Packaging of solid-pack type apples in retort pouches. Part 2: Pectin behaviour in the products during processing and storage

• Published in: Carbohydrate polymers Vol. 11; no. 2; pp. 113 - 125
• Main Authors: Forni, Elisabetta, Senesi, E., Viganò, Liliana, Bertolo, G., Maestrelli, A.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1989; Elsevier Science
• Subjects: Biological and medical sciences; Food industries; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; Apple; Decomposition; Pectin; Texture
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/0144-8617(89)90019-2

The influence of processing on the degradation of pectic substances of apples (‘Golden Delicious’ variety) was studied. The three pectin fractions — water-soluble (WS), oxalate-soluble (OS) and residual pectin (protopectin, RP) — were determined in fresh apples, after blanching, after processing and in the following stored products: fruit slices packed both in retort pouches (half stored at 20°C, half at 4°C, both for 12 months) and in tinned cans (stored at 20°C for 12 months). The galacturonic acid content of the three fractions was determined by RP-IP-HPLC and the methanol content by GC. Due to the high protopectin level in apple, which comprises about 75% of the total pectins, the slices kept a good texture even after thermal processing in either cans or retort pouches. The analysis of the sugar content of the products showed that the sucrose from the syrup penetrated the slices during blanching and sterilising; this might produce gelling of the pectins giving the higher texture observed for these products.