The production process of flavor compounds from apple pomace was developed by a combination of fermentation and membrane technology in this study. Flavor compounds of apple pomace were extracted with 4 volumes of water containing L-ascorbic acid under agitation for an hour. After centrifugation, the extract was subjected to ultrafiltration and reverse osmosis (RO) membranes to concentrate the flavor compounds. The filtrate contained n-butanol, 2-methyl butanol, n-hexanol, and ethyl-2-methyl butyrate which were the general apple flavor compounds. These flavor compounds were concentrated in the RO membrane, but the membrane permeation flux decreased by the viscosity increase due to saccharides. The apple flavor compounds were concentrated to about 6.5-fold at that point. The yeast strains, D5-2, K5-1, and E-1 were isolated from the fruits in order to decompose the saccharides of the extract and improve the concentration of the flavor compounds. Bench plant experiments were performed with the use of strain D5-2 which, of the three strains selected, fermented a much larger amount of n-hexanol due to the decomposition of saccharides in the extract. A seed culture of 20l was added to an extract of 200l and incubated at 20°C for 2 days in a jar fermenter. After removing yeast cells by filtration, the filtrate was concentrated with the RO membrane. Compared with the RO filtrate without saccharide fermentation, it contained 28-fold concentration of 2-methyl butanol, 18-fold of n-hexanol, and 7-fold of ethyl-2-methyl butyrate. The flavor obtained with fermentation and membrane technology was almost equal to the flavor of an apple. Membrane technology and fermentation can be combined to produce concentrated apple flavor compounds from apple pomace.

View full abstract

In order to clarify major volatile compounds responsible for the aroma of the dried bonito (Katuo-bushi), volatile compounds produced in each smoking process (boiled bonito meat to katuobushi) were analyzed by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactmetry (GC-O). The volatile compounds identified in boiled bonito meat were aldehydes, ketones, furans, etc. These compounds increased or decreased during smoking process. Pyrazines, phenols and many other compounds did not appear until smoking process. Sulfur-containing compounds (dimethyl sulfide, dimethyl disulfide) showed little change through smoking process. Main odor in boiled bonito meat detected by GC-O provided sulfurous note due to sulfur-containing compounds (dimethyl sulfide etc.) and nutty note of unidentified compounds, probably due to very small amounts of pyrazines. As the smoking process proceeded roasty note of pyrazines and smoky note of phenols appeared and intensified. Sulfurous note derived from sulfur-containing compounds changed little throughout the smoking process. These changes induced in the smoking process will convert the aroma of boiled fish changed into that of dried bonito (Katuo-bushi). Consequently, some ethyl-dimethylpyrazines of roasty note and guaiacol and 4-methylguaiacol of smokey note were considered as main effective volatile compounds causing the aroma of the dried bonito (Katuo-bushi). The sulfur-containing compounds were also important, to develop strong and unique odor.

View full abstract

In this study, partial structure of polypeptide chains of glycoprotein responsible for viscosity from three kinds of yams (Tsukuneimo, Ichoimo and Nagaimo) was characterized. The N-terminal amino acid sequences of 32- and 28-kDa glycoproteins obtained from SDS-PAGE in the absence of 2-mercaptoethanol (2-ME) were determined as V-E-D-E-F-S-Y-I-E-G-N-P-N-G-P-E-N-W-G-N. The N-terminal amino acid sequences of 56-kDa glycoproteins from Tsukuneimo and Ichoimo were identical, D-G-D-F-S-Y-I-E-G-S-P-N-G-P-E-N-W-G-N-L, whereas the N-terminal sequence (D-E-D-D-F-S-Y-I-E-G-S-P-N-G-P-E-N-W-G-N) for that from Nagaimo was different from it. On thedatabase search via World Wide Web network, a consensus sequence, obtained from these sequences, was similar with that of dioscorin, one of the storage proteins of yam. On the SDS-PAGE in the presence of 2-ME, the glycoproteins demonstrated one peptide band with molecular mass of 32 kDa. Based on N-terminal amino acid sequence analysis, the 32-kDa peptide was identified asmixture of two kinds of polypeptides, designated as 32kDa (A) for the dominant peptide and 32 kDa (B) for the minor peptide. Consequently three proteins obtained by non-reduced SDS-PAGE wereconcluded as follows; the 56-kDa glycoprotein consisted of two 32kDa (B) joined by disulfide bond, the 32-kDa glycoprotein was monomer of 32kDa (A) without any disulfide bonds, and the 28-kDa glycoprotein was monomer of 32kDa (A) whose apparent molecular mass was decreased due to internaldisulfide bond. The peptide mapping analysis using limited proteolysis and amino acid composition analysis for 32kDa (A) peptide suggested that the glycoproteins of three yams had slightly different primary structure.

