To supply fresh garlic bulb with keeping quality for a long period, preparative drying immediately after harvest is required. Heated aeration is one of the effective drying methods, however the bulb itself changes to brown color if the air temperature is too high. In this paper the permissible upper limit of air temperature and its effect on phenolic compounds relating to browning of the bulb were investigated. When the air temperature increased from 40 to 80°C (drying time : 40-528 h), the rate of drying increased as an exponential function, but visible browning of the bulb was detected at 50°C and at higher temperature. Absorbance at 420 nm wavelength of the water soluble fraction of garlic bulbs, which was dried at the corresponding air temperatures, showed extremely high value at 50°C. From the hypothesis that phenolic compounds would be related to browning, the contents of their water soluble fraction were measured. The results showed that the highest value was observed at 50°C and lower values at 60°C and at higher temperature. Further, seven kinds of phenolic compounds were tentatively identified by gas chromatography, and it was found that four of them decreased over 60°C.

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The addition of glycyrrhizic acid (GR) caused deeper anthocyanin color and increased stability of anthocyanin. We examined the structure of GR which caused copigmentation effect using various kinds of oleanolic triterpenoids. Furthermore, we examined copigmentation effect of GR whose glycoside was digested by β-glucronidase. Addition of every oleanolic triterpenoids including glycyrrhetinic acid (aglycone of GR) caused deeper anthocyanin color, suggesting that copigmentation effect of GR was originated from aglycone of GR. After the enzyme digestion of the glycoside (glucronic acid) of GR, anthocyanin color was decreased. The glucronic acid addition decreased anthocyanin color. Existence of glucronic acid inhibited the copigmentation effect with GR and α-glucocylrutin.

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The potential for detection of non-metallic foreign materials in food using X-ray spectral analysis method was discussed. X-ray measuring system with CdTe crystal sensor was developed and X-ray spectrum of food could be measured and analyzed. X-ray linear absorption coefficients (μ) at each X-ray photon energy level of various materials were calculated from X-ray spectra. As the μ value was shown a function of X-ray characteristic of material, it was considered to be valid for detection of foreign material in food. The vinyl chloride plate in distilled water was investigated as a simple model. The percentage and different type of foreign materials in uniform sample could be estimated by measurement of peek position of derivative X-ray spectrum. The X-ray spectrum measuring system was then tried to be applied for detection of foreign materials in food. Three samples of hamburger patty, one free of foreign materials and two with foreign materials (glass and vinyl chloride) were tested. Peek position of derivative X-ray spectrum at hamburger patty without foreign materials was 15.5 keV and that at hamburger patty with glass and vinyl chloride plate moved to 17.5 and 17.0 keV, respectively. These results showed that, the X-ray spectrum analysis method has potential and can be applied in detecting non-metallic foreign materials in food with a proper threshold value at derivative X-ray spectrum. However, in practical use, the effect of thickness, mixing material and unevenness of material have to considered in the X-ray measurement. It is expected that different types of non-metallic foreign materials in various kinds of foods could be automatically detected by the X-ray spectrum measuring system with CdTe crystal sensor.

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The effects of hydroponic culture (water culture) and Ca-solution spray to tree of conventional soil culture on enzymatic browning of the apple fruits were examined in comparison with the conventional soil culture (soil cultured fruit: SCF). The cultivars of apple were Fuji and Jonagold of water cultured fruit (WCF), and Starking of Ca-solution sprayed fruit (CaF). We investigated the relationship among the enzymatic browning, polyphenol (PP) content and polyphenoloxidase (PPO) activity by using the apple fruits harvested at Morioka in 1992-1994. The results were as follows. (1) Total PP (TPP) contents in WCF and CaF with low browning degree were higher than that in SCF with high browning degree. It seemed that TPP content didn't relate to the browning directly. (2) Chlorogenic acid content was found to be higher in WCF than in SCF, however the relationship between culture condition and epicatechin content of same samples was not clear. (3) The contents of chlorogenic acid and epicatechin in Starking were not affected by spraying of Ca-solution. (4) The PPO activity in WCF was weaker than that in SCF significantly. These results indicated that the browning reaction of WCF was influenced by the PPO activity. (5) The PPO patterns by Native PAGE differed between the apple cultivars but had no difference among the culture conditions. It is evident that the low browning degree of WCF depended on only quantity of PPO, not on quality.

