The importance of Strecker degradation lies in its ability to produce Strecker aldehydes and 2-aminocarbonyl compounds, both are critical intermediates in the generation of aromas during Maillard reaction, however, they can also be formed independently of the pathways established for Strecker degradation. Strecker aldehyde can be formed directly either from free amino acids or from Amadori products. Several pathways have been proposed in the literature for the mechanism of this transformation. On the other hand, Amadori or Heyns rearrangements of ammonia with reducing sugars can also generate 2-aminocarbonyl compounds without the formation of Strecker aldehyde. In addition, isomerization of the imine bond of the Schiff base formed between a reducing sugar and an amino acid, can initiate a transamination reaction and convert the amino acid into the corresponding α-keto acid and the sugar into its α-amino alcohol derivative. The reverse of this reaction, has been documented to produce Amadori products. The α-keto acids can either decarboxylate to produce Strecker aldehydes or undergo Strecker degradation (as a α-dicarbonyl compound) with amino acids to also produce Strecker aldehydes. This review will examine the role of Strecker degradation and Amadori rearrangement, under the light of recent findings, in controlling the balance among four critically important key intermediates: α-dicarbonyl, α-hydroxycarbonyl, 2-amino carbonyls and 2-(amino acid)-carbonyl compounds, during the Maillard reaction and hence control relative importance of aromagenic versus chromogenic pathways.
Application of microwave and infrared radiation was explored for thermal processing of honey and its effect on the physico-chemical characteristics as well as the microbiological quality of honey were studied. Microwave heating provided a rapid means of achieving the desired level of yeast reduction with reduced thermal damage. Though different combinations of heating duration and microwave power intensity achieved the commercially acceptable level of yeast reduction in honey, heating for a shorter duration (15 s) at higher power intensity (16 W/g) was desirable in terms of lower hydroxymethylfurfural (HMF) value (3.8 mg/kg) and higher diastase activity (12.0). Infrared heating was not as rapid as microwave heating but achieved the desired results in a relatively shorter period (3–4 min) offering advantages over the conventional method.
The random-centroid optimization (RCO) method using computer was applied to determine the optimum conditions of the emulsifying activity of soy protein isolate. Levels of factors including the temperature during emulsification, pH of the protein solution and the concentration of NaCl were optimized. After the second cycle of measurement of the emulsifying activity in 22 samples, we were able to determine the optimum conditions for practical use, namely, a temperature of 30°C, pH 8.2, and concentration of NaCl of 0.35 mol/l. We concluded that this RCO method is suitable for the optimization of food processing conditions with a minimum number of measurements.
Monolauroyl maltose was synthesized through the immobilized-lipase-catalyzed condensation of maltose and lauric acid in acetone using a batch reactor or a continuous stirred tank reactor. The presence of 4A molecular sieves significantly increased the conversion by the removal of water from the reaction mixture. The surfactant properties of the monolauroyl maltose were measured at different temperatures, and the critical micelle concentration depended little on the temperature.
Essential oils of citrus fruits have many uses in consumer products so that efficient methods for their isolation are needed. Membranes are often used in the separation process but a common problem is that the flux through the membranes decreases with time. In the present study we examined whether ceramic membranes might be better at maintaining the flux at acceptable levels. To test the membranes, we attempted differential recovery of nonpolar terpene hydrocarbons and aqueous oxygenated compounds from condensates produced as a by-product during the concentration of citrus juices. When zirconia membranes (ZrO2-UF, cut-off molecular weight 50,000 and ZrO2-MF, pore size 0.08 μm) were used, little decrease in the flux was observed during filtration. The nonpolar terpene hydrocarbons were retained while more polar oxygenated flavor compounds passed through the membrane. The percentages of alcohols, esters, and aldehydes in the permeate increased markedly compared with their percentages before filtration. When the condensate from the concentration process of citrus juice sampled from a juice factory was filtered using ZrO2-UF, the hydrocarbons was concentrated, and a water-soluble essence consisting primarily of oxygenated compounds was obtained in the permeate.
We screened the bacteria affecting the quality of alkaline noodles to improve the noodles by biological methods. Brevibacterium helvolum B8 and Arthrobacter sp. B25 were selected as strains providing favorable effects on alkaline noodles from 158 bacteria able to grow under a high alkaline condition. The addition of these strains to alkaline noodles increased the degree of yellowness of the noodles and repressed the formation of organic acids which caused reduction in the pH. The increase of other bacteria in the noodles and the appearance of mold on the noodle surface were also suppressed, so that it was assumed that these bacteria had also the ability to prevent microbial spoilage of the noodles. These results suggested that B. helvolum B8 and Arthrobacter sp. B25 were useful in improving the appearance and retaining the quality of alkaline noodles.
