A comparison of apple cultivars regarding ethylene production and physico-chemical changes during cold storage

Abstract

Measurements of titratable acidity, soluble solids, firmness, ethylene production and weight loss were made for five apple cultivars held in cold storage for 100 days. Carbosieve G in the traps of the enrichment column, which has only a moderate affinity for light hydrocarbons, was found to meet the requirements for the optimal thermal desorption of ethylene (130°C for 2 minutes) from the enrichment column to the analytical column. ANOVA showed significant differences in all these five parameters between the five cultivars Golden Delicious Reinders, Resista, Topaz, Meteor and Rubinstep, and also in the course of storage. In all cases, the changes in titratable acids measured during storage were especially significant, but the observed changes in sugar levels, as measured by refractometry, were too variable to be useful in this context. High rates of ethylene production impacted probably only indirectly on the loss of firmness and the other parameters which were measured. Discriminant analysis of the measurements of firmness, ethylene production and titratable acid provided the best means of differentiating the cultivars, although Golden Delicious Reinders and Resista still could not be completely separated. Other parameters (soluble solids and loss in weight) did not contribute to the discriminant resolution.

Keywords

• apple cultivars
• composition
• ethylene production
• firmness
• headspace gas analysis