Study On Modification And Anti-hyperglycemic Activity Of Deoiled Cumin Dietary Fiber

In this study, extraction parameters of shear homogenization assisted enzymatic hydrolysis method were optimized to extract dietary f iber(DF) from deoiled cumin; proximate composition, structure, physicochemical and functional properties of deoiled cumin dietary fiber obtained by above optimum conditions were analyzed; effects of high hydrostatic pressure(HHP)-enzymes modification on proximate composition, structure, physicochemical and functional properties and antioxidant activity of deoiled cumin dietary fiber were determined; meanwhile, the anti-hyperglycemic effect on the type 2 diabetes rats of modified dietary fiber from deoiled cumin were studied. The aim of the research is to increase the additional value of cumin production, and provide theoretic support for the development of anti-hyperglycemic foods and health care products.Deoiled cumin DF was obtained by shear homogenization assisted enzymatic hydrolysis method using the response surface methodology, and the chemical components were also investigated. The results showed that the optimum conditions for preparing DF from deoiled cumin were as follows: shear homogenizaton speed of 7000 r/min, shear homogenization time of 30 min, solid and liquid ratio of 1:35(w/v), enzyme to substrate ratio of 4.5%, a reaction temperature of 57 °C, a pH value of 7.7, and a reaction time of 155 min. Under these conditions, DF extraction efficiency and total DF content were 95.12% and 84.18%, respectively. In addition, DF of deoiled cumin was constituted by pectin(5.44 g/100g), cellulose(33.40 g/100g), hemicellulose(37.25 g/100g) and lignin(23.91 g/100g).Effects of alkali extraction, enzymatic hydrolysis, shear homogenization assisted enzymatic hydrolysis methods on the proximate composition and structure of three kinds of DF from deoiled cumin were investigated. In addition, five different mesh sizes(40, 80, 100, 120, and 150 mesh) were used to separate the above three kinds of DF into different particle sizes, then particle size distribution on the physicochemical properties(water retention capacity, water swelling capacity, oil adsorption capacity), and functional properties(α-amylase activity inhibition ratio, glucose adsorption capacity, and bile acid retardation index) were also studied. Compared to AEDF(62.14 g/100g) and EHDF(75.58 g/100g), SEDF had the highest total DF(84.18g/100g), exhibited honey-comb structure and had crystalline regions(12.5-28°). Furthermore, SEDF exhibited better water swelling capacity(6.79–7.98 ml/g), oil adsorption capacity(6.12–7.25%), α-amylase activity inhibition ratio(14.79–21.84%), glucose adsorption capacity(2.02–60.86%), and bile ac id retardation index(16.34–50.08%) than EHDF and AEDF. The physicochemical properties of sieved DFs improved with increasing sieve mesh sizes(40–120), but decreased with sieve mesh sizes >120, while the functional properties increased with increasing sieve mesh sizes.Effects of high hydrostatic pressure(HHP, 0.1 MPa-400 MPa) and enzymes(laccase and cellulase) modification on the structure, physicochemical and functional properties and antioxidant activity of deoiled cumin DF were evaluated. Results showed that compared to unmodified DF(12.26 g/100g), DF treated with HHP(200 MPa) –enzymes(laccase and cellulase) had the highest soluble DF(SDF) content(increased by 1.48-fold); HHP–enzymes treatment altered the honey-comb structure of DF and generated new polysaccharides; DF modified by HHP–enzymes treatment exhibited improved water retention capacity(10.02 g/g), water swelling capacity(11.19 mL/g), fat and glucose absorption capacities(10.44 g/g, 22.18–63.54 mmol/g), α-amylase activity inhibition ration(37.95%), bile acid retardation index(48.85–52.58%) and antioxidant activity(0.45μg trolox equivalent/ mg DW).Type2 diabetes model rats were used to investigate the anti-hyperglycemic activity of SDF and IDF from deoiled cumin. The results showed that treatment of high-(5 g/kg body weight), middle-(0.5 g/kg body weight), low-dose(0.25 g/kg body weight) of SDF and IDF, especially middle-dose SDF, could increase body weight and food efficienc y ratio of type 2 diabetic rats; decrease concentrations of fasting blood glucose, improve insulin resistance, leptin resistance and inflammatory response; decrease the level of acetate, while increase the concentration of lactate, butyrate, and propionate; ameliorate fatty degeneration in the liver, prevent the production of liver inf lammation; protect the pancreas from atrophy and inhibit islet β cell degeneraton.