Studies on the CA-storage of fruits and vegetables

Abstract

This paper reports the investigation on the changes of some chemical contents, the metabolism and the qualities of tomatoes (Ogata Fukuju; mature green and breaker stages) stored in air and CA-conditions.1) Mature green tomatoes during CA-storage (5% CO2-10% O2, 10% CO2-10% O2, 25% CO2-10% O2 short term treatment, at 6.5±0.5°C) were ripening slowly and reached a light pink stage after 6 weeks. The surface colour of tomatos stored in air turned fair red and the tomatoes in CA-storage (5% CO2; 10% CO2) showed retardation of colour development by postponing after-ripening, but the fruits were weakened and more subject to decay by Alternaria after transfer to room temperature(18°C).2) Also after-ripening of tomatoes treated at breaker stage was inhibited by CA-condition at 6.5±0.5 and 7.5±0.5°C. Tomatoes stored in air reached a soft ripe stage after 2-3 weeks and the surface colour turned red. On the other hand, tomatoes stored under CA-conditions (5% CO2 and 10% CO2) reached a dark pink stage after 4 weeks and the fruits were edible after 5 weeks. It was found that tomatoes at breaker stage might be suitable for CA-storage.3) The L-ascorbic acid content in tomatoes treated at breaker stage decreased gradually at 7.5°C in all plots, especially at the end of the storage period under CA-conditions. The organic acid content in the tomatoes decreased during storage in all plots. The decreases of total acid content in the fruits was not inhibited by CA-conditions but the decreases of malic acid content was inhibited under the CA-conditions.4) O2 uptake and CO2 output in Warburg espirometer measurements of tomato pulp slices decreased gradually during storage. The O2 uptake of the tissue slices stored in 10% CO2 plot was small in comparison with other plots. The effect of addiiton of pyruvate on CO2 output of pulp slices from the tomatoes in CA-condition was higher than that of tomatoes in air, indicating that high concentration of CO2 in an atomosphere might stimulate pyruvate carboxylase activity of tomatoes.5) In pulp slices, succinic-1, 4-14C was converted into the other acids in the TCA-cycle. From this tracer method, it was observed, that succinic dehydrogenase might be inhibited in tomatoes stored under CA-conditions.