Trial products of laver, Japanese mushroom and butterbur on the control (usual selection of materials) and test plots (with xylose and the sub materials added to the control) were made. Scavenging activity against superoxide of the products on the test plot was much higher than on the control plot for the three kinds of Tsukudani. No report has been found concerning the utilization of xylose accelerating browning and being expensive for Tsukudani. It was concluded that the taste of the trial products was not influenced by the operations according to the sensory scores.
Effects of oregano (Origanum vulgare L.) and sage (Salvia fruticosa L.) extracts on microbiological quality of butter were investigated. The extracts and their combinations were individually added into butter at 0.3% (w/w) concentrations. For comparison, 0.2% (w/w) sorbic acid was used. The close-up samples were stored at 20°C for 4 weeks. Microbiological qualities of butters treated with spices extracts were better than that of control. Spices extracts and their combinations exhibited antimicrobial effects in butter; however their antimicrobial activities were lower than that of sorbic acid. Oregano among the spices extracts showed highest inhibition effect on moulds and yeasts, lipolytic, proteolytic microorganisms and coliform group, and sage was effective on total bacteria, lactobacilli.
A method for group discrimination is examined which treats the observations of an unknown group (test group) as a set, while the usual discrimination method treats each observation separately. Effectiveness of the method is confirmed by simulation. The method is applied to differentiate rice cultivars and producing districts based on the brown rice grain contour shape. Statistically significant differences among cultivars and producing districts are observed in the shape of rice grain, however, the differences are small and distributions of parameters representing the shape of rice grain contour closely overlap each other. The precise discrimination was not possible in the usual discriminant analysis of each grain. The method of group discriminant analysis showed more effective results in discrimination of rice cultivars and producing district for the case of closely alike populations.
The commercial hard wheat flour, “Cameria” replaced by amaranth flour (∼20%), was tested for its dough properties and baking qualities including sensory evaluation. The loaf volumes of bread baked with 5%, 10% and 20% of amaranth flour substitution were 94%, 89% and 83%, respectively, of the control (wheat only). Additions of lipase (2,250 units/kg of flour) and hemicellulase (1×104 units/kg of flour) to the 10%-amaranth flour-substituted wheat flour increased the loaf volumes about 18% and 23%, respectively, over the control. The firmness of bread-crumbs baked from 10%-amaranth flour-substituted wheat flour added with lipase, hemicellulase, or both of them after storage for three days became significantly softer than that of the control. Farinograph data showed the increase of water absorption, arrival time and weakness in proportion to the increase of amaranth flour substitution. Viscoelastic parameters of dough, such as modulus of elasticity and viscosity coefficient increased in proportion to the increase of amaranth flour substituted for wheat flour. Pasting properties of starch prepared from 10%-amaranth flour-substituted wheat dough with the addition of lipase, hemicellulase or both decreased setback and peak viscosity. Amaranth flour contained a higher amount of alkaline-insoluble protein than wheat flour. Sensory test of 10%-amaranth flour-substituted wheat bread did not show significant improvement compared to the control. However, the bread baked with lipase was preferred by most of the panel members to the control, except for its color.
To utilize fishery waste products as functional food material, the fish protein hydrolysate (FPH) was prepared from fish scraps of three marine species by protease treatment. The added-concentration dependent effects of FPH (2.5-12.5%, dry weight/wet weight) on the state of water and denaturation of lizard fish myofibrils were evaluated by desorption isotherm curves, myofibrillar Ca-ATPase activity, and unfrozen water which was determined by differential scanning calorimetry during dehydration. The water activity (Aw) in myofibrils was distinctly decreased with the increasing concentration of FPH from 2.5% up to 10.0%, although the Aw added with 12.5% of FPH was almost equal to that with 10.0% of FPH. The amount of unfrozen water in myofibrils during dehydration was increased by the addition of FPH, and the greatest increase was found at 5.0-10.0%. The FPH suppressed the inactivation of myofibrillar Ca-ATPase activity during dehydration, and a larger effect of suppression was observed at 7.5% addition of FPH. These findings suggest that peptides produced in FPH functioned to stabilize the hydrate water surrounding the myofibrils and suppressed their dehydration-induced denaturation.
