Sensorial and physicochemical quality responses of pears (cv Rocha) to long-term storage under controlled atmospheres

Pears (cv Rocha) kept under controlled atmospheres (CA) and air were evaluated after long-term storage in terms of sensory attributes and physicochemical parameters, namely colour, firmness, polyphenoloxidase (PPO) activity and concentration of hydroxycinnamic compounds. The CA conditions were all combinations of 2 and 4% (v/v) O₂ with 0.5 and 1.5% (v/v) CO ₂. Storage under CA conditions produced a beneficial effect on 'Rocha' pears in maintaining their quality and, consequently, in extending their shelf life and acceptability. Clear differences in sensorial attributes, colour parameters and PPO activity were found between CA- and air-stored pears. The effect provided by the CA conditions persisted throughout the time of exposure to the open air. The 2% O₂ concentration produced a more beneficial effect than its 4% counterpart on the sensorial and physical characteristics of the pears. The former concentration of O₂ prevented yellowing and allowed regular softening, hence keeping a high flavour quality. No clear effects could be associated with CO₂ levels. Empirical models were developed that describe the effects of O₂ and CO₂ concentrations, as well as time at room temperature on physicochemical parameters pertaining to 'Rocha' pears.