Characterization of perseoranjin, a natural orange pigment from avocado (Persea americana) seed, and its uses as a natural food colorant
Open Access
- Author:
- Shegog, Rachel Marie
- Graduate Program:
- Food Science
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- November 05, 2015
- Committee Members:
- Joshua D Lambert, Thesis Advisor/Co-Advisor
Gregory Ray Ziegler, Thesis Advisor/Co-Advisor
Ryan John Elias, Thesis Advisor/Co-Advisor
Dr. Emmanual Hatzakis, Thesis Advisor/Co-Advisor - Keywords:
- avocado
food
colorant
natural product
natural colorant - Abstract:
- The global natural colors market is estimated to reach US $ 2.3 billion by 2020. This is due in part to increasing consumer desire for natural food ingredients and the desire of food companies to produce “clean-label” products. We examined an extract of Hass avocado (Persea americana) seeds crushed in water as a potential source of natural orange colorants. The extract color is pH dependent, and can produce a range of colors from pale yellow near pH 2.5 to deep red and brown colors near pH 10. Treating the extract under alkaline conditions to pH 12.32 shifts the extract’s color range towards the red end of the visible light spectrum. After treatment with alkali, the extract can produce rich orange colors even at low pH values near 2.5, while the native extract produces only pale yellow in this range. A polyphenol oxidase (PPO) catalyzed reaction produced the most abundant pigment in this extract, 2-(4-hydroxy-8-(2-((5-hydroxy-2-oxo-2,6,7,7a-tetrahydrobenzofuran-6-yl)oxy)ethyl)-5-oxo-6-((3,4,5,6-tetrahydroxytetrahydro-2H-pyran-2-yl)methoxy)-5H-benzo[7]annulen-3-yl)acetic acid, or perseoranjin, which is a novel glycosylated benzotropolone compound with carboxylic acid and fused-ring butenolide containing side chains. Though the color is stable at room temperature, liquid chromatography-mass spectrometry (LC-MS) indicates that the individual compounds are not stable, forming dimers and other compounds in aqueous solution. The most abundant colored fraction showed Perseoranjin to have a parent ion [M+H]+ with m/z 603.1675 in positive mode. Based on the presence of an abundant m/z 441 fragment (Δm/z 162), we hypothesized that the compound was a glycosylated compound. The same extract also contained other [M+H]+ ions including an unrelated m/z 603.1687 compound, a m/z 917.2639 compound with a m/z 603 moiety, and finally an m/z 1205 dimer produced from the combination of two m/z 603 compounds. Using LC-MS-based metabolomics and principal component analysis (PCA) of the colored and PPO-inhibited-uncolored extracts, we found approximately forty-nine masses unique to the colored or uncolored extract as well as some known compounds present in both. Abscisic acid and perseitol, the 7-member sugar alcohol, were present in both extracts while epicatechin, catechin, procyanidin B2 and salidroside were found only in the uncolored extract. Here, we report the results of our on-going studies to chemically characterize this new orange pigment. We also provide some preliminary results on its colorant properties in various food products. These results will support a new, value-added use for avocado seeds which are frequently viewed as a low-value waste product.