Impact of hot water treatment on sprouting, membrane permeability, sugar content and chip colour of reconditioned potato tubers following long-term cold storage

Abstract

BACKGROUND: The efficacy of hot water treatment in facilitating successful reconditioning of processing potato (Solanum tuberosum L.) cultivar Hermes following 6months cold storage at 4.5°C was examined. Tubers were subjected to hot water treatments (HWTs) at 52.5, 55.0, 57.5 and 60.0°C for 0-60, 0-50, 0-40 and 0-20 min, respectively, and then reconditioned for 20 days at 16°C before evaluated for sprouting, fresh weight loss, membrane permeability, sugar content and processing quality. RESULTS: The study demonstrates that in order to achieve complete inhibition of sprouting during potato reconditioning HWTs must exceed the thermal tolerance threshold of the tubers. Short-duration HWT was effective in retarding sprout growth and tuber dehydration without significantly affecting storage parenchyma membrane permeability, tuber sugar content or processing quality. On the contrary, prolonged HWT caused extensive heat damage, loss of membrane integrity and induced an increase in tuber sucrose and reducing sugar content resulting in deterioration of chip colour in proportion to treatment duration. CONCLUSION: Although HWT at 52.5-60°C following long-term cold storage did not improve the processing quality of potato tubers after 20 days of reconditioning, future work is needed to evaluate the effect of short-duration HWT on the permissible extent of reconditioning and subsequent processing quality. © 2008 Society of Chemical Industry.