Preparation and physicochemical properties of dietary fiber in flat almond skin

Flat almond skin produced in westhern Liaoning region were used as material to extract dietary fiber.Parameters of ultrasonic-assisted extraction were optimized.The liquid-material ratio,alkali solution concentration,extraction time and extraction temperature were selected as factors to carry out the single factor experiment.The response surface method was applied to optimize technical parameters of dietary fiber preparation using liquid-material ratio,alkali solution concentration,extraction time as variables,and SDF extraction rate as response value.The results showed that the optimum parameters were liquidmaterial ratio 16.5:1,alkali solution concentration 3.6%,extraction time 2.3 h at temperature 45 ℃,with parameters of ultrasonic-assisted extraction:power 600 W,treatment time 15 min.Under this condition,The extraction percentage of water soluble dietary fiber(SDF) and water insoluble dietary fiber(IDF) reached to 7.23%,38.97%,respectively.Water-holding capacity and swelling property of SDF were 5.22 g/g and 4.37 mL/g,while water-holding capacity and swelling property of IDF were 7.16 g/g and 5.43 mL/g in almond skin.The almond skin dietary fiber has excellent physicochemical properties.