Quality and Aroma Production of Doyenne du Comice Pears in Relation to Harvest Date and Storage Atmosphere

Abstract

The effect of harvest date and storage atmosphere on quality and volatiles was investigated in Doyenne du Comice pears grown in the region of Lleida (NE Spain). Fruits were harvested at 2 dates (119 and 126 days after full bloom) and stored in regular air (RA) atmosphere (21% O2: 0.03% CO2) and in low oxygen (LO) atmospheres with two carbon dioxide concentrations: low CO2 (2% O2: 0.7% CO2) and high CO2 (2% O2: 5% CO2); the storage periods were 3, 5 and 7 months. After storage plus a shelf-life period (1 and 4 days at 20 C), flesh firmness, soluble solids content, titratable acidity and skin colour (parameter a* + b*) in the fruits were determined. Furthermore, volatiles production (ethylene and aroma) was determined at 4 days after storage. After 5 months, pears from regular air storage showed poorer quality than fruits held under low oxygen atmospheres. At 3 and 5 months of storage plus 1 and 4 days at 20 C fruit firmness was higher in LO when compared with RA-stored fruit, in both early- and late-harvested fruits. For long-term (7 months) storage high CO2 atmospheres permitted a good retention of fruit firmness and skin colour, but fruits stored in low CO2 achieved a quality more suitable for consumer acceptance (at the end of the shelf life period at 20 C). Differences between LO atmospheres were frequently not significant for soluble solids content and titratable acidity. The highest aroma production was obtained after 3 months of RA storage for early-harvested pears and after 7 months of LO-low CO2 storage for lateharvested fruits. Otherwise, LO-high CO2 had a depressing effect on total aromatic volatile production. Storage conditions and the period of ripening at 20 C influenced the occurrence of individual esters and alcohols.