Biochemical Composition and Chipping Quality of Potato Tubers During Storage as Influenced by Fertilizer Application

Changes in free sugars, phenols, free amino acids (FAA) and dry matter (DM) content of potato tubers as influenced by fertilizers NPK and farm yard manure (FYM) in balanced and unbalanced combinations were studied in relation to chipping quality of tubers during storage in an evaporatively cooled store (13-30°C, 75-98% RH). Reducing sugars decreased significantly (39.3%) till 90 days of storage (DOS) followed by an increase (31.3%) up to 120 days. Sucrose showed a steady increase during storage, while total sugars decreased till 90 days followed by a steep increase up to 120 DOS. Total phenols showed an increasing trend and FAA recorded an increase till 90 days followed by a decrease up to 120 DOS. Application of balanced NPK and NPK+FYM significantly decreased the reducing sugars and glucose content of tubers at harvest and improved the chip colour. NPK also increased the DM content at harvest and reduced the phenol content of tubers after 120 DOS. Mean chip colour score (CC) which was of unacceptable range at harvest (7.55) improved progressively (2.40) up to 90 DOS when light yellow, crispy and highly acceptable chips could be made. The findings are of significance for the processing industry, which can get suitable potatoes after 90 DOS in the cooled store. Regression analysis showed chip colour to be more closely associated with reducing sugars (r^2 = 0.672), particularly glucose (r^2 = 0.705) content in tubers.