"Trial and error" experiments vs. general model designs for finding an appropiate MAP of fresh - cut lettuces

Active modified atmosphere packaging (MAP) design, dise?o del envasado en atm?sfera modificada activa (EAM), fresh-cut lettuce, lechuga fresca troceadaActive modified atmosphere packaging (MAP) of fresh - cut lettuce has become a successful technique to control browning by flushing the bags with N2 to generate an initial low O2 concentration. However, if the range of O2 level is too low, it may lead to fermentation or browning if it is too high. The purpose of this study was to evaluate if an adequate MAP design for fresh - cut lettuce, avoiding browning and fermentation, was possible. We studied the main parameters implied in MAP design such as respiration rate (RR), oxygen transmission rate (OTR) and optimal O2 range. The respiration rate was measured during the winter season at 7?C and 0.3 kPa O2 using a closed system. OTR was determined at 7 ?C and 97% relative humidity (RH). The weight of the plant material was increased to generate a range of O2 atmospheres to know the optimal O2 range that maintain sensory quality of fresh - cut lettuce. When the steady - state was reached, overall visual quality and off - odours were evaluated.We observed that RR changed with the genetic variation and maturity at harvest.Respiration rate registered along the season varied between 1.5 - 3.0 mL CO2/kg h. The optimal O2 range that suppressed browning and fermentation was found between 0.2 and 0.5 kPa. When these data were used for the design of MAP by the general model, most of the commercial fresh - cut lettuce packages were found to result fermented lettuce and the equation used did not adequately predict the anaerobic conditions reached.An adequate MAP design for fresh - cut lettuce to control browning and fermentation is difficult. ?Trial and error? experiments do not contribute to understanding MAP design for fresh - cut lettuce.Original title, complete list of authors, and sources:MODIFIED ATMOSPHERE PACKAGING OF FRESH - CUT LETTUCE: TRIAL AND ERROR?Gil, M.I. and Tudela, J.A. migil@cebas.csic.esResearch Group on Quality, Safety and Bioactivity of Plant Foods, Food Science and Technology Department, CEBAS - CSIC, SpainCAMA 2013, XI International Controlled & Modified Atmosphere Research ConferenceTrani (Italy), 3-7 June Picture: Active modified atmosphere packaging (MAP) of fresh - cut lettuce. Source: www.technewsworld.com