View full abstract

The concentrations of polyphenols in green tea infusions were analyzed using a newly developed polyphenol sensor. The principle of the sensor lays in the measurement of a decrease in hydrogen peroxide using a peroxidase-ferrocene-carbon paste electrode. First, polyphenols and peroxide was added to a measurement cell filled with a buffer. Second, soluble peroxidase was added to it. The enzyme oxidized the polyphenols and the concentration of hydrogen peroxide decreased according to the amount of polyphenols. The concentration of polyphenols was monitored by the decrease of current at the electrode. It needed less than nine minutes to measure a tea infusion. The results obtained by this method showed high correlation to those measured using high performance liquid chromatography. This method was applicable to canned tea drink by adding ascorbate oxidase to the buffer.

View full abstract

The effects of heat and pH on the radical-scavenging activity of proanthocyanidins, oligomeric and polymeric polyhydroxyflavan-3-ol units, and ascorbic acid were compared. The radical-scavenging activity was evaluated by measuring the decrease of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) detected at 517nm. Proanthocyanidin-rich extract from grape seeds (GSE) had stronger radical-scavenging activity than ascorbic acid and (+)-catechin, which is the monomeric compound of proanthocyanidin. This result suggested that more phenolic OH groups in a molecule caused stronger DPPH radical-scavenging activity. GSE was more stable against heat and pH than ascorbic acid. In acidic region, pH 4.0, the DPPH radical-scavenging activity of GSE almost possessed at 100°C for 5 hours, while that of ascorbic acid decreased less than 10%. In neutral region, pH 7.0, the activity of GSE was stable less than 50°C for 5 hours. In alkaline region, pH 10.0, 60% of activity of GSE remained at 100°C for 30 min, although the activity of ascorbic acid were completely lost. As it was clear that GSE was suitable for food ingredient of food processing and cooking, GSE was adapted to Konjac production, which is necessary for alkaline treatment. Konjac enriched with GSE significantly showed the DPPH radical-scavenging activity.

View full abstract

Contents of minerals (N, P, K, Mg, Ca, Zn, Mn, Na, Fe and Cu) in polished rice (milled to yields of 90-91%) grown in various regions of Japan in different cultivation years (1991, 1993 and 1994) were investigated. Rice crops of the same variety grown in the same region in different years were analyzed. The polished rice was digested with nitric acid in a microwave oven, and the mineral contents were then measured with an Inductivity Coupled Plasma Atomic Emission Spectrophotometer (ICP-AES). The mineral content data were divided into groups corresponding to individual minerals and subjected to cluster analysis. One result of this analysis was that, in the N, P and K groups, rice crops with similar crop report indexes were classified into the same cluster. The mineral contents of the rice grown in 1994 differed from those of the rice grown in 1991 and 1993. The agricultural climate in 1991 and 1993 resulted in rice crop report indexes of 95 and 74, respectively, whereas the 1994 index was 109. Therefore, the present results indicate that agricultural climate affects the contents of minerals, especially N, P and K, in polished rice.

View full abstract

Black chokeberry (Aronia melanocarpa Elliott), belonging to Rosaceae, is low wood of North America origin. It was introduced for the berry into Japan (Hokkaido) from former Soviet Union in 1976. Now in Hokkaido, it is cultivated in Sapporo (at Hokkaido National Agricultural Experiment Station), Ebetsu and Otaki. As for the cultivation, there were both trees of the North America derivation and the Russia derivation in Ebetu, and were the Russia derivation in the other places. In order to develop processed foods for Black chokeberry, chemical components and characteristics, i.e., proximate composition, organic acids and dietary fiber, polyphenol contents, mineral and vitamin contents, Brix, pH and one fruit weight, were investigated on 4 kinds of Black chokeberries in 3 places. The berries contained more β-carotene (770.6μg/10og), dietary fiber(5.62g/100g) than other fruits and berries. The content of β-cryptoxanthin (463.0μg/100g) and polyphenol (748.4mg/100g) in these were also high. The berries of the Russia derivation, as compared with those of the North America derivation, tended to be higher content of vitamin C, β-carotene, β-cryptoxanthin and organic acids, but to be lower content of polyphenol.

