67B-15 |
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C. M. LIYANA-PATHIRANA, Dept. of Biology, Memorial Univ. of Newfoundland, 300 Prince Phillip Dr., Saint John's, NF A1B 3X9, Canada and F. Shahidi, Dept. of Biochemistry, Memorial Univ. of Newfoundland, 300 Prince Philip Dr., Saint John's, NF A1B 3X9, Canada. Response surface methodology (RSM) allows prediction of the best performance conditions with minimum number of experiments in extraction and other processing experiments. The objective of this study was to determine the optimum conditions for extraction of crude phenolics from whole grain and bran of soft (SW) and hard (HW) wheat using RSM. A face-centered cubic design (FCCD) was used to investigate effects of three independent variables on response variable. The process variables studied included solvent composition (%), extraction temperature (C) and time (min) for measuring antioxidant activity (AA) response of crude phenolic extracts determined using Trolox equivalent antioxidant capacity assay, expressed as Trolox equivalents (TE). The independent variables were coded at three levels and their actual values selected on the basis of preliminary experimental results. The FCCD consisted of 14 experimental points and three replications at the center point. Data were analyzed using Design Expert and Statistical Analysis System. A second order polynomial model was used for predicting the response variable. The regression analysis showed that more than 94% of the variation was explained by the model. Canonical analysis of surface responses revealed that the stationary surface for AA was a saddle. The optimal conditions for the extraction of phenolics obtained using ridge analysis were 53.6%, 68.4C, 73.4min and 52.9%, 57.6C, 74.7 min respectively, for whole grain and bran of SW. Under these conditions the predicted response values were 50.74 and 45.2 TE, respectively. The crude phenolics were extracted using the derived optimum conditions to check the validity of the second order model. The values were 53.1±2.1 and 47.9±0.8 TE, respectively. A similar trend was observed for hard wheat. The experimental values agreed closely with those predicted and were within the acceptable limits, thus indicating suitability of the model employed and the success of RSM in optimizing the extraction process.
Session 67B, Food Chemistry: Antioxidants and bioactive agents
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