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Title:Isolation of a carotenoid-protein complex from carrot root and the effects of components of carrot and heat on the relative bioavailability of carotenoids from carrots
Author(s):Zhou, Jin-Rong
Doctoral Committee Chair(s):Nishida, Toshiro
Department / Program:Nutritional Sciences
Discipline:Nutritional Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Chemistry, Biochemistry
Health Sciences, Nutrition
Abstract:The objectives of this work are: (1) to isolate and purify carotenoid-protein complexes from carrot roots and to determine the location of carotenoid-protein complexes within the carrot chromoplast, and (2) to utilize the ferret to evaluate the effects of carotenoid-protein complexes, crystalline form of carotenoids, carrot matrix, and heat treatment on the bioavailability of carotenoids from carrots.
A carotenoid-protein complex has been purified from carrot juice or from carrot chromoplasts by detergent treatment followed by ammonium sulfate precipitation, gel filtration and ion exchange chromatography. Results from SDS-urea-PAGE analysis indicated that the carotenoid-protein complex contained a major protein subunit with a MW of 18 KDa. HPLC analysis of pigments associated with this complex indicated that $\beta$-carotene, $\alpha$-carotene and lutein were major carotenoids present with small amounts of phytoene and zeta-carotene. Carrot chromoplast subfractionation and sucrose density centrifugation also resulted in a major carotenoid-containing fraction from the carrot which was enriched in the 18 KDa protein, suggesting that the 18 KDa protein-containing-carotenoid complex is the major complex associated within the carrot chromoplast. Evaluation of the amounts of 18 KDa protein and carotenoids present in chromoplasts shows that the carotenoid-protein complex only associate with small percentage of total carrot carotenoids. It is thus unlikely that the 18 KDa protein influences carotenoid bioavailability from carrots. This carotenoid-protein complex may function enzymatically in carotenoid biosynthesis.
In the feeding study, groups of ferrets (n = 6) were fed a low carotene diet for 2 weeks and then were fed 10 mg of $\beta$-carotene daily for three days from one of the following sources: (1) commercial $\beta$-carotene beadlets dispersed in distilled water, (2) unheated carrot juice, (3) heated carrot juice, (4) unheated carrot chromoplasts, or (5) heated chromoplasts. The tissue analysis of $\beta$-carotene concentrations indicated that $\beta$-carotene-beadlet-supplemented animals had significantly higher $\beta$-carotene concentrations than other groups (p $<$ 0.01). Carrot chromoplast-supplemented animals had significantly higher tissue $\beta$-carotene and $\alpha$-carotene concentrations than carrot juice-supplemented animals. Heated-material-supplemented animals did not show significant differences of tissue $\beta$-carotene and $\alpha$-carotene concentrations compared to unheated-material-supplemented animals. These results suggest that the food matrix, probably pectin-like fibers, and the crystalline form of carotenoids in carrots are major factors that reduce the bioavailability of carotenoids from carrot juice, while heat treatment does not significantly affect the bioavailability of carotenoids from carrots in this animal model.
Issue Date:1994
Rights Information:Copyright 1994 Zhou, Jin-Rong
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9512609
OCLC Identifier:(UMI)AAI9512609

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