Comprehensive evaluation of different storage conditions for the varietal screening of lettuce for fresh-cut performance

• A methodology for the screening of lettuce cultivars for fresh-cut was established.
• Storage in air, CA and passive and active MA were compared.
• Suitability of active MA for the evaluation of off-odors was confirmed.
• Suitability of active MA plus 24 h in air for browning evaluation was demonstrated.
• Correlations of subjective and objective parameters to browning and off-odors were established.

Cultivar selection is of great importance for the fresh-cut industry and new cultivars and breeding lines with low response to cutting are constantly required. However, there is no standardized protocol for lettuce breeding and processing companies to select those cultivars most appropriate for the specific requirements of fresh-cut. The objective of this study was the comparison of different storage conditions under which the varietal screening of lettuce cultivars for fresh-cut was carried out based on the development of browning and off-odors as the two main causes of quality loss. Additionally, as the lettuce breeding and processing companies needed quantitative objective parameters for the evaluation, correlations of subjective and objective parameters to browning and off-odors were established. Advantages and limitations of storage in air, controlled atmosphere (CA) and passive and active modified atmosphere (MA) were discussed. Even though the storage in active MA for 10–12 days (d) at 7 °C generated a wide range of headspace gas atmospheres that varied between 0.2–3.2 kPa O2 and 6–9 kPa CO2, it was shown to be the best storage regime for the screening of cultivars based on off-odor development. The screening of cultivars based on browning was achieved after opening the bags and exposure for 24 h to air. Results obtained under storage conditions in active MA plus 24 h in air showed a significant correlation with those data obtained under passive MA (P< 0.001). The relationship between objective and subjective measurements such as ethanol for off-odors and a* and Hue angle for color was demonstrated. This evaluation methodology provides a more systematic analysis of individual genotypes and interrelated preharvest factors such as genotype-to-environment interaction to establish a deeper understanding of the relationship among variables affecting quality of fresh-cut products.

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