Recovery of pectic hydrocolloids and phenolics from huanglongbing related dropped citrus fruit.

BACKGROUND: Citrus pre-harvest fruit drop, caused by huanglongbing infection, has increased dramatically concomitant with declining tree health and crop harvest size. This loss of harvestable fruit is damaging to both growers and juice processors. Recovering and converting this fruit to alternative value added products would benefit the citrus industry. Therefore, we have explored the potential of using this fruit as a feedstock in our newly developed pilot scale continuous steam explosion process.

RESULTS: Whole fruits were converted to steam-exploded biomass using a continuous pilot scale process. The sugar composition of raw fruit and steam-exploded biomass was determined. Recovered pectic hydrocolloids and phenolic compounds were characterized. Pectic hydrocolloids comprised 78 g kg-1 of the dry material in the dropped fruit. Following the steam explosion process almost all of the pectic hydrocolloids were recoverable with a water wash. They could be functionalized in situ or separated from the milieu. Additionally, approximately 40% of the polymethoxylated flavones, 10% of the flavanone glycosides, 85% of the limonoids and almost 100% of hydroxycinnamates were simultaneously recovered.

CONCLUSION: The continuous steam explosion of pre-harvest dropped citrus fruit provides an enhanced, environmentally friendly method for the release and recovery of valuable coproducts from wasted biomass. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.