Study On The Functional Properties And Application Of Soluble Dietary Fiber From Defatted Coconut Flour By Subcritical Water

Defatted coconut flour is a by-product of coconut products.It contains a large amount of cellulose and still has high economic value.It 1s a high-quality plant fiber resource with great development potential.This article uses defatted coconut flour as raw material.The preparation of soluble dietary fiber from defatted coconut flour and it’s antioxidant activity in vitro were studied.Establishment kinetic model of subcritical water degradation of defatted coconut flour.Funtional properties of defatted coconut flour,soluble dietary fiber of defatted coconut flour and residue in lower blood fat and sugar.Finally,the samples with the best functional properties were applied to bread.The main research contents are as follows:1.Basic composition of defatted coconut:crude fiber:63.15±0.23%,protein:13.50±0.93%,ash:1.89±0.02%,fat:4.9±0.12%,total sugar:6.07±0.13%,crude fiber:63.25±0.01%,total dietary fiber:70.14±0.34%,moisture:3.5±0.03%.2.The soluble dietary fiber of defatted coconut flour was prepared by enzyme-chemical method,subcritical water extraction method and ultrasonic-chemical method.①The optimum process parameters for preparation of ESDF by enzyme-chemical method were follows:the addition amount of mixed enzyme were 0.6%,enzyme time was 50min,the mass fraction of NaOH was 5%and the alkali-hydrolysis was 40min.Under this condition,the yield of soluble dietary fiber of defatted coconut flour is 11.99%.②The optimum process parameters for preparation of SSDF by subcritical water method were follows:extraction temperature was 140 ℃,extraction time was 30 min,the ratio of liquid to material was 30:1 mL/g and the mesh number was 80.Under this condition,the yield of soluble dietary fiber of coconut meal is 13.99%.③The optimum process parameters for preparation of USDF by ultrasonic chemical method were follows:the ratio of liquid to material was 30:1 mL/g,mass fraction of NaOH was 7%,the ultrasonic time was 30min and the ultrasonic temperature was 40 C.Under this condition,the yield of soluble dietary fiber of coconut meal is 10.53%.3.The antioxidant activity of soluble dietary fiber from defatted coconut flour was studied by simulating the digestive system of gastrointestinal fluid in vitro.In this study,the antioxidant activities of digestive production of soluble dietary fiber from defatted coconut flour,including DPPH·,·OH and O2-· free radical scavenging capacity,were evaluated by simulating human oral saliva and gastrointestinal digestive tract in vitro.The results showed that the SSDF digestion products had the largest DPPH·,·OH and O2-·free radical scavenging capacity when simulated oral saliva for 15 min.When simulated gastric digestion for 1 h,the digestive product had the largest DPPH·and O2-· free radical scavenging capacity,while the largest OH· free radical scavenging capacities were observed when simulated gastric digestion for 4 h.When simulated small intestinal digestion for 8 h,the digestive product had the largest DPPH·,OH·and O2-·and free radical scavenging capaties.4.Using the defatted coconut flour as raw material,the study investigated the influence of different subcritical water degradation conditions on the degradation process and determined the content of reducing sugar in Residue with different reaction times of 100-200℃.The model of Saeman was used to simulate the experimental data,and the kinetics equation of the subcritical water degradation reaction was established.Based on this,the kinetic parameters of subcritical water degradation and the morphological analysis of the degradation are obtained.The results show that the Seaman model could better reflect the subcritical water degradation process of defatted coconut flour.The initial degradation energy of material Eal is 35.94 kJ/mol and the reducing sugar degradation activation energy Ea2 is 32.12 kJ/mol,respectively.And the pre-exponential factors K10 is 6.50 ×102min-1,K20 is 3.24 × 102 min-1.5.The physical and chemical properties and structural characteristic of DCF,SSDF and residue were studied.Determination of water holding capacity,swelling holding capacity and oil holding capacity properties in terms of physical and chemical properties.The structures were characterized by HPLC,FT-IR,X-ray diffraction,TG and SEM.The results showed that the water holding capacity of DCF、SSDF of DCF and residue were 3.82±0.04 g/g,6.11±0.12 g/g and 3.23±0.10 g/g,respectively.The swelling capacity of DCF,SSDF and residue were5.12±0.14 mL/g、4.86±0.08 mL/g and 3.15±0.04 mL/g,respectively.The oil holding capacity were 4.68±0.11 g/g,5.59±0.10 g/g and 2.54±0.09 g/g.The major component of monosaccharide of DCF was mannose,galactosamine,glucose and arabinose.The major component of monosaccharide of SSDF and residue was mannose and galactose.Infrared spectra showed that SSDF had the characteristics absorption peaks of polysaccharide and higher thermal stablity,the DCF and residue had the characteristics absorption peaks of polysaccharide and lignin.The results of X-ray diffraction indicated that DCF,SSDF and residue had cellulosel crystal structure.The scanning electron microscope showed that DCF has a compact,stacked structure,the SSDF had a loose structure with multiple,dense cavities.The residue had large holes and were sparse under high temperature conditionsand the residue.6.The functional properties of different numbers of DCF,SSDF and residue on reducing blood fat and blood gulose,including the adsorption capacity of sodium cholate,cation exchange capacity,inhibitory capacity of pancreatic lipase activity,glucose binding capacity and inhibition of a-amylase activity,were studied.The results showed that 80 mesh of DCF and SSDF have good effect on reducing blood fat and blood gulose.7.Add 80 mesh DCF and SSDF to the bread,and the effects on the bread quality was evaluated by texture characteristics,specific volume,water holding capacity,aging degree and sensory quality.The results showed that the added 3%SSDF bread had better texture and sensory quality.The shelf life of bread with 3%SSDF was predicted to be about 13d by ASLT method,which was greater than the shelf life of bread on the market and significantly extended the shelf life of bread.