Effects of Gas Concentrations on Fruits
VII. Comparisons of CO2 Effects at Different Relative Humidities, and of Low O2 Effects with and without CO2 in CA storage of Natsudaidai
1973 Volume 42 Issue 1 Pages 49-55
Details
1973 Volume 42 Issue 1 Pages 49-55
To compare the effects of CO2 concentrations at two humidity levels (98-100% RH, and 85-95% RH), fruits were stored in the air mixed with 0, 5, 10 and 20% CO2 at 4°C for 50 days.
At the higher CO2 levels, button browning was equally retarded at both humidity levels, and development of granulation and decrease of acidity were retarded markedly at low humidity. Acidity decreased considerably at 20% CO2. Under high humidity conditions, water content in the peel and ethanol content in the juice increased, and abnormal flavor developed at the higher CO2 levels. At 10% and 20% CO2, internal O2 levels decreased extremely in fruits with watery breakdown. At low humidity, no injuries were found, and the optimum CO2 level in CA storage seemed to be higher and more storage merits of CO2 were obtained than at high humidity.
To compare the effects of low O2 levels with and without 5% CO2, fruits were stored in the mixed gases (0% CO2+5% O2, 5% CO2+7% O2). Without CO2, no distinct effects of low O2 were found in button browning and acidity. Granulation was retarded, and abnormal flavor and ethanol accumulation were found at low O2 levels. Combined with 5% CO2, low O2 levels retarded decrease of acidity markedly, and accelerated development of abnormal flavor at high humidity. At 5% CO2+7% O2 under low humidity conditions, no abnormal flavor developed and acidity did notdecrease, and the best storage quality was obtained.
In citrus CA storage, there seemed to be three peculiarities (1, susceptibility to low O2 storage, 2. gas diffusion resistance of the peel, as important factor for storage, 3. unfavorable under high humidity conditions). Disccusions were made about the abnormal flavor in relation to high water content in the peel, high gas diffusion resistance of the peel, low internal O2 level, anaerobic respiration and ethanol accumulation in the juice.