This article describes a microbiological study of lactic acid bacteria involved in the fermentation process of Miso. The bacteria were counted and isolated from Miso during fermentation and, based on the results of traditional phenotypic tests, divided into nine groups. The isolates were identified by biochemical analysis and 16S rRNA sequence analysis. During Miso fermentation, the halophilic bacterium Tetragenococcus halophilus increased moderately. The non-halophilic strains displayed a complex growth pattern and were identified as Enterococcus faecium, Enterococcus durans, Enterococcus faecalis, Pediococcus acidilactici, Pediococcus pentosaceus, Lactobacillus plantarum and Weissella confusa. The predominant species throughout the fermentation process were T. halophilus, E. faecium and E. durans. Among them, only the strains of E. faecalis and E. durans produced bacteriocins that had an antibacterial effect on B. subtilis, but had none on T. halophilus. The bacteriocin producers appear to play an important role in maintaining normal bacterial flora during Miso fermentation.
Polysaccharide showing inhibitory activity against hyaluronidase, which is known to be related to inflammation and tumor metastasis, was purified from the sporophyll of Undaria pinnatifida by fractionated extraction and column chromatography. On the basis of chemical analyses, the purified compound was found to be a kind of sulfated polysaccharide. The molar ratio of sugars and sulfuric acid in the purified compound was estimated to be L-fucose : D-galactose : D-glucuronic acids : sulfuric acid1.0 : 1.0 : 0.04 : 5.2. The number-average molecular weight of the sulfated polysaccharide was estimated to be 63,000 by high-performance liquid chromatography. This polysaccharide inhibited hyaluronidase activity (IC5013.0 μg/ml) in a dose-dependent manner.
Aspartic proteinase from Laetiporus sulphureus was purified by sequential chromatographies on Sephadex G-100, DEAE-Sepharose Fast Flow, and Butyl-Toyopearl 650S. The final preparation was judged homogeneous by SDS-PAGE. The molecular mass of the purified enzyme was estimated to be 50,000 and the isoelectric point of the enzyme was 3.5. The enzyme was most active at pH 2.6 and was inhibited completely by a specific aspartic proteinase inhibitor, pepstatin A. The enzyme was extremely labile as compared to other milk-clotting enzymes and N-terminal amino acid sequence of the enzymes was closely related to that from a basidiomycete, Irpex lacteus. Comparison of substrate specificities of milk-clotting enzymes on αs1- and β-casein indicated that β-casein is a suitable substrate for identifying the specificities of these enzymes, because these enzymes showed different specificity on β-casein but similar specificity on αs1-casein.
Olive (Olea europaea L.) is recognized as a folk medicine for diabetes in Europe. The inhibitory action of an ethanol extract of olive leaves (OEE) on the activities of human amylases was examined in vitro. OEE inhibited the activities of α-amylases from human saliva and pancreas with IC50 values of 4.0 and 0.02 mg/ml, respectively. Two anti-α-amylase components were purified from a 50% ethanol soluble fraction of OEE using Sephadex LH-20 column chromatography. One was identified as luteolin-7-O-β glucoside and the other as luteolin-4′-O-β glucoside. The 50% ethanol insoluble fraction of OEE was dissolved in 98% ethanol and fractionated using Cosmosil C18-OPN column chromatography. The anti-α-amylase component purified by this chromatography was identified as oleanolic acid. Both luteolin and oleanolic acid have an inhibitory effect on postprandial blood glucose increase in diabetic rats. Olive leaves suppressed the elevation of blood glucose after oral administration of starch in borderline volunteers (fasting blood glucose: 110–140 mg/dl), and thus they may be a useful food supplement for the prevention of diabetes.
Sixty-five grams of sudachi (Citrus sudachi Hort. ex Shirai) essential oil from 18 kg of peel was isolated by a modified solvent extraction (MSE) in a semi-preparative scale with a hand-screw pressing instrument and a solution of pentane and dichloromethane. Twenty-four compounds were newly identified. The essential oil retained its original aroma without any off-flavor. The odor character of sudachi essential oil prepared by MSE method was described by means of odor impact spectra (OIS). The combination of preparing a large quantity of the oil and the OIS method enabled clarification of the potent aroma components. Thus, (E,E)-α-farnesene, (E)-β-farnesene, diisopropyl disulfide, cumin aldehyde and dill ether were newly selected as the aroma-active compounds.
