Monitoring shelf life of fresh-cut apples packed in different atmospheres by electronic nose

Packaging in modified atmosphere is one of the most used techniques to control the respiration rate and ethylene production, responsible for senescence phenomena of fresh-cut fruits. Senescence phenomena can be assessed by electronic nose, which is based on inexpensive, nonspecific solid-state sensors, sensitive to the volatile compounds emitted in the headspace atmosphere by the sample. Apples ('Golden Delicious'), at harvest and after seven months' storage in CA, were peeled and cut into 8 wedges, dipped for 2 min in 0.5% ascorbic acid + 1% citric acid solution, then packed and sealed in polypropylene bowls, previously sanitized by UV radiation. The following atmosphere compositions were used: air (A); 99% N-2, 1% O-2 (B); 90% N-2, 5% CO2, 5% O-2 (C). Analyses were carried out after 1, 4, 7, 10 days of shelf life at 4 degrees C. Ethylene, O-2 and CO2 concentrations and electronic nose patterns of the headspace bowls were evaluated (N-bowls/atmosphere/days of shelf life = 4). Results showed a remarkable rise of ethylene concentration in A samples, but not in the B and C ones. During shelf life there was a significant increase of CO2 amount in all samples, affected by the stage of ripeness. Simultaneously, a progressive consumption of available O-2 occurred. E-nose patterns changed with the atmosphere, time of processing, day of shelf life. Discriminant analysis of electronic nose data gave a good classification of samples (>90%) according to time of processing and days of shelf life.