Effects of Sugars on Texture and Biochemical Properties of Dried Pork during Heat-drying

Abstract

In order to clarify the reason for soft texture of dried meat containing sugars, moisture content and shear force value of sliced pork as well as biochemical properties of myofibrillar proteins prepared from sliced pork such as Ca-ATPase activity and solubility in 0.6M KCl, 40mM Tris-HCl (pH 7.5) solution were measured during heat-drying of sliced pork with or without sugars. Plots of the logarithms of rate constants versus initial molarity of sugars provided liner relations for all indices employed. The slopes (denoted as e) of these linear plots were calculated using the following relation; e=(log k_Da-log k_D0)×1/a, where kDa and k_D0 are the rate constants for changes of indices in the absence and presence of a M of sugars. The "e value" was found to be highest for inactivation of Ca-ATPase of myofibril followed by a decrease of solubility of myofibril and lowest for the decrease of moisture content. Judged from "e value", it was strongly suggested that the added sugar during the heat-drying treatment of sliced pork effectively delayed the rate of denaturation of contractile proteins compared with that of the decrease of moisture content of sliced pork. In addition, the effect of sucrose was nearly two-fold higher than that of glucose for the change of indices employed. From these results, we assumed that the dried pork would be hard since the denaturation of contractile proteins would occur prior to the decrease in moisture of sliced pork during heat-drying treatment without sugar, and that, on the contrary, dried pork would be soft since the decrease in moisture of sliced pork would occur prior to the denaturation of contractile proteins during heat-drying treatment with sugar.