This review summarizes the properties of Maillard-type protein-polysaccharide conjugates through naturally occurring reaction in a dry state from the viewpoint of the development of new industrial proteins. Maillard-type protein-polysaccharide conjugates showed excellent emulsifying properties superior to conventional commercial emulsifiers, heat stability, and antimicrobial activity. Therefore, the conjugates can be useful for industrial applications as natural emulsifiers, antimicrobial agents devoid of toxicity. The possibility has also been proposed that conjugation of the allergen protein with polysaccharides may be effective to reduce the allergenicity. The molecular mechanism of the improvement of functional properties of proteins by attachment with polysaccharide was elucidated using the genetically glycosylated lysozyme constructed in the yeast expression system. The polymannosylation of lysozyme was effective in improving these functional properties, while oligomannosylation was not. Although single polyglycosylation of lysozyme was adequate to improve the functional properties, double polyglycosylation was even better.
Several pasteurization procedures for alfalfa (Medicago sativa) seeds were investigated to completely disinfect inoculated Escherichia coli (Migula) Castellani and Chalmers ATCC(25922). Hot-water treatments (85°C for 9 s) were equally or more effective than 20,000 ppm calcium hypochlorite treatments, yielding a reduction of 2 log10CFU/g. A greater reduction (4 log) was obtained by soaking the seeds prior to the heat treatments and, in some cases, no inoculated bacteria were detected after enrichment of the seeds in peptone. No survival of inoculated bacteria was detected from the seeds or the sprouts after deeply presoaking (15°C for 60 min) and treating the seeds with heat, but the germination decreased to 73% along with the yield which fell to 78.4% that of the control. We describe the hot-water treatment as an alternative method to hypochlorite treatments for disinfecting pathogenic bacteria in seeds for alfalfa sprout production.
A continuous and non-destructive method for measuring the moisture content of foods during the drying process is proposed. Changes in the dielectric property (capacitance), weight and temperature of samples of agar gel, vegetables and meats during the air-drying process were measured automatically. The results showed significant correlation between the capacitance of each sample and moisture content. This technique will enable us to control drying conditions automatically without sampling the material during the drying process.
Protein hydrolysates were prepared from Antarctic krill and two types of shrimp by enzymatic treatment using protease. Hydrolysates prepared from the krill were added to lizard fish myofibrils, and changes in the amount of unfrozen water in myofibrils during freezing were analyzed by differential scanning calorimetry. Ca-ATPase activity of myofibrils was measured concurrently and the results were compared with those using hydrolysates from shrimp. The amount of unfrozen water increased after addition of the hydrolysates and decreased moderately during frozen storage. When hydrolysates were not added to myofibrils, the amount of water rapidly decreased during frozen storage. The decrease in ATPase activity during frozen storage followed that of unfrozen water, indicating a close correlation between ATPase activity and the amount of unfrozen water. These results suggest that the denaturation of myofibrils may be suppressed by the addition of hydrolysates, since the hydrolysates appeared to increase the amount of unfrozen water.
To estimate the effects of two different kinds of sugar on soymilk freeze-gel, sucrose and trehalose, respectively, were added to raw untreated soymilk. Soymilk containing sugar was processed to form the freeze-gel. The apparent hardness and gumminess of freeze-gel increased with a relatively low concentration of sucrose or trehalose and reached a maximum of 0.5% for each sugar. On the other hand, the higher the concentration of sugar tested, the more inhibited the gelation became. However, up to 1% the syneresis of the freeze-gel simply decreased with an increase of sucrose or trehalose. NMR relaxation experiments appeared to show that the motion of water molecules gradually slowed with the increase of sucrose, so, although the interactions of water, sucrose and protein, possibly through hydrogen bonding, were complicated, they were significantly related to the formation of the freeze-gel.
A combination of freeze-grinding and screening to separate flesh and bone in processed marine food waste (head and backbone offal of fish) was evaluated. Samples were dorsal muscle (flesh), spine (bone), and backbone offal of yellow-fin tuna. A hammer mill with a screen opening size of 5.00 mm was used for the freeze-grinding process. Flesh, bone, a mixture of both, and backbone offal were separately freeze-ground to measure variations in particle size. Flesh and bone were also separately subjected to batch grinding to measure changes in particle sizes over time. By passing the ground product through a sieve with an appropriate screen opening size, flesh and bone could be separated into small and large particles, respectively, Grinding temperature and time were found to be important operational parameters optimizing the efficiency of the separation method.
A large-scale consumer test was made seeking preferences for regular coffee (RC). Based on preferences for 12 RC samples with various blend ratios of coffee beans, panels were divided into four preference clusters. Then, 88 RC samples were prepared and preferences against them were tested for clustered panels. To predict preference scores for each cluster, highly accurate models were constructed by applying a fuzzy neural network. We then conducted reverse estimation for optimum preference blends on each cluster by applying a genetic algorithm. The RC samples of optimum preference blends identified above were prepared and preference tests were again performed for the same panels. Those samples showed good preference scores and good agreement with predictions by models for each cluster. Consequently, this approach, consisting of consumer clustering and modeling for each cluster, provides an excellent tool for the rapid and efficient development of coffee products.
