Mitogenic activity and antitumor activity of Aloe arborescens Miller, Aloe barbadensis Miller and Aloe africana Miller, which have been used as traditional drugs and health food, were studied. The raw fresh aloe was divided into flesh and skins, and was lyophilized. Fraction were obtained by extraction with hot water, 0.1M NaOH and 0.5M NaOH. Mitogen assay was performed for all fraction using spleen cells from mice (_??_), C3H/HeN and C3H/HeJ. Six fractions showed mitogenic activity towards spleen cells of C3H/HeN. In addition, although the proteins were removed with actinase, the samples continued to show this activity. Among them, the non-dialyzable fraction of hot water extracts from a skin of Aloe arborescens Miller and the non-dialyzable fraction of hot water extracts from a skin of Aloe africana Miller showed strong mitogenic activity towards cells of C3H/HeJ, suggesting that it was free from bacterial endotoxic lipopolysaccharide. These results suggest that the activity components are not located in the protein region. No fraction showed antitumor activity against Sarcoma 180 ascites in mice.

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Degree of browning, phenolic content, phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO) activities were measured during storage in air at 5°C, 10°C, 15°C and 20°C to examine the undesirable enzymatic browning in shredded lettuce tissue. The browning of tissues was significantly dependent on storage temperature. High temperature markedly promoted the development of tissue browning. There was no significant change in activity of PPO at all temperatures during the storage. On the other hand, wounding induced marked increase in PAL activity. The initial increase of PAL activity was greater at higher temperatures. These results suggest that the increase in PAL activity due to wounding is probably one of the major reasons for the development of shredded lettuce tissue browning.

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To be able to produce a new antioxidant from yeast, 2250 yeast strains of this microorganism, both wild and commercial strains, were screened. Of the strains tested, AN231 gave the highest amount of antioxidant which we identified as Pichia ohmeri based on morphological and physiological features. The strain was grown in a medium made up of 2% glucose, 1% yeast extract and 1% polypeptone and incubated with shaking at 30 °C for 5 days. The culture was harvested by centrifugation and the supernatant was obtained. The supernatant was subjected to ultrafiltration and extracted with ethyl acetate. The extract was fractionated and purified using 2-dimensional TLC. A single spot corresponding to a single substance was detected using FeCl₃. The substance possessed high antioxidant activity and had phenolic compounds as functional groups. It was produced at a rate of 56 mg per l of culture broth. Comparison with known commercial antioxidants revealed that the activity was less than or equal to those of synthetic antioxidants, i.e. BHA and BHT, where as higher than those of α-tocopherol and ascorbic acid. The activity of the purified antioxidant was not lost even after 11 days at 40°C.

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High temperature treatment (HTT) with hot air at 45, 50 or 55°C for 1 to 5 hr prior to storage at 20°C was conducted to delay the yellowing of harvested broccoli florets. HTT at 50°C for 2 and 3 hr were more effective than others for maintaining green color and good quality of broccoli florets. Loss of chlorophyl and increase of carbon dioxide and ethylene production in the florets during storage at 20°C were inhibited by HTT at 50°C for 1, 2 and 3 hr except for the chlorophyll loss of 1 hr treatment. Inhibitions rates increased with in duration of HTT. 1-aminocyclopropane-1-carboxylic acid (ACC) content in florets during storage increased with the same rates in the control and HTT at 50°C for 1 and 2 hr, but the HTT for 3 hr retarded the increase in ACC content. Activity of ACC oxidase in the florets during storage increased remarkably in the control and HTT at 50°C for 1 hr, followed by those with the HTT for 2 hr, which reached maxima and subsequently declined quickly to low levels. However, in the florets with HTT at 50°C for 3 hr, scarcely any enzyme activity was detected during storage. These results suggest that HTT at 50°C for a short-term period would inhibit the conversion of ACC to ethylene and reduce ethylene production resulting in the retardation of yellowing in broccoli florets.

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The phospholipase D (PLD) was purified from leaves of cabbage (Brassica oleracea L. var. capitata L.). The molecular weight of the enzyme was estimated as 87 and 73.5-kDa on SDS-PAGE and gel filtration using Superdex 200 HR 10/30 column. The transphosphatidylation capacity of cabbage PLD was shown to be higher than that of Streptomyces chromofuscus PLD. Although cabbage PLD showed a single band, Streptomyces chromofuscus PLD gave several bands on nondenaturing and denaturing PAGE. These results indicated that the cabbage PLD was a monomer protein, while the Streptomyces chromofuscus PLD was hetero oligomer, having several types with different molecular weights. Furthermore, the cabbage PLD included the duplicated HxKxxxxD catalytic motifs in the molecule, but the Streptomyces chromofuscus PLD did not. Previously, YAMANE et al. reported that the transphosphatidylation capacity of Streptomyces sp. PLD was higher than that of Streptomyces chromofuscus. These results indicated that the high degree of the transphosphatidylation capacity of cabbage PLD was due to the existence of HxKxxxxD catalytic motifs.

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The proteolytic activity of Pseudomonas strains including P. fragi, P. taetrolens, P. aeruginosa, P. chlororaphis, P. fluorescens, P. putida, and P. synxantha was determined at various temperatures from 4°C to 37°C. Out of 43 strains tested, 33 strains grew well at 10°C within 3 days, and all strains except for a P. aeruginosa strain grew at 4°C within 7days. Four P. fragi strains, one P. taetrolens strain, one P. chlororaphis strain, two P. fluorescens strains, and one P. synxantha strain decomposed skimmilk at 10°C within 7 days. Ten P. fragi strains, one P. taetrolens strain, one P. chlororaphis strain, three P. fluorescens strains, and one P. synxantha strain did so at 4°C within 3 weeks. Strains of P. putida did not decompose skimmilk within 3 weeks. The proteolytic activity of P. fragi, P. taetrolens and their related species at low temperatures was discussed from the viewpoint of food hygiene

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