Study On Processing Technique And Properties Of Dietary Fiber From Lemon Pomace

Sichuan is a big production province of lemon. At present fresh lemon is sold as well asbeing processed to lemon oil, lemon juice, dried sliced lemon, etc. About40%~50%lemonpeel is produced after processing and the majority is taken as rubbish. It wastes the resourceand pollutes the environment. The present research is about making dietary fiber (DF) fromlemon skin. The optimum process is selected according to parameters in lemon DF includingtotal dietary fiber (TDF), soluble dietary fiber (SDF), insoluble dietary fiber (IDF), waterholding capacity (WHC), oil holding capacity (OHC), swelling capacity (SWC), viscosity,whiteness, glucose dialysis retardation index (GDRI), cation exchange capacity, total flavoneand vitamin C (Vc). Application effect of lemon dietary fiber in bread has been investigated.The main conclusion is as follows:1. Processing conditions of lemon dietary fiber has a relation with many factors, such aspretreatment process, drying method, product size, extraction process, etc. The property oflemon dietary fiber varies with the above factors.1.1Impact of Pretreatment Process on Lemon Dietary FiberWhen lemon dietary fiber is made by blanching with hot water and cooling with flowingwater, it has high SDF, good WHC, SWC, viscosity, whiteness and GDRI. When lemondietary fiber is made by washing with warm water, it has high TDF and IDF, with OHC,whiteness, WHC and SWC being significantly improved. When lemon dietary fiber is madeby drying without any pretreatment, it has high total flavone and Vc, and good cationexchange capacity.1.2Impact of Drying Method on Lemon Dietary FiberLemon dietary fiber made by freeze-drying method has high TDF, SDF, total flavoneand Vc, and good OHC, viscosity, whiteness, GDRI and cation exchange capacity. Whenhigh IDF and WHC are emphasized, hot air drying method at60℃can be adopted.1.3Impact of Product Size on Lemon Dietary FiberWhen lemon dietary fiber with high WHC, OHC and SWC is required, grain size ofproduct should be16to30meshes. When lemon dietary fiber with good viscosity, whiteness,GDRI and cation exchange capacity is required, grain size of product should be less than80meshes.1.4Impact of Extraction Process on Lemon Dietary FiberWhen lemon dietary fiber with high total flavone and Vc and good OHC is required, rawmaterial in same volume water is extracted at the room temperature for1minute and thenfreeze-dried. When lemon dietary fiber with good WHC and viscosity is required, rawmaterial in same volume water is extracted at60℃for90minutes and then dried by hot air. When lemon dietary fiber is made by extracting with95%ethanol of same volume at60℃for90minutes and then freeze-drying, it has high TDF, IDF and SDF, good SWC, viscosity,whiteness, GDRI and cation exchange capacity.1.5Taking pretreatment process, extraction process, drying method and product finenessinto full consideration, the optimum preparation process should be determined according tothe required index. When lemon dietary fiber with good OHC, high total flavone and Vc isrequired, the optimum preparation process is extracting1minute in water of equal volume atthe room temperature and then freeze-drying. When lemon dietary fiber with high TDF, SDFand IDF, good WHC, viscosity, whiteness, GDRI and cation exchange capacity is required,the optimum preparation process is extracting in95%ethanol at60℃for90minutes and thenfreeze-drying. When lemon dietary fiber with good SWC is required, the optimumpreparation process is warming by hot water and extracting in95%ethanol at60℃for90minutes and then freeze-drying.2. Improvement of Bread Quality by Addition of Moderate Lemon Dietary Fiber2.1Addition of lemon dietary fiber reasonably to bread can improve the appearance,taste, hardness, elasticity, viscousness, conglutination, chewing and recovery property ofbread.2.2When one percent of lemon dietary fiber is added, bread has high productivity, softtaste, good toughness and teeth stickyless with shelf life prolonged.