Optimization Techniques for the Extraction of Soluble Dietary Fiber from Okra with Complex Enzymes and Its Physicochemical Properties and Structure Characterization

Soluble dietary fiber from okra pods was obtained by mixed enzyme extraction method. Effects of enzyme content,material-to-water ratio,extraction temperature and extraction time on the extraction of SDF were investigated by single-factor experiments. Based on single-factor experiments,response surface analysis was employed to investigate the optimal parameters of the extraction. Physicochemical properties and structure characterizations of the SDF extracted under optimal conditions were studied. The result showed that the optimal conditions were as follows:Material-to-water ratio 1:24 g/mL,enzyme content 1.8%,extraction time 54 min,extraction temperature 62℃,under these conditions,the yield of SDF achieved 10.94%,the relative error with the predicted value was 1.48%. The SDF from okra exhibited significant water holding capacity(5.61 g/g),swelling capacity(3.35 mL/g)and oil holding capacity(4.88 g/g),which could be developed as ingredient of laxative functional food in the future. Microstructure of SDF from okra showed that starch substances on its surface were removed completely. The crystal structure of okra SDF accorded with crystal form of cellulose I. Fourier transform infrared spectroscopy of SDF accorded with typical characteristics of dietary fibers.