New insights into early biochemical prediction of internal browning disorder in 'Conference' pears

Abstract

This study aimed to identify markers in pear capable of predicting the development of internal browning disorder (IBD) at harvest or during early storage. ´Conference´ pears were harvested from different orchards at commercial maturity and stored under high CO2 atmosphere conditions to induce disorders. The predictive markers studied were associated with 1-aminocyclopropane-1-carboxylic acid (ACC) metabolism, antioxidants and the tricarboxylic acid cycle (TCA cycle). The partial least square (PLS) model built for prediction at harvest identified ACC, malonyl ACC (MACC), and dehydroascorbic acid (DHA): the oxidized form of ascorbate, as the best markers for defining initial fruit sensitivity to IBD. A clear relationship was also found between increases in succinate levels during the first two weeks of storage and the incidence and severity of IBD after storage. Collectively, the results presented in this work reinforce the idea that IBD is determined by initial fruit maturity. They also question the current dogma concerning ascorbate, suggesting that rather than ascorbate, the most reliable marker for sensibility at harvest is DHA. Our results also highlighted that increased succinate levels should be considered one of the earliest responses to damaging storage conditions and offer an interesting short-term marker for IBD. The paper discusses how succinate is regulated during storage in relation to IBD development and an explanatory model is presented.