(1) Background: Safety problems associated with aflatoxin B₁ (AFB₁) contamination have always been a major threat to human health. Removing AFB₁ through adsorption is considered an attractive remediation technique. (2) Methods: To produce an adsorbent with a high AFB₁ adsorption efficiency, a magnetic reduced graphene oxide composite (Fe₃O₄@rGO) was synthesized using one-step hydrothermal fabrication. Then, the adsorbent was characterized using a series of techniques, such as SEM, TEM, XRD, FT-IR, VSM, and nitrogen adsorption–desorption analysis. Finally, the effects of this nanocomposite on the nutritional components of treated foods, such as vegetable oil and peanut milk, were also examined. (3) Results: The optimal synthesis conditions for Fe₃O₄@rGO were determined to be 200 °C for 6 h. The synthesis temperature significantly affected the adsorption properties of the prepared material due to its effect on the layered structure of graphene and the loading of Fe₃O₄ nanoparticles. The results of various characterizations illustrated that the surface of Fe₃O₄@rGO had a two-dimensional layered nanostructure with many folds and that Fe₃O₄ nanoparticles were distributed uniformly on the surface of the composite material. Moreover, the results of isotherm, kinetic, and thermodynamic analyses indicated that the adsorption of AFB₁ by Fe₃O₄@rGO conformed to the Langmuir model, with a maximum adsorption capacity of 82.64 mg·g⁻¹; the rapid and efficient adsorption of AFB₁ occurred mainly through chemical adsorption via a spontaneous endothermic process. When applied to treat vegetable oil and peanut milk, the prepared material minimized the loss of nutrients and thus preserved food quality. (4) Conclusions: The above findings reveal a promising adsorbent, Fe₃O₄@rGO, with favorable properties for AFB₁ adsorption and potential for food safety applications.

Citrus aurantium L. (sour orange) is a significant Chinese medicinal and fruit crop rich in flavonoids. However, the pathways and genes involved in flavonoid biosynthesis at the key developmental stages of Citrus aurantium L. are not fully understood. This study found that the total flavonoid concentration gradually decreased as the fruit developed. Additionally, it showed that neohesperidin was the main flavonoid in the early stages of sour orange fruit development. However, as the development stage progressed, naringin content increased rapidly and emerged as the main flavonoid component. From 27 cDNA libraries, RNA sequencing yielded 16.64 billion clean bases, including 8989 differentially expressed genes. We identified 74 flavonoid related unigenes mapped to the phenylalanine, tyrosine, and phenylpropanoid biosynthesis pathways. A total of 152 UDP-glucuronosyltransferase genes (UGTs) were identified from C. aurantium L. transcriptome database, in which 22 key flavonoid-correlated UGTs were divided into five main AtGT groups: E, G, I, L, M. We observed that the ethylene responsive factors (ERF) and myeloblastosis (MYB) family mainly regulated the key genes involved in flavonoid biosynthesis. Overall, our study generated extensive and detailed transcriptome data on the development of C. aurantium L. and characterized the flavonoid biosynthesis pattern during its fruit developmental stages. These results will benefit genetic modification or selection to increase the flavonoid content in sour oranges.

Peanut Fusarium rot, which is widely observed in the main peanut-producing areas in China, has become a significant factor that has limited the yield and quality in recent years. It is highly urgent and significant to clarify the regulatory mechanism of peanuts in response to Fusarium oxysporum. In this study, transcriptome and proteome profiling were combined to provide new insights into the molecular mechanisms of peanut stems after F. oxysporums infection. A total of 3746 differentially expressed genes (DEGs) and 305 differentially expressed proteins (DEPs) were screened. The upregulated DEGs and DEPs were primarily enriched in flavonoid biosynthesis, circadian rhythm-plant, and plant–pathogen interaction pathways. Then, qRT-PCR analysis revealed that the expression levels of phenylalanine ammonia-lyase (PAL), chalcone isomerase (CHI), and cinnamic acid-4-hydroxylase (C4H) genes increased after F. oxysporums infection. Moreover, the expressions of these genes varied in different peanut tissues. All the results revealed that many metabolic pathways in peanut were activated by improving key gene expressions and the contents of key enzymes, which play critical roles in preventing fungi infection. Importantly, this research provides the foundation of biological and chemical analysis for peanut disease resistance mechanisms.

