HongJun Tofu is a pure fermented okara food with great commercial potential. However, the succession of core microorganisms and bioactive metabolites during HongJun Tofu fermentation remains unclear. This study aimed to apply multiomics techniques to reveal its fermentation process. Based on the dominant microorganisms, HongJun Tofu fermentation was divided into two stages. The first stage (0–24 h) was dominated by bacteria, primarily Weissell spp. (i.e.Weissella confusa, Weissella cibaria, and Weissella unclassified). In the next stage (24–48 h), Neurospora spp. (i.e., Neurospora crassa and Neurospora tetrasperma) displaced the dominance of bacteria at 24 h. This shift was the key to fermentation success. Some bioactive metabolites, such as l-serine, oleic acid, puerarin, and salidroside, were detected in HongJun Tofu. The metabolic network between flavonoid and isoflavonoid was then predicted. This study provided a novel insight into fermentation, laying the foundation for the further development and commercialisation of HongJun Tofu.
HongJun Tofu is produced by fungal (named "HongJun") fermentation of okara, which is a major byproduct of the soymilk and tofu industry. The dynamic characteristics of the fungal community (predominantly "HongJun") might have significant influences on HongJun Tofu during a short period, however, this remains unclear. In the present study, the "HongJun" was identified, and the edible quality of HongJun Tofu including nutritional composition, physical properties, and sensory level was evaluated. Further, the correlation between fungal diversity and edible quality during fermentation was analyzed. The results showed that "HongJun" is a novel strain (named OM009248) of Neurospora crassa. In the pre-fermentation (0–24 h), Neurospora crassa multiplied rapidly and reached the maximum abundance, while in the pro-fermentation (24–48 h), other fungi including Trichosporon and Rhizopus occupied certain content. The correlation analysis showed that Neurospora crassa was positively correlated with increased nutrients including oligopeptides, free amino acids (FAAs), β-carotene, and soluble dietary fiber (SDF) as well as enhanced texture, including springiness and chewiness; Trichosporon was negatively correlated with fat and Rhizopus was positively correlated with SDF. These findings provide a theoretical reference for quality control of HongJun Tofu commercial production.
The co-operative effect of exogenous dextranase (Dex) and sodium fluoride (NaF) on Streptococcus mutans monospecies biofilms is impressive. Here we investigated the effects of the combination on a mature cariogenic multispecies biofilm and analyzed the potential mechanism.A multispecies biofilm of S. mutans, Lactobacillus acidophilus, and Actinomyces viscosus was established in vitro. Dex and NaF were added separately or together. The effects of the agents on the biomass were measured. The exopolysaccharide production was determined with the scintillation counting method. The viability and morphology were evaluated using colony forming unit and confocal laser scanning microscopy, respectively.In general, biofilms treated with Dex and a little concentration of NaF exhibited a lower biomass, exopolysaccharide production, and viability compared with the control group (P < 0.05). Confocal laser scanning microscopy using a vital fluorescence technique showed the combination treated biofilms appeared to be loose relatively and single cells could be observed. Furthermore, the thickness and viability were also lower than either of the separate agent groups (P < 0.05).Overall, these findings reveal that a combination of 1 U/mL Dex and 80 μg/mL NaF is a promising candidate for disrupting complex cariogenic multispecies biofilms. This feature may be in that Dex loses the structure of biofilms, thereby facilitating NaF penetration and enhancing its antibacterial effects.
Termitomyces albuminosus (Litchi Jun) was a typical wild mushroom of Zhuhai fruits reserve area in Guangzhou, which was an ecological type for mutualism and commensalism with termite. Termitomyces albuminosus was grew in June with abundant rainfall and high temperature and humidity, of which precipitation and sunshine hours per ten days were 132 mm, 28.8 h, and average temperature, relative humidity, average soil temperature per ten days were 28.9℃, 80.3%, 28.6℃. The fungus gardens had high water content (20.74%) and acidic (pH 4.38), in which Litchi Jun contained nutrients rich in total sugars and protein (40.38% and 6.27%).