View full abstract

The composition of cell fusion vegetable "Yamagata Midorina" was investigated comparing with parental mustard vegetable "Yamagata Seisai" (Brassica juncea) and Chinese cabbage (Brassica rapa), harvested from the same field in the same season. "Yamagata Midorina" was produced between these parents to give the property of late bolting to a Yamagata prefectural special product "Yamagata Seisai". Contents of protein, lipid, carbohydrate, dietary fiber, ash, several kind of minerals and vitamin B1 in "Yamagata Midorina" showed between those in "Yamagata Seisai" and Chinese cabbage. Contents of β-carotene, vitamin B2, vitamin C, monosaccharides, and content patterns of free amino acids of "Yamagata Midorina" were close to those of "Yamagata Seisai" Although "Yamagata Midorina" has pungent taste like "Yamagata Seisai", main pungency component was not allylisothiocyanate detected much from "Yamagata Seisai" It was indicated that the other kind of isothiocyanates was main pungency component in "Yamagata Midorina".

View full abstract

Basic physical and chemical properties were evaluated on amylose extender mutants of rice (ae mutants) in order to evaluate the presumption of the suitable utilizations. Ae mutants showed higher amylose content than the others. The chain length distribution of the debranched starches indicated that Fr. II/Fr. III ratio of ae mutants were much less than Koshihikari, and ae mutants had longer chain of amylopectin than that of Koshihikari. The tension strength of starch films of ae mutants were stronger than that of Koshihikari and amylopectin, and apparently the films of ae mutants were paper-like by the tearing feel. Thus, the suitable utilizations of ae mutants were presumed to be materials with high strength, such as rice paper, rice noodle, sizing and biodegradable plastic films.

View full abstract

The concentration of oxalic acid in vegetable juices was determined in a flow injection system by using roots of barley seedlings as an immobilized oxalate oxidase reactor. In the pretreatment of the extracted vegetable juices, ascorbic acid was eliminated by the acetone powder of cucumber. Hydrogen peroxide produced from the decomposition of oxalic acid was reacted with the ABTS (2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) reagent and peroxidase. The oxidized ABTS was monitored spectrophotometrically at 405nm. The precision (coefficient of variation) was 3.1% at oxalic acid concentration of 0.2 mg/m/ level by 10 successive injections. The calibration curve of oxalic acid in this system gave the relative coefficient of 0.998. When this system was applied to some vegetable juices, the measured values agreed well with those obtained by the HPLC method.

View full abstract

Proteolysis of egg yolk in an acid solution was investigated. Egg yolk solutions (yolk 1: water 4), adjusted to pH 4.0 by acetic acid, were kept at 40°C for 3 hours and at 5°C for 3 weeks. Tyrosine contents of 5% trichloroacetic acid filtrates increased in both conditions to give 20μg/ml tyrosine after 3 hours at 40°C and 50μg/ml after 3 weeks at 5°C respectively. According to SDS-PAGE analysis, the patterns changed with incubation time, and especially the protein of relative molecular mass of about 200KDa decreased clearly. Addition of pepstatin A prevented these changes. It may be concluded from these results that the proteolysis of egg yolk under acidic conditions is caused by egg yolk aspartic proteinase.

View full abstract

We examined the effect of composition of agar medium for the detection of viable cells of Escherichia coli JCM1649^T. The nutrient agar supplemented with NaCl (NA) and two commercial products of plate count agar (standard method agar) exhibited practically the same level of colony count for intact cells, but NA was the most suitable for the detection of sublethally injured cells induced by heat treatment at 55°C for 15 min. Addition of 0.5% NaCl to the commercially-available plate count agar improved the detection rate of heat-injured cells, while glucose in the agar medium was found to decrease the detection rate. NA was shown to be useful as repair medium in the selective detection of heat-injured E. coli.

View full abstract

It has been reported that dietary Chlorella reinforces the immune system and protects rodents against bacteria and cancer. These effects are attributed to the increment of helper T cell type I population responsible for the cellular immunity. In this study we examined whether dietary Chlorella pyrenoidosa powder (CPP) influences the production of immunoglobulins (Ig) which play an important part in the humoral immunity. After CPP was fed to SD rats for 3 weeks, IgM concentration of the serum and IgM productivity of mesenteric lymph node (MLN) lympho-cytes were dose-dependently increased. Dose-independent IgG productivity of spleen and MLN lymphocytes was also enhanced. These results showed that dietary CPP reinforced IgM immunoglobulin production and may be useful for activation of host defenses.

View full abstract

[in Japanese]

View full abstract