Modulation of Gut Microbiota by Cold Plasma Modified Apple Pomace Pectin and Its Physicochemical Properties

IntroductionApple pomace, a major by-product of apple juice and cider production, is rich in functional dietary fiber (pectin) with well-documented gut anti-inflammatory effects. Pectin’s structural diversity, which comprises linear homogalacturonan (HG) and branched rhamnogalacturonan (RG) domains, enables selective gut microbiota modulation, as specific bacteria secrete carbohydrate-active enzymes (CAZymes) to hydrolyze its glycosidic bonds. Altering the HG/RG ratio significantly impacts pectin’s prebiotic potential. Cold plasma (CP) technology is an energy-efficient, sustainable technology for modifying functional food components, but its application to enhance dietary fiber fermentability remains underexplored. We hypothesize that CP-modified apple pectin will exhibit reduced molecular weight and HG/RG ratio, thereby altering its capacity to modulate gut microbiome composition and function.MethodsApple pomace pectin was treated at different voltages and frequencies plus an untreated control. Structural modifications were characterized by assessing changes in molecular weight, monosaccharide compositions and linkage profiles. Subsequently, we conducted 5-day in vitro sequential batch fecal fermentation with 3 healthy adult fecal inocula, measuring fermentation responses (pH, gas production, short-chain fatty acid (SCFA) profiles: acetate, propionate, butyrate) and analyzing microbial community succession via 16S rRNA gene sequencing.ResultsOur results showed that CP treatment increased the extraction yield by nearly 2.5-fold. CP modification also reduced the HG/RG ratio as expected. During in vitro fecal fermentation, CP-modified pectin generally produced more gas than the control. In terms of short-chain fatty acid production, CP-treated samples resulted in lower acetate and propionate levels but higher butyrate production, depending on the donor. Overall, these shifts in fermentation profiles suggest that CP modification alters pectin fermentability and shape distinct gut microbiota structures.SignificanceThis project is innovative in two ways: (1) it applies a novel and efficient cold plasma technology to produce functional prebiotic pectic fibers, and (2) it uncovers structural modifications of fibers that may enable precise regulation of gut microbial communities and health outcomes.