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The effects of packaging with polyethylene bags and the inclusion of ethylene absorbent and/or CO2 absorbent on the keeping quality of mume (Japanese apricot) fruits were investigated. Concurrently, the concentrations of oxygen, carbon dioxide, ethylene, ethyl alcohol, and acetaldehyde in the bags and their production by the fruits were monitored.1. Yellowing and softening of green mume fruit were noticeably retarded by the combination of packaging with polyethylene bags (0.02 mm) and the inclusion of an ethylene absorbent. This retardation of the ripening process was reversed when a carbon dioxide absorbent was included.2. The inclusion of ethylene absorbent in the bags kept ethylene concentration at very low level, whereas oxygen concentration was higher and carbon dioxide concentration lower compared with bags in which the absorbents were omitted. In sealed bags with carbon dioxide absorbent or without both absorbents, acetaldehyde and ethyl alcohol accumulated, resulting in a physiological disorder known as internal browning. Addition of the ethylene absorbent suppressed the accumulation of both volatiles and prevented the occurrence of the internal browning. Inclusion of carbon dioxide absorbent with ethylene absorbent negated the beneficial effect of the latter and resulted in the accumulation of volatiles which induced the physiological disorder.3. The respiration rate of the fruit was slower in sealed polyethylene bags with ethylene absorbent than in that without the absorbent; this suppression of respiration was overcome by the inclusion of the carbon dioxide absorbent. The ACC (1-aminocyclopropane-1-carboxylic acid) content in the fruit changed, parallelling the trends of ethylene evolution in all treatments. Among the different treatments, the ethylene forming enzyme (EFE) activity was lowest in fruits sealed in polyethylene bags containing the ethylene absorbent.

Relation between the ripening and the drift of carbon dioxide production of harvested fruits was investigated to reconsider the meaning of respiratory pattern. The materials used were as follows: strawberries(Donner)and peaches(Hakuto, white flesh variety) as the species of which respiratory pattern has not been necessarily clear, tomatoes (Fukuju No. 2) as a typical climacteric class, and Satsuma oranges (Sugiyama, Citrus unshiu) as a non-climacteric class. The respiratory activities of pulp (or peel) homogenates of these fruits were measured to investigate the changes of respiratory mechanisms during ripening.1. It was proposed from the results obtained in the present and preceding experiments that the respiratory pattern of the harvested fruits should be classified in three types, not in two types of usual classification as climacteric and non-climacteric. It is as follows: (1) Respiratory rates gradually decrease through ripening process…… the gradual decrease type. (2) Respiratory rates increase temporarily, and full-ripe occurs after the peak of respiration…… the temporary rise type. (3) Maximum rate of respiration is shown from full-ripe to over-ripe stages…… the late peak type.According to the classification mentioned above, citrus fruits belong to the gradual decrease type, and the temporary rise type corresponds to the typical climacteric class including fruits such as tomatoes, bananas, pears, avocados, etc. Japanese persimmons, strawberries, and peaches belong to the late peak type. In the fruits of the late peak type, as a characterististics of the type, the relation between the time of respiratory maximum and the degree of ripeness is not clear as compared with temporary rise type, and the peak height of respiration varies remarkably among individual fruits.2. Regardless of respiratory pattern, it was seemed that qualitative change of respiration took place in the course of ripening. The increasing effect of cofactors(NAD, AMP, ATP, cytochrome c) on the oxygen uptake in strawberry homogenates changed remarkably during ripening. In the tissue slices and the cell-free extract of Satsuma orange peel, the effect of organic acids application on oxygen uptake changed during yellowing of the fruits which had been harvested at almost-green stage. At immature stage, the addition of malic and succinic acids increased respiration greatly, but citric acid had no effect. At yellow-colored stage, the effect of the former two acids diminished, but citric acid showed the effect in a high degree.

In previous report it was suggested that peas and broad beans should be held at strictly low temperature immediately after harvest to keep the quality. Present study was carried out to investigate the time-temperature tolerance of these materials for keeping the taste and to find out the factors concerning deterioration of taste. Peas and broad beans with pods were packed in perforated polyethylene bags, and treated at 1°C, 6°C and 20°C with scheme shown in Fig. 1.1. Organoleptic test showed that the taste of peas markedly deteriorated in a day at 20°C. Even at 6°C the deterioration was considerably rapid and the difference from 1°C-storage was detected 5 days after. Delayed cooling, transferring to 20°C from 1°C-storage, and fluctuation between 1°C and 6°C resulted in hastening of deterioration in comparison with steady 1°C-storage. With broad beans, such tendency was approximately the same as peas.2. While total sugar content of peas and broad beans showed some increase at 1 °C, it decreased markedly at upper temperatures, i.e., the content became a half or a quarter of initial in a day at 20°C, about a half in 2 days at 6°C and 10°C. Transferring to 20°C from 1°C resulted in rapid decrease. Fluctuation between 1°C and 6°C showed the value between steady 1°C and steady 6°C, then gradually reached to the level of 6°C. When the materials were transferred from 20°C to 1°C, the sugar content which had once decreased was recovered to the extent of steady 1°C, however, in taste test significant recovery was not observed.3. Neutral and acidic amino acids were determined using TLC and automatic analyzer. Threonine, glutamic acid, alanine, valine, iso-leucine, leucine, tyrosine, phenylalanine and other ninhydrin-positive products were detected in both peas and broad beans at harvest. They decreased drastically at upper temperatures. For example, alanine which was found abundantly in both materials decreased by 1/12 in peas and 1/5 in broad beans in 2 days at 20°C. At 1°C the decreasing rate was slowed down considerably, but 6°C of storage temperature was insufficient to prevent the rapid change.4. Sucrose-U-14C and alanine-U-14C were applied by vacuum infiltration to the slices of broad bean cotyledons and incubated for 10 and 24 hours at 20°C. They were incorporated rapidly into alcohol-insoluble fractions, presumably starch from the sucrose and protein from the alanine. Incorporation into alcohol-soluble cationic and anionic fractions was also observed to some extent.5. Hardening of cotyledons took place rapidly in both materials at 20°C. At 1°C the texture was kept soft for considerable period. Hardness of cotyledon measured by Curd meter paralleled with organoleptic test to considerable degree with peas, however, good correlation was not obtained with broad beans.6. It is concluded that three factors as decrease of sugar and amino acid contents and hardening would largely concern with the rapid quality deterioration of peas and broad beans. For keeping the quality, strictly low temperature is needed.