Digestibility of mannooligosaccharides obtained from thermal hydrolysis of spent coffee grounds was examined by in vitro digestion method. Mannooligosaccharides were resistant to human salivary α-amylase, artificial gastric juice, porcine pancreatic enzymes and rat intestinal mucous enzymes. Fermentation products of mannooligosaccharides in human large intestine were estimated by in vitro fecal incubation method. Mannooligosaccharides were fermented by human fecal bacteria and the products of fermentation were short chain fatty acids. Acetic, propionic and n-butyric acids were the main short chain fatty acids as end fermentation products. These results suggest that mannooligosaccharides are indigestible saccharides and are converted to short chain fatty acids in human large intestine. The short chain fatty acids are thought to improve the large intestinal environment. Moreover, they are absorbed and utilized by the host as an energy source.
The difference of combination between Glu-B1 and Glu-D1 alleles in bread-making quality was investigated using the near-isogenic lines (NILs) of Glu-1 alleles. We found that composition of the HMWG subunits had different effects on bread-making quality. The SDS-sedimentation volume, physical dough strength, and specific loaf volume of Harunoakebono (79/510) and NIL 1718/510 were significantly higher than those of the other NILs. NIL 20/2.212 showed the least value among NILs. The results were a sticky dough and a poor-quality loaf. NIL 20/510 or NIL 20/2.212 was found to have a large negative effect compared to subunits 79/510 or NIL 79/2.212. The functional properties of NIL 20/212 were not significantly different from those of NIL 79/212. Subunit 20 had different effects on the functional properties when coupled with other subunits at Glu-D1 alleles.
The influence of polyphenol oxidase and ascorbate oxidase on radical-scavenging activity and contents of total phenol, chlorogenic acid, and ascorbic acid in vegetables during the cooking process were investigated. In the case of burdock and lettuce, which have a high activity of polyphenol oxidase, the radical-scavenging activity and the content of total phenol and chlorogenic acid decreased drastically within 1 min. In the case of broccoli, however, only a small decrease of radical-scavenging activity was observed, and total phenol and chlorogenic acid decreased almost not at all. The decrease of the activity in broccoli depended on the oxidation of ascorbic acid by ascorbate oxidase. None of these compounds decreased after the enzymes had been inactivated by heating.
The preventive effects of dietary nasunin on a liver injury induced by D-galactosamine (GalN) were investigated in rats. Increases in plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) activities, which were induced by GalN, were suppressed by the feeding of nasunin before the intraperitoneal injection of GalN. Increases in liver oxidized-form glutathione (GSSG) concentration and the ratio of GSSG to reduced-form glutathione (GSH) by the injection of GalN were also suppressed by the dietary nasunin. A slight increase in the liver α-tocopherol concentration and an increase in the liver SOD activity due to the injection of GalN tended to return to the level of the control rat by the feeding of the nasunin. These results suggested that nasunin is effective to prevent liver injury and that it is also effective to prevent oxidative stress which may be induced by GalN-induced liver injury.
The use of electrolyzed water for washing and sanitizing eggshells and an egg washer was evaluated for its effectiveness at a Grade & Packing Center adjacent to a poultry farm for a period of nine months. The test results indicate improvement in sanitation control. Dissolving yolks of broken eggs with electrolyzed alkaline water followed by sanitizing with electrolyzed acidic water produced favorable effects. Also, the use of electrolyzed water has an advantage in that it simplifies the conventional washing and sanitizing process and motivates operators to employ the process more frequently. This sense developed in operators may be a significant factor in the improvement of sanitation control.
We have confirmed the existence of genotypic and environmental differences in the apparent viscosity of heat-treated wheat flour paste. The positive year-to-year correlation indicates that the value is principally genetically controlled. Among 64 genotypes, arabinoxylan content and flour particle size were significantly correlated with apparent heat-treated flour paste viscosity, indicating that genotypic differences are mostly ascribable to differences in these two factors. Wheat cultivars grown under diverse conditions showed different viscosity and flour protein content, and these were positively correlated, implying that environmental differences are due to differences in protein content. The viscosity of unheated flour paste was found to be highly correlated with that of heat-treated flour.
Traditional wheat flour foods in many Asian countries are produced by natural fermentation. Enterobacter cloacae GAO was isolated from the starter of traditional flour fermented foods. Immunoblotting with the serum of the patient using this flow showed that an immunological reaction of the fermented foods with Enterobacter cloacae GAO was different from that with yeast. The bacteria were isolated from traditional wheat flour foods and identified as Bacillus sp, Lactobacillus sp, Leuconostoc sp. and Lactococcus sp. The fermentation time of ‘mantou’ by enzymes of a B. pumilus and yeast mixture was shorter than the time with yeast alone. The sensory evaluation showed that the ‘mantou’ prepared with B. pumlus and yeast was as good as that with Enterobacter cloacae GAO or yeast alone. Different immunoblotting patterns were observed in the case of the ‘mantou’ prepared with yeast or E. cloacae GAO. The salt-soluble protein of ‘mantou’ prepared with B. pumilus and yeast has about 1/20–1/30 in comparison of the inhibition obtained with the control in RAST inhibition experiments.
