Optimizing essential oil application to prevent postharvest decay in strawberries

Authors: MARIN, ANNA - Universidad De Valencia; Sun, Xiuxiu; MIRANDA, MARCELA - Sao Paulo State University (UNESP); Ference, Christopher; BALDWIN, ELIZABETH - Retired ARS Employee; Bai, Jinhe; RITENOUR, MARK - University Of Florida; ZHANG, JIUXU - University Of Florida; Plotto, Anne

Submitted to: Proceedings of Florida State Horticultural Society
Publication Type: Proceedings
Publication Acceptance Date: 5/1/2020
Publication Date: 7/15/2020
Citation: Marin, A., Sun, X.N., Miranda, M., Ference, C.M., Baldwin, E.A., Bai, J., Ritenour, M., Zhang, J., Plotto, A. 2020. Optimizing essential oil application to prevent postharvest decay in strawberries. Proceedings of Florida State Horticultural Society. 132:185-188.

Interpretive Summary: Consumers demand produce without any pesticide residues. Plant essential oils (EO) are generally recognized as safe (GRAS) and have gained popularity owing to their demonstrated effectiveness in suppressing fruit fungal pathogens. In this study, two methods of application of thyme EO were tested on fresh strawberries. When applied in a coating on the fruit surface, thyme EO tended to have a residual off-flavor perceived by untrained panelists. EO was also encapsulated in a polysaccharide matrix and placed in sachets attached to the fruit container (clamshells) lids. Encapsulated EO did not impart any off-taste to strawberries, and the highest dose had the best decay control. Further tests will be performed to optimize applications of thyme EO in an encapsulated matrix.

Technical Abstract: Strawberry is a fragile commodity highly susceptible to postharvest decay. With antifungal activity, thymol is a potential candidate for postharvest decay prevention. A coating consisting of whey protein isolate (WPI) (1% w/v) with 0.05, 0.1 and 0.2% thymol, was sprayed on strawberries cv. Radiance using an airbrush. Fruit were air dried and repacked in 1-lb commercial clamshells. Another treatment consisted of sachets (pouches) containing 0.2, 0.4, and 0.8 g of spray-dried pectin with 11% thymol, attached to the lids of 1-lb clamshells. Fruit were stored at 7 °C for 9 d, then moved to 21 °C for 3 d. Taste panels were performed after 1, 5 and 8 d and decay incidence/severity recorded. None of the treatments reduced decay in comparison with the control (untreated) when fruit were stored at 7 °C. However, after 3 d stored at 21 °C, fungal decay was reduced by the 0.8 g sachet treatment. Off-flavor due to thymol was perceived in all WPI-treated fruit the day after coating application, while none of the fruit with sachet treatments had off-flavor. By day 8, strawberries packed with sachets in clamshells at all concentrations of thymol had better appearance than those treated with WPI coatings and control. Essential oils microencapsulated in a polysaccharide and packed in a sachet in a clamshell is a promising method to apply antimicrobials to fragile fruit such as strawberries.