Retentate, highly pigmented pulp, from red colored Star Ruby grapefruit juice was placed in glass test tubes and stored in a refrigerated locker at 4.5°C for 8 weeks. The effect of light exposure (Cool White Fluorescence, 4150 K) on visual color changes using CIE color parameters (L*, a*, b*, hue angle, and chroma), and predominant carotenoid pigment (lycopene, β-carotene) contents by HPLC were investigated during the storage period. The changes in color parameters in the retentate were small, causing a slight color shift. Gradual decline of CIE a* value indicated the apparent loss of red character in the samples. Total carotenoid concentration gradually declined by more than 25% for both samples after 8 weeks of storage, but no significant effect of light-exposure on pigment loss was observed. Analysis of lycopene and β-carotene by HPLC indicated slight differences in loss but were not statistically significant under this condition.
We determined the protective activity of melanoidins against DNA damage using the comet assay. We used nitric oxide (NO) as a DNA damaging agent and HL60 (human promyelocytic leukemic cell line). Melanoidins were prepared from soy sauce and soy paste (miso). When the cells were incubated with NO (1 mM) and melanoidin (0–0.25%) for 30 min, soy sauce melanoidin strongly inhibited NO-induced DNA damage in a dose dependent manner. Miso melanoidin and melanoidin prepared from a glycine/glucose model system also inhibited the DNA damage. Melanoidins showed the protective effect even when cells were subsequently incubated with NO after the treatment and removal of melanoidins. As melanoidins did not trap NO under the condition used, they seemed to inhibit the DNA damage indirectly through a modification of some cellular function.
Defatted soybean-ontjom (D-ontjom, defatted soybean fermented with Neurospora intermedia) was prepared to utilize defatted soybean (DSB) as a food source. The antioxidant activity of hydrophilic components of D-ontjom and the mechanism were investigated. The 1,1-diphenyl-2-picryl-hydrazyl-radical scavenging activities of three extracts from D-ontjom, hexane, methanol and water extracts, were all stronger than those from DSB. Among them, the water extract from D-ontjom showed the strongest activity. I prepared an 80% methanol soluble fraction (hydrophilic fraction) from the water extract, which showed much stronger DPPH-radical scavenging activity. This hydrophilic fraction strongly suppressed the generation of superoxide anion and glutathione-autoxidation. To confirm the antioxidant activity of the hydrophilic fraction in vivo, rats were fed the fraction prepared from D-ontjom or DSB. The serum and liver thiobarbituric acid reactive substance (TBARS) values, hepatic superoxide dismutase (SOD, EC 220.127.116.11) activity and serum glutathione peroxidase (GSH-PX, EC 18.104.22.168) activity in rats fed the D-ontjom diet were significantly lower compared with those in rats fed the DSB diet, while their serum levels of α-tocopherol and glutathione were remarkably higher than those of rats fed the DSB diet. These results suggest that some hydrophilic components of D-ontjom have a high antioxidant activity in vivo, perhaps due to their radical scavenging activity.
Differences in the degree of disintegration after cooking were studied in three potato cultivars: Kita-akari, May Queen, and Hokkaikogane. Although the degree of disintegration increased with increase in the starch content in these cultivars, there were even differences in cultivars with identical starch content. For example, at 16%, the disintegration in Kita-akari, according to the standard grades for breeding, was “moderate-complete;” that of May Queen, “moderate;” and that of Hokkaikogane, “none.” Microscopic observations showed that cell separation had occurred in the disintegrated tissues and that the separated cells were full of swollen-gelatinized starch after cooking. Analysis of the starch distribution within a tuber, from the skin to the pith, revealed that cells with a high-starch content appeared in the area outside the vascular ring in Kita-akari but around the ring in Hokkaikogane. The cell size and intercellular space were larger in Kita-akari than in the other two. The results suggest that these structural differences may be one cause of the difference in degree of disintegration among these three cultivars with the same starch content.
Hydrogen peroxide (H2O2) formed in aqueous solutions of tea catechins such as epicatechin (EC), epicatechin gallate (ECg), epigallocatechin (EGC), and epigallocatechin gallate (EGCg) was measured by an HPLC method. The amount of H2O2 formed depended on their chemical structures, pH, temperature and incubation time. The gallyl moiety in the B-ring of the gallocatechins, namely EGC and EGCg, mainly contributed to the H2O2 formation. Superoxide dismutase inhibited oxidation of the gallocatechins and, consequently, the H2O2 formation. Cytotoxic effects were investigated by a colony formation assay with Chinese hamster V79 cells, and the effects of the gallocatechins were stronger than those of EC and ECg. The cytotoxic effects of the gallocatechins were inhibited completely by catalase and partially by superoxide dismutase. These results indicate that the gallocatechins were oxidized by superoxide, accompanied by the formation of H2O2, and their cytotoxic effects were ascribed to the H2O2 formation.
