Quantitative determination of galacturonic acid in pectin and pectin products by combined pectinase hydrolysis and HPLC determination

Abstract

Pectin is a complex heteropolysaccharide with a predominantly galacturonic acid (GalA) main chain and various branching sugars, leading to some analytical and quantitative determination challenges. By comparison with various acid hydrolysis methods, an effective and precise hydrolysis method for GalA determination from pectin was investigated using a combination of pectinase hydrolysis (PH) and HPLC determination, which was named the PH-HPLC method. With a pectinase loading of 2250 U/g pectin, 4.0 g/L commercial pectin was almost completely hydrolysed to the intact and detectable GalA at 50 °C after 24 h, for quantitative determination by HPLC. Acid-catalysis methods showed obvious disadvantages in terms of GalA degradation or incomplete hydrolysis of pectin, resulting in imprecise determination results. Moreover, the PH-HPLC method was employed for the quantitative determination of GalA in three common natural pectin feedstocks and indicated 45.5–233.1% higher content of GalA than the acid hydrolysis method. Thus, the PH-HPLC method is demonstrated to be a precise approach for analysing and quantifying the GalA of pectin and respective feedstock.

Graphical Abstract

Keywords:

• Pectin
• galacturonic acid
• pectinase enzymatic hydrolysis
• galacturonic acid degradation
• quantitative analysis
• PH-HPLC method

Author contributions

Danfeng Li designed and performed experiments, analysed data, and prepared the manuscript. Xia Hua: conceptualization, formal analysis, investigation, data curation. Jing Luo analysed data and revised the manuscript. Yong Xu conceived experiment and supervised the project, and revised the manuscript. All authors read and approved the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data and materials in the current study are available from the corresponding author on reasonable request.

Additional information

Funding

The authors acknowledge the financial support from the National Natural Science Foundation of China (32171730 and 32211530071).