Abstract: The incidence of ulcerative colitis (UC) has been increasing in recent years. Due to the limitations of traditional drug therapies for UC, natural foods that can prevent this disease and alleviate its symptoms are becoming a research hot topic, but the effects of processing methods on their activity remain unknown. Therefore, the effects of three different processing methods (pulping, high-temperature cooking, and fermentation) on carotenoid and dietary fiber contents as well as carotenoid bioaccessibility in carrots were explored in this study. C57BL/6J mice were used to create a mouse model of UC induced by dextran sulfate sodium (DSS) and the mice received dietary intervention with freeze dried powder of carrots (5.05%, on a dry mass basis) for 14 days. Body mass change, disease activity index (DAI) and colon parameters (length, pathology, inflammatory factors, oxidative stress level, goblet cell number, tight junction protein expression, and short-chain fatty acid content) were analyzed to evaluate the effects of three differently processed carrots on UC. The results showed compared with pulping, high-temperature cooking and fermentation significantly decreased the soluble, insoluble and total dietary fiber contents of carrots (P < 0.05), increased the bioaccessibility of carotenoids (P < 0.05), while fermentation significantly increased the proportion of soluble dietary fiber in total dietary fiber (P < 0.05). Compared with the model group, all processed carrots could significantly inhibit the change of body mass loss and DAI (P < 0.05), decrease the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6 (P < 0.05), increase the level of IL-10 (P < 0.05), and up-regulate the expression of tight junction proteins (ZO-1, claudin-1, and occludin) (P < 0.05). High-temperature cooked or fermented carrots could significantly alleviate colon shortening (P < 0.05), and relieve the pathological damage of colon tissue (P < 0.05). Meanwhile, fermented carrots could significantly inhibit the production of malondialdehyde (MDA) (P < 0.05), improve the decrease in the number of goblet cells (P < 0.05), increase the level of butyric acid (P < 0.05) and possess the best inhibitory effect on IL-6 production. In summary, differently processed carrots could ameliorate ulcerative colitis to different extends, the most pronounced effect being observed with fermented carrots.

Key words: carrots; processing methods; colitis; intestinal barrier