Correlations of processing characteristics with variety and specific gravities of potatoes

Studies of Processing Characteristics of Potatoes Part 7

Abstract

The differences in texture parameters between fresh and steamed potatoes of two defferent varieties, Mayqueen and Danshaku imo, which are the two main varieties of potatoes produced in Japan were examined. Fresh samples of both varieties showed increases in hardness, cohesiveness and gumminess with increasing specific gravity. Steamed samples of both varieties showed decreses in all texture parameters with incresing specific gravity. A primary regression equation was computed to express the relationship between specific gravity and texture parameter. Samples of both varieties with identical specific gravities showed high binding strengths. Mayqueen showed a high viscoelasticity and a high resisitance to collapse. However, Mayqueen also showed a texture similar to that of Danshaku imo white using high-density potato samples, which showed no resistance. Potato thermal analysis of fresh potato samples showed a low density and a high heat capacity peak of the cell wall component in both varieties at 70-100°C. This indicates that a large amount of heat is necessary to change the properties of hypobaric samples of both varieties by steaming. It was surmised that the properties of Mayqueen being highly mucilaginous and having a high binding strength are the main reason a large amount of heat is necessary to change the physical properties of this variety by steaming.