Green tea extract as a natural antioxidant to extend the shelf-life of fresh-cut lettuce
Author: Ana B. Martín-Diana and Daniel Rico and Catherine Barry-Ryan
Green tea extract (GT) was evaluated as a preservative treatment for fresh-cut lettuce. Different quality markers, e.g. respiration, browning, ascorbic acid and carotenoid content were evaluated. GT concentration (0.25, 0.5 and 1 g 100 mL− 1) and temperature (20 °C and 50 °C) were tested. Optimal GT treatment (0.25 g 100 mL− 1 at 20 °C) was compared with chlorine (120 ppm at 20 °C). High GT concentrations (0.5 g 100 mL− 1 and 1.0 g 100 mL− 1) maintained better prevent ascorbic acid and carotenoid loss than 0.25 g 100 mL− 1 GT and chlorine. GT increased browning of samples, probably due to the content of polyphenols of the treatment; the use of heat-shock reduced this negative effect. GT and heat-shock combined also showed negative effects, reducing the antioxidant content (ascorbic acid and carotenoids). No significant differences were observed between chlorine and optimal GT (0.25 g 100 mL− 1 at 20 °C) in browning appearance and sensory properties. GT better kept the antioxidant activity of the samples than chlorine. Industrial relevance An alternative treatment for minimally processed Iceberg lettuce is tested, based on its antioxidant capacity. Minimally processed industry is constantly looking for new treatments to avoid the use of chlorine which is a standard at the moment.