Enzymatic browning is a serious quality limitation for fresh-cut potato (Solanum tuberosum L.) that has been successfully controlled by heat treatment in other commodities. The use of brief heat treatments with 55 °C water (HW) applied to ‘Russet Burbank’ tubers for 10, 20, 30, or 40 min before cutting was evaluated for potential implementation to control tissue browning. After heat treatment, tubers were held at 20 °C for 0 or 1 day before peeling and slicing. Control tubers were not previously immersed in hot water. All slices were placed in perforated plastic bags and stored at 5 °C for 6 days. Exposure to HW for 30 or 40 min caused severe heat injury. Browning developed in all treatments as indicated by color measurements and discoloration scores (index of extent of discolored area on the slice surface) during storage. Hot water treatment for 10 min best reduced browning, but only when treated tubers were stored intact for 1 day at 20 °C before cutting, as indicated by discoloration scores and changes in L*, a*, and Ho values, which were significantly different from either the control or the other HW treatments. Generally, the severe browning that developed in control slices during storage was associated with significant increases of 25% and 71% in phenolic content and antioxidant capacity, respectively. On the other hand, phenolic synthesis increased by only 6.25% to 13.2% in HW-treated slices during storage and polyphenoloxidase (PPO) activity was 24% to 31% lower compared with the activity before storage. Immersing potato tubers in 55 °C water for 10 to 20 min followed by storage at 20 °C for 1 day before processing reduced but did not prevent browning of peeled slices in terms of color changes and discoloration score. There was no significant correlation between browning and phenolic content or PPO activity.
Pavlos Tsouvaltzis, Angelos Deltsidis and Jeffrey K. Brecht
Angelos I. Deltsidis, Charles A. Sims and Jeffrey K. Brecht
Harvesting before ripening initiation (i.e., mature green) may negatively affect the flavor of fresh tomatoes (Solanum lycopersicum) even though the ripening process off the vine is physiologically the same as that on the plant. Low temperature storage at or below the putative chilling injury (CI) threshold can also have detrimental effects on fresh tomato flavor regardless of the developmental stage of the fruit at harvest, but sensitivity to CI declines with ripening. Controlled atmospheres (CA) using reduced oxygen and elevated carbon dioxide partial pressures can extend the shelf life (SL) of tomatoes while possibly minimizing the negative effects of low temperatures. In this study, we explored the possibility that a combination of temperature and CA could be used to achieve similar SL for pink-harvested tomatoes as has been found in other studies with green-harvested fruit while avoiding the negative effects of CI on sensory quality. Consumer panels were given samples of pink-harvested tomatoes after they had reached the red ripeness stage in terms of surface hue following storage for 7 days in air or CA at 7.5, 15, or 20 °C followed by 2–7 days ripening in air at 20 °C. Exposing pink tomatoes to 7.5 °C before ripening to the full-red stage at 20 °C negatively affected fruit sensory quality, holding fruit constantly at 20 °C until they reached the full-red stage resulted in better quality for one taste panel, whereas there was no difference in another taste panel. The time to reach the full-red stage was extended by CA. Sensory quality of air- and CA-stored fruit was similar at the nonchilling temperatures of 15 and 20 °C. Pink stage tomato fruit stored in CA at 7.5 °C for 7 days did not attain full red color within the subsequent 7 days in air at 20 °C.
Andrew J. Macnish, Malkeet S. Padda, Francine Pupin, Pavlos I. Tsouvaltzis, Angelos I. Deltsidis, Charles A. Sims, Jeffrey K. Brecht and Elizabeth J. Mitcham
The efficacy of several proprietary plastic pallet cover systems to maintain strawberry (Fragaria ×ananassa) fruit quality during commercial shipment was determined. ‘Albion’ fruit were harvested from farms near Watsonville, CA. Fruit in vented plastic clamshells were palletized and forced-air cooled to 33–35 °F. Different cover systems (CO2 West, PEAKfresh, PrimePro, Tectrol) were placed over the pallets. Pads that released carbon dioxide (CO2) gas were placed inside the CO2 West cover. The Tectrol cover was sealed to the pallet base, a partial vacuum was applied, and pressurized CO2 gas was injected inside. The systems other than Tectrol remained open at the base. Six separate shipments of palletized fruit were transported in refrigerated (32–39 °F) truck trailers to distribution centers in either Florida or Georgia in 2.3–4.7 days. CO2 concentrations within pallets at the beginning and end of transport were highest (11% to 16%) in the sealed Tectrol system and relatively low (0.06% to 0.30%) in the open CO2 West, PEAKfresh, and PrimePro cover systems. Relative to noncovered control fruit, which lost 0.8% fresh weight during shipment, the pallet covers reduced the transport-related weight loss by 38% to 52%. The incidence of fruit decay was low (1.0% to 1.4%) after transport but increased substantially following a 2-day shelf life at 68 °F. However, fruit from the Tectrol pallets exhibited significantly less decay (36%) after shelf life than the CO2 West (39%), noncovered control (41%), PrimePro (42%), and PEAKfresh (43%) pallets. Fruit sensory quality was unaffected by the different pallet cover systems. Our findings show that transporting strawberries in the sealed Tectrol pallet cover system, in which CO2 concentrations were elevated to 11% to 16%, was most effective in complementing current low temperature management practices to maintain fruit quality.