Extraction and characterization of pectin from Yuza (Citrus junos) pomace: A comparison of conventional-chemical and combined physical–enzymatic extractions

Pectin from Yuza (Citrus junos) pomace was extracted by using combined physical and enzymatic (CPE) treatment, and their characteristics were compared with those of chemically-extracted pectin. Their physico-chemical and thermo-mechanical properties were also investigated in a wheat flour–water system. The CPE extraction produced pectin with 55% of galaturonic acid and the extraction yield was 7.3%. Also, the pectin obtained by CPE extraction exhibited a higher degree of esterification (46%) than chemically-extracted pectin (41%), which was confirmed by FT-IR analysis. When the pectin solutions were subjected to steady-shear conditions, both samples had shear-thinning properties while high apparent viscosity was observed in the chemically-extracted pectin. Even though the use of both pectins raised the pasting parameters of wheat flour as well as its gelatinization temperature, less change in the pasting properties was found in the wheat flour–water system containing the pectin prepared by CPE treatment. The Mixolab results demonstrated that during mechanical shearing and thermal treatments, the dough samples containing chemically-extracted pectin exhibited enhanced mixing stability, strong protein network structure, and increased peak viscosity.