45G-1 |
Anthocyanin pigments from purple corn as natural colorants for dairy product: Whole-fat milk and skimmed milk |
P. JING, Department of nutrition and food science, University of maryland, 8402 Adelphi Rd., Hyattsville, MD 20783 and M. M. Giusti, Nutrition and Food Science, University of Maryland. Anthocyanin pigments have been traditionally used to provide color to acidified food systems (usually pH below 3) such as fruit beverages, and jams. However, reports of anthocyanins stable at pH higher than 6 suggest that these compounds may be suitable for coloring matrices with neutral or slightly alkaline pH. Our objective was to evaluate the stability of anthocyanins from purple corn (Zea mays L) as natural colorants for milk (whole-fat and skimmed), and investigate the potential interactions between anthocyanins and milk constituents (fat, protein or both) that may exert a protective effect on pigment stability. Anthocyanins from purple corncob were used to color whole-fat milk, skimmed milk, and a phosphate buffer solution (pH 6.8), to a final concentration of 130 mg monomeric anthocyanin/100ml. Pigment stability was evaluated using an accelerated stability test, at 700C for different time periods. Changes in color characteristics (CIELAB, hue and chroma), monomeric anthocyanin content and anthocyanin profiles were monitored during the study. Purple corn anthocyanins provided an attractive purple hue (324 and 347 degrees for skimmed and whole fat milk, respectively) at neutral pH. Heat treatment favored degradation of anthocyanins, but a clear protective effect by milk constituents was evident when comparing the changes in pigment content and profiles in milk versus the buffer solution. After 90min heat treatment, 53% on the pigments had degraded in the phosphate buffer, while only 12% and 4.5% decrease of monomeric anthocyanins were detected in skimmed and whole-fat milk, respectively. The results showed the potential of purple corn anthocyanins as colorants for milk products. A protective effect of matrix constituents on the stability of anthocyanins at neutral pH was evident. Elucidating these mechanisms may provide light into the understanding of how anthocyanins may interact in the small intestine in vivo, where the pH values are in the 7.5-8.5 range.
Session 45G, Fruit & Vegetable Products: Vegetables (Fresh)
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