Analysis and Potential Value of Compounds Extracted From Star Ruby, Rio Red, and Ruby Red Grapefruit, and Grapefruit Juice Processing Residues via Steam Explosion.

Christina Dorado,Kyle L Ferguson,Jinhe Bai,Randall G Cameron,John A Manthey

doi:10.3389/fnut.2021.691663

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 coproducts, this would improve the overall value of the grapefruit crop. In this study, 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% of grapefruit juice oils and peel oils could be volatilized and contained 87–94% d-limonene. The recovery of pectin, as determined by galacturonic acid content, was between 2.06 and 2.72 g 100 g−1. Of the phenolics and flavonoids analyzed in this study, narirutin and naringin were extracted in the amounts of up to 10,000 and 67,000 μg g−1, respectively.

Highlights

Florida, Texas, and California are the major producers of grapefruit (Citrus paradisi Macfad.) in the United States, where approximately 256,000 metric tons were collectively cultivated during the 2018–19 season [1]
There was little to no effect on the yield of the soluble sugars for all three varieties of GP subjected to steam explosion as compared to water extraction of fresh GP (Supplementary Figures 8C,D)
Potential Value of Sugars While steam explosion did not yield a marked increase in the amount of sugars extracted from Whole Grapefruit (WG) or GP as compared with water extraction of fresh WG or GP, steam explosion did allow for the simultaneous extraction and isolation of other valuable compounds, such as pectin, volatiles, phenolics, and flavonoids

Summary

Introduction

Texas, and California are the major producers of grapefruit (Citrus paradisi Macfad.) in the United States, where approximately 256,000 metric tons were collectively cultivated during the 2018–19 season [1]. Citrus juice processors convert these residues to low-value animal feed [8] through the most energy-intensive operation of the juice-processing plant [9]. Grapefruit process residues contain valuable pectic hydrocolloids, sugars, volatiles, phenolics, and flavonoids that are lost when the residues are converted to animal feed. If these compounds could be extracted from the residues, these high-value chemicals could bring new revenue streams to grapefruit processing plants and improve profit margins. Sugars, volatiles, phenolics, and flavonoids have been extracted from orange juice-processing residues previously, using a continuous pilot scale steam explosion

Methods

Results

Conclusion