Fermentative metabolism in ‘Conference’ pears under various storage conditions

Abstract

SummaryThe aim of this work was to investigate the fermentative metabolism of ‘Conference’ pears during different storage regimes. Fruits were stored at 0°C in the following controlled atmosphere (CA) conditions: 6 kPa CO2 + 0.5 kPa O2;3 kPa CO2 + 1 kPa O2; or 1 kPa CO2 + 2 kPa O2; and also in regular air (RA) as a control. Pears kept in RA showed low pyruvate decarboxylase (PDC) and alcohol dehydrogensase (ADH) activities, and correspondingly low levels of ethanol and acetaldehyde production as long as the fruits were maintained at low temperatures. During shelf-life at 20°C, RA-fruits released higher amounts of acetaldehyde, while ethanol production remained low. Lactate concentrations in RA-stored pears increased continuously in the second part of the storage period and during shelf-life, while lactate dehydrogenase (LDH) activity remained low. During CA-storage, ‘Conference’ pears showed continuous increases in the activities of PDC and ADH, mainly in fruits stored under high CO2 and/or low O2 partial pressures. The production of ethanol and acetaldehyde was not influenced in fruits stored in 6 kPa CO2 + 0.5 kPa O2. LDH activity in CA-stored pears increased during storage, while lactate concentrations diminished. During shelf-life at 20°C, the concentrations of all measured fermentation products increased, particularly acetaldehyde and lactate. We conclude that PDC, ADH, and LDH activities are not rate-limiting factors in the accumulation of fermentation products in ‘Conference’ pears during storage and shelf-life at 20°C.