Extraction and Enrichment of Flaxseed Lignan (Linum usitatissimum L.)
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Plant lignans are a class of natural plant diphenolic compounds that are made by the condensation of two phenylpropanoid moieties. Oilseed and cereal crops including flaxseed and sesame seed are major sources of plant lignan with flaxseed containing the highest amount of lignan among all plants tested. Secoisolariciresinol (SECO), a compound that can elicit responses in mammals that mimic estrogen, is the primary lignan produced by flaxseed. The lignan SECO can be transformed into enterodiol (END) and enterolactone (ENL) by intestinal bacteria and these molecules can be absorbed and affect mammalian physiology. Flaxseed SECO is in the form of a heteropolymer that contains SDG crosslinked with HMGA by ester bonds. The objective of this study is to establish procedures to recover the SDG polymer, SDG and SECO with acceptable yield and quality. Experiments were conducted to optimize three operations: first, optimization of aqueous ethanol extraction of SDG polymer from whole flaxseed; second, hydrolysis of SDG polymer ester bonds to release SDG; and finally, enzymatic hydrolysis of SDG ether bonds to produce free SECO. Optimization of ammonium hydroxide hydrolysis and enzymatic hydrolysis were investigated. Whole flaxseed (CDC Sorrel) was used as the raw material; SDG polymer extraction included two extractions with 70% ethanol (v/v) at room temperature; SDG polymer was hydrolysed using 29% (w/w) ammonium hydroxide solution at a ratio of 4:1 (w/w) at 80 °C for 2 h; SDG was refined over resin; finally, SECO was released using 30 U/mL cellulase from Trichoderma viride in sodium acetate buffer solution in ratio of 5:7 (v/v) at 60 °C for 48 h. Yields of SDG polymer, SDG and SECO were 2.7(of defatted meal mass), 51.9 (of isolated SDG polymer mass), and 66.6% (of SDG mass), respectively. The content of SDG in the polymer, SDG and SECO were 65.8 (g SDG/g polymer), 89.5 (g SDG/g), and 86.4 (g SECO/g), respectively. These results indicate a possible industrial process for recovery of flaxseed lignan from defatted flaxseed meal. The approach may reduce total production cost and the price of enriched flaxseed lignan. This would be beneficial for intensive applications of flaxseed lignan as a medicine, dietary supplement or other health ingredient.
DegreeMaster of Science (M.Sc.)
DepartmentChemical and Biological Engineering
SupervisorReaney, Martin JT; Meda, Venkatesh
CommitteeBaik, Oon-Doo; Zhang, Lifeng; Cree, Duncan
Copyright DateJanuary 2021