Structure Modification of Orange and Grapefruit Peel Fibers by Pin-to-Plate Non-Thermal Plasma for Gut Microbiome Applications

• Jenna Moffett, Food Science, University of Delaware

• Juzhong Tan, Animal and Food Sciences, University of Delaware

Structure Modification of Orange and Grapefruit Peel Fibers by Pin-to-Plate Non-Thermal Plasma for Gut Microbiome Applications

Citrus juice production generates substantial quantities of peel byproducts that are often underutilized despite being rich sources of dietary fiber, pectin, and bioactive compounds. This study investigates the potential of non-thermal atmospheric plasma (NTAP) as a green processing technology to modify orange and grapefruit peel fibers for gut microbiome applications. We hypothesize that plasma-generated reactive species can alter the structural and physicochemical properties of citrus fibers, promoting the formation of more fermentable, prebiotic carbohydrate fractions while preserving or enhancing their antioxidant properties.

Orange and grapefruit peel powders (25 g) were treated using a PlasmaLeap Leap100 pin-to-plate atmospheric plasma system. Samples were exposed to plasma at applied voltages of 225, 250, and 275 V for 10, 15, or 20 min, with intermittent mixing every 5 min to ensure uniform treatment. Following plasma processing, samples were analyzed for total phenolic content (TPC), DPPH radical scavenging activity, and soluble and insoluble dietary fiber contents to evaluate plasma-induced modifications in antioxidant capacity and fiber composition.

We anticipate that plasma treatment will increase the soluble fiber fraction through controlled depolymerization of cell wall polysaccharides, potentially generating pectin-derived oligosaccharides with prebiotic functionality while maintaining or improving antioxidant activity. The findings will provide insights into the use of non-thermal plasma as a sustainable, chemical-free technology for valorizing citrus processing byproducts into functional food ingredients that support gut health. This work contributes to circular bioeconomy strategies by transforming agricultural waste streams into value-added ingredients with potential applications in functional foods and nutraceuticals.