Citrus fruits such as oranges, lemons, and grapefruits suffer physiological injury when subjected to low but non-freezing storage temperatures. On natsudaidai fruits, of which production is a considerable amount among Japanese citrus fruits, there has been little available report concerning low temperature storage. Our preliminary experiments, purported to establish optimum storage temperature, showed occurrence of typical chilling injury on natsudaidai fruits. The present study was carried out to confirm this phenomenon in reference to its physiological aspects.(1) When natsudaidai fruits were stored at 1-1.5°C for two month or longer, chilling injury developed gradually. On the peel of chilled fruits brown pitting appeared and the fruits became susceptible to decay. Darkening of whole peel color was also found. Furthermore, prior to the appearing of visible injury during low temperature storage, the fruits increased susceptibility to microorganisms, and when transferred to 20°C severe decay took place rapidly. At 6°C, the fruits were stored without chilling injury and kept good external appearance for three months. At 13°C, half of fruits decayed during the storage of three months.(2) Respiration rate of fruits decreased with duration of storage at 6°C, showing the same tendency as ordinary citrus fruits. On the contrary, the respiration of fruits stored at 1°C exhibited continuous increase, and reached higher rate than that of the fruits at 6°C in the latter portion of storage period. When the fruits transferred from 1°C to 20°C, spur of carbon dioxide output was observed, and the degree of stimulation was more conspicuous with increasing exposure time at low temperature.(3) Respiration of flavedo tissue slices was measured at 30°C. Respiration rate of the slices prepared from 1°C-stored fruits was higher than that from 6°C- or 13°C-stored fruits especially in the latter portion of storage period. Respiratory quotient became lower than unity in the tissues from non-chilled fruits. However, at 1°C the RQ value remained at high level throughout the storage period.(4) Because the measurement was carried out with externally sound fruits, the results mentioned above suggest that abnormality of metabolism may have occurred in the healthy-appearing fruits during the 1°C storage.(5) Ascorbic acid content remained higher in the fruits stored at low temperature, indicating no relation to mechanism of chilling injury.(6) Potassium ion leakage from flavedo tissue slices suspended in water or sucrose solution was measured to detect the change of cellular permeability during the low temperature storage. However, no relation was found between the leakage and cause of chilling injury.(7) Prior to low temperature storage, a portion of fruits were treated with N6-benzyladenine, gibberellin, indoleacetic acid, and fruit wax. No effect was found to prevent the development of chilling injury with all chemicals used.

1. The present study was carried out to confirm the effect of gamma radiation on the inhibition of sprouting of onions during the storage and to investigate the physiological changes following the treatment. Onion bulbs were irradiated with the doses of 3000, 7000, and 12000 r. soon after the harvest (June 28) and at the presprouting period when the dormancy ends, i.e., Sept. 20. 2. The sprouting of onion bulbs was completely inhibited even at the dose as low as 3000 r., and the storage period of treated bulbs was eventually prolonged so long as 4-5 months over ordinary storage period. 3. Inner buds of onion bulbs which were inhibited the sprouting by the irradiation were browned and dead, but the injured parts did not extend to the outside of the buds. In the bulbs which had been irradiated on September 20, the browned parts were somewhat larger than that of the bulbs treated soon after the harvest. It means that the elongation and/or differentiation of the inner buds might have occured during the period, so the irradiation in theearly stages (during the rest period) would be preferable for practical use. 4. The oxygen uptake in the disk part (bottom part) of the bulbs was not directly influenced by the gamma radiation, while, when the control bulbs had increased the respiratory activity after the presprouting period, the increase of respiration in the treated bulbs was remarkably suppressed. 5. Also the contents of sugar and ascorbic acid in the bulbs were not immediately affected by any dose of radiation used in this study. However, when the non-reducing sugar content in the untreated bulbs was gradually decreasing after the bulbs had commenced sprouting, the contents in the treated bulbs were not affected for any change. 6. The characteristic flavor of onion bulbs did not appneciably alter by the irradiation. 7. No significant differences of the concentra-tions of growth promoting and inhibiting substances in the inner buds were found to exist between the irradiated bulbs and the untreated ones.