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We investigated the changes in polyphenol (PP) content and polyphenoloxidase (PPO) activity of apple fruits (flesh, core and peel) during ripening process. The apples were cultivated with the experimental hydroponics (water cultured fruit of Fuji: WCF) or sprayed with Ca-solution on conventional soil culture (Ca-solution sprayed fruit of Starking: CaF). The control apples of the same cultivar were cultivated by conventional soil culture (soil cultured fruit: SCF). These apples were harvested at 3 stages during ripening process at Morioka in 1993. The following results were obtained. (1) Total PP (TPP) contents in WCF and CaF, which had low browning degree were higher than that in SCF with high browning degree. (2) In peel of all apples, regardless of cultivar and culture condition, TPP was included four of five times the other parts. (3) The contents of chlorogenic acid and epicatechin in WCF and CaF were higher than those in SCF. In Fuji, regardless of culture condition, chlorogenic acid content was higher than epicatechin content in all parts. In Starking, same result was obtained in flesh and core, but reverse result was found in peel. (4) The contents of TPP, chlorogenic acid and epicatechin decreased during ripening process, and fell rapidly during the early stage of development. (5) The PPO activity in WCF was weaker than that in SCF significantly, but it was not affected the spraying of Ca-solution. (6) The PPO activity decreased rapidly during the early stages of development.

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Screening of acetic acid bacteria that display higher tolerance and productivity of acetic acid was carried out by the continuous culture method from vinegar mash. Twenty strains of acetic acid bacteria were isolated with agar medium from the culture broth that contained 193g/l of acetic acid. Fed batch fermentation which was maintained at ethanol concentration of 1% (v/v) using an ethanol controller was carried out for isolated acetic acid bacteria, and most of 20 strains were able to produce vinegar containing 16% (w/v) of acetic acid and upward. Strain No. 11 of acetic acid bacteria was selected on the final acetic acid concentration (172g/l) and productivity. This strain produced vinegar containing 185g/l of acetic acid at 24°C of cultivation temperature. Strain No. 11 was identified as Acetobacter aceti from the physiological and biochemical characteristics.

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Polymerization of the melanoidin in a heated onion juice and a model system of glucose and glycine was investigated by dialysis and gel filtration chromatography on a Sephadex G-25 column. The melanoidin in a heated-onion juice was eluted in the fractions of smaller molecular weight than those of sugar and amino acid, with a similar chromatography to caramel rather than those of model melanoidin and soy sauce. Adding onion juice tothe model system of glucose and glycine, the ratio of dialyzable melanoidin in the whole melanoidin increased. The inhibitory effect of onion juice on the polymerization of melanoidin was speculated.

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An identification method based on the nucleotide sequences of 16S ribosomal RNA (rRNA) gene was applied to the analysis of microflora in a food. We isolated bacteria from "Japanese pickles", "smoked salmon"and "seasoned pig bowels", and then analyzed about 300 bases of the 5'-terminal sequences of their rRNA genes. In the 35 sequences which were different each other being referred to a DNA data-base, each sequence showed a homology with that of the known species in an extent of 91 to 100%, in an average of 97.9%. In Japanese pickles of "Hasamizuke" which is moderately pickled, lactic acid bacteria were considered to occupy the majority of the microflora. On the other hand, in Japanese pickles of "Nozawanazuke", various species of bacteria were intermixed. In smoked salmon, bacteria belonging to Staphylococcus sp., Acinetobacter sp. and Flabobacterium sp. were detected. In seasoned bowels, 5 species including 2 species of bacteria inhabiting in animal's bowels were detected. When lactic acid bacteriawere searched in various pickles, species which is closely related to Leuconostoc cremoris or Lactobacillus sake were always isolated.

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A microorganism in Juten-tofu (heated after packaging) with yellow spots was isolated and identified. The microorganism was isolated on a soymilk agar plate at 5°C under anaerobic con- ditions. Tofu yellow coloring isolate, a type of lactic acid bacteria, was identified as Leuconostoc mesenteroides subsp. mesenteroides. Because of its heat resistance (about 50°C), it was estimated that the contamination of this strain occured after heating of a package in the process of Juten-tofu manufacturing.

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We have studied a method which addresses the problem of precision measurement of dispersed droplet diameter in W/O emulsions and W/Ospreads.With the usual methods of centrifugal sedimentation, etc., used to measure dispersed droplet diameter in W/O emulsions and W/O spreads, errors in measurement result from sheer stress which causes droplet collapse and droplet agglomeration, as well as from the presence of other solids. To address this problem, measurement by means of an image analyzer using an optical microscope for direct observation of dispersed droplet diameter in sample material made it possible to eliminate the above mentioned causes of error. Since use of an optical microscope made precise measurement possible, this report examines W/O spread dispersion medium, dispersion method and measurement temperature. For the measurement of W/O spread, using liquid oil with hydrophobic emulsifier as the dispersion medium, it was found that heating to a temperature of 40°C was suitable. Based on these results, it is possible to suitably assess W/O spread products.

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