Physicochemical, Thermal and Rheological Properties of Pectin Extracted from Sugar Beet Pulp Using Subcritical Water Extraction Process.

Seyed Hadi Peighambardoust,Rubén Domínguez,Mirian Pateiro,José M Lorenzo,Maryam Jafarzadeh-Moghaddam

doi:10.3390/molecules26051413

Seyed Hadi Peighambardoust, Rubén Domínguez + Show 3 more

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https://doi.org/10.3390/molecules26051413

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Abstract

The objective of this study was to characterize the properties of pectin extracted from sugar beet pulp using subcritical water (SWE) as compared to conventional extraction (CE). The research involved advanced modeling using response surface methodology and optimization of operational parameters. The optimal conditions for maximum yield of pectin for SWE and CE methods were determined by the central composite design. The optimum conditions of CE were the temperature of 90 °C, time of 240 min, pH of 1, and pectin recovery yield of 20.8%. The optimal SWE conditions were liquid-to-solid (L/S) ratio of 30% (v/w) at temperature of 130 °C for 20 min, which resulted in a comparable yield of 20.7%. The effect of obtained pectins on viscoamylograph pasting and DSC thermal parameters of corn starch was evaluated. The contents of galacturonic acid, degree of methylation, acetylation, and ferulic acid content were higher in the pectin extracted by SWE, while the molecular weight was lower. Similar chemical groups were characterized by FTIR in both SWE and CE pectins. Color attributes of both pectins were similar. Solutions of pectins at lower concentrations displayed nearly Newtonian behavior. The addition of both pectins to corn starch decreased pasting and DSC gelatinization parameters, but increased ΔH. The results offered a promising scalable approach to convert the beet waste to pectin as a value-added product using SWE with improved pectin properties.

Highlights

Sugar beet (Beta vulgaris L.) pulp (SBP), a by-product of the sucrose producing factory, undergoes processing steps including pressing and drying
Sugar beet pulp pectin (SBPP) is a biopolymer that consists of polygalacturonic chains, methyl, and acetyl ester groups as well as neutral sugars and phenolic compounds expressed as ferulic acid [5,6]
Viscosity was decreased with increasing the shear rate, showing a shear-thinning behavior. These observations were in agreement with the results found for pectin extracted from sugar beet pulp in other studies [16,33], and it is characteristic of random coil polysaccharides [34]

Summary

Introduction

Sugar beet (Beta vulgaris L.) pulp (SBP), a by-product of the sucrose producing factory, undergoes processing steps including pressing and drying. Pulp drying is an energyconsuming process and uses about one-third of the whole energy needs of a sucrose factory [1]. Researches have been previously accomplished to use this renewable byproduct as pectin precursors [3,4]. Sugar beet pulp pectin (SBPP) is a biopolymer that consists of polygalacturonic chains, methyl, and acetyl ester groups as well as neutral sugars and phenolic compounds expressed as ferulic acid [5,6]. Pectin is conventionally obtained from vegetable materials using a hot dilute mineral acidic solution [7]. Conventional acid extraction of pectin is a time-consuming process using harsher extraction conditions of temperature and pH, which cause the

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