Post-harvest shelf-life of banana and guava: Mechanisms of common degradation problems and emerging counteracting strategies

Banana and guava have short shelf-life at tropical ambient temperature due to climacteric ripening associated changes like rapid softening, senescence spotting, off-odor development, anthracnose, and crown rot disease incidence, and chilling injury occurrence during storage below 13 °C. Commercially post-harvest treatment involved submerging banana and guava in solutions of benomyl or thiabendazole or imazalil. These chemicals are harmful to human health and the environment. Moreover, the fungal pathogens have developed resistance to these fungicides. Hence search of alternative non-chemical, health and environment friendly strategies are major focus of the researchers over the world. Treatment with organic acids, plant extract having antimicrobial properties prevented diseases either by direct action on the fungus or by inducing defense response by increasing the activity of antioxidant enzymes like superoxide dismutase, lipoxygenase, catalase. Degradation of plant parts occurs due to accumulation of reactive oxygen species and enzymatic oxidation of polyphenols during senescence, chilling stress, low oxygen, or high carbon dioxide injury. The deteriorations are evaluated by physical parameters like color change, accumulation of superoxide anion, hydrogen peroxide, malondialdehyde byproducts, accumulation of thiobarbituric reactive compound and ion leakage percentage. The selection of application concentration and treatment duration of 1-methylcyclopropane (1-MCP) treatment which act as an ethylene inhibitor is critical in extending shelf-life of banana and guava. The modified atmosphere, controlled atmosphere storage and edible coating reduced time to occurrence and intensity of climacteric peak respiration, slowed down ripening associated changes, prevented accumulation of reactive oxygen species (ROS) thereby extended shelf-life of guava and banana.