Modification of pectin structure and improvement of pectin gelling capacity by high-pressure processing treatment of fresh orange peel prior to pectin extraction

Authors: Zhao, Wei; Xu, Yixiang; Dorado, Christina; Chau, Hoa - Rose; Hotchkiss, Arland; Yadav, Madhav; Cameron, Randall - Randy

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/29/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The possibility of utilizing endogenous plant pectin methyl-esterase (PME) to modify pectin in source material prior to pectin extraction is proposed and explored in this study. Fresh orange (Hamlin) peel from a local commercial juice plant was pretreated with high-pressure processing (HPP) at different combinations of pressures and durations, followed by pectin extraction with a commercial method. The effects of HPP pretreatments on pectin yield and structural properties of the extracted pectins were determined. HPP pretreatment increased the yield of subsequent pectin extraction by 41.10 %. Crude extracts from HPP-treated peels showed higher PME activities than the untreated peel. Pectins extracted from HPP pretreated peel (Hp) had a lower degree of methyl-esterification (DM), accompanied by an increase in degree of blockiness (DB) of non-esterified galacturonic acid (GalA) than the control (pectin extracted from un-treated peel). GalA content and linearity of pectin (LP) were higher, while neutral sugar content and degree of branching (DBr) were lower in Hp. The reduction in weight average molecular weight of Hp was minor, and it was positively correlated with a reduction in neutral sugars, indicating an effect of pectin debranching without degradation of the pectin main chain. The effects of HPP on the pectin main chain, degree, and distribution of methyl-esterification in this study were similar to the reported effects of orange PME on extracted pectin. The identified pectin structural features were validated by Fourier Transform Infrared Spectroscopy analysis and a newly developed lateral flow assay. The functionalities of Hp were evaluated and compared with commercial low methoxy (LM) and high methoxy (HM) pectins. The calcium sensitivity of Hp was comparable to that of commercial LM pectin, which was remarkably higher than the control pectin and commercial HM pectin. Hp had a dramatically higher gelling capacity for calcium-mediated gelation than the control and commercial HM pectin. The strength and viscoelastic properties of Hp-calcium gels were comparable to that of commercial LM pectin. Meanwhile, most of the Hp also showed a comparable gelling capacity for sugar-acid-mediated gelation to that of the control and commercial HM pectin. Hp also had higher emulsifying stability than the control and commercial pectins. The study reveals a great potential of modifying pectin in source plant material by HPP pretreatment to produce high-quality pectin with increased gelling capacity and a broadened scope of applications.