Concentration and retention of ascorbic acid, carotenoids, and sugars in fresh-cut lettuce in modified atmospheric packaging

Authors: Sthapit Kandel, Jinita; Simko, Ivan; Hayes, Ryan; Mou, Beiquan

Submitted to: Horticultural Plant Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2023
Publication Date: 2/29/2024
Citation: Sthapit Kandel, J., Simko, I., Hayes, R.J., Mou, B. 2024. Concentration and retention of ascorbic acid, carotenoids, and sugars in fresh-cut lettuce in modified atmospheric packaging. Horticultural Plant Journal. https://doi.org/10.1016/j.hpj.2023.07.008.
DOI: https://doi.org/10.1016/j.hpj.2023.07.008

Interpretive Summary: Fresh-cut lettuce is widely used in ready-to-eat packaged salads. Packaged lettuce tissue can deteriorate in a week after processing and can lose nutrient contents quickly making salad unmarketable. Lettuce cultivars with extended shelf life and good nutrient retention are important for the lettuce industry and consumers. Fifty lettuce accessions were investigated for variation in nutrient content and their retention and to determine the relationship between shelf life and nutrient retention. Accessions with high content and/or good retention of vitamin C (ascorbic acid, AsA), vitamin A (carotene), and sugars were identified. The romaine cultivar ‘Floricos’ had high levels of all the three tested nutrients. ‘Salinas 88’, ‘Siskiyou’, ‘Solar’, SM09A, ‘Romance’, and ‘Green Towers’ had relatively high retention of all the three nutrients. Longer shelf life showed correlation to better retention of the nutrients suggesting that longer shelf life may improve nutrient retention too. No specific relation was determined between the amount of nutrient content in the accession and level of their retention. This suggests that besides content, lettuce nutritional improvement program should also focus on breeding for retention of the nutrients. Romaine cultivars, ‘Balady Barrage’, ‘Green Towers’, and ‘Darkland’ were identified as having relatively high initial levels of all tested vitamins and sugars and good rate of their retention as well. Lettuce with high nutrient content, extended shelf life and good nutrient retention are valuable resources for the lettuce industry and breeding programs.

Technical Abstract: Fresh-cut lettuce is widely used in ready-to-eat salads shipped and sold in modified atmosphere packages (MAP). Even in MAP, fresh-cut lettuce has short shelf life that results in loss of nutrients. Lettuce cultivars exhibit genetic variation for shelf life in MAP, but their variation for nutrient retention is not known. The objectives of this research were to investigate the variation among cultivars for retention of nutrients and to determine the relationship between shelf life and nutrient retention. Fifty lettuce accessions from five lettuce types were evaluated for the initial content of vitamin C (ascorbic acid, AsA), vitamin A (carotene), and sugars and also their retention in storage. Accessions with high content and/or good retention of one or more nutrients were identified. The romaine accession ‘Floricos’ had high level of all the three nutrients. Accessions with relatively high retention of all the three nutrients were ‘Salinas 88’, ‘Siskiyou’, ‘Solar’, SM09A, ‘Romance’, and ‘Green Towers’. Romaine cultivars, ‘Balady Barrage’, ‘Green Towers’, and ‘Darkland’ had relatively high initial levels of all tested nutrients and good rate of their retention. There was little correlation between initial AsA/carotene concentrations and their retention rates, suggesting that besides content, retention of nutrients should also be a breeding target in a lettuce nutritional improvement program. Statistical analyses also determined negative correlation between tissue deterioration (AUDePS) and retention of all nutrients with Pearson’s correlation coefficient r at -0.52 (P < 0.0001) for AsA, -0.27 (P < 0.01) for total carotene, and -0.59 (P < 0.0001) for total sugars, suggesting that an increase in tissue deterioration intensifies nutrient decay and longer shelf-life may improve nutrient retention. Broad-sense heritability (H2) across the experiments was 0.15 for AsA, 0.23 for total carotene, and 0.50 for total sugars. These findings and the identification of germplasm with high nutrient content, extended shelf life and good nutrient retention provide valuable information for the lettuce industry and associated breeding programs.