Mode of action of plastic film in extending life of lemon and bell pepper fruits by alleviation of water stress.

The mechanism by which seal-packaging individual fruit in high density polyethylene film delays deterioration was investigated with lemon (Citrus limon [L.] Burm. f. cv Eureka) and bell pepper (Capsicum annuum L. cv Maor) fruits. Seal-packaging effects were due to the water-saturated atmosphere in the sealed enclosure around the fruit. Softening of fruit was highly correlated with declining water potential of fruit. Sealing drastically inhibited softening as well as changes in cell wall pectins. Sealing also delayed disintegration of membrane as shown by the inhibited leakage of amino acids, in particular, and electrolytes in general. All these effects of sealing were prevented or reduced by including hygroscopic CaCl(2) in the sealed enclosure which reduced the ambient humidity. Furthermore, some of these effects of sealing could be achieved also by maintaining nonsealed fruit in water-saturated atmosphere. Sealing effects could not be related to a possible ;modified atmosphere' mechanism in O(2), CO(2), or ethylene. This work supports the hypothesis that the mode of action of sealing in the polyethylene relates to the alleviation of water stress which exists in harvested fruit.