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Subcritical water extraction and reaction of bioactive pectic polysaccharides Open Access


Other title
pectic polysaccharides
subcritical water
bioactive films
pomegranate biomass
Type of item
Degree grantor
University of Alberta
Author or creator
Valdivieso, Carla S
Supervisor and department
Saldaña, Marleny (AFNS)
Examining committee member and department
King, Jerry W(Depts. of Food Science/Chemistry University of Arkansas)
Velázquez, Carlos A. (Katz Group-Rexall Centre for Pharmacy & Health Research)
Department of Agricultural, Food, and Nutritional Science
Bioresource and Food Engineering
Date accepted
Graduation date
Master of Science
Degree level
Natural pectic polysaccharides have drawn considerable attention as promising multifunctional materials for food, pharmaceutical and biomedical uses. Pectic polysaccharides production, however, involves the utilization of inorganic acids such as sulfuric, hydrochloric and nitric acids. The objective of this study was to isolate novel bioactive pectic polysaccharides from pomegranate Punica granatum L. biomass using a subcritical binary fluid system as well as to obtain pectin-based sols under subcritical water conditions prior to the production of pectin-based 2D films or 3D cryogel structures. Pomegranate pectic polysaccharides (PPs) were extracted using a semi-continuous subcritical water system at 100-140˚C, 50 bar and 5 mL/min with binary solvent systems (aqueous citric acid or aqueous ethanol) and, pectin-based sols were formed within a stirred-tubular subcritical water batch reactor at 100˚C and 70 bar. The variables evaluated were yield, galacturonic acid content, degree of esterification and anti-oxidant properties of isolated pomegranate pectic polysaccharides. Pectin-based sols were then used to obtain films and cryogels. The physico-chemical, mechanical, optical and functional properties of such gels were determined. These results showed that subcritical water and the above subcritical binary aqueous systems at 120˚C/50 bar and 30 min favored the extraction of bioactive pomegranate pectic polysaccharides with high galacturonic acid content (>70%) and degree of esterification (>60%). The total phenolic content and the anti-oxidant activity of extracted PPs were 152.9 mg GAE/g PPs and I %DPPH >87%, respectively. Pectin-based sols obtained with subcritical aqueous citric acid at 100˚C/70 bar led to flexible films with tensile strength, percent elongation and phenolics release capacity comparable to pectin-based films produced by the traditional sol-gel method. Subcritical sol formation and freeze-dried gel integration led to lightweight and highly porous bioactive pectin-based cryogels. Through this thesis, subcritical water technology has shown to be a versatile, environment-friendly and sustainable alternative that can be used for pomegranate biomass conversion into value-added products as well as in combination with other processes to obtain novel biocomposite materials.
This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for the purpose of private, scholarly or scientific research. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
Citation for previous publication
Saldaña, M. D. & Valdivieso-Ramírez, C. S. (2015). Pressurized fluid systems: Phytochemical production from biomass. Journal of Supercritical Fluids, 96, 228-244.

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