Fourier-transform infrared spectroscopy (FT-IR) on attenuated total reflectance (ATR) sampling was used for the quantitative analysis of the major components (protein, lipid, and sugar) in soymilk. Since mid-infrared spectroscopy shows specific absorption of each functional group of each molecule, it is possible to determine the amount of each component without complicated statistical computation. The determination of protein content was performed by using amide II absorbance at wavenumber 1545 cm-1 for protein, ester absorbance at 1745 cm-1 for lipid, and C-C·C-O absorbance at 1000 cm-1 for sugar. The protein and lipid contents were determined directly from these absorbencies, and the sugar content was calculated by subtracting the effect of protein. There was a linear relation (R2>0.99) between each absorbance and each concentration of purified components (soybean protein, lipid, or sugar), and the values by this method were well consistent with those by chemical method. This technique of measurement of the major components in soymilk by FT-IR with ATR is more convenient and rapid.
Effects of porphyran (POR), a sulfated galactan from an edible red alga Porphyra yezoensis (Susabinori), on growth and lipid metabolism were examined using Sprague-Dawley rats fed a cholesterol-free diet. Rats were divided into four dietary groups: those fed diets containing 5% cellulose (control), agar or two types of POR differing in sugar composition and sulfate content (low sulfate content, LS-POR and high sulfate content, HS-POR) for 3 weeks. Ingestion of the diets containing LS- and HS-POR resulted in a significant decrease in food intake and body weight gain relative to the control diet. Renal adipose tissue weight and serum cholesterol level were also significantly lower in the LS-POR group and the HS-POR group than in the other groups. In contrast, agar, which consists of the same sugar components as POR, had no effect on the above-mentioned growth and lipid parameters. Fecal excretion of neutral sterols was markedly enhanced by POR ingestion, suggesting that POR has a potent effect to interfere with the absorption of neutral sterols within the gastrointestinal tract. Fecal excretion of fatty acids and neutral sterols was significantly higher in the LS-POR group than in the HS-POR group, and it was suggested that the ability to interfere with the absorption of cholesterol and fatty acid within the gastrointesitinal tract depends on the sulfation rate of porphyan.
The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity and polyphenol content of 25 dried fruits were evaluated and compared with fresh fruits. The contribution of ascorbic acid to this activity was also determined. All dried fruits contained DPPH radical-scavenging activity with hawthorn, apricot and blueberry having the highest. Other dried fruits containing rind also had high activity. The DPPH radical-scavenging activity and polyphenol content of dried fruits were highly correlated.
Okara was hydrolyzed in subcritical water to increase the inhibitory activity of angiotensin I-converting enzyme (ACE) and soluble dietary fiber (SDF) content. The IC50 of okara and subcritical water-treated okara (SC-okara) for ACE were 11.2 and 4.7 mg/ml, respectively, showing that SC-okara had about 2.4-fold higher inhibitory activity than okara. The SDF content in okara and SC-okara were 3.4 and 17.1%, respectively, showing that SC-okara had about 5-fold higher SDF content than okara. Powdered SC-okara or okara was fed to spontaneously hypertensive rats (SHR) at the level of 5% in a 1% NaCl (control) diet for 28 days. On the 14th and 28th days, the SHRs of the SC-okara group showed significantly lower systolic blood pressure compared to the control group. Thus, hydrolysis of okara by subcritical water is an effective technology for increasing ACE inhibitory activity and SDF content, which cause the hypotensive action.
The two chromogenic enzyme substrate mediums of chromocult coliform agar (CCA) and XM-G were applied to detect freeze-, heat-, and high-pressure-injured coliforms (Enterobacter aerogenes, Enterobacter cloacae, Escherichia coli, Klebsiella ozaenae, and Klebsiella pneumoniae) as well as coliforms in various food items. Their detection abilities were then compared with the following three conventional media: tryptic soy agar (TSA), violet red bile agar (VRBA), and VRBA/TSA. The enumerated results of injured coliforms showed that the ability to detect injured cells was in the following descending order: non-selective medium TSA>VRBA/TSA>XMG≥CCA≫VRBA. The recovery rate of injured coliforms, when compared with selective agars, was higher in CCA and XM-G than in VRBA. Investigation of the total coliform counts from 100 food samples showed that the enumeration results of the three selected media (CCA, XM-G, and VRBA) were quite similar. The correlation coefficients were 0.89 for CCA vs. VRBA, 0.91 for XM-G vs. VRBA, and 0.91 for CCA vs. XM-G; indicating that CCA and XM-G are recommendable and can substitute for the conventional selective medium VRBA. In addition to the advantage of simultaneous detection of coliforms and Escherichia coli by CCA and XM-G, their superiority in detecting injured coliforms reveals that these two methods were highly effective and suitable to monitor total coliforms and E. coli including injured cells in food samples.
