Potassium bicarbonate reduces postharvest decay development on bell pepper fruits

Bicarbonate salts are widely used in the food industry and have broad-spectrum antimicrobial activity. We investigated whether bicarbonate salts can serve as alternatives to synthetic chemical fungicides for controlling postharvest diseases of fruits and vegetables. Potassium bicarbonate (PBC) inhibited in vitro mycelial growth, spore germination and germ tube elongation of Botrytis cinerea and Alternaria alternata. Germ tube elongation was found to be more sensitive to elevated PBC concentrations than mycelial growth and spore germination, as measured by EC(50) Treatment with PBC resulted in shrinkage and collapse of hyphae and spores, and consequent inability of fungi to sporulate. PBC action was fungistatic rather than fungicidic. Dipping commercially harvested sweet red peppers for 2 min in 1 or 2% potassium bicarbonate reduced decay development after storage and shelf life simulation to a commercially acceptable level of 5-8% compared with untreated or water-dipped controls. Higher concentrations of PBC (3%) significantly reduced fruit quality.