Determinants of sensory acceptability in grapefruit

Authors: Obenland, David - Dave; CAMPISI-PINTO, SALVATORE - University Of California; ARPAIA, MARY LU - University Of California

Submitted to: Scientia Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2017
Publication Date: 12/22/2017
Citation: Obenland, D.M., Campisi-Pinto, S., Arpaia, M. 2017. Determinants of sensory acceptability in grapefruit. Scientia Horticulturae. 231:151-157. https://doi.org/10.1016/j.scienta.2017.12.026.
DOI: https://doi.org/10.1016/j.scienta.2017.12.026

Interpretive Summary: Grapefruit consumption in the United States has declined, at least partly as a result of increasing competition with other fruit in the marketplace and consumers being more demanding for greater fruit quality. In order to determine ways to improve grapefruit flavor quality a study was undertaken to evaluate both sensory and other quality attributes in a diverse group of grapefruit obtained from California, Texas, and Florida over a nine-month period. Seven different harvest dates of fruit were acquired, sometimes obtaining fruit from multiple states at the same time. It was found that likeability was most closely linked to sweetness, with bitterness having a smaller role. Tartness was not an important factor in determining how well a fruit was liked. In accordance with the sensory results regarding sweetness, fruit with high soluble solids, a measure of the sugar within the fruit, had better flavor than did fruit with low soluble solids. The ratio of soluble solids to acidity, a commonly-used measure of maturity and flavor in grapefruit did not relate as well to likeability as the California standard, a newer measure of maturity utilized for navel oranges. Surveys of purchase intent that were conducted for each sample indicated that it would require grapefruit of very high flavor quality to induce the panelists to purchase grapefruit more often in the future. The results of this study suggest that revising the current maturity standards to raise the concentration of soluble solids in the fruit would likely increase both consumer satisfaction and the sale of grapefruit.

Technical Abstract: Early research reported that flavor in grapefruit was associated with the ratio of soluble solids (SSC) to titratable acidity (TA) and the juice content of the fruit. This led to the development of maturity standards based upon these parameters to define when grapefruit could be legally harvested in different regions of the United States. Increasing consumer demands regarding fruit quality coupled with decreasing consumption of grapefruit in the United States prompted a reassessment of the factors that influence consumer acceptability in grapefruit in this study using more thorough methods of sensory evaluation and fruit sampling for analytical characteristics than were previously done. Over a 9-month period commercially-packed grapefruit were obtained on seven different harvest dates during the commercial season from either California, Texas, or Florida, sometimes obtaining fruit from multiple states at a time. Presentation to the semi-expert panelists was in the form of halved grapefruit with four segments prepared for easy removal. The fruit were evaluated by the panelists for overall likeability, grapefruit flavor intensity, juiciness, sweetness, tartness and bitterness. The panelists were also asked questions regarding purchase intent. From the same grapefruit halves that were tasted juice was obtained that was used to assay for SSC, TA and narinigin. It was found that likeability was most strongly linked to sweetness, with bitterness having a lesser role. Accordingly, SSC was closely related to likeability. The traditionally-used measure for harvest maturity SSC/TA did not relate as well to likeability as did the California standard (CAstd), a calculated value that subtracts acidity from SSC rather than dividing. Purchase intent questions asked for each sample indicated that grapefruit should have a very high flavor quality to ensure both an immediate and future purchase.