Evaluation of beef aging by determination of hypoxanthine and xanthine contents: application of a xanthine sensor

The changes of ATP-related compounds were measured during the aging of sirloin meat of eight bullocks, together with changes in myofibrillar fragmentation index (FI) and inosine-5-monophosphate (IMP) content. The increase in hypoxanthine (Hx) content, (Hx + 12 Xanthine (X)) content and K value correlated well with the observed increase in FI (R2 = 0.804, 0.819 and 0.801, respectively) and decrease of IMP content (R2 = 0.809, −0.839 and −0.965, respectively). An immobilized xanthine oxidase biosensor was tested for its usefulness as a convenient method for measurement of (Hx + 12X) content. Also, organoleptic evaluation and measurement of FI, free amino acids and ATP-related compounds were carried out. The findings suggested that the xanthine sensor could provide accurate measurements of the (Hx + 12X) content, and was useful for assessing the progress of aging by the estimation of the changes in tenderness and IMP content.