Extending market potential of blueberries with controlled atmosphere storage.

摘要

The goal of this research was to determine if controlled atmosphere (CA) storage could be used to extend the market period of fresh Pacific Northwest blueberries and to evaluate the effects different storage atmospheres have on fruit quality. Furthermore, this research also investigated heat and mass transfer characteristics during cooling and storage of fresh blueberries in controlled atmosphere storage “Elliott” blueberries were stored at −1°C (30°F) with 80–95% RH in combinations of 2% and 5% O₂ with 5% and 15% CO₂ during the 1996 storage season and in combinations of 2% and 5% O₂ with 10% and 15% CO₂ in the 1997 and 1998 storage seasons.; Fruit quality attributes were determined after 53 and 80 days of storage in 1996 and after 53 and 93 days of storage in 1997 and 1998. In the 1996 storage season, berries stored in combinations of 15% CO₂ were firmer, developed less decay, and were lower in SS/Ac after 53 and 80 days in storage than berries stored in 5% CO₂. After 80 days in storage, fruit stored in combinations of 5% CO₂ exhibited high levels of visible fungal decay. In the 1997 and 1998 seasons, storage of berries in high CO₂ concentration levels of 15% resulted in greater percentages of marketable and firm fruit, and better sensory ratings, than storage in carbon dioxide concentration levels of 5%. Controlled atmosphere conditions of 5% O₂ and 15% CO₂ were rated as superior for blueberries stored 93 days.; A simple model was developed to determine the cooling process parameters including cooling coefficient, lag factor, half cooling times, seven-eighths cooling times, and effective heat transfer coefficients. Estimated cooling coefficient, lag factor, half cooling times, and seven-eights cooling times ranged from 0.23 hr−1 to 0.40 hr−1; 1.01 to 1.05; 1.56 hrs to 2.85 hrs; and 5.57 hrs to 8.81 hrs, respectively. The effective heat transfer coefficient varied from 10.17 W/m2 K to 16.05 W/m2 K depending upon berry basket position. The greater the surface area exposed to the cooling medium, the higher the heat transfer coefficients and the lower the half cooling time and the seven-eighths cooling time.; Transpiration coefficients, on per unit mass and per unit area basis, were determined for “Elliott” blueberries stored in bulk refrigerated CA environments. Fruit mass loss was greatest during the cool down period because both respiration and transpiration rates were high, then decreased exponentially. Fruit stored in controlled atmosphere conditions of 5%O ₂ and 15%CO₂ (Box D) had the lowest mass loss and the lowest transpiration rate of 0.00023 mg/s·kg·kPa.