Storage and shelf-life of apples grown in Norway - II.Effects of controlled atmosphere storage on ‘Summerred’

Summary

Apples of the cultivar ‘Summerred’, grown in the south-eastern part of Norway (59*40’N) and harvested in September, were stored in controlled atmosphere (CA) at 3-4% O2 + 3% CO2 or in normal air (NA) at 2*C (*1*C) until the middle of January. After removal from storage in December and January, the apples were kept one week at room temperature, simulating shelf-life. Principal component analysis (PCA) revealed three components explaining 84% of the total variation. The most important cause of variation was the storage time (50% explained), followed by the storage methods (23% explained) and the variation caused by year of harvest (11% explained). Weight loss, pH, and the ratio of soluble solids/titratable acidity (SS/TA) all increased during storage, while firmness, sensory preference, titratable acidity and L-ascorbic acid decreased. SS/TA was higher in apples stored in NA compared to apples stored in CA. In simulated shelf-life, storage method was more important than storage time, as shown by means of PCA. During simulated shelf-life, pH and the SS/TA-ratio decreased less in CA-apples than in NA-apples. The concentrations of soluble solids, titratable acidity and L-ascorbic acid were all lower in January than in December. Beneficial effects of CA-storage for ‘Summerred’-apples were of minor importance and therefore they cannot justify the cost of CA-storage.