Emerging Zein-Bound Zearalenone in Maize: Thermal-Induced Mechanism of Binding or Releasing

Biodegradation of ZEN by Bacillus mojavensis L-4: analysis of degradation conditions, products, degrading enzymes, and whole-genome sequencing, and its application in semi-solid-state fermentation of contaminated cornmeal

Zearalenone (ZEN), a naturally occurring estrogenic mycotoxin prevalent in cereals and animal feed, poses significant challenge to livestock industry owing to its detrimental effects on animal reproduction. In this study, the strains with high degradation rate were screened through co-culture with ZEN, and identified by bacterial morphology, 16S rDNA sequencing and whole genome sequencing. The detoxification effect of L-4 strain on ZEN was evaluated under different ZEN concentration, treatment time, pH value and temperature, the degradation products were identified, and the degradation effect of L-4 strain on ZEN contaminated corn meal was evaluated. The ZEN degrading enzyme sequence was obtained through the whole genome protein sequence analysis of strain L-4, and the ZEN degrading enzyme was verified by molecular binding and addition of catalase. We isolated Bacillus mojavensis L-4 from the cecal content of laying hens, which demonstrated exceptional ZEN-degrading efficiency. Under optimized conditions (pH 7.0, 37 °C), L-4 completely degraded 0.5-1.0 μg/mL ZEN into less toxic 15-OH-ZEN within 24 h. Importantly, L-4 achieved a 49.41% degradation rate for ZEN in cornmeal. Whole-genome sequencing of L-4 revealed the presence of ZEN-degrading genes and enzymes. In particular, efeB 3668, a peroxidase-like enzyme with high homology (95.91%) to BsDyP from Bacillus subtilis, played a key role in ZEN detoxification primarily through hydrogen bonding and hydrophobic interactions. Thus, the rapid and effective degradation of ZEN by B. mojavensis L-4, coupled with its adaptability to diverse environments, underscores its potential application in safeguarding animal health and mitigating environmental pollution.

Comparison of the effects of pectin with different esterification degrees on the thermal aggregation of wheat glutenin and gliadin

Our previous study found that pectin with different degrees of esterification (DE) could affect the thermal aggregation of gluten, but the mechanism was not clear. Analyzing the thermal aggregation of glutenin and gliadin supplemented with pectin can clarify this mechanism. With the increase of temperature, the particle size, disulfide bonds and β-sheet of glutenins increased, the surface hydrophobicity (H0) and fluorescence intensity decreased, and the network gradually aggregated, but the change trend of gliadins was opposite. These results suggested that the thermal aggregation of gluten mainly depended on glutenin. Glutenin and gliadin supplemented with low ester pectin (LEP) were in an aggregated state. At 95 °C, LEP (DE = 37 %) increased the particle size of glutenin and gliadin (141.83 μm and 19.91 μm), promoted the conversion of thiol to disulfide bonds, increased β-sheet (34.01 % and 31.13 %), decreased fluorescence intensity (2186.33 and 5165.33) and H0 (49.65 and 369.26). Scanning electron microscope (SEM) indicated that glutenin and gliadin supplemented with LEP retained a dense network structure, especially glutenin. This study elucidated the specific mechanism of how pectin affected the thermal aggregation of gluten. These results provide a more comprehensive theoretical support and scientific basis for understanding how pectin regulates the final quality of gluten-based products.

Tea saponin-Zein binary complex as a quercetin delivery vehicle: preparation, characterization, and functional evaluation

In this study, in order to solve the application problems of poor water solubility and low bioavailability of quercetin, we prepared a nano-delivery system with core-shell structure by anti-solvent method, including a hydrophilic shell composed of tea saponin and a hydrophobic core composed of Zein, which was used to improve the delivery efficiency and biological activity of quercetin. Through the optimal experiments, the loading rate and encapsulation rate of nanoparticles reached 89.41 % and 7.94 % respectively. And the water solubility of quercetin is improved by 30.16 times. At the same time, the quercetin acted with Zein through non-covalent interaction and destroyed its spatial network through structural characterization, while tea saponin covered the surface of Zein through electrostatic interaction, making it change into amorphous state. In addition, the addition of tea saponin makes the nanoparticles remain stable under the changes of external environment. During simulating gastrointestinal digestion procedure, ZQTNPs has higher release rate and bioavailability than free quercetin. Importantly, ZQTNPs can overcome the limitations of a single substance through synergy. These results will promote the innovative development of quercetin precision nutrition delivery system.

Focusing on New Discoveries in Food Technology and Creating a New Future of Nutrition and Health: An Introduction to the 4th International Symposium of Food Science, Nutrition and Health in Dalian, China

The 4th International Symposium on Food Science, Nutrition and Health (ISFSNH) was held at the Shangri-La Hotel in Dalian, China, on May 29-31, 2023. The symposium explored the connotations and needs of "The Great Food Perspective" under the theme "Focusing on new discoveries in food technology and creating a new future of nutrition and health" to better address the global emerging diverse food needs. The ISFSNH covered four areas: (1) food processing theory and technology, (2) food safety and quality control, (3) precision nutrition and health, and (4) creation of nutritious and healthy foods. More than 1000 scholars and entrepreneurs from more than 100 colleges and universities globally attended the conference. This special issue of the Journal of Agricultural and Food Chemistry highlights the important topics of the 4th ISFSNH and includes more than 20 papers.

A Hydrolase Produced by Rhodococcus erythropolis HQ Is Responsible for the Detoxification of Zearalenone

Zearalenone (ZEN), an estrogenic mycotoxin, is one of the prevalent contaminants found in food and feed, posing risks to human and animal health. In this study, we isolated a ZEN-degrading strain from soil and identified it as Rhodococcus erythropolis HQ. Analysis of degradation products clarified the mechanism by which R. erythropolis HQ degrades ZEN. The gene zenR responsible for degrading ZEN was identified from strain HQ, in which zenR is the key gene for R. erythropolis HQ to degrade ZEN, and its expression product is a hydrolase named ZenR. ZenR shared 58% sequence identity with the hydrolase ZenH from Aeromicrobium sp. HA, but their enzymatic properties were significantly different. ZenR exhibited maximal enzymatic activity at pH 8.0-9.0 and 55 °C, with a Michaelis constant of 21.14 μM, and its enzymatic activity is 2.8 times that of ZenH. The catalytic triad was identified as S132-D157-H307 via molecular docking and site-directed mutagenesis. Furthermore, the fermentation broth of recombinant Bacillus containing ZenR can be effectively applied to liquefied corn samples, with the residual amount of ZEN decreased to 0.21 μg/g, resulting in a remarkable ZEN removal rate of 93%. Thus, ZenR may serve as a new template for the modification of ZEN hydrolases and a new resource for the industrial application of biological detoxification. Consequently, ZenR could potentially be regarded as a novel blueprint for modifying ZEN hydrolases and as a fresh resource for the industrial implementation of biological detoxification.