Multi-strain fermentation has a better effect on the flavor of fermented foods than single strain. Meanwhile, the traditional HongJun tofu was fermented with a single fungal strain, Neurospora crassa, giving it a single flavor — mushroomy, and a bland taste with only a slight aftertaste of sweetness. Adding probiotics can enhance the flavor of fermented food. In this study, multi-strains (Lactiplantibacillus plantarum or/and Meyerozyma guilliermondii) were co-fermented with N. crassa to improve the flavor of HongJun tofu. L. plantarum is a probiotic that adds to the pleasant flavor of HongJun tofu. M. guilliermondii is an ester-producing non-brewer’s yeast. Therefore, co-fermentation of L. plantarum and M. guilliermondii with N. crassa resulted in significantly lower relative aroma activity values for odor of beans (aldehydes). Meanwhile, the main flavor compounds retained were fruity, mushroomy, floral, and nutty flavors, with a reduction of bitterness, an increase in freshness, and a richer taste without sourness. Results indicated that L. plantarum and M. guilliermondii synergistically worked, and their simultaneous use did not result in flavor deterioration. Every played an advantageous role in adding pleasing flavors to HongJun tofu. This work provides a reference method for improving the flavor of HongJun tofu and facilitated its commercial production.
The olecranon honey peach is China’s national geographic identification product because of its crisp texture and high sweetness. In recent years, new field management practices have been developed. In this study, fruits (‘SJH’) grown through new planting methods, i.e., black bags combined with bio-organic fermentation fertilizer, were compared with those (‘SBY’) grown by conventional planting methods, i.e., using a chemical fertilizer without bagging, to determine their effects on improving fruit quality. At maturity, the ‘SJH’ was significantly higher than ‘SBY’ in terms of weight, hardness, and sugar content by 14.43%, 19.55% and 9.66%, respectively. RNA sequencing (RNA-seq) technology analysis was performed on ‘SJH’ and ‘SBY’ to identify the main regulatory pathways involved in fruit development, especially focusing on cell-wall biogenesis and sugar metabolism. We identified a total of 1660 differentially expressed genes (DEGs) in ‘SJH’ and 5673 genes in ‘SBY’ throughout the development. A clustering analysis of DEGs revealed that the expression patterns of key genes involved in cell-wall biogenesis and sugar metabolism pathways in ‘SJH’ differed from those in ‘SBY’, such as cellulose synthase-like protein D (CS-LPD), sucrose-phosphate synthase (SPS) and sucrose synthase (SUS). The new cultivation technology promoted soluble sugar accumulation and cell-wall synthesis through molecular regulation, which improved the sweetness and sensory quality of the fruit. These findings contribute towards to the development of novel ideas for the better cultivation of peaches and provide a deeper investigation into the molecular mechanism of their development.
Pomelo seed as a by-product from pomelo consumption is rich in bioactive compounds, however, a huge volume of pomelo seed was disposed as wastes, the comprehensive utilization of pomelo seed could not only generate valued-added products/ingredients, but also decrease the environmental pollution. In this study, the main active substance limonin in pomelo seed was considered as a high-value bioactive compound. The purification of limonin from pomelo seed was investigated, and the neuroprotective and mechanism were characterized. The UPLC-MS/MS results indicated that 29 compounds in pomelo seed were identified, including 14 flavonoids, 3 limonids, 9 phenols and 3 coumarins. Moreover, high purity of limonin was obtained by crystallization and preparative-HPLC. Furthermore, limonin pretreatment can antagonize the cell damage mediated by Aβ 25−35 in a concentration-dependent relationship. The regulation of Bax/Bcl-2, expression of caspase-3 protein and the activation of PI3K/Akt signaling pathway were observed in the cells pretreated with limonin. Treatment of PC12 cells with PI3K inhibitor LY294002 weakened the protective effect of limonin. These results indicated that limonin prevented Aβ 25−35 -induced neurotoxicity by activating PI3K/Akt, and further inhibiting caspase-3 and up-regulating Bcl-2. This study enables comprehensive utilization of pomelo seed as by-product and offers a theoretical principle for a waste-to-wealth solution, such as potential health benefits of food ingredient and drug.
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