Effect of pH, xylose content and heating temperature on colour and flavour compound formation of enzymatically hydrolysed pork trimmings

Abstract

This study investigated colour and flavour compound formation in enzymatic pork trimmings hydrolysates under different conditions (pH, xylose level and heat treatment) with a view to develop a pork-based flavouring. Different amounts of xylose (0, 0.5, 1.5, 2.5, 3.5 g/100 mL) were added to the enzymatically hydrolysed pork with pH adjusted to 5.5 or 4.5 prior to heat treatment at 90, 95 or 100 °C for 60 min. It was found that the browning of pork hydrolysate was mainly affected by the amount of xylose added, where the highest colour differences (ΔE) were found in the samples with the highest amount of xylose. Heat treatment eliminated the dominant off-flavour compound, hexanal, in pork hydrolysate. A higher temperature and xylose concentration promoted the generation of furfural and 2-pentylfuran, which are known to impart an overall roasted and sweet flavour note. By comparison, more furfural was detected at pH 4.5. However, the desirable savoury “meat-like” sulfur-containing and nitrogen-containing aroma compounds were not detected, which might be due to deficient levels of sulfur-containing amino acids such as cysteine, as well as high water activity of the pork hydrolysate.