The control of enzymatic browning of apple slices with papain is presented. Fresh apple slices dipped in a 1% Papain solution for 2 min did not brown for more than 12 hours at room temperature. Papain also gave good browning control of sliced pears. Further study indicated that polyphenoloxidase, a key enzyme involved in browning, was inactivated by this treatment.
Yaguang Luo and Max E Patterson
Robert C. Ebel, Edward L. Proebsting, and Max E Patterson
`Delicious' apple (Malus domestica Borkh.) trees received regulated deficit irrigation (RDI) early in the growing season to determine if fruit quality and storage life would he altered compared to well-watered trees. Soil moisture and leaf water potential were lower in RDI trees than in those that did not receive RDI most of the season. Internal ethylene concentration increased logarithmically earlier in RDI apples. At harvest, RDI fruit were smaller and had a higher soluble solids concentration (SSC) and lower titratable acidity. Starch degradation was delayed in RDI fruit, and their color was not affected. Firmness was not affected when the effect of size on firmness was removed. The SSC of RDI apples remained higher during storage, but starch content, titratable acidity, firmness, and color were similar.
Loretta J. Mikitzel, Max E Patterson, and John K. Fellman
Walla Walla Sweet onions (Allium cepa L.) have a short storage and marketing season. Studies to determine viable shelf life and to extend post-harvest life with controlled atmosphere (CA) storage were conducted. Onions were exposed to various CA gas mixtures in combination with heat curing (35°C) and/or chlorine dioxide (ClO2) fumigation, to control disease. Preliminary results indicated Botrytis was the primary cause of post-harvest losses. A 1% O2, 5% CO2 atmosphere appeared to maintain onion quality better than other gas mixtures tested during 15 weeks of CA storage (0°C). Carbon dioxide series above 5% show promise in reducing the 35% storage loss that occurred with the 5% CO2 treatment. Curing for at least 72 hours followed by a 1-hour ClO2 fumigation resulted in the least bulb decay and after 15 weeks of storage (1% O2, 5% CO2), 75% of the bulbs were in marketable condition. Onions stored 15 weeks in air (0°C, 70% RH) were unmarketable. Shelf life of freshly harvested onions was 18 days, after which the onions rapidly decayed. After CA storage, shelf life was reduced to 10-14 days due to rapid sprouting. To enjoy a 30-day market window, disease control is necessary for freshly harvested onions and sprouting must be controlled in post-storage onions.
Max Patterson, M. Ahmedullah, Frank Younce, Jo Ann Robbins, and Yaguang Luo
Blueberries were exposed to a series of atmospheric gas mixtures using an automated, computerized, gas-mixing, monitoring, controlling and recording system. Nitrogen was obtained from a PSA generator, O2 from an in-house air compressor and CO2 from compressed gas cylinders. Precise mixtures were made by introducing source gas streams into electronic gas-mixing valves where they were pre-mixed at desired concentrations and directed to fruit chambers. Gas mixtures giving maximum decay control and retention of harvest quality at 0°C were determined. Mixtures preserving fruit without causing fermentation or toxicity were also determined. Quality was retained in excess of 60 days at optimum gas levels. Increasing the fresh market period of blueberries with CA storage and prolonging shelf life and extending shipping distances with MA packaging appears promising.