Influence of low oxygen and high carbon dioxide on shredded Galega kale quality for development of modified atmosphere packages

Respiration rate, sensory attributes, colour alterations, and water, chlorophyll and ascorbic acid contents were monitored during storage of shredded Galega kale (Brassica oleracea var. acephala DC.) at 20 degrees C to define an adequate range of O-2 and CO2 partial pressures for product preservation. Different low O-2 and high CO2 atmospheres were tested. First, tolerance to low O-2 partial pressures (1, 2, 3 or 21 kPa O-2 with balance N-2) was tested. Quality retention was improved as O-2 partial pressure was reduced and there was no induction of anaerobic respiration. Then, tolerance to high CO2 partial pressures (0, 10, 15 or 20 kPa CO2 plus 21 kPa O-2 and balance N-2) was tested. The high CO2 partial pressures extended the shelf life of the shredded kale and no symptoms of CO2 injury were detected. Finally, combinations of low O-2 and high CO2 (1 or 2 kPa 02 Plus 15 or 20 kPa CO2, with balance N-2, and an air control) were analysed. No differences were observed among the different gas combinations. An atmosphere of 1-2 kPa O-2 Plus 15-20 kPa CO2 and balance N-2 extends the shelf life of shredded Galega kale to 4-5 days at 20 degrees C, compared with 2-3 days in air storage. Predictive models of chlorophyll a and b degradation as a function of time and gas composition were developed. (c) 2004 Elsevier B.V. All rights reserved.