Formaldehyde is a major industrial chemical and has been extensively used in the manufacture of synthetic resins and chemicals. Numerous studies indicate that formaldehyde can induce various genotoxic effects in vitro and in vivo. A recent study indicated that formaldehyde impaired antioxidant cellular defences and enhanced lipid peroxidation. Selenium is an important antioxidant. We hypothesized that reactive oxygen species (ROS) and lipid peroxidation are involved in formaldehyde-induced genotoxicity in human lung cancer cell line, A549 cell line. To test the hypothesis, we investigated the effects of selenium on formaldehyde-induced genotoxicity in A549 cell lines. The results indicated that exposure to formaldehyde showed the induction of DNA–protein cross-links (DPCs). Formaldehyde significantly increased the malondialdehyde levels and decreased the activities of superoxide dismutase and glutathione peroxidase. In addition, the activations of necrosis factor-κB (NF-κB) and activator protein 1 (AP-1) were induced by the formaldehyde treatment. The pretreatment with selenium counteracted the formaldehyde-induced oxidative stress, ameliorated DPCs and attenuated the activation of NF-κB and AP-1 in A549 cell lines. All the results suggested that the pretreatment with selenium attenuated the formaldehyde-induced genotoxicity through its ROS scavenging and anti-DPCs effects in A549 cell lines.

The fortification of bread is considered an effective approach for improving its nutritional properties. However, the incorporation of free bioactive components into bread formulations may affect the overall quality of breads in different ways, depending on the sensitivity of bioactive components to baking factors. In this study, the incorporation of encapsulated vitamin C (ascorbic acid and its salts) and fish oil in breads was investigated for their stability and effect on bread quality. The combination of fish oil emulsions increased the retention of encapsulated ascorbic acid, calcium ascorbate, or sodium ascorbate in breads compared to that of the free non-combined vitamin. At the same time, the combination of vitamin gels increased the retention of docosahexaenoic acid (DHA) and decreased the lipid oxidation in breads compared to the non-combined encapsulated forms. The highest retention values of ascorbic groups, eicosapentaenoic acid (EPA), and DHA were about 70%, 88%, and 95% in breads after baking, respectively. There was the negative correlation between the ABTS radical scavenging capacity and peroxide value in breads. The specific volume of breads was improved by vitamin gels but reduced by fish oil emulsions. Their combination resisted individual impact on the specific volume of breads. The breads with combined ascorbic acid gels and fish oil emulsions showed similar textural properties to the control one. The functional bread with calcium ascorbate gel and fish oil emulsion had the highest moisture content of 45.87%. The inclusion of vitamin gels plus fish oil emulsion decreased free water but increased the bound water. Combining ascorbic acid gels with fish oil emulsions effectively reduced and masked the fishy flavor. The integration of encapsulation techniques and multi-nutrient fortification is proposed as an effective way to enhance the nutritional value and quality of functional bread through synergistic effects.

To reduce the inhibition sensitivity of a thermoresistant xylanase AusM to xylanase inhibitor protein (XIP)-type in wheat flour, the site-directed mutagenesis was conducted based on the computer-aided redesign. First, fourteen single-site variants and one three-amino acid replacement variant in the thumb region of an AusM-encoding gene (AusM) were constructed and expressed in E. coli BL21(DE3), respectively, as predicted theoretically. At a molar ratio of 100:1 between SyXIP-I/xylanase, the majority of mutants were nearly completely inactivated by the inhibitor SyXIP-I, whereas AusM^N127A retained 62.7% of its initial activity and AusM^PKK retained 100% of its initial activity. The optimal temperature of the best mutant AusM^PKK was 60 °C, as opposed to 60–65 °C for AusM, while it exhibited improved thermostability, retaining approximately 60% of its residual activity after heating at 80 °C for 60 min. Furthermore, AusM^PKK at a dosage of 1000 U/kg was more effective than AusM at 4000 U/kg in increasing specific bread loaf volume and reducing hardness during bread production and storage. Directed evolution of AusM significantly reduces inhibition sensitivity, and the mutant enzyme AusM^PKK is conducive to improving bread quality and extending its shelf life.

This study aimed to investigate the effect of the incorporation of 0–25% pitaya (Hylocereus undatus) fermented by Pediococcus pentosaceus on physicochemical and bioactive properties of yeast-leavened wheat-mung bean bread. The results revealed that β-glucosidase activity increased during dough proofing, which may contribute to changes in dietary fiber. Compared to wheat bread, experimental bread had an increased content of soluble dietary fiber (SDF), total phenolic, total flavonoid, and slowly digestible starch, especially in wheat-mung bean bread prepared with 15% pitaya fermentates (WMB-15F). The effect of bread consumption on systemic inflammation, glucose tolerance, and blood lipid profiles was also evaluated via a mice model. The results indicated that levels of pro-inflammatory cytokines declined and glucose tolerance improved, while LDL and HDL were positively modified compared to control. Furthermore, an increased abundance of Lactobacillus, Lachnospiraceae, and Bifidobacterium spp. was observed in WMB-15F mice. Acetic acid was the dominant short-chain fatty acids (SCFAs) in feces and serum in all groups. Total SCFAs in circulation were highest in WMB-15F mice compared to other groups. In summary, an increased abundance of beneficial gut microbiota and promoted SCFA production might be highly associated with increased SDF and the release of key phenolic compounds during dough proofing, which exerts health benefits aroused from the consumption of yeast-leavened bread.

In this study, a potential producer of prebiotics, a novel endo-polygalacturonase pePGA from Penicillium rolfsii BM-6, was successfully expressed in Komagataella phaffii, characterized and applied to produce pectic oligosaccharides. The optimum temperature and pH of pePGA were 60 °C and 6.0. The purified recombinant enzyme showed a good pH stability and was stable from pH 3.5 to 8.0. The K_m, V_max and k_cat values of pePGA were 0.1569 g/L, 12,273 μmol/min/mg and 7478.4 s⁻¹, respectively. More importantly, pePGA-POS, the pePGA hydrolysis products from commercial pectin, had good prebiotic and antibacterial activities in vitro. The pePGA-POS was able to significantly promote the growth of probiotics; meanwhile, the growth of Escherichia coli JM109, Staphylococcus aureus and Bacillus subtilis 168 was effectively inhibited by pePGA-POS. In addition, pePGA-POS also had the DPPH radical scavenging capacity. These properties of pePGA-POS make pePGA attractive for the production of prebiotics.