The effect of furcellaran-gelatin edible coatings with green and pu-erh tea extracts on the microbiological, physicochemical and sensory changes of salmon sushi stored at 4 °C

This study investigated the effect of application of previously designed furcellaran-gelatin edible coatings with 20% green (GT) and pu-erh (RT) tea extracts on the changes in the cold stored salmon nigiri. Nigiri samples were divided into four groups (control, film control, GT and RT) and analyzed for their microbiological quality (total aerobic bacteria, total psychrotrophic bacteria, lactic acid bacteria, yeasts and moulds and thermotolerant coliforms), sensory scores and physicochemical properties (pH, water activity, dry weight, color, shear force, TBARS and TVB-N) during 8 days of storage at 4 degrees C. The treatment did not affect the shelf-life of the stored sushi, with total aerobic bacteria counts reaching the upper acceptability limits between day 4 and 6 of storage, while the sensory panelists discarded sushi only after 6-8 days of storage. The sensory analysis showed that although the panelists observed the differences between the coated samples and the control, there were no significant differences in sensory scores between the groups. The treatment significantly inhibited the oxidation, with TBARS at day 8 reaching for GT and control 0.47 and 0.81 mg/kg respectively. The TVB-N of the samples remained constant despite progressive microbiological contamination of the samples, reaching the maximum of 109.8 mg/kg. No other physicochemical properties have been affected by the treatment with the exception of color. Despite the promising results of in vitro studies on dry films with GT and RT extracts, their application on salmon nigiri did not prove beneficial in terms of shelf-life extension.