Dietary fiber from coconut flour: A functional food

Abstract

To determine the effectiveness of dietary fiber present in coconut flour as a functional food, the following studies were conducted: (a) Dietary Fiber Composition and Fermentability of Coconut Flour; (b) The Effect of Coconut Flour on Mineral Availability from Coconut Flour Supplemented Foods; (c) Glycemic Index of Coconut Flour Supplemented Foods in Normal and Diabetic Subjects; and (d) The Cholesterol Lowering Effect of Coconut Flakes in Moderately Raised Cholesterol Levels of Humans. The dietary fiber content of coconut flour was 60.0 ± 1.0 g/100 g sample, 56% insoluble and 4% soluble. Fermentation of coconut flour produced short chain fatty acids with butyrate (1.73 ± 0.07 mmol/g fiber isolate) > acetate (1.40 ± 0.12; ( P < 0.05) > propionate (0.47 ± 0.01; P < 0.05). Iron and zinc availability were highest for carrot cake (Fe, 33.3 ± 0.7%; Zn, 12.6 ± 0.1%) supplemented with 20% coconut flour while multigrain loaf supplemented with 10% and macaroons with 25% coconut flour were highest for calcium availability (63.4 ± 8.0% and 38.7 ± 1.1%, respectively). Increasing concentrations of dietary fiber from coconut flour did not affect mineral availability from all test foods. The significantly low glycemic index foods (< 60 mmol × min/l) investigated were: macaroons (45.7 ± 3.0), carrot cake (51.8 ± 3.3) and brownies (60.1 ± 5.4) with 20–25% coconut flour. The test foods containing 15% coconut flour has a glycemic index ranging from 61 to 77 mmol × min/l. Among the test foods, pan de sal (87.2 ± 5.5) and multigrain loaf (85.2 ± 6.8) gave significantly higher glycemic index with 5% and 10% coconut flour. On the other hand, granola bar and cinnamon which contained 5% and 10% coconut flour, respectively gave a glycemic index ranging from 62 to 76 mmol × min/l and did not differ significantly from the test foods containing 15% coconut flour ( P < 0.05). A very strong negative correlation ( r = − 85, n = 11, P < 0.005) was observed between the glycemic index and dietary fiber content of the test foods supplemented with coconut. There was a significant reduction (%) in serum total and LDL cholesterol for: oat bran flakes, 8.4 ± 1.4 and 8.8 ± 6.7, respectively; 15% coconut flakes, 6.9 ± 1.1 and 11.0 ± 4.0, respectively; and 25% coconut flakes, 10.8 ± 1.3 and 9.2 ± 5.4, respectively ( P < 0.05). Serum triglycerides were significantly reduced for all test foods: corn flakes, 14.5 ± 6.3%; oat bran flakes, 22.7 ± 2.9%; 15% coconut flakes, 19.3 ± 5.7%; and 25% coconut flakes, 21.8 ± 6.0% ( P < 0.05). Results from the above study can be a basis in the development of coconut flour as a functional food. The functionality of coconut flour in terms of prevention for risk of chronic diseases, e.g. diabetes mellitus, cardiovascular diseases (CVD) and colon cancer, revealed increase production of coconut and coconut flour. The production of coconut flour is very economical because it can be produced in a small or large scale. The raw material is obtained from the by-product (waste) of the coconut milk industry and the process and equipment used in its production is simple and cheap. Coconut flour as a good source of dietary fiber can be added to bakery products, recipes and other food products for good health.