Nouveaux diffuseurs plastiques du SO2 pour la conservation frigorifique du raisin de table
Abstract Following a study of the production and emission of SO2 from metabisulphite contained in plastic sachets or bags, new diffusers of SO2 have been made, using polyethylene bags. These have been used in experiments on the storage of table grapes. Each diffuser held 50 g of potassium metabisulphite, 5 g of ‘celite’ and 5 g of water. Experiments showed that most of the SO2 given off by the bisulphite was oxidized to potassium sulphate, by oxygen contained in, or diffusing into, the bags. Only that part of the SO2 which diffused out of the bags was useful in storage of grapes. Subsequent experiments on refrigerated storage of ‘Razaki’ and ‘Sultanina’ grapes have shown that these plastic diffusers (one to each tray of grapes) in a pack or over-wrap of polyethylene or even of paper, enable storage of grapes for two to three months, with no development of mould, and retention of the freshness of the produce. The stalks remain green and the absorption of SO2 by the grapes is minimal.