The effects of a small dose of mannooligosaccharides (MOS) from coffee mannan on defecating conditions and the human intestinal environment were investigated. Powder of MOS was administered to 13 healthy volunteers in two doses (0.5 g/day and 1.0 g/day) for two weeks. During the MOS 0.5 g/day administration period, defecation frequency was significantly increased from 4.8 times/week to 6.5 times/week (p<0.05), but the ratio of Bifidobacterium to the total anaerobic bacteria did not increase significantly compared with before the administration period. During the MOS 1.0g/day administration period, defecation frequency was significantly increased from 4.8 times/week to 6.3 times/week (p<0.05) and the ratio of fecal Bifidobacterium significantly increased from 14.0% to 25.9% compared with before the period (p<0.05). These results suggest that the minimum effective dose of MOS would range between 0.5 g/day and 1g/day.
To obtain basic information on the effect of the dissociation of L-ascorbic acid (AsA) on its radical scavenging ability, 1,1-diphenyl-2-picrylhydrazyl (DPPH) was used in both homogeneous and heterogeneous reaction systems. In the homogeneous system, the dissociation of AsA did not affect its DPPH scavenging ability. In the heterogeneous system, the DPPH scavenging ability of the monoanion form of AsA was lower than that of the non-dissociated form. The same tendency was also found in the case of DPPH in liposome. Although it has been emphasized that the antioxidant ability of AsA originated from its electron donation function, the ability of AsA to act as a hydrogen donor should also be considered. A new aspect of the possibility of AsA functioning as an antioxidant not only in the hydrophilic region but also in the hydrophobic region, was also strongly suggested.
This paper studies the effects of fructose diet on plasma isoflavonoids and floral enzyme activities in adult mice. Male 6-week-old mice were fed a fructose-isoflavone (FI) diet or a starch-isoflavone (SI) diet for four weeks. Plasma daidzein and equol were analyzed by HPLC, and cecal bacterial β-glucosidase and β-glucuronidase activities were also measured. The plasma equol concentration was significantly higher in the FI diet group as compared to the SI diet group. No significant difference was observed in the plasma daidzein concentration between the two dietary groups. There were no significant differences in cecal β-glucosidase activities between the FI diet group and the SI diet group. However, the ratio of cecal β-glucuronidase activity to β-glucosidase activity was significantly higher in the FI diet group. The present study suggests that a high content of fructose in the diet may affect the biological activity of dietary isoflavones on the host.
A test drink termed a “coffee mix drink” containing mannooligosaccharides (MOS) (0.5 g×2 as an effective component) from coffee mannan was administered to 19 healthy volunteers and its effect on defecating conditions and the fecal microbiota was investigated. Volunteers were divided into two groups for a double-blind crossover design test. Two cups of the coffee mix drink were drunk each day by volunteers for two weeks and two cups of coffee mix containing dextrin instead of MOS as a placebo drink were also drunk for two weeks. A significant increase was observed in the number of day of defecation during the test drink intake compared with the placebo drink intake and interval (p<0.01). In fecal microbiota of 10 volunteers, the ratio of Bifidobacterium spp. of the total anaerobic bacteria was significantly increased. (p<0.05) The results suggest that coffee mix containing MOS from coffee mannan improve defecating conditions and human intestinal microbiota.
Pyrazines generated from aqueous sugar-glutamine model systems heated at 90°C were investigated quantitatively. To determine trace levels of pyrazines in aqueous matrices, an efficient method using solid-phase extraction (SPE) and gas chromatography/mass spectrometry (GCMS) was developed. A series of alkylpyrazines as well as trace levels of acetylpyrazines and bis-(2-furyl)pyrazines were detected in the model systems by this method. Remarkable difference in the formation of pyrazines between monosaccharide and disaccharide was observed. The yield of acetylpyrazines and bis-(2-furyl)pyrazines from maltose was larger than those from fructose and glucose, while that of alkylpyrazines was less. The pH dependency on the generation of pyrazines in maltose-glutamine model systems was also examined.
