Digestive Fate of Ultra-Processed Foods: From Bolus to Stool

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Zhou, Zhitong

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University of Guelph


Ultra-processed foods (UPFs) formulated from highly refined ingredients are not simply a sum of their macronutrients; composition alone cannot explain the association between high UPFs intake and increased malnutrition risks (i.e., obesity, metabolic syndrome). A knowledge gap exists in understanding the role of food structure on lipid digestion and colonic fermentation of formulated foods compared to the whole food they seek to emulate. Ultra-processed, plant-based burgers (PB) and traditional comminuted-beef burgers (BB) share similar organoleptic and most physicochemical properties, but PB does not contain intact whole food structures, while BB entraps lipids throughout their myofibrillar protein network. The markedly different food structures result in significantly higher free fatty acid (FFA) bioaccessibility for PB (28.2 ± 4.80%) than BB (8.73 ± 0.52%) during simulated in-vitro digestion using the TIM Gastrointestinal Model-1 (TIM-1). Linear discriminant analysis effect size (LEfSe) shows supplement fed with PB enriched Clostridium and Citrobacter during colon fermentation using the Simulated Human Intestinal Microbial Ecosystem (SHIME), whereas BB differentially increased Megasphaera, Bacteroides, Alistipes, and Blautia at the genus level. PB produced more short-chain fatty acids (SCFA) than BB in the ascending and descending colon but less in the transverse colon (p < 0.05). The second experiment compared sliced to formulated fried potato chips containing similar macronutrient profiles but divergent physical structures. Sliced chips preserve the intact cellular structure, while reformulated chips comprise a starch matrix with minimal remaining cell integrity. The total cumulative FFA bioaccessibility during TIM-1 digestion presents no significant difference between the two chips (p > 0.05). However, the absolute FFA bioaccessibility of sliced chips steadily increases after 180 min of digestion due to food matrix erosion continually exposing triacylglycerols, whereas the matrix of reformulated chips results in rapid dispersion of triacylglycerols causing FFA hydrolysis to peak at ~240-300 min. To conclude, formulated UPFs (e.g., PB, formulated chips) lack the whole food structure in processed foods (e.g., BB, sliced chips), leading to a higher rate and extent of FFA release and affecting the gut microbial composition and metabolism site-specially. This research furthers understanding of how food structure may regulate lipemic response and gut microbiota performance.



food structure, TIM-1 in-vitro digestion, SHIME colonic fermentation, plant-based meats, potato chips


Zhou, Z., Amer, H., Sultani, A., Nasr, P., Wang, Y., Corradini, M. G., ... & Rogers, M. A. (2023). The digestive fate of beef versus plant-based burgers from bolus to stool. Food Research International, 167, 112688. https://doi.org/10.1016/j.foodres.2023.112688
Zhou, Z., Nasr, P., Sultani, A., Goff, H. D., Corradini, M. G., Joye, I. J., & Rogers, M. A. (2022). Sliced versus formulated potato chips�??Does food structure alter lipid digestion? Food Structure, 32, 100272. https://doi.org/10.1016/j.foostr.2022.100272