EFFECT OF A PARTIAL DRYING PRETREATMENT ON THE RESPIRATION ACTIVITY OF FRESH-CUT APPLE

Some experiments were performed in order to evaluate the effect of a partial drying on the respiration and the metabolic activity of fresh-cut apples.
Fresh-cut apple ‘Golden Delicious’ segments were dried up to a water loss of 10%, 20%, 30%, 40% and 50% in an air dryer set at a constant temperature of 50°C. Partially dried apple segments were checked for the respiration rate (O₂ consumption and CO₂ production in a sealed container in 24 hours), ethylene production (amount of ethylene produced in one hour in a sealed container up to 24 hours), water activity (a_w), total soluble solids, titratable acidity and pH. The results showed some changes of the chemical indexes, which were related to the level of the partial drying.
The fresh-cut apple segments maintained the respiration even at 50% weight loss.
After 24 hours, the oxygen percentage decreased to 19,55, 19.60, 18.65, 19.39 19.20, 19.96% and carbon dioxide increased to 1.50%, 1.40%, 2.40%, 2.05%, 1.5% and 0.85% in, respectively, untreated samples, 10%, 20%, 30%, 40% and 50% weight loss.
Ethylene production showed a trend to increase in all the samples but the amount varied noticeably.
Untreated samples showed a peak after 7 hours.
The 50% dehydrated samples showed the minimum amount of ethylene production (24 μL
kg^-1 h^-1), while the highest amount was in the 30%, 20% and 10% dehydrated apple segments (respectively 110, 90 and 79 μL kg^-1 h^-1 after 24 hours). The experiments demonstrated that the respiration is not completely inactivated by partial drying even at 50% water reduction and that the drying parameters can have some influence on the respiration rate.

V International Postharvest Symposium

E. Senesi, A. Calabretto, M. Macario, R. Lo Scalzo

activity water, oxygen consumption, carbon dioxide production, ethylene production

https://doi.org/10.17660/ActaHortic.2005.682.246