The behavior of water molecules in refrigerated cooked rice was examined by measuring spin-spin relaxation time T2 using a pulse NMR spectrometer. T2 decay curve was analyzed using two-component and non-linear regression analysis and the presence of three kinds of water components with different T2 were revealed. In the case of fresh cooked rice, the observed T2 and the relative population were 0.9 ms (short T2) and 13%, 26 ms (intermediate T2) and 76%, and 200 ms (long T2) and 11%, respectively. The short T2 component was ascribed to the water molecules hydrated directly on the starch molecules. Intermediate T2 component was dominant and ascribed to the water molecules accommodated in the starch matrix inside the rice grain. The mobility of water molecules was suppressed remarkably during the storage at 0°C while it was almost independent of the refrigerated storage below −18°C. The long T2 component was ascribed to those grains accommodated in the surface luster film that was formed in the initial stage of the cooking process and composed of low molecular weight polysaccharides. The relaxation property observed by NMR was well consistent with the physicochemical properties.
We tested the stimulative effect of Lactobacillus casei subsp. casei 327 isolated from rice on the growth of bifi-dobacteria. No effect on the in vitro growth of bifidobacteria was observed. The number of bifidobacteria and the relative percentage of bifidobacteria of 14 female volunteers with constipation were measured. Then 7 volunteers who had less than 1010 cfu/g of bifidobacteria were administered 100 g of fermented milk with L. casei subsp. casei 327 each day for 2 weeks. The number of bifidobacteria, the relative percentage of bifidobacteria and the number of lactobacilli during the administration period significantly increased compared to before that period. Seven male volunteers who evacuated everyday were administered fermented milk to determine the change in the number of intestinal lactobacilli. The number of lactobacilli significantly increased during the administration period and returned to the original level 5 days after administration. These results indicate that the administration of fermented milk with L. casei subsp. casei 327 improves the intestinal environment.
The degree of methylesterification of pectin was measured using a modified alcohol oxidase method to determine the methanol liberated from pectin by saponification. When the alcohol oxidase method was used to determine the degree of methylesterification from crude pectin extracted from raw vegetables, the colorimetric determination value was thought to be low compared with the net value. From this result it was hypothesized that crude pectin contained some substance which had a reduction effect (inhibitory factor) on the determination value. This inhibitory factor could be removed by the addition of a copper sulfate in the alkaline condition. Two alcohol oxidase methods were applied to investigate a method to determine the degree of methylesterification of pectin; one was the method reported by Hamano et al. (1990) and the other was that reported by Klavons & Bennett (1986). The determination value of the two methods agreed when a copper sulfate was added.
The D-values at 80, 90 and 100°C of Bacillus cereus spores (Philippine strain 1061) in 2% broth of Philippine rice cultivar PSB Rc72H were 38, 12 and 5 min, respectively. The Z-value of the test spore was 20°C. The mathematically calculated lethality for the Bacillus spores in rice cooked at 100°C was established to be 25 min, which could be adequately attained during normal rice cooking times of ≥25 min by boiling.
Antioxidant effects of the phenolic acids, caffeic acid, p-coumaric acid, and ferulic acid, were investigated by monitoring O2 consumption in the linoleic acid micelles in the presence of H2O2 and metmyoglobin. O2 consumption usually consists of two phases: In the first phase, O2 is consumed slowly until the concentration of linoleic acid hydroperoxide reaches a certain value; then in the second phase O2 is consumed rapidly. At pH 7.4, the phenolic acids prolonged the period of the first phase and showed no effect on the second phase. At pH 3.4, the phenolic acids decreased the oxygen consumption rate in the second phase. These results suggest that the main antioxidant effects of the phenolic acids should be ascribed to reduction of ferrylmyoglobin in the first phase at pH 7.4 and inhibition of the chain reaction occurring inside of the micelles in the second phase at pH 3.4.
Amylomyces rouxii, the filamentous fungus widely used in the production of Asian fermented foods, is closely related to certain strains of Rhizopus oryzae secreting lactic acid. Among seven strains of A. rouxii, CBS 438.76T most vigorously produced both lactic acid and ethanol from glucose, starch, and pectin in liquid media. When this strain was grown on apple peels and successively mixed with potato pulp, the concentration of lactic acid produced was lower than that produced by Rhizopus oryzae NBRC 4707. However, the growth of A. rouxii CBS 438.76T acidified the pulp to less than pH 4, the level found in conventional silage fermented by lactic acid bacteria. A. rouxii may be preferable to R. oryzae for recycling potato pulp and other agricultural by-products into food materials because this fungus was being consumed long before written history, which attests to its safety for humans.