Combined Impacts of Initial Freezing Rate and Thawing/Cooking Conditions on Physicochemical and Textural Properties of Pork Patties

This study aimed to investigate the combined impact of freezing rates (slow freezing rate [SFR]: 0.06°C/min; fast freezing rate [FFR]: 0.45°C/min; ultra-fast freezing rate [UFR]: 1.20°C/min) and thawing methods (cooking from frozen state [UTC]; water immersion in a 25°C water bath [WAT]; refrigerator at 2°C [RFT] until the core temperature reaches 2°C) on the physicochemical and texture characteristics of cooked pork patties. In 3 independent batches, biceps femoris muscles from 6 pork carcasses were ground to manufacture pork patties, which were assigned to 3 freezing conditions.The patties were thawed and cooked on the electric grill until they reached a core temperature of 72°C. An increase in the freezing rate increased moisture content and lowered water loss characteristics (P<0.05), resulting in the reduced total loss (sum of freezing, thawing, and cooking losses) of cooked patties (P<0.05). Thawing methods only affected the total loss in cooked patties, in which UTC patties had a lower total loss than RFT and WAT (P<0.05), but no difference was found between RFT and WAT (P>0.05). Instrumental color attributes were not affected by either freezing or thawing conditions (P>0.05). Fast freezing significantly decreased hardness values, and accelerated thawing (WAT) also resulted in lower hardness values compared with other thawing methods (P<0.05). Reduction in diameter during cooking was only affected by freezing rate (P<0.05), in which patties assigned to FFR and UFR had more reduction in diameter than SFR patties. Thawing methods only affected lipid oxidation, in which WAT had lower 2-thiobarbituric acid reactive substance values than UTC and RFT (P<0.05). These results indicate that the freezing rate would have more predominant impacts on cooked pork patties, in which FFR improved moisture contents and minimized freezing/thawing-induced water loss of cooked patties. Although thawing conditions have some minor impacts, no differences between UTC (direct cooking without thawing) patties and other frozen/thawed-then-cooked patties (RFT and WAT) in cooking loss and most texture profile attributes were found. Our results suggest that fast freezing can improve the overall quality of cooked patties, whereas combined impacts with thawing would be practically less meaningful.