Revalorization of sunflower stalk pith as feedstock for the coproduction of pectin and glucose using a two-step dilute acid pretreatment process

Qibo Zhang,Lu Cheng,Xin Zhou,Xutong Ma,Yong Xu

doi:10.1186/s13068-021-02045-2

Abstract

BackgroundSunflower stalk pith, residue from the processing of sunflower, is rich in pectin and cellulose, thereby acting as an economic raw material for the acquisition of these compounds. In order to increase the commercial value of sunflower processing industry, a two-step dilute sulfuric acid treatment process was conducted on spent sunflower stalk pith to obtain the value-added products, pectin and glucose.ResultsIn this study, pectin was firstly extracted under mild acid condition to avoid pectin degradation, which was conducted at 90 °C with a pH of 2.0 for 2 h, and ~0.14 g/g of pectin could be recovered. Then the remaining solids after pectin extraction were subjected to the reinforced treatment process with 0.75% H2SO4 at 150 °C for 30 min to further improve enzymatic hydrolysis efficiency. Moreover, by combining a fed-batch enzymatic hydrolysis strategy, a solid loading content of 16% was successfully achieved and the glucose titer reached 103.1 g/L with a yield of 83.6%.ConclusionFinally, ~140 g pectin and 260 g glucose were produced from 1 kg of raw sunflower stalk pith using the integrated biorefinery process. This work puts forward a two-step dilute acid pretreatment combined with enzymatic hydrolysis method to produce pectin and glucose from sunflower spent waste.

Highlights

Sunflower stalk pith, residue from the processing of sunflower, is rich in pectin and cellulose, thereby acting as an economic raw material for the acquisition of these compounds
Pectin extraction from sunflower pith with acid, alkali and enzyme In order to squeeze the maximum quantity of pectin products from sunflower pith materials, acidic, alkaline- and enzymatic- extraction strategies were first compared in this study [17, 18]
The extraction of pectin and glucose from Sunflower stalk pith (SSP) using a two-step dilute acid pretreatment combined with enzymatic hydrolysis was presented

Summary

Introduction

Residue from the processing of sunflower, is rich in pectin and cellulose, thereby acting as an economic raw material for the acquisition of these compounds. Pectin is well known as stabilizers in food industries due to its ability to gel and give viscosity, and the use of pectin in food formulations or pharmaceuticals industry has beneficial effects on human health such as stimulating the immune response, reduces the cholesterol absorption in the blood and lower cancer risk [10, 11] These benefits lead to a high price that exceeded $21/kg, justifying the search for new raw pectin-extraction materials; the extraction of high value-added pectin products from SSP can potentially increase the commercial value of sunflower processing industry [10]. After the pectin has been extracted, a large amount of cellulose (a polymer composed of repeating units of glucose) is still retained in the remaining solids, and it can be hydrolyzed enzymatically to glucose, which is transformed to the other value-added biochemicals [14]

Methods

Results

Conclusion