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`Golden Delicious' apples (Malus domestica Borkh.) harvested at the preclimacteric and climacteric stages of ripening were stored for up to 8 months at 1C in air and under various controlled atmosphere(s) (CA), including ultralow oxygen (ULO) storage conditions. Aroma volatiles were measured at 2-month intervals in fruit ripened for 10 days at 20C. Fruits harvested at the climacteric stage produced more volatiles during all storage conditions than preclimacteric fruit. All CA storage treatments suppressed aroma production compared to cold storage. The greatest reduction was found under ULO (1% O2) and high CO2 (3%) conditions. A partial recovery of aroma production was observed when CA fruits were subsequently stored for 14 days under cold storage conditions. Suppression of aroma production under ULO conditions seems to be related to low fatty acid synthesis and/or degradation, and is restricted to volatiles having a straight C chain. Production of branched C-chain aroma compounds was suppressed by high CO2 concentrations. The reduced capacity of aroma production during shelf life after ULO storage is confined to apple cultivars producing mainly ester compounds with a straight C-chain, e.g., `Golden Delicious'.
Abstract
Dipping ‘Jonathan’ apples in CaCl 2 solution prior to storage greatly reduced the development of internal breakdown (IB) and retarded flesh softening during 19 weeks at 2.2°C plus 1 week at 23°C. Infiltration of fruit with sorbitol produced IB symptoms, whereas glucose caused a dissimilar browning coloration and sucrose yielded no visible damage. Infused Ca inhibited IB symptoms and browning, retarded respiration, reduced the metabolism of endogenous substrates, and increased the oxidation of exogenous substrates. The results suggest Ca inhibits IB by enhancing the uptake and compartmentation of substrates, particularly sorbitol.