Studies Of Extraction And Purification Of Active Components From Flaxseeds And Stability In Food Processing

Worldwide, flaxseed has become a rising star in the natural food ingredient market. This thesis studied the extraction of flaxseed gum and secoisolariciresinol diglucoside, and SDG’s stability in food processing.Dietary fiber (DF) is essential to a healthy digestive system. As a grain, flaxseed contains a dietary fiber level higher than the average level of grains, including soluble dietary fiber (SDF) and insoluble dietary fiber (IDF). Flaxseed gum feature very high water-holding and swelling capacity.It could be used in products for weight management, blood fat and blood sugar control, and cardiovascular health. Flaxseed gum has won global recognition as a natural food additive for conventional food and functional food.Lignans are one of the major classes of phytoestrogens, which are estrogen-like chemicals and also act as antioxidants. Flaxseeds, sesame seeds and many other vegetables and cereals are rich in lignans. Secoisolariciresinol diglucoside (SDG) is a major lignan known to the health supplement industry.According to published reports, the main health claims on SDG include:breast cancer prevention, cardiovascular health, diabetes prevention and protestate health. Thus, as a rich source for SDG, flaxseed extract is drawing more and more interests. In this thesis, we focused on the extraction and purification of SDG from flaxseed meal, and the identification and quantification of SDG in flaxseed extract. In addition, we also looked into the stability of SDG during food processing, as part of an application study for flaxseed to be used as a food additive.In the first chapter of this thesis, we introduced the history, physicochemical properties, pharmacological effects and biological sources of SDG. On this basis, the research contents of this thesis were described.In the second chapter of this thesis, we used the sulphuric acid-phenol method to quantify polysaccharides in flaxseed gum to determine gum quality. And we used orthogonal experiment to determine an optimal process for gum extraction at mild conditions.In the third chapter of this thesis, we established an HPLC analytical method for SDG, that is simple, accurate and sensitive. We also looked into UV-VIS and TLC to swiftly quantify and identify SDG on site.In the fourth chapter of this thesis, we used an orthogonal experiment to determine the optimum extraction procedure for SDG in flaxseed meal. And then we studied the adsorption and desorption of SDG on macroporous adsorption resin. The concentration of extraction solution, adsorption velocity, elution velocity, and eluction solvent were discussed to determine the purification procedure.In the fifth chapter, we discussed the impact food processing might have on SDG content in flaxseed powder. SDG content was studied in steamed, boiled, fried and deep fried samples. We also looked into the removal of cyanogentic glycosides in flaxseed powder with microwave treatment.In the last chapter, all of the experimental work was summarized. We found the deficiencies in this thesis and proposed the idea of latter research.