Betty Hess-Pierce

Quality changes in fresh-cut pear slices as affected by controlled atmospheres and chemical preservatives

Low O2 (0.25 or 0.5 kPa) elevated CO2 (air enriched with 5, 10 or 20 kPa CO2), or superatmospheric O2 (40, 60, or 80 kPa) atmospheres alone did not effectively prevent cut surface browning or softening of fresh-cut pear slices. A post-cutting dip of 2% (w/v) ascorbic acid, 1% (w/v) calcium lactate and 0.5% (w/v) cysteine adjusted to pH 7.0 did significantly extend shelf-life of ‘Bartlett’ pear slices, by inhibiting loss of slice flesh firmness and preventing cut surface browning. Participants in a quality evaluation could not distinguish between pear slices treated with this preservative solution and stored overnight at 0 °C and freshly prepared control pear slices. After 10 days storage in air at 0 °C, 82% of participants judged treated pear slices to be acceptable in appearance and 70% judged flavor to be acceptable.

Identification of optimum preprocessing storage conditions to maintain quality of black ripe 'Manzanillo' olives

Black-ripe olives (Olea europaea cv. ‘Manzanillo’), used for processing into canned olives or oil were stored at 0, 2.2 and 5°C in air or 2 kPa O2 (balance N2). Olive samples were analyzed initially, and after 2, 4 and 6 weeks for fruit quality based on color, visual quality and fruit firmness, weight loss, water and oil content. Respiration rate, ethylene production and incidence of physiological disorders and decay were determined. Olive oil quality was evaluated based on titratable acidity, peroxide value, K232 and K270 coefficients, and fatty acid composition. Decay incidence increased with storage temperature and duration but it was lower in black-ripe olives kept in 2 kPa O2 than in those kept in air. Fruit decay after 4 weeks storage in 2 kPa O2 was 9.2, 8.2, and 7.7% in olives kept at 0, 2.2, and 5°C, respectively. No visual chilling injury symptoms were observed in any of the storage treatments. Storage time and atmospheres had no significant effect on olive color but visual quality scores of olives stored in 2 kPa O2 at 0°C were generally higher than other treatments. Ethylene production and respiration rates were considerably higher at 5°C than at 0 or 2.2°C and in air than 2 kPa O2. Fruit firmness declined markedly after 4 weeks storage in both the air and 2 kPa O2 treatments, irrespective of storage temperature. There was no significant difference between the air and 2 kPa O2 stored fruit. There were no significant differences in water and oil content among treatments. Oil obtained from olives stored at 0°C, was within the limit of ‘extra’ virgin quality in terms of acidity, irrespective of storage atmosphere after 4 weeks storage, whereas oils extracted from olives stored at 2.2°C in air and 2 kPa O2 and olives stored at 5°C in 2 kPa O2 were qualified as ‘fine’ virgin quality. K232 and K270 values were not surpassed in any of the treatments except oil obtained from olives stored at 20°C. Fatty acid composition was within the range required for ‘extra’ virgin olive oil, except for slightly higher linolenic acid. In conclusion, black-ripe ‘Manzanillo’ olives can be stored at 0‐5°C in air or in 2 kPa O2 for up to 4 weeks between harvesting and processing while maintaining fruit and oil quality.