Effect of Ultra-fast Chilling on the Expression of Glycolytic Enzymes in Fresh Mutton

The pH value, glucose content, glycolytic potential, and expression levels of five glycolytic enzymes in lamb longissimus dorsi muscle at different time after slaughter were compared and analyzed, which treated at different cooling rates and stored at different temperatures. The impact of two steps in the process of ultra-fast chilling on the expression levels of glycolytic enzymes was determined. The regulatory mechanism of ultra-fast chilling on the glycolytic rate was elucidated from the perspective of protein expression. The results showed that ultra-fast chilling treatment significantly delayed the decrease of pH and the increase of glycolytic rate, promoted the expression levels of aldolase (ALDOA), glycogen phosphorylase (PYGM), and triosephosphate isomerase (TPI1), and inhibited the expression levels of phosphofructokinase (PFKM) and phosphoglycerate kinase (PGK). After cooling treatment, refrigeration and controlled freezing-point storage delayed glycolysis by inhibiting the expression level of PGK, without altering the effect of ultra-fast chilling. The expression level of PFKM was positively correlated with the rate of glycolysis at different temperatures. It was found that different glycolytic enzymes had different responses to temperature changes. Ultra-fast chilling affected energy supply and demand by changing the expression of enzymes involved in glycolysis. The high expression level of PFKM was associated with fast glycolysis. PFKM can be regarded as a key enzyme in the ultra-fast chilling process.