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dc.contributor.supervisor Mazza, Giuseppe (Food Science, Agriculture and Agri-Food Canada) en Ho, Colin Hao Lim 2007-01-08T15:44:23Z 2007-01-08T15:44:23Z 2007-01-08T15:44:23Z
dc.description.abstract The physiological benefits of flaxseed against pathological disturbances, such as cancers and heart diseases, are mainly attributed to its high lignan content. This study (Experiment 1) examined the application of pressurized low polarity water (PLPW) for extraction of lignans, proteins and carbohydrates from defatted flaxseed meal. Key processing conditions included temperature (130, 160, 190°C), solvent pH (4, 6.5 and 9), solvent to solid ratio (S/S) (90, 150 and 210 mL/g) and introduction of co-packing material (0 and 3 g glass beads). The addition of 3 g glass beads as co-packing material facilitated extraction by enhancing surface contact between the liquid and solid thus shortening extraction time. Elevated temperature accelerated the extraction rate by increasing the solid diffusion coefficient thereby reducing the extraction time. The maximum yield of lignans (99 %) was obtained at temperatures ranging from 160°C to 190°C, with solvent volume of 180 mL (90 mL/g meal) at pH 9. Optimal conditions for protein extraction (70 %) were pH 9, extraction volume of 420 mL (210 mL/g meal) and 160°C. Total carbohydrates yield was maximized at 50% recovery at pH 4 and 160°C with 420 mL solvent (210 mL/g meal). Increased temperature accelerated extraction, thus reducing solvent volume and time to reach equilibrium. For the extraction of proteins, however, a temperature of 130-160°C is recommended, as proteins are vulnerable to thermal degradation due to heat decomposition. The effects of flow rate and geometric dimensions for extraction of lignans and other flaxseed meal bioactives were further investigated in Experiment 2, based on the variables optimized in the previous experiment. Defatted flaxseed meal was extracted with pH 9 buffered water with meal to co-packing glass beads ratio of 1:1.5 at 5.2 MPa (750 psi) and 180°C. The aqueous extracts were analyzed for lignan, protein and carbohydrate using HPLC and colorimetric methods. The optimal extraction yields for lignan, protein and carbohydrate were found at flow rates of 1 to 2 mL/min with bed depth between 20 and 26 cm and a S/S ratio of 40 to 100 mL/g. The combination of low flow rate and high bed depth allowed the use of lower S/S ratio with reduced total solvent volume consumption. This study also evaluated the mass transfer kinetics governing the process of lignan extraction from flaxseed meal in a fixed bed extraction cell. Diffusion of solute into the continuously flowing solvent was mainly responsible for the mass transfer mechanism as flow rate did not increase proportionally with the yield and rate of extraction. The extraction kinetics were studied on the basis of two approaches: Fick’s diffusion equation and a two-site exponential kinetic model. The proposed two-site exponential kinetic model corresponding to the two-stage extraction (rapid and slow phases) successfully described the experimental data. Diffusivities attained from Fick’s diffusion model ranged from 2 x 10-13 to 9 x 10-13 m2s-1 while mass transfer coefficients were between 4.5 x 10-8 and 2.3 x 10-7 ms-1 for extraction of lignans at 180°C, pH 9 with 1:1.5 meal to co-packing material ratio. en
dc.format.extent 5693027 bytes
dc.format.mimetype application/pdf
dc.language.iso en_US
dc.subject Phenolics en
dc.subject Functional foods en
dc.subject Bioactives en
dc.subject Subcritical water en
dc.subject Flaxseed meal en
dc.subject Extraction en
dc.subject Lignans en
dc.subject Proteins en
dc.subject Carbohydrates en
dc.subject Optimization en
dc.subject Diffusion en
dc.subject Mass transfer en
dc.subject Packed bed en
dc.subject Kinetic en
dc.subject Linum en
dc.subject Response surface en
dc.title Pressurized low polarity water extraction of lignans, proteins and carbohydrates from flaxseed meal en Food Science en
dc.contributor.examiningcommittee Mazza, Giuseppe (Food Science, Agriculture and Agri-Food Canada) Scanlon, Martin (Food Science) Holley, Rick (Food Science) Jayas, Digvir (Biosystems Engineering) en Master of Science (M.Sc.) en
dc.description.note February 2007 en

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