No abstract

It is commonly believed within the citrus industry that handling, waxing, and storage of navel oranges may have undesirable effects on flavor. However, the effect of each potential influencing factor under commercial conditions is not completely understood. The purpose of this study was to systematically investigate these potential influences on navel orange flavor. Navel oranges were harvested on two separate dates, using three grower lots per harvest date, and the fruit run on a commercial packing line. Fruit were sampled at four different stages of the packing process: in the field bin; after the washer; after the waxer; and after packing into standard cartons. Fruit quality, flavor, and juice ethanol concentration were evaluated immediately after sampling and following 3 and 6 weeks of storage at 5 °C. The overall hedonic score, a measure of flavor, significantly declined from 6.5 to 5.7, as a result of 6 weeks storage. Fruit selected from field bins, from after the washer, and after the waxer were all judged by the taste panel to be equivalent in flavor. The packed fruit were judged to be slightly inferior in flavor. Titratable acidity declined while soluble solids increased as a result of storage; the stage of the packing process influenced neither. Waxing and storage both were associated with higher ethanol levels in the fruit.

Maturity standards that determine when navel oranges can be harvested in California are currently based upon the ratio of soluble solids content (SSC) to titratable acidity (TA) and the rind color of the fruit. These standards may be inadequate to describe the quality of the fruit, which is important given the increased competition from other commodities in the marketplace and declining consumption of fresh citrus. To reevaluate the basis of the maturity standard, navel oranges were harvested at intervals throughout the season and evaluated for SSC, TA, juice ethanol concentration, percent juice, peel coloration, and sensory characteristics. Three varieties of navel oranges, representing early-, mid- and late-season maturities, were used. SSC: TA ratios averaged 6.3 at the beginning of the season and steadily increased to 23.4 at the end of the season. Changes in the hedonic rating, or likeability of the fruit taste as rated by the sensory panelists, were closely related to the SSC: TA ratio and ratings of sweetness and tartness. These relationships showed a similar pattern for all of the navel varieties. A hedonic rating of 6 (like slightly) was not reached until the SSC: TA ratio exceeded the current legal minimum of 8:1, suggesting that the standard should be raised. Juice ethanol levels and percent juice did not have any apparent influence on the sensory ratings. Fruit that were run over a packing line and waxed developed higher amounts of ethanol during storage than control fruit but did not differ substantially from them in hedonic rating.