Study On Technologies Of Chemical Modification And Properties Of Dietary Fiber From Lentinula Edodes Stem

The annual output of lentinus edodes is very large in China,of which the ratio of lentinus edodes stalks is about 30%.Lentinus edodes stems are mainly used as primary agricultural products in the market,which has not been fully developed and utilized,resulting in a waste of resources.The stalk of lentinus edodes is rich in dietary fiber,including some lentinus edodes polysaccharides,which have biological activities such as anti-oxidation,lowering blood sugar,lowering blood pressure,anti-tumor,etc.But the bioactivity of natural lentinula edodes stalk dietary fiber is low.In this paper,high quality dietary fiber was obtained by modifying dietary fiber.In this experiment,lentinus edodes dietary fiber(LDF)was extracted from lentinus edodes by enzyme method.Carboxymethyl modification and cross-linking modification with sodium trimetaphosphate / Sodium triphosphate(STMP / STPP)of dietary fiber from lentinula edodes stems were studied.The single factor orthogonal design was used to optimize the cross-linking modification and carboxymethyl modification of lentinus edodes dietary fiber.Finally,the basic composition,water holding capacity(WHC),oil holding capacity(OHC)and swelling capacity(SC)of dietary fiber of lentinula edodes stalk were determined to compare the properties of unmodified and modified dietary fiber.The results are as follows:1.The carboxymethyl modification of dietary fiber from lentinus edodes stems was carried out by single factor orthogonal optimization experiment from the following five aspects: The dosage of Ethanol(0 ~ 95%),the time of alkalization(0~150min),the mass fraction of sodium monochloroacetate(5% ~ 25%),the temperature of etherification(25 ~ 80 °C),and the time of etherification(1.5 ~ 4.5 h).The optimum conditions of carboxymethyl modification are as follows:the mass fraction of ethanol was 80%,the alkalization time was 120 min,the mass fraction of sodium monochloroacetate was 10%,the etherification temperature was 50 °C,the etherification time is 3.5 hours.2.The cross-linking modification of lentinula edodes stem dietary fiber was optimized by single factor orthogonal design from the following four aspects: The addition of STMP / STPP(0~1.0g),pH(6~13),reaction temperature(30~80°c)and reaction time(60~210min).The optimum conditions of crosslinking modification were as follows: the amount of STMP / STPP was 0.6 g,pH was 12,reaction temperature was 60°C,reaction time was 2 h.3.Double modification of dietary fiber was carried out by combining carboxymethyl modification with cross-linking modification.The results showed that the water-holding capacity of the modification of dietary fiber by carboxymethyl followed by crosslinking was 5.96 g/g better than that of the modified lentinus edodes dietary fiber cross-linking first.The oil-holding capacity of the modification of dietary fiber by crosslinking followed by carboxymethyl was 3.33 g/g better than that of carboxymethyl first.4.Properties of modified and unmodified dietary fiber:(1)water-holding capacity: The water-holding capacity of unmodified dietary fiber was 5.65g/g,and that of carboxymethyl-modified dietary fiber was 6.29 g/g.Comparing with the unmodified dietary fiber,the water holding capacity of the carboxymethyl-modified dietary fiber was increased by 11.72%.The water-holding capacity of dietary fiber modified by carboxymethyl followed by crosslinkingand dietary fiber modified by carboxymethyl followed by crosslinking was 5.96 g/g and 5.82 g/g respectively.Comparing with the unmodified dietary fiber,it increased by 5.49% and 3%respectively.(2)swelling capacity: The swelling capacity of the dietary fiber of the unmodified dietary fiber was 8.81 mL/g,and that of the cross-linked dietary fiber was 9.06 mL/g,which was2.84% higher than that of the unmodified dietary fiber.The swelling capacity of carboxymethyl modified dietary fiber was 5.64 mL/g,which was 56.20% lower than that of unmodified dietary fiber.(3)oil retention: The oil holding capacity of unmodified lentinus edodes dietary fiber was3.12 g/g,and that of carboxymethyl modified dietary fiber was 3.36 g/g,which was 23.72% higher than that of the original.The oil-holding capacity of double modified dietary fiber was improved.Through comparing the properties of modified and unmodified lentinus edodes stem dietary fiber,it was found that carboxymethyl dietary fiber and cross-linked dietary fiber had good properties.In conclusion,the modified dietary fiber of lentinus edodes handle has better water-holding capacity,oil-holding capacity and swelling capacity than the unmodified dietary fiber.The invention has better processing characteristics and application prospect.