Akebia trifoliata (A. trifoliata) is a significant medicinal and edible fruit crop and has some important bioactivities. However, there are few studies on the bacteriostatic activity of A. trifoliata, and the underlying mechanism of A. trifoliata for antibacterial activity is still unknown. Therefore, the bacteriostatic activity and antibacterial mechanism of A. trifoliata were investigated by a combination of chemical assays, using the UHPLC-TOF-MS/MS technique. The results indicated that alkaloids, triterpenoids, and flavonoids are the major secondary bioactive compounds in A. trifoliata that play a crucial role in antibacterial activity. We found that EEPA exhibited both bacteriostatic and bactericidal effects against all Gram-positive and Gram-negative bacteria tested, with IZDs ranging from 13.80 ± 0.79 to 17.00 ± 0.58 mm. Significant differences in terms of sensitivity between Gram-positive and Gram-negative bacteria were not observed. In contrast, both antibiotics (kanamycin sulfate and ampicillin sodium salt) exhibited much better antimicrobial activity against Gram-positive bacteria than Gram-negative bacteria. In addition, the primary antimicrobial mechanism was that EEPA increased cellular content leakage, altered the cell morphology, and destroyed the internal cell structure. Meanwhile, MA, UA, and OA, as the common triterpenoid components existing in plants, were used to analyze the relationships between the structures and the antimicrobial activities among homologous compounds, to determine the key functional group that plays an antibacterial role in MA, UA, and OA. As result, it was found that both the hydroxide and methyl groups present are important for their antibacterial activity. These findings suggested that EEPA exerted significant antimicrobial activity against S. aureus, E. coli, B. subtilis, and P. aeruginosa and might be a potential natural antibacterial.

Tea has become one of the most popular drinks worldwide thanks to its pleasant sensory attributes and diverse health benefits. However, tannin-rich compositions have several negative effects and significantly impact the quality of tea beverages. Among various detannification methods, tannase treatment appears to be the most secure and environmentally friendly strategy. Although numerous microbial tannases have been identified and used in food processing, they are predominantly mesophilic with compromised heat tolerance, which limit their application in high-temperature tea extraction processing. Computer-assisted rational design and site-directed mutagenesis has emerged as a promising strategy in enzyme engineering to improve the thermostability of industrial enzymes. Nevertheless, relevant studies for tannase thermostability improvement remain lacking. In the present study, a novel thermophilic tannase called TanPL1 from marine fungus Penicillium longicatenatum strain SM102 was expressed in the food-grade host Yarrowia lipolytica. After purification and characterization, the thermostability of this enzyme was improved through site-directed mutagenesis guided by computer-aided rational design and molecular dynamics simulations. Then the thermostable mutant MuTanPL1 was applied in green tea processing for both polyphenol extraction and ester catechin hydrolysis. The tannase yield and specific activity values of 166.4 U/mL and 1059.3 U/mg, respectively, were achieved. The optimum pH and temperature of recombinant TanPL1 were determined to be 5.5 and 55 °C, respectively, and the enzyme exhibited high activity toward various gallic acid ester substrates. The site-directed mutagenesis method successfully generated a single-point mutant, MuTanPL1, with significantly enhanced thermostability and a higher optimum temperature of 60 °C. After 2 h of detannification by MuTanPL1, nearly all gallated catechins in green tea infusion were biotransformed. This resulted in a 202.4% and 12.1-fold increase in non-ester catechins and gallic acid levels, respectively. Meanwhile, the quality of the tea infusion was also markedly improved. Sensory evaluation and antioxidant activity assays revealed notable enhancements in these properties, while turbidity was reduced considerably. Additionally, the α-amylase inhibition activity of the tannase-treated tea infusion declined from 50.49% to 8.56%, revealing a significantly lower anti-nutritional effect. These findings suggest that the thermostable tannase MuTanPL1 holds strong application prospects in tea beverage processing.