Total Anthocyanin Levels in Commercially-Available Pigmented Grain Products
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Hauver, Alexandra
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Abstract
This thesis reports an observational research project, which analyzed the anthocyanin content of products with black soybeans or blue corn as an ingredient. The objectives of the study were: 1) gather a minimum of 8 commercially available food products with black soybean or blue corn as predominant ingredients, and produce triplicate anthocyanin-rich extractions of each, 2) assess anthocyanin content of each extraction by two methods: HPLC to measure the common anthocyanins as determined by a literature search, and the pH differential colorimetric assay for assessing total anthocyanin content, and 3) compare anthocyanin content of processed pigmented grain products to known values for fruit, and amounts demonstrated to be necessary for achieving health benefits. Total anthocyanin content determined by colorimetric assay ranged from 106.1 mg/kg to 261.5 mg/kg full-fat chip, while yellow corn chips contained a mean of 3.8 mg/kg full-fat chip. All six brands of blue corn tortilla chips had a significantly (p<0.05) higher anthocyanin content than yellow corn chips. HPLC analysis of the individual anthocyanins in blue corn tortilla chips showed the presence of 5 out of 6 of the common anthocyanins. Cyanidin-3-glucoside was the most prominent anthocyanin in blue corn tortilla chips ranging from 13.3 mg/kg full-fat chip to 29.5 mg/kg full-fat chip. Pelargonidin-3-glucoside, delphinidin-3-glucoside, peonidin-3-glucoside, and petunidin-3-glucoside were all present in blue corn chips listed in order of highest quantity. Malvidin-3-glucoside was not found to be present in any of the blue corn chip samples, while no individual anthocyanins were detectable in the yellow corn tortilla chips. The anthocyanins in black soybean milks were unable to be extracted. In a 100 g portion, the amount of anthocyanins found in blue corn tortilla chips is comparable to the amount found in plums.
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Anthocyanins, Blue corn, HPLC, Food processing