QUALITY CHANGES OF 'LOBO' APPLES DURING COLD STORAGE

Abstract

Apples of cultivar Lobo from two orchards (1 and 2) situated in the southwest of Finland were harvested either at the end of August (early harvest) or at the beginning of October predicted optimal or normal harvest), and stored at +3°C and 85% RH for three months. For reducing water evaporation from apples, they were kept in unsealed paper or unsealed, not perforated polyethylene bags. Macronutrients (N, P, K, Ca and Mg) and dry matter in fruit flesh, fruit diameter and firmness as well as soluble solids content (SSC) in juice were determined before and after the storage. The incidence of physiological storage disorders was recorded. Apples from orchard 2 were smaller in diameter and their firmness per diameter was higher, whereas dry matter and soluble solids content were lower than in apples from orchard 1. At normal harvest time, macronutrient concentrations were higher in apples from orchard 2, and at early harvest, nitrogen and potassium were higher in apples from orchard 1. Fruit firmness per diameter, dry matter and SSC (orchard 1) were higher at normal harvest. During storage of normally harvested apples fruit firmness per diameter decreased and SSC in juice increased due to the progressive ripening process. Low or even decreasing soluble solids concentration of early-harvest apples indicated improper ripening. The dry matter increased and fruit diameter decreased because of water loss and shrivelling of apples during the storage period. The nutrient concentrations of apples also increased along with increasing dry matter content. In the early harvested apples from orchard 1, physiological disorders increased significantly during storage. Normally harvested apples stored in polyethylene bags had higher diameter and firmness per diameter, lower dry matter, soluble solids and nutrient levels, and less physiological storage disorders than early harvested fruit.