Some commercial ethylene absorbents and natural materials were evaluated for their ethylene removal efficiency at different moisture conditions. Among the 13 commercial ethylene absorbents, 6 of them had some deficiencies in the ethylene removal rate or efficiency even under dry conditions. Three of the ethylene absorbents such as artificial zeolite lost their efficiency at high humid conditions. Five of the absorbents released the absorbed ethylene when they were moistened with water. Four of the commercial ethylene absorbents, for example, activated carbon with palladium chloride and molecular sieve treated with potassium bromate, were effective at all moisture conditions. No significant ethylene removal effect was found in natural materials such as green tuff (Oyaishi) and rice hulls. Packed broccoli with polyethylene film was stored at 10°C with or without ethylene absorbents, and the chrolophyll, ascorbic acid and surface color were analyzed. The activated carbon with palladium chloride showed the better effect on the retention of freshness than the activated carbon or artificial zeolite. The results obtained by the evaluation of ethylene absorbents and the effect of ethylene absorbents on the retention of freshness of broccoli were well correlated.

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Sterilization efficiency of ozone is well known, it is using in food field recently. In this study, sterilization efficiency of ozonated water and the influence to retain the freshness of vegetables-cabbage and spinach-were investigated. Resistance of ozone to microorganisms differed with the species, it is similar to that the theory of heat sterilization. D value of Bacillus species was high, it was necessary to contact at high concentration for a long time. The surface cells of cabbage were damaged by ozone treatment of 2 ppm for 40 minutes. Then the pectin and reducing sugar concentration in the treated ozonated water increased proportionately with ozone concentration and treating time. The yield of cell wall components after ozone-treated cabbage and spinach was examined, the pectin fraction of cabbage was decreased by ozone treatment.

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The change of the temperature of spinach (Spinacia oleracea L.) during transportation in the summer season and the effects of film packages and supplementary materials for shipment cases on quality control of spinach were examined. (1) The higher the storage-temperature was, the higher the respiration rate was. 7 days after harvest, the respiration rate decreased at a level from 60 to 70% of that at the time of harvest. (2) The improvement in film sealing methods that were the change from open state to upper sealing or closed sealing with the film in use made the period of quality maintenance longer. However, as the closed sealing with the film is likely to cause stuffiness, it is considered that the upper sealing type is better as a practical sealing method. (3) The temperature of spinach in a cardboard box changed more slowly than that in a sectional and plastic plying case during transportation. The quality of spinach in the cardboard box was much higher than that in the plying case. (4) The temperature of spinach covered with a styrofoam sheet as the supplementary material changed the slowest of all during transportation. On the contrary, the temperature of spinach covered with 1 sheet of newspaper was influenced by the outside temperature. The fluctuation of the temperature of spinach covered with 2 sheets of newspaper was intermediate between those of styrofoam sheet and 1 sheet of newspaper. The quality of spinach was much higher with the styrofoam sheet or 2 sheets of newspaper than with 1 sheet of newspaper. These results indicate that the styrofoam sheet and 2 sheets of newspaper have effects of quality maintenance in case of the sectional plying case now in use.

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