Effects of oxygen and carbon dioxide on respiration, storage life, and organic acids of green bananas

Abstract

Green bananas were held in humidified gas streams comprising air (control); “high carbon dioxide” (A) (5% CO2, 20% O2,75% N2); “low oxygen” (B) (0% CO2, 3%,02,97% N2); “high carbon dioxide-low oxygen” (C) (5% CO2, 3% O2, 92% N2). Ripening in A, B, and C was delayed at least 2, 8, and 12 times respectively compared with air. These three gas streams also reduced the rates of oxygen uptake by the fruit but increased the total oxygen uptake over the period before the beginning of the respiratory climacteric. In the first 4 days of treatment, A caused increases in pyruvate, oxaloacetate, 2-oxoglutarate, glyoxylate, glutamate, aspartate, citrate, and malate but not in succinate; B caused larger increases in the 2-oxo acids and decreases in the other acids; C caused smaller increases in pyruvate, 2-oxoglutarate, and glyoxylate, retarded the increase in oxaloacetate, and caused a further reduction in citrate, malate, and aspartate compared with B. The largest changes in the acids were found at 0-1 days. Application of the crossover theorem of Chance to the data suggested that low oxygen limited the operation of the Krebs cycle between pyruvate and citrate, and 2-oxoglutarate and succinate. No control points for high carbon dioxide were apparent. © 1972 CSIRO.