ETHYLENE AND RESPIRATORY METABOLISM OF CAULIFLOWER (BRASSICA OLERACEA L. CONVAR. BOTRYTIS) IN CONTROLLED ATMOSPHERE STORAGE

In two subsequent years (autumn 1986 and 1987) cauliflower heads with and without trimmed jacket leaves were stored in 0–1°C, > 95% RH, 5% CO₂ - 3% O₂ and in normal air during 4 and 6 weeks. Shelf life was tested for 4–7 days at 10°C and 85% RH. Ethylene production, ACC (1-aminocyclopropane-1-carboxylic acid) and MACC (1-(malonylamino)-cyclopropane-1-carboxylic acid) content, respiration, sugar content and external quality of head and leafpart were determined.

Ethylene production of air-stored cauliflowers was higher than of the CA-stored ones, also during shelf life. The substantial increase in ethylene production during shelf life was mainly due to the contribution of the senescing leafpart as was shown by the strong increase in ACC and specifically MACC content of the leafpart during shelf life. ACC and MACC content of the leafpart increased at a higher rate in air storage.

Respiration of the cold-stored heads was slightly higher in CA storage. After CA or air storage respiration declined in the first three days of shelf life and remained constant thereafter. Total sugar content was marginally higher and external quality of the head was sometimes slightly better in CA storage. Leafpart showed a much higher benefit from CA storage, also after shelf life.

From these findings it was concluded that storage in 5% CO₂ - 3% O₂ had a very small effect, if any, on CO₂ and C₂H₄ metabolism of the head but a clear effect on CO₂ and C₂H₄ metabolism of the leafpart of cauliflower. This possibly explained the better external appearance of the leafpart after CA storage and also after shelf life.