New Research Challenges Conventional Methods For Increasing Cuticle Deposition In Cherries & Apples

New research published in HortScience provides significant insights into the limitations of current strategies used to manage fruit cracking and improve fruit quality through cuticle modification. Two separate studies focusing on sweet cherries and apples demonstrate that common treatments—topical applications and nutrient precursors—do not result in increased cuticle deposition or improved structural integrity.

The first study, investigated the efficacy of a commercial biofilm designed to prevent rain-cracking in sweet cherries. Despite the product's intended use to supplement the fruit's natural cuticle, researchers found that repeated applications of Parka® did not increase the mass of the fruit's cuticle, nor did it alter its mechanical properties, such as strain relaxation. Most notably, the treatment failed to reduce water uptake or the incidence of fruit cracking compared to untreated controls.

In a parallel investigation involving apples, researchers explored whether feeding a cutin precursor could naturally stimulate cuticle growth. The study, tested the hypothesis that providing oleic acid—a primary building block of cutin—directly to developing fruit would enhance the protective barrier. The results showed that while the fruit absorbed the precursor, it did not lead to a measurable increase in cuticle thickness or mass. This suggests that cuticle deposition is strictly regulated by the plant's internal developmental programs rather than the availability of raw materials.

Together, these findings indicate that the fruit cuticle is a highly stable structure that is resistant to external manipulation during the growing season. For growers and researchers, this highlights the ongoing challenge of managing fruit integrity and suggests that future efforts may need to focus more on genetic selection or alternative environmental management rather than topical or metabolic supplements.

Professor Dr. Knoche is a professor of Horticulture at the Leibniz University of Hannover, Germany where he teaches and conducts research in fruit science. His research focuses on fruit surface disorders in a wide range of fruit crops including sweet cherry, apple, strawberry, grape, banana and mango.

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