Comparison of glucose, glucose 6-phosphate, ribose, and mannose as flavour precursors in pork; the effect of monosaccharide addition on flavour generation

The effect of glucose, glucose 6-phosphate, mannose and ribose on the generation of aroma volatiles in pork was investigated. The monosaccharides were added individually to minced pork prior to heat treatment (160 °C for 10 min) in the following concentrations: glucose (27.5 μmol/g), ribose (1.2 μmol/g), mannose (8.3 μmol/g) and glucose 6-phosphate (0.5 μmol/g). The natural concentrations of the monosaccharides in the pork used were found to be 4.0 μmol/g for glucose, 0.1 μmol/g for ribose, 0.3 μmol/g for mannose and 2.6 μmol/g for glucose 6-phosphate. The major aroma compounds identified in the headspace of the heated samples were pyrazines, aldehydes (Strecker and lipid-derived), ketones, and sulphides. Glucose generated the highest amounts of volatiles followed by glucose 6-phosphate. However, when related to the added concentration of glucose 6-phosphate, this phosphorylated monosaccharide showed the highest aroma generating potential. The addition of ribose did not increase the concentration of volatiles compared with pork without the added monosaccharide. The fates of ribose 5-phosphate and ribose in pork were studied over time. The concentrations of ribose and ribose 5-phosphate clearly decreased during 2 h equilibration, which may be due to enzymatic activities. These precursors may, therefore, be less important pork flavour precursors than glucose and glucose 6-phosphate.