BROWNING INHIBITION OF HARVESTED LETTUCE (Lactuca sativa L.)

Browning reactions affect the nutritive quality and appearance of fresh products. Oxidative browning is attributed to activity of the enzyme polyphenol-oxidase (PPO). Application of organic acids is the inhibitory mechanism most commonly used to maintain the pH below that necessary for polyphenol-oxidase activity (Castañer et al., 1997).

Browning of the lettuce stem butt is one of the main postharvest changes induced by wounding during harvest. The browning process of the harvested lettuce starts with yellowing, then becomes reddish brown, and finishes with an intense brown pigmentation (Tomás-Barberán et al., 1997). Castañer et al. (1996) reported promising results to prevent butt discoloration of iceberg lettuce with solutions of acetic acid (10 ml/L and 50 ml/L), and vinegar. The objective of this work was to evaluate alternative methods to prevent butt discoloration of butterhead and iceberg lettuce during postharvest handling.