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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Citrus and Other Subtropical Products Research » Research » Publications at this Location » Publication #317465
Title: Evaluation of natural colorants and their application on citrus fruit as alternatives to Citrus Red No. 2

Author
item SUN, XIUXIU - University Of Florida
item Baldwin, Elizabeth - Liz
item RITENOUR, MARK - University Of Florida
item Plotto, Anne
item Bai, Jinhe

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2015
Publication Date: 9/1/2015
Citation: Sun, X., Baldwin, E.A., Ritenour, M., Plotto, A., Bai, J. 2015. Evaluation of natural colorants and their application on citrus fruit as alternatives to Citrus Red No. 2. HortScience. 50(9):1353-1357.

Interpretive Summary: The color of orange peel is a significant attribute influencing consumer product acceptance. Citrus Red No.2 (CR2) has been used to improve color in Florida. However, it was listed as a group 2B carcinogen by the European Union (EU) and the International Agency for Research on Cancer (IARC). This study investigated the effect of five oil-soluble natural colorants on citrus fruit peel color. The results suggest that one of the natural colorants, annatto, would be the most successful replacement of CR2 for use as a natural colorant on citrus fruit.

Technical Abstract: Warm field temperatures can often result in poor peel color of some citrus varieties, especially early in the harvest season. Under these conditions, Florida oranges, temples, tangelos, and K-Early citrus fruit are allowed to be treated with Citrus Red No.2 (CR2) to help produce a more acceptable peel color. Unfortunately, CR2, the commercial colorant used in Florida, has been listed as a group 2B carcinogen by the European Union (EU) and the International Agency for Research on Cancer (IARC). Although not likely dangerous at levels used on citrus, and on a part of the fruit that is not ingested, there is a negative health perception, and thus, a need for natural or food grade alternative colorants to replace CR2 for use on citrus. The current research demonstrated that three out of five oil-soluble natural red/orange colorants resulted in peel colors somewhat similar to the industry standard CR2. These three (annatto extract, paprika extract and paprika oleoresin) were selected for further in vivo studies. The stability of the natural colorants along with CR2 was evaluated by applying them on test papers and then on fresh ‘Hamlin’ oranges. All natural colorants were found to be easily oxidized and faded when applied on test papers. However, coating the colored surfaces with carnauba wax apparently inhibited oxidation and the subsequent discoloration of the surface. When applying the natural colorants to ‘Hamlin’ oranges before waxing, the treatments retained the improved color after storage in the dark at 5 °C, simulating cold storage. However, only annatto extract maintained a stable color when subsequently stored in a simulated market condition, at 23 °C exposed to 300 Lux of standard fluorescent white light.