Influences of modified atmosphere packaging using active breathable films on antioxidant activity and quality of minimally processed Teaw leaves (Cratoxylum formosum Dyer)

A study was conducted to investigate influences of modified atmosphere packaging using active breathable films (FF3) on postharvest qualities of minimally processed Teaw leaves (Cratoxylum formosum Dyer), a tropical leafy vegetable having high total phenolic content and antioxidant activity, kept at 10 and 20°C. Teaw leaves stored at 20°C became wilted, and having visible microbial appearance within 2-3 days, which were considered unmarketable in regardless of either FF3 or Low Density Polyethylene (LDPE, as control) films studied. High permeabilities of FF3 film to O2 and CO2 significantly affected levels of modified atmosphere conditions in package headspaces. At all temperatures studied, high O2 concentrations (17-19% v/v) and relatively low CO2 concentrations ( 0.1% v/v) accumulated in FF3 bags and such gaseous accumulations were in contrast to those accumulated in LDPE bags i.e. lower O2 (9-15% v/v) and higher CO2 (2-6% v/v). Low levels of CO2 in FF3 bags apparently minimised rates of losses of ascorbic acid and antioxidant activity during 5 days of storage, although there were no significant differences in the parameters measured in leaves kept in LDPE bags. There were no significant effects of packaging films and storage temperatures on total phenolic contents, which slightly increased from the initial value and became stable throughout the storage period. Higher mass loss percentage of Teaw leaves kept in FF3 bags were noticed and were attributed to high permeabilities of FF3 to water vapour. However extents of mass losses were significantly reduced when leaves were kept at 10°C. Whilst total viable counts of leaves packaged in FF3 bags tended to be lower than those in LDPE due to lower humidity levels accumulated, there was unclear effects of packaging films on yeast and mould. Consumer panel tested accepted overall quality of the products packaged in the FF3 kept at 10°C of which the visual appearances of Teaw leaves appeared to be rated with higher scores, compared to those in LDPE bags.