Analysis and potential value of compounds extracted from star ruby, rio red, and ruby red grapefruit, and grapefruit juice processing residues via steam explosion

Authors: Dorado, Christina; Cameron, Randall - Randy; Manthey, John; Bai, Jinhe; Ferguson, Kyle

Submitted to: Frontiers in Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2021
Publication Date: 9/13/2021
Citation: Dorado, C., Cameron, R.G., Manthey, J.A., Bai, J., Ferguson, K.L. 2021. Analysis and potential value of compounds extracted from star ruby, rio red, and ruby red grapefruit, and grapefruit juice processing residues via steam explosion. Frontiers in Nutrition. 8:691663. https://doi.org/10.3389/fnut.2021.691663.
DOI: https://doi.org/10.3389/fnut.2021.691663

Interpretive Summary: When grapefruit is processed more than half of the fruit is left behind in the form of peel, membrane, juice sacs and seeds. Rather than disposing these residues, processors convert them to low cost animal feed. But this conversion process results in low profit margins and destroys valuable compounds in the residues. If the valuable compounds within the residues could be extracted, processors could improve their profit margins. Therefore, steam explosion was explored as a method to extract pectin, sugars, flavors, aromas and phytonutrients from grapefruit juice processing residues and whole fruit. The conditions for maximum recovery of these compounds using steam explosion were identified and their potential value was calculated. Ultimately it was determined that if steam explosion was implemented, millions of dollars of value could be earned by processors.

Technical Abstract: Culled whole grapefruit (WG) and grapefruit juice processing residues (GP) are currently incorporated into low cost animal feed. If individual chemical components found within these side streams could be recovered as high value co-products, this would improve the overall value of the grapefruit crop. In this work, pectic hydrocolloids, sugars, volatiles, phenolics, and flavonoids were extracted from Star Ruby, Rio Red, and Ruby Red GP and WG using a continuous pilot scale steam explosion system. Up to 97 percent of grapefruit juice oils and peel oils could be volatilized and contained 87.06-93.73 percent d-limonene. The recovery of pectin, as determined by galacturonic acid content, was between 2.06 and 2.72 g/100 g . Of the phenolics and flavonoids analyzed in this study, narirutin was extracted in the greatest amounts of 3000 – 10,000 µg/g.