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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Citrus and Other Subtropical Products Research » Research » Publications at this Location » Publication #429534
Research Project: Augmenting Value-Added Products from Citrus

Location: Citrus and Other Subtropical Products Research

Title: Citric acid-based microwave and ultrasonic extractions of lemon peel pectin and their effects on the properties of pectin films

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

Submitted to: International Journal of Biological Macromolecules
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/2026
Publication Date: 1/19/2026
Citation: Chandrasekar, C., White, A.K., Simon, S., Hotchkiss, A.T., Jackson, M.A., Evans, K.O., Pankaj, K., Rishabh, G., Sablani, S.S., Zhao, W. Citric acid-based microwave and ultrasonic extractions of lemon peel pectin and their effects on the properties of pectin films. International Journal of Biological Macromolecules. 2026. 150367. https://doi.org/10.1016/j.ijbiomac.2026.150367.
DOI: https://doi.org/10.1016/j.ijbiomac.2026.150367

Interpretive Summary: To develop pectin-based biodegradable edible films for food-packaging, pectin was extracted from lemon peel and pectin films were prepared from the pectin extracted by two different methods that utilize distinct technologies to disrupt plant cell walls and release pectin. The properties of pectin and the pectin films were comprehensively analyzed to elucidate the relationship between pectin structure and functional properties of pectin films.

Technical Abstract: This study investigates the valorization of agro-industrial lemon peel waste using microwave and ultrasonic-assisted organic acid (citric acid) extractions. The resulting pectin samples were designated as CMP and CUP, respectively. The microwave extraction yield is significantly higher and requires shorter processing times compared to the ultrasonic process. Physicochemical characterization revealed that both pectins shared similar high degrees of methylation (~71%), CUP possessed a substantially higher molecular weight (748.10 kD) compared to CMP (464.60 kD). Bioplastic films were subsequently prepared to evaluate the functional properties of the extracted pectins. Despite its lower molecular weight, the CMP film exhibited markedly superior mechanical performance, with a tensile strength (39.55 MPa) 2.7 times greater than that of the CUP film (14.81 MPa). This counterintuitive result is attributed to the more efficient packing of polymer chains in the smaller CMP molecules, resulting in a denser and more cohesive network. The larger CUP chains are believed to cause steric hindrance, resulting in a less ordered and weaker film structure. This structural difference directly influenced other film properties. The CUP film was significantly smoother and more transparent, with a visible light transmittance of 54.60% versus 41.27% for the rougher CMP film. The less compact network of the CUP film also resulted in higher water retention. Thermogravimetric analysis revealed that, although the pure pectins exhibited similar thermal stability, the plasticized films for both CUP and CMP displayed degradation at lower temperatures, a common effect of plasticizer addition.