Color changes of beef using contact-dehydrating sheet.

Abstract

A sheet containing highly osmotic agents was used for foodstuff dehydration. This sheet can remove the water in the foodstuffs when it comes in direct contact with them. Color changes of sheet-dehydrated beef were studied. Beef round cuts of 1.5cm thick were dehydrated by covering the samples with the sheet on the top side. After dehydration for 5, 12 hours as well as 1, 2, 3 and 5 days at 3°C, samples were sliced horizontally along the treated side into 3 layers of equal thickness. The uppermost layer (U) was found to be dehydrated the most, wherein the moisture content decreased from 71.7 to 59.1%. A dark red color has gradually developed in the U when dehydration time was prolonged. There was a parallel increase in both the TBA value and ratio of metmyoglobin in both the control and dehydrated U. A preventive effect on oxidations of lipid and myoglobin could be observed when beef was dehydrated for more than 2 days. However, oxidations of myoglobin and lipid were not the main factors in the formation of the dark color of U, but rather the concentration of red myoglobin pigment, in which the iron level was considered over 4mg of Fe/100g meat was considered to be the main cause of this darkening. There was a gradual change in the color at the surface of control and lower layer forming into a yellowish-brown color of metmyoglobin due to exposure to air. The inner layers were dehydrated less (from 71.7 to 68.0%) which might suggest that owing to indirect exposure to air, maintained a desirable redness.