Salivary polymorphonuclear leukocytes (SPMN) produce O2− and H2O2 reducing molecular oxygen, and quercetin is a phenolic compound found in vegetables and fruits. The aim of the present study was to elucidate the interaction between SPMN and quercetin. The oxygen consumption by SPMN, which was stimulated by phorbol myristate acetate (PMA), was suppressed by quercetin. Half-inhibition was observed at about 20 μM quercetin. During inhibition of the oxygen uptake, quercetin was oxidized; the oxidation was inhibited by superoxide dismutase and enhanced by horseradish peroxidase. Quercetin was taken up into SPMN and myeloperoxidase in SPMN could oxidize quercetin if H2O2 was provided. These results indicate that quercetin can inhibit the formation of O2− and H2O2 by PMA-stimulated SPMN and that the flavonol can scavenge O2−and H2O2 generated by the SPMN. Quercetin inhibited the growth of Porphyromonas gingivalis that might cause periodontal disease. According to the above results, quercetin seems able to suppress SPMN-dependent inflammation caused by reactive oxygen species inhibiting the growth of bacteria in the mouth.
We studied the impact of heating on the aluminium ion (Al(NO3)3) binding amount of IDF (insoluble dietary fiber) and SDF (soluble dietary fiber) fractions extracted by the modified Prosky method from 14 kinds of food after different heat treatments. Al binding of unheated IDF was high in edible burdock, carrot, cabbage and hijiki. Heating marginally raised the Al binding amount of aloe and okra, but the other samples showed a tendency for the Al binding amount to fall when heated. Al binding of unheated SDF was extremely high in aloe, which has a high mucilage content, followed by okra and eggplant. Whereas non-mucilaginous foods had lower binding capacities when heated, the binding capacities of such viscous foods as aloe, okra, and moroheiya were increased by microwaving.
The obligatory two-electron reduction of quinones by quinone reductase (NAD(P)H:quinone oxidoreductase) competes with the one-electron reduction of quinones and protects cells against the cytotoxicity of quinones. We assessed the inhibitory effects of quercetin and curcumin against the menadione-induced cytotoxicity toward murine Hepa1c1c7 cells. tert-Butylhydroquinone, a positive control, induced the quinone reductase activity and suppressed the menadione-induced cytotoxicity. Both quercetin and curcumin induced the quinone reductase activity. While quercetin suppressed the menadione-induced cytotoxicity, curcumin showed no such suppressive effect.
The radical scavenging activity of the Japanese late-fermented black tea, Toyama Kurocha, was investigated. The activity was determined by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method, and its radical scavenging activity was found to be lower than that of green tea. Dried leaves of Toyama Kurocha were extracted in boiling distilled water for 10 min, the resulting extract was fractionated in the usual way, and the strongly acidic fraction was purified by silica gel column chromatography and HPLC. Five peaks of phenolics and 4 unknown peaks were detected by HPLC, and the main phenolics component in Toyama Kurocha was believed to be a gallic acid. Gallic acid has the highest DPPH radical scavenging activity.
Peptides having potent antioxidant activity were separated from the hydrolysate of wheat gluten by ion-exchange and gel filtration chromatography. Peptides obtained by SP Sephadex C-25 chromatography of the most active fraction (WP-3) were further separated using reversed-phase high performance liquid chromatography. The amino acid sequences of these peptides were Leu-Gln-Pro-Gly-Gln-Gly-Gln-Gln-Gly and Ala-Gln-Ile-Pro-Gln-Gln.
Two antitumor promoters against tumor promoter-induced Epstein-Barr virus activation were isolated from the leaves of jute (Corchorus capsularis L.). The antitumor-promoting activity was examined by an immunoblotting analysis. Their active components were identified as phytol (3,7,11,15-tetramethyl-2-hexadecen-1-ol) and monogalactosyldiacylglycerol (1,2-di-O-α-linolenoyl-3-O-β-D-galactopyranosyl-sn-glycerol) by spectroscopic data and chemical and enzymatic reactions. The content of the latter in four cultivars of C. capsularis L. and C. olitorius L. was found to vary with the cultivar. The detectable amount of each active component increased by treatment of the leaves with hot water.
We examined the characteristics of eight types of rice collected from three regions of Myanmar to identify why certain types are cooked immediately before eating, while other types are processed into fermented noodles. The protein content and blue value were in the range of 6.35–8.13% and 0.289–0.472, respectively. The types of rice with a high gelatinization temperature and high enthalpy are milled into flour for noodle making. There was a correlation coefficient of 0.995 between the gelatinization peak temperature by differential scanning calorimetry and the proportion of 12 chain length. The apparent activation energy of Kachin A was the lowest at 4.51 kJ/mol, followed by 5.61 kJ/mol for Nga Kyai.
Total and food component-specific saliva IgAs of six donors was determined to obtain information on the secretion of salivary IgA. Saliva was collected from each donor for three consecutive days. There was no time-dependency shown on the time of collection or food intake during the three days. Saliva of five other donors showed different concentrations among them. We showed that IgAs against food components exist in saliva, and these were determined by enzyme-linked immunosorbent assay.