Prof. Adel A. Kader, Professor Emeritus, University of California, Davis (aakader@ucdavis.edu), January 2009.
Plant breeders have been successful in selecting genotypes with much higher contents of ascorbic acid (vitamin C) in guava, pineapple, and tomatoes, beta carotene (provitamin A) in pineapple and tomatoes, and flavonoids in berries and tomatoes. Biotechnology approaches coupled with plant breeding can be utilized to improve the content of vitamins, minerals, dietary fiber, and phytonutrients in fruits, especially those with high per capita consumption rates. Phytonutrients that can lower the risk of heart disease, cancer, and other diseases include carotenoids and flavonoids (anthocyanins, phenolic acids, polyphenols). The antioxidant capacity of fruits is related to their contents of anthocyanins, phenolic compounds, carotenoids, ascorbic acid, and vitamin E. Large genotypic variation in total antioxidant capacity have been shown in many fruits, indicating the potential for further genetic improvements.
Providing better flavored fruits is likely to increase their consumption, which would be good for the producers and handlers (making more money or at least staying in business) as well as for the consumers (increased consumption of healthy foods). To achieve this goal, future research and development efforts should address the following objectives:
- Replace poor flavor cultivars with good flavor cultivars from among those that already exist and/or by selecting new cultivars with superior flavor and good textural quality.
- Identify optimal cultural practices that maximize flavor quality, such as optimizing crop load and avoiding excess nitrogen and water, which along with low calcium shorten the postharvest-life of fruits due to increased susceptibility to physical damage, physiological disorders, and decay.
- Encourage producers to harvest fruits at partially‑ripe to fully‑ripe stages by developing handling methods that protect the fruits from physical damage.
- Identify optimal postharvest handling conditions (time, temperature, relative humidity, atmospheric composition) that maintain flavor quality of fruits and their value‑added products. Postharvest‑life should be determined on the basis of flavor rather than appearance. The end of flavor‑life results from losses in sugars, acids, and aroma volatiles (especially esters) and/or development of off‑flavors (due to fermentative metabolism or odor transfer from fungi or other sources).
- Develop ready‑to‑eat, value‑added products with good flavor and adequate shelf-life for successful marketing.
- Optimize maturity/ ripeness stage in relation to flavor quality at the time of processing and select processing methods to retain good flavor of the processed products.