RESPIRATION MODEL FOR FRESH-CUT PRODUCTS AS A FUNCTION OF DEGREE OF CUTTING

The Michaelis-Menten type respiration model for fresh-cut products was used to describe the effect of cutting, the respiration rates of four sizes of green pepper, eggplant and cucumber slices at different O₂ partial pressures, using a flow through system at 20°C. The degree of cutting (D-value) was quantified by determining the surface area created through cutting per unit weight of the product. CO₂ production decreased in response to decreasing O2. In addition, increases in D-value resulted in increased respiration rates. The Michaelis-Menten type equation was fitted to each data set of different cutting sizes using nonlinear least squares method, and the parameters K_m and V_max were estimated. With an increase in D-value, K_m decreased and V_max increased, but at a higher range of D-value, both parameters approached constant values. The dependencies of both these parameters on D-value could be expressed by exponential equations. The extended Michaelis-Menten type respiration model provided a good prediction of respiration rate of fresh-cut products at any O₂ partial pressure and degree of cutting.