Branching out of the tropics: Sustainable star fruit production yields high market potential

20 Dec 2019 --- Tropical fruits are gaining global popularity, as is the carambola, also known as star fruit, which is known for being high in fiber, antioxidants and other nutrients. A researcher from Florida International University is currently investigating cultivation of the geometric fruit using cover crops unharvested plants that enhance soil health. This research demonstrates how tropical fruit farming for food industries can be both environmentally sustainable and economically viable.

“When produced sustainably through alternative fertilization regimes, star fruit can be a low input crop that has great potential to feed many because of its high production potential. Specialty tropical fruits can also sell for a premium in markets outside of the tropics, where they are not readily available,” Ariel Freidenreich, lead researcher and PhD candidate at Florida International University, tells FoodIngredientsFirst.

The sunn hemp's extensive roots help with soil health.Star fruit is not very popular sold as a fresh produce product in the grocery store in areas outside of the tropics. The fresh product is more common in Southeast Asia, Latin America and the Caribbean – its native regions for cultivation. Since it is a very fragile fruit, transportation in its fresh form can be difficult and expensive. 

The carambola tree is incredibly productive and generally has a very high yield. The fruit is also nutrient-rich and high in antioxidants, including vitamins A, B, and C, potassium and magnesium, making it appealing for the health food market and specialty restaurants.

Star fruit is a great addition to tropical fruit salad due to its appearance and flavor.“Star fruit is delicious on its own or as a value-added product. This fruit is more often being incorporated into restaurants with health consciousness in mind,” Freidenreich says. New incorporations of star fruit include pre-packaged salads, as a base for fruit wines, or even dried. Star fruit is also known to be anti-inflammatory and may help with a variety of skin conditions.

Sustainable production
Star fruit is a low input crop, especially when grown in its native tropical environment. The carambola tree has the ability to flower and produce fruit all year round when grown in a truly tropical environment, Freidenreich explains.

Freidenreich trimmin sunn hemp, which inspires the crop to branch laterally and create more biomass.“It is a medium-sized tree with few soil requirements other than being well-drained. With the proper nutrients, one tree has the potential to produce up to 180 kg of fruit per year. With its low nutrient requirements, this crop can be grown sustainably through alternative fertilizer regimens,” she outlines.

Freidenreich's research with carambola includes cover crops. Two cover crops the team studied are sunn hemp and velvet bean. Both are in the legume family and can take nitrogen from the air and metabolize it into a plant nutrient. Their mulches also have the potential of insulating the carambola’s tree roots to protect them from cooler temperatures in the winter. Sunn hemp especially acts as a windbreak for the fruit trees, as star fruit trees are wind-sensitive can defoliate with strong gusts.

“We incorporated the cover crops into the soil as green manure for two summer growing seasons. This helps ensure healthy tree development without the addition of synthetic inputs, decrease soil erosion as well as nutrient leaching, making it a very environmentally friendly practice. Therefore, producing these specialty crops becomes easier and more sustainable,” says Freidenreich.

The research is currently taking place on a certified organic farm in Florida and these practices are being developed to help farmers transition to organic production or those interested in sustainable practices.

By Anni Schleicher