Respiration rate of pomegranate arils as affected by O₂ and CO₂, and design of modified atmosphere packaging

The effect of CO₂ and O₂ on respiration rate of pomegranate arils was determined and suitability of common packaging materials was evaluated for designing MAP. Respiration rate of arils from a local pomegranate cultivar, 'Hicaz', was measured at different O₂ (2, 10, 21%) and CO₂ (0, 10 20%) concentrations at 4°C. Oxygen consumption and CO₂ production rate of the arils were modeled by enzyme kinetics based models. Inhibitory effect of CO₂ on respiration rate was evaluated by four types of inhibition models (competitive, uncompetitive, combination of competitive and uncompetitive, non-competitive types). MAP design was conducted for different package sizes to determine the characteristic of required packaging materials for fresh pomegranate arils. Respiration rate of the arils was significantly affected by O₂ and CO₂ concentrations. As O₂ concentration decreased respiration rate decreased. Respiration rate decreased by 10 and 20% CO ₂ levels. No difference between the effect of 10 and 20% CO ₂ concentration was detected. The competitive inhibition model for respiration rate can be used in package design for the arils. MAP design analysis indicated that common packaging materials (LDPE, PP) did not provide desired atmospheric conditions for pomegranate arils. Required packaging material's permeabilities were determined for several package sizes from 250 g to 2 kg.