The fatty acid compositions in the body wall, gonads, and alimentary canal of male and female Stichopus japonicus caught in the Sea of Okhotsk off the coast of Abashiri were analyzed to clarify their characteristics. The fatty acid composition was studied also in konowata sold at the market. The analysis was performed by capillary gas chromatography. Major fatty acids that constituted the lipids of the body wall were iso-C15, C16:0, C16:1n-7, C18:0, C18:1n-7, C20:4n-6, C20:5n-3, C23:1n-9, and C22:6n-3. The fatty acid compositions in various tissues were nearly identical between males and females. Although the fatty acid compositions in the body wall and gonads were similar, they markedly differed from the fatty acid composition in the alimentary canal. The iso-C15, C16:0, and C16:1n-7 levels were very high in the body wall, and the C20:1n-9, C20:4n-6, and C20:5n-3 levels were high in the alimentary canal. A very high monoenoic acid content and the absence of polyunsaturated fatty acids with the exception of icosapentaenoic acid were characteristics of the fatty acid composition in konowata.
After the operation of boiling soybean [Glycine max (L.) Merr.], 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activities of soybean cultivars with different seed coat colors of yellow, green, red-brown, and black were investigated. The DPPH scavenging activities of soybean-boiled extracts and the remaining boiled soybeans were in the order of soybean cultivars with black seed coats . cultivars with red-brown seed coats . cultivars with green or yellow seed coats, and the activities were dependent on the anthocyanin contents in the cultivars. Since soybean cultivars with black seed coats containing anthocyanins had the highest DPPH scavenging activities, these radical-scavenging activities made them the most suitable materials for the soybean-boiled extracts and/or the boiled soybeans.
Chardonnay grapes were fermented with or without juice of apple, pear, cantaloupe, peach, banana, or orange with a Saccharomyces cerevisiae yeast strain. Volatile chemicals formed in the seven wines were isolated and identified by gas chromatography/mass spectrometry. A total of 29 major volatile compounds were identified in the seven wines. They were 8 alcohols, 12 esters, 6 acids, and 3 miscellaneous compounds. Isoamyl alcohol was the most abundant volatile chemical found in all the wines. It comprised from 31.35% (pear wine) to 44.94% (orange wine) of the total GC peak area. Cantaloupe wine contained the highest amount of 2-phenyl alcohol in the seven wines. Amounts of monoethyl succinate, which was one of the most abundant compounds found in wine fermented alone, ranged from 8.35% (apple) to 23.95% (banana). Ethyl 2-hydroxy propionate, amounts of which ranged from 3.93% (cantaloupe) to 5.41% (without fruit), was one of the major esters found in wines. The addition of fruit juices did not significantly change the overall volatile composition of fermented grapes. However, each fruit juice gave its characteristic flavor to the final wine. There have been only a few reports on wines flavored with other fruits.
The stimulatory effect of wasabi leafstalk extract (Wasabia japonica MATSUM.) on bone calcification was compared with the anabolic effect of insulin, insulin-like growth factor I (IGF-I), 17β-estradiol, and genistein. Mouse calvaria tissues were cultured for 48 h in a serum-free Dulbecco’s modified Eagle’s medium (high glucose, 4.5%). The presence of wasabi leafstalk extract (25 μg/ml) caused significant increases in bone calcium content. The combination of 10−10 M 17β-estradiol and 15 μg/ml wasabi leafstalk extract had an additive effect on bone calcium content, while the increasing effect of phyotoestrogen genistein (10−9 or 10−7 M) on this content was not significantly greater in the presence of the same amount of the extract. Insulin (10−8 or 10−7 M) had a significant effect on bone calcium content, and the combination of both 10−8 or 10−7 M insulin with 15 μg/ml wasabi leafstalk extract had an additive effect. Such an effect was not seen in the case of IGF-I (10−8 M), however which increased bone calcium content. The present study demonstrates that wasabi leafstalk extract has an enhancing effect on the anabolic action of 17β-estradiol or insulin, which regulates bone formation and calcification in vitro.
We studied the physiological functions of enzymatic hydrolysates of collagen or keratin contained in livestock and fish waste, for the purpose of determining optimal utilization of those wastes. The enzymatic hydrolysate of meat meal, a collagen-waste, showed strong angiotensin-I-converting enzyme (ACE) inhibiting activity (IC500.6–2.8 mg/ml). In contrast, the enzymatic hydrolysate of a mixture of horn and hoof, a keratin-waste, showed high antioxidative activity. Thus, collagen or keratin contained in livestock and fish waste may be convertible to useful products by enzymatic hydrolysis, providing new physiologically functional food materials.