Impact of changing wax type during storage on mandarin flavor and quality attributes

Authors: Obenland, David - Dave; ARPAI, MARY LU - UNIVERSITY OF CALIFORNIA

Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/17/2017
Publication Date: 3/1/2018
Citation: Obenland, D.M., Arpai, M. 2018. Impact of changing wax type during storage on mandarin flavor and quality attributes. Acta Horticulturae. 1194:807-814. https://doi.org/10.17660/ActaHortic.2018.1194.114.
DOI: https://doi.org/10.17660/ActaHortic.2018.1194.114

Interpretive Summary: Packers of mandarins sometimes apply a storage wax designed to limit water loss during the initial part of storage and then replace it with a higher shine pack wax prior to shipment of the fruit. Mandarins are prone to developing off-flavors in storage following waxing and are damaged more easily during handling so it was important to determine if multiple wax applications would harm or improve fruit quality. ‘Tango’ mandarins were harvested twice during the first season and subjected to various combinations of storage wax and pack wax, with storage times up to seven weeks. Similar experiments were conducted in the second season of the study using ‘Tango’ and ‘W. Murcott' mandarins with a single harvest. Evaluations of visual and internal fruit quality, including flavor, were conducted at the end of each storage period. In the first season application of multiple waxes caused many of the fruit to have unsightly brown marks on the peel, likely due to additional mechanical impacts from the fruit running down the pack line twice. In addition, the flavor quality was sometimes judged to be worse than fruit with pack wax alone. These problems were not evident in the second season. Multiple wax applications have the potential to damage both mandarin appearance and flavor and care must be taken in the implementation of these treatments to maintain mandarin quality.

Technical Abstract: Mandarin (Citrus reticulata Blanco) packers sometimes apply a storage wax (SW) designed to limit water loss during the initial part of storage and then replace it with a higher shine pack wax (PW) prior to shipment of the fruit. Mandarins are prone to the development of off-flavors as a result of low internal oxygen levels following waxing and may lose flavor quality if the applied coating has insufficient permeability to oxygen. In order to better understand the impact of this waxing protocol on mandarin quality, ‘Tango’ mandarins were harvested twice during the season and subjected to various combinations of SW and PW, with storage times up to seven weeks. Evaluations of visual and internal fruit quality, including flavor, were conducted at the end of each storage period. Flavor quality was worse after 4 weeks storage in fruit sequentially treated with both SW and PW in comparison to PW alone, although only for harvest 2, and the flavor differences among wax treatments were not significant after 7 weeks. Fruit receiving multiple wax applications were found to have more visual defects than fruit receiving SW or PW alone, mainly in the form of peel pitting and browning. ‘Tango’ and ‘W. Murcott’ mandarins in the second year of the study developed far less rind injury in any of the treatments than had been observed in the initial year, indicating that the impact of applying multiple waxes is likely dependent on the initial condition of the fruit. No flavor differences were found among the wax treatments in year 2. Inclusion of gibberellin into the wax had no clear impact on peel injury. Multiple wax applications have the potential to damage both mandarin appearance and sensory quality and care should be taken to minimize mechanical impacts on the packing line and optimize the gas exchange characteristics of the coatings used.