Two-stage air thawing as an effective method for controlling thawing temperature and improving the freshness of frozen pork loin

Abstract

Reduction in the total thawing time for pork loin subjected to two-stage air thawing was investigated. The pork loins were frozen at −60 and −18 °C and stored for up to 6 months at the freezing temperature. Samples were thawed using constant-temperature air thawing (−1.5, 2, and 25 °C) and two-stage air thawing methods. In the two-stage air thawing method, the samples were thawed at 25 °C in the initial stage. When the core temperature of the sample reached −5 °C, the samples were transferred to −1.5 °C (25/-1.5 method) or 2 °C (25/2 method). The physicochemical properties of the thawed pork loins, including thawing loss, cooking loss, water holding capacity (WHC), volatile basic nitrogen (VBN), and thiobarbituric acid reactive substances (TBARS) were analyzed. Thawing at 25 °C was the most rapid thawing method, and the total thawing time were reduced effectively using two-stage air thawing. Generally, samples thawed by two-stage air thawing (25/-1.5, and 25/2 methods) exhibit better moisture related properties. The effects of the thawing methods on VBN content were minimal; only trace levels of TBARS were detected in the samples. Therefore, two-stage air thawing is expected to reduce the total thawing time and prevent meat quality deterioration caused by the freezing and thawing processes.