EFFECT OF SOLVENT EXTRACTION AND FLOUR LIPID COMPOSITION ON CAKE VOLUME
Abstract
Effects of direct (22(DEGREES)C), Soxhlet (50(DEGREES)C), and water-bath (60(DEGREES)C), hexane extraction on oxidation of flour lipid was measured by peroxide value and conjugated diene content. The initial peroxide values of the three lipid extracts were comparable. With further oxidation, at 90(DEGREES)C, peroxide value of direct extracts reached a maximum (10 hrs) then declined, while peroxide values of Soxhlet and water-bath extracts reached a plateau at 40 hrs. Maximum peroxide values of Soxhlet and water-bath extracts were half the direct extract. Diene content was comparable for the three lipid extracts, initially and after oxidation. Lipid phosphorus, a measure of phospholipid, in the Soxhlet and water-bath extracts was double the direct lipid extract. Lipid phosphorus accounted for the observed differences in peroxide value among lipid extracts. In conclusion, peroxide value is unsatisfactory for monitoring oxidation of flour lipid containing 80 to 160 ug phosphorus/mg lipid. Optimum cake batter expansion and maximum cake volume was achieved when oxidized lipid (10 hrs) was added to unchlorinated flour. Cakes prepared with oxidized lipid and unchlorinated flour has batter expansions like chlorinated cake flours. Soxhlet and water-bath extracts produced cakes which initially had greater volumes than direct extracts but with oxidation, volume decreases less for direct extracts. Cake flour stored at 5 - 8(DEGREES)C in polyethylene containers or multi-layer paper bags showed no change in diene content over a 12 month period. Cake volume was correlated to flour treatment, pH, and diene content. Flour mass median diameter and hexane extracted lipid composition were correlated to cake volume. Correlations were determined on nine hard and soft wheat flours and on the soft wheat flour subset. Flour glycolipid was separated on a silicic acid column and monogalactosyl diglyceride and digalactosyl diglyceride (DGDG) content determined by liquid chromatography. Flour mass median diameter (r = -0.73), DGDG (r = 0.92), and nonpolar to polar ratio (r = -0.70) were significantly related to cake volume for the complete flour set but the nonpolar to polar ratio was not correlated to soft wheat cake volumes. Results indicate DGDG content of soft wheat flour warrants further investigation as a predictive index of cake volume potential.
Degree
Ph.D.
Subject Area
Food science
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