PSVII-17 - Differential freeze/thaw rates affect water-holding capacity and lipid oxidation in beef rib primal cuts

Abstract: Fresh meat is vulnerable to microbial contamination and loss of quality. Hence, freezing is used to mitigate these issues during transport and storage. However, freezing may negatively impact the same quality characteristics it was meant to preserve, resulting in products that are dissatisfying to the consumer. During the freezing process of meat, water forms ice crystals of various shapes and sizes. The degree of ice crystal growth, mainly due to the freezing rate, has been shown to affect several meat quality characteristics, including tenderness, juiciness, and color. Previous research has primarily evaluated the effect of freezing/thawing on the quality of beef retail cuts. To the best of our knowledge, however, minimal research has been devoted to examining the impact of freezing/thawing on the quality of beef primal and sub-primal cuts. Therefore, this study aimed to gain deeper insight into the histological, ultrastructural, and physiochemical changes occurring in whole beef ribs in response to different freezing/thawing treatments. To achieve our objective, we purchased 32 choice beef rib primals from a local harvest facility 24 h postmortem. Ribs were vacuum packaged and randomly divided into four groups (8 ribs/group). The first group was frozen in a −20 °C freezer (slow freezing), stored in the same freezer for 12 weeks, and thawed at 4 °C for 24 h (slow thawing). The second group was frozen in an ultralow temperature freezer (−80 °C; fast freezing), stored in the same freezer for 12 weeks, and thawed at 4 °C for 48 h. The third and fourth groups were frozen and stored in the same manner as groups one and two, respectively, but were thawed in a water bath (10 °C) for 8 h (fast thawing). Two 2.5-cm-steaks from the middle and each end were collected to represent the entire rib. One steak from each of the three areas was used for color, cook loss, and tenderness evaluation, while the other three supplied tissue for drip loss and lipid oxidation analysis. Data were analyzed using the mixed model of SAS with P ≤ 0.05 considered significant. No differences were observed in color or tenderness between the treatments (P > 0.05). However, slow thawing increased drip loss, regardless of the freezing rate (P < 0.05). Greater cook loss was observed in the fast frozen-slow thawed samples compared to fast frozen-fast thawed samples (P < 0.05). The slow frozen-fast thawed steaks had greater lipid oxidation than the slow frozen-slow thawed treatment (P < 0.05). In general, our data show that subjecting whole beef rib sections to fast freezing may reduce water loss at the expense of increased lipid oxidation. This demonstrates that additional research is needed to further optimize beef primal cut storage.