This study investigated the influence of Bacillus subtilis fermentation on the composition of phenolic substances and antioxidant activity in cornmeal. The results indicate that the fermentation process significantly increased both the total phenolic content (TPC) and total flavonoid content (TFC). After 5 days of fermentation, the TPC rose from 31.68 ± 1.72 mg/g to 39.46 ± 2.95 mg/g, representing a 24.56% increase, while the TFC increased from 2.13 ± 0.11 mg/g to 7.56 ± 0.29 mg/g, marking a 254.93% increase. Additionally, the proportion of free phenolic compounds in cornmeal increased from 20.24% to 83.98%, while the proportion of bound phenolic compounds decreased from 79.76% to 16.02%. Furthermore, the hydrolytic enzyme activities of cellulase, β-glucosidase, and xylanase were significantly correlated with the free phenolic content (FPC) (r > 0.85, p < 0.05), indicating their crucial role in releasing free phenolic compounds from cornmeal. Employing scanning electron microscopy, differential scanning calorimetry, X-ray diffraction, and Fourier-transform infrared spectroscopy analyses, we inferred that the enzymes produced by the microorganisms disrupted the cellular structure of cornmeal and weakened the interactions between bound phenolics and the food matrix, thereby facilitating the release of phenolic compounds. This release resulted in an overall increase in the antioxidant activity of the cornmeal. The study provided a novel approach to enhancing the bioavailability of phenolic acids in cornmeal, indicating the potential benefits of fermentation in food processing.

Probiotics are considered as desirable alternatives to antibiotics because of their beneficial effects on the safety and economy of farm animals. The protectant can ensure the viability of probiotics, which is the prerequisite of the beneficial effects. The objective of this study was to evaluate the effects of a novel nano-protectant containing trehalose, skim milk powder, phytoglycogen nanoparticles, and nano-phytoglycogen Pickering emulsions on the viability of Lactobacillus casei K17 under different conditions. The results indicated that the optimal concentration of the carbohydrate substrate was determined to be 10% skim milk powder (w/w) instead of trehalose. The combination of 10% skim milk powder (w/w), 1% phytoglycogen nanoparticles (w/w), and 10% Pickering emulsions (w/w) was selected as the optimal component of the protectant. Trilayer protectants with an optimal component had a more significant protective effect on the bacteria than that of the monolayer and bilayer protectants, or the control in feed storage, freeze-drying, and simulated gastrointestinal environment. A scanning electron microscope was used to monitor the morphological characteristics of the protectants for different layers on L. casei. In conclusion, the trilayer protectant exhibited a substantial effect on L. casei during storage and consumption, which could be used in the feed and functional food.

We previously demonstrated that Lactobacillus casei K17, isolated from Korean kimchi, has high antioxidant levels in vitro and in vivo. However, its effect on Micropterus salmoides is unknown. In this study, we investigated the impact of L. casei K17 supplementation on the lipid metabolism, antioxidant response, liver histology, and fillet quality of M. salmoides. We randomly assigned 450 M. salmoides (33.0 ± 0.5 g) to six diet groups for 69 days. The diets were as follows: 0.85% normal saline; 10% skim milk powder; 1 × 10⁸ CFU/g live L. casei K17 (LB); 1 × 10⁸ live L. casei K17 protected by skim milk powder (MB); 1 × 10⁸ dead L. casei K17 (DB); and L. casei K17 fermentation supernatant. MB significantly improved the crude protein, total collagen, alkaline-insoluble collagen, fiber numbers, hardness, chewiness, and gumminess of M. salmoides fillets (p < 0.05). LB significantly improved crude protein and fiber numbers (p < 0.05). Furthermore, dietary supplementation with LB, MB, and DB maintained normal liver histology, preserved liver function, and increased hepatic and hemal antioxidant status by enhancing antioxidant enzyme activities. Meanwhile, the three diets also promoted lipid metabolism by increasing HDL-C effectiveness and reducing total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels in serum and liver tissues, indicating that dietary supplementation with DB, LB, and MB had hypolipidemic effects on M. salmoides. MB and LB significantly improved fillet quality and LB, MB, and DB improved hemal and hepatic lipid metabolism and antioxidant response and reduced reactive oxygen species production, protecting M. salmoides hepatic cells from injury.

Ellagic acid (EA) is a food-derived polyphenol with multiple biological activities, but its poor water solubility and aggregation in aqueous systems limit its accessibility to gut microorganisms. In this study, Fucus vesiculosus polysaccharide (FVP) was used as a natural carrier to prepare EA/FVP solid dispersions (SDs) with different mass ratios by solvent-assisted evaporation. Compared with pure EA, the SDs markedly improved the apparent solubility and aqueous dispersion stability of EA. The highest apparent solubility was observed for the EA/FVP 3/1 formulation (0.75 ± 0.03 mg/mL), which was approximately 6.25-fold higher than that of pure EA (0.12 ± 0.01 mg/mL). The improved dispersion behavior was associated with increased apparent viscosity, reduced aggregation, decreased crystallinity and possible non-covalent interactions between EA and the polysaccharide matrix. In vitro fecal fermentation showed that SDs enhanced the production of urolithins, including urolithin M5, urolithin M6, urolithin C, iso-urolithin A and urolithin B, without generating new metabolite types. The EA/FVP 1/3 formulation showed the strongest promotion of urolithin production, with iso-urolithin A reaching 2.36 ± 0.28 μM. 16S rRNA sequencing showed that the enhanced urolithin production was accompanied by shifts in the fecal microbial community. Several bacterial genera positively correlated with urolithin biosynthesis, including Bacteroides_H, Negativicoccus, Parabacteroides_B, Unclassified_Eggerthellaceae and Lactococcus_A, were significantly enriched in the SDs groups. These findings suggest that FVP-based SDs may serve as a potential strategy for improving the apparent solubility, aqueous dispersion and microbial biotransformation of EA.