The Study On Extraction And Spray Drying Of Flaxseed Gum

Flaxseed gum is a natural macromolecule plant gum, which primarily consists of polysaccharide as well as a little protein and mineral elements. The unique functional properties of this gum, such as viscosity, water-holding, emulsifying, effervescing, stability, etc., make it widely utilized in food, cosmetic chemical, and pharmacy industries. Emphases of research have been paid on the extraction kinetics, effects of extraction process parameters and spray drying of flaxseed gum, which are the fundamentals for development and utilization of flaxseed gum.Based on the first Fick's law, a kinetics model of extraction was established on the consumption that the changing rate of concentration gradient against time was proportional to the concentration gradient at that time, the relationship between diffusion coefficient and temperature accorded with the Arrhniues equation, and there was a power function relationship between diffusion coefficient and current concentration of solute. The model directly describes how the solute gaining rate relates to the operational parameters of extraction, such as solvent:seed ratio, temperature and time, and is suitable not only for extraction of flaxseed gum, but also for that of other similar products.Selecting water as the solvent and flaxseed as material, extraction experiments were conducted for analyzing the effects of operational parameters on the yield of flaxseed gum. The rules of how the yield of flaxseed gum varying with these factors was obtained and then used to evaluate the unknown constants in the kinetics model. The validation experiments showed that the model could predict the yield of flaxseed gum with an absolute error less than 0.5%.The effects of solvent:seed ratio, temperature and time were studied on the viscosity of flaxseed gum and raw protein. The relationships between the parameters of extraction and emulsifying property of dried gum, total cyanogen content, effective lysine content in whole-kernel flaxseed were firstly studied. In order to accurately evaluate the relationship between flaxseed polysaccharide and the technical parameters of extraction, a concept of non-nitrogen yield of flaxseed gum was established. Experimental results showed that the extraction performance varies with the value of the influencing factors in different ways and compromises should be made during the optimization of extraction.A target function was constructed from the analysis to the experiments and a new multi-index optimization experiment method was proposed. Based on an orthogonal regression experiment, a multi-index optimization of extraction of flaxseed gum was carried out, and a group of optimized parameters was obtained.A laboratory spray drier was employed in drying of flaxseed gum. The effects of spraying rate, air temperature and air flow rate on moisture content, viscosity, emulsifying property and total cyanogen content of dried flaxseed gum were studied. The results indicated that spray drying did not affect flaxseed gum's emulsifying property, but the change of moisture content had a high correlativity with that of viscosity and total cyanogen content. The process conditions leading to low moisture content always brought low viscosity as well as low total cyanogen content.A mathematic model was obtained by an orthogonal regression experiment, which described the relationships between moisture content, viscosity, total cyanogen content of dried flaxseed gum and spraying rate, air temperature, and air flow rate. Based on the model, the flaxseed gum spray drying process was optimized by the multi-index optimization method. An optimized spray drying conditions was obtained, under which the moisture content, viscosity, total cyanogen content were synthetically proved to be satisfied.