Packaging films prepared from hot acid vs ultrasound-assisted microwave extracted pectin: a comparative study

Authors: CHANDRASEKAR, CHANDRA MOHAN - Orise Fellow; Jackson, Michael; Vermillion, Karl; Evans, Kervin; White, Andre; Simon, Stefanie; Hotchkiss, Arland; KOIRALA, PANKAJ - Washington State University; GOYAL, RISHABH - Washington State University; SABLANI, SHYAM - Washington State University; Zhao, Wei

Submitted to: Food Hydrocolloids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/2026
Publication Date: 1/27/2026
Citation: Chandrasekar, C., Jackson, M.A., Vermillion, K., Evans, K.O., White, A.K., Simon, S., Hotchkiss, A.T., Koirala, P., Goyal, R., Sablani, S.S., Zhao, W. Packaging films prepared from hot acid vs ultrasound-assisted microwave extracted pectin: a comparative study. Food Hydrocolloids. 2026. 112508. https://doi.org/10.1016/j.foodhyd.2026.112508.
DOI: https://doi.org/10.1016/j.foodhyd.2026.112508

Interpretive Summary: The study compared conventional heating (CH) and ultrasonic-assisted microwave extraction (UAME) methods regarding pectin extraction efficiency, the physicochemical properties and structural characteristics of the resulting pectins, as well as the functional characteristics of the films produced from the pectins. The results revealed profound structural differences between the pectins extracted by the different methods. Compared with the traditional heating method, UAME yielded pectin with a much higher molecular weight and a greater degree of branching. This superior structural integrity led CUME pectin to adopt a compact, globular conformation in solution, whereas CH pectin formed a flexible coil. The differences in pectin structure resulted in the differences in the functional properties of the derived pectin films. The CH pectin film showed better mechanical toughness and strength; while CUME pectin film showed better thermal stability, transparency, and UV protection.

Technical Abstract: This project presents a comparative analysis of pectins extracted from lemon peel using two distinct methods: conventional heating and ultrasonic-assisted microwave extraction (UAME). The study aimed to elucidate how these extraction paradigms influence the physicochemical properties of the resulting pectins and, consequently, the functional characteristics of films produced from them. A comprehensive suite of analytical techniques was employed to characterize the molecular architecture of the pectins, including monosaccharide composition, molecular weight (Mw), degree of methylation (DM), and solution conformation. Subsequently, films were cast from both pectin types and evaluated for their mechanical, thermal, optical, and surface properties. The results revealed profound structural differences. CUMP pectin exhibited a 71% higher molecular weight (663.90 kD) and a greater degree of branching compared to the significantly degraded CHP pectin (388.80 kD). This superior structural integrity led CUMP to adopt a compact, globular conformation in solution, whereas CHP formed a flexible coil. These molecular distinctions are directly translated to the functional properties of the derived films. The CHP film demonstrated superior mechanical toughness and strength, attributed to more effective entanglement of polymer chains. Conversely, the CUMP film exhibited significantly higher thermal stability, greater transparency, and improved UV-barrier properties, although it also had a more pronounced yellow hue. This study highlights that the extraction method greatly influences the structure of extracted pectin and the functional properties of the pectin film, underscoring a trade-off between preserving molecular weight with the UAME method and achieving superior mechanical film properties with the heating method.