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- Author or Editor: M. Joseph Ahrens x
Fresh, peeled, whole baby carrots are fast becoming the driving force in sales of fresh carrots. In 1991, 200 million tons were marketed to food service and retail outlets. “Peeled whole baby carrots” are mature carrots cut to 5 cm lengths and peeled in a modified potato peeler. Two problems have developed which are limiting the expansion of this market: 1) the product as currently packed develops a slimey rot in 10 days and 2) a “white blush” forms on the exposed surface of the product after 5 days.
Tests on the atmosphere of the bag indicated that the product was generating a low O2 environment, causing the growth of anaerobic rots. Evaluations of several film materials were undertaken to find a formulation which would provide an O2 level above 5% and CO2 below 7%, a level above which some cultivars are injured. Sucrose ester and cellulose based edible films and anti-oxidants were applied to the product to help eliminate white blush, which could be the product of dehydration or lignin formation.
A cellulose-base edible film supplied from the USDA and a mineral impregnated single ply low density polyethylene 1.5 mil bag were selected as the optimum packaging combination. Storage at 5C was improved to 50 days, with white blush and decay greatly reduced. Studies on the logistics of the edible film application are continuing.
Previous investigations have shown that severe injury and bruising result from impacts, compression, and vibration scuffing during transport. Work specifically on vibration has focused on damage caused by “micro impact” and not true vibration. Our study looked at true vibration-imparted energy and analyzed the effects of force and frequency.
Mature green tomato fruit were secured to a platform and energized with a vibration cell at different frequencies and force for 0, 10, 20, 30, 40, 50 and 60 minutes. The fruit were then allowed to ripen at 20C. Ethylene and respiration rates were determined along with general condition for two weeks.
Ethylene production and respiration rate increased initially and remained high with increasing force and length of treatment. Fruit vibrated for 40, 50, and 60 m developed an uneven ripening pattern. When the control fruit were red, the vibrated fruit showed blotchy ripening. In addition, the ripening rate was slower, although respiration and ethylene production were higher. However, when the control fruit were full red to overripe, the blotchy ripening disappeared in the treatments, but they never developed as deep a red as the controls. We are continuing to investigate vibrational effects on gel breakdown and membrane integrity
Abstract
Direct heat injury to plant parts may occur in areas of high insolation and high humidity where transpiration is low. Using electrolyte leakage procedures, critical high temperatures of detached leaves of ‘Glen’ citrange [Citrus sinensis L. (Osbk.) × Poncirus trifoliata L. (Raf.)], ‘Swingle’ citrumelo [C. paradisi Macf. × P. trifoliata L. (Raf.)], and ‘Hamlin’ orange [C. sinensis L. (Osbk.)] were determined by exposure to temperatures between 25° and 65°C. Lethal temperatures for a 20 min exposure ranged from 54.3° ± 0.5° for ‘Glen’ citrange to 56.1° ± 0.4° for ‘Swingle’ citrumelo. Maximum canopy temperatures of 36.6° were recorded. Therefore, it appears that under field conditions in Florida, these cultivars are normally not subjected to temperatures that would cause direct heat injury.