Finger millet grain phenolics and their impact on malt and cookie quality
| Autor: | Siwela, Muthulisi |
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| Rok vydání: | 2009 |
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| Druh dokumentu: | Diplomová práce |
| Popis: | Phenolics in finger millet (FM) grain, including tannins, may impact significantly on its antimicrobial properties, functionality and health-promoting potential. Unfortunately, the location of tannins in the grain is unknown and there is limited information on the influence of variety on grain phenolic composition and antioxidant activity (AA). The effect of phenolics in FM grain on its malt fungal load and on the functional quality of its food products, including baked goods, is barely known. Twenty two FM grain types of varied visual kernel colour were analysed to determine the influence of grain type on phenolic composition, AA, and tannin localisation in the grain. Condensed tannins, anthocyanins and flavan-4-ols were detected. Light coloured grain types had no tannins and had much lower total phenolics (TP) relative to the pigmented types, and types that stained black with the Bleach test had much higher tannin content and much higher AA. The grains that stained black with the Bleach test and had high tannin content (0.60 to 2.08 mg catechin eqivalents/100 mg, db) had a dark coloured testa layer, indicating that the tannins were located in that layer. The results indicate that occurrence of tannins in FM is a varietal property and the tannins are predominantly responsible for the AA of the grain. Germinative energy (GE), enzymic activity, and total fungal count [TFC], and infection levels of 12 FM grain types of varied phenolic content were measured to determine the impact of phenolics in FM grain on its malt quality. The malt quality of high-phenol FM types was much higher than that of the low-phenol types, with respect to enzymic activity. TFC was negatively correlated with grain total phenolics (TP) and amount of phenolic type (APT) and there were some negative correlations between fungal species infection levels and TP and APT (p Thesis (PhD)--University of Pretoria, 2009. Food Science unrestricted |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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