Methanolic extract fractionation phenolic content

Figure 11. Molecular weight distributions of middle molecular weight phenolic (solid line) and acidic (broken line) fractions from methanol extract, and higher molecular weight acidic (dotted line) fraction from subsequent aqueous 96% dioxane ract, of spruce wood chips degraded by P, ckrysosporium to 20% loss in lignin content Sephadex LH60A).10 M LiQ-DMF profiles adapted and redrawn from reference 67.

Dabrowski and Sosulski, 1984 Shahidi and Naczk, 1989 Wanasundara and Shahidi, 1994a). Kozlowska et al. (1983) reported the presence of free phenolic acids (22.4 mg/100 g) in the methanolic extracts of defatted flour, but Dabrowski and Sosulski (1984) did not detect any free phenolic acids in the meal, perhaps due to the use of tetrahydro-furan for extraction. Phenolic acids released from soluble esters constituted the largest fraction (55—89%) of the total content of phenolic acids. Furthermore, Dabrowski and Sosulski (1984) reported that ferulic acid was the predominant phenolic acid in the soluble esters and insoluble residues of flaxseed. 

These results concurred with the findings of Thiyam et al. (2006a) that rapeseed meal extracts contained free sinapic acid, which was equivalent to just one-tenth of the content of sinapine. This was further illustrated by the Iree-phenolic fractions of the meal extracts that could recover the free sinapic acid safisfactorily. Usually in analysis, the phenofic extracts are hydrolysed with NaOH and the released-phenolics are extracted with diethyl ether, ethyl acetate or both. Comparisons between the aqueous fraction (rich in sinapine) before and after hydrolysis producing the released fraction (rich in sinapic acid) showed reasonable results with minimum hydrolysis losses affecting the accuracy of the process. Additionally, fiactionation of the 70% methanolic extract showed comparable extraction efficiency to the original extract before fractionation. 

Phenolic Content of Different Fractions of 70% Methanolic Extract Estimated Using HPLC (330 nm) and Folin-Ciocalteu Assay (750 nm)... 

---