Search

• Yeast extract amino acids can shape the fermentation microbiota of soy sauce. • Yeast extract amino acids boost the competitiveness of aroma-producing microbiota. • The best mass ratio of neutral: acidic: basic amino acids is 58:27:15. • The best amino acid formula can increase the malt aroma of soy sauce by 52.6%. Yeast extracts, of which amino acids are the main component, can be directly applied to improve the flavor of final soy sauce. In this study, the potential of commercial yeast extracts was explored from amino acid approach to enhance the flavor quality of soy sauce by shaping the core fermentation microbiota. Alkaline and neutral amino acids favored the competitive benefits of flavor-producing bacteria, while acidic amino acids promoted the stress resistance of the fermentation microbiota, especially the abundance of Lactobacillus , which increased to 18.03–23.78% and became the predominant microbiota. The mass ratio of neutral-nonpolar: neutral-polar: acidic: alkaline amino acids was 40: 18: 27: 15, which provided the optimal improvement of soy sauce aroma. The formulation and activated the metabolic pathways of 3-methyl-1-butyraldehyde, 3-methyl-1-butanol and 2-methyl-1-propanol through Leu and Ile, resulting in a 52.6% increase in malt-like aroma. This study provides a new idea for the regulation of soy sauce fermentation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Acid conditions promote ZEN-zein interaction, while basic conditions do the opposite. • Acid condition-induced rearrangement of zein causes the binding of ZEN with zein. • Alkaline condition-induced stretching of zein causes the releasing of ZEN from zein. Zein-bound zearalenone (ZEN) complexes are naturally existed in maize by their spontaneous interaction, which significantly impacts the risk assessment of ZEN. Additionally, the pH levels in processing could affect the binding or release of zein-bound ZEN. In this study, pH-induced interaction mechanism of ZEN with zein were studied. Results showed that the acid conditions increased the binding constant (K a) from 3.46 to 10.0 × 104 L/mol, binding energy from −17.38 to −43.49 kJ mol−1. By increasing hydrophobic interaction and hydrogen bond of ZEN with zein, the binding of ZEN with zein was promoted, forming zein-bound ZEN. Whereas, alkaline conditions decreased the K a to 1.45 × 104 L/mol and binding energy to 148.48 kJ mol−1, weakened ZEN-zein interaction and stretched zein molecules, resulting the release of ZEN from zein. This study could provide important theoretical basis for perfecting risk assessment and controlling zein-bound ZEN during processing. [ABSTRACT FROM AUTHOR]

• Modified mycotoxins in cereals can be formed by plant, microorganism, and processing. • Transformation of modified with free mycotoxins can occur during cereal processing. • Modified mycotoxins co-occur with free mycotoxins in cereals and their products. • Modified mycotoxins can be detected by direct and indirect methods. Modified mycotoxins in cereals and their products are formed by plant, microorganism, and the other physical/chemical approaches during processing, which could pose a serious threat to food safety worldwide. The transformation between modified and free mycotoxins during cereal processing could occur, which could further cause the uncertainty of mycotoxin exposure and risk. Most of the current reports about the occurrence of modified mycotoxins focus on the modified DON, ZEN and T-2 toxin, while the data about other modified mycotoxins (e.g., modified OTA and FB 1) in cereals are still scarce. Structural changes of modified mycotoxins affect the physicochemical properties, which caused that the direct and indirect methods need to be further improve to detect modified mycotoxins. This review focuses on updates in formation, transformation, occurrence and analytical strategy for modified mycotoxins. Overall, this review is significant for perfecting risk assessment of modified mycotoxins. [ABSTRACT FROM AUTHOR]

• Zein extraction methods affect its structure and zein-zearalenone interaction. • Zein extraction methods can control the conversion of hidden and free zearalenone. • Alkaline method promotes the conversion of hidden zearalenone to free zearalenone. • Acid method promotes the conversion of free zearalenone to hidden zearalenone. Zein, the plant protein, has received great attention in the last years. However, hidden zearalenone (ZEN), the zein-bound ZEN present in zein would have a great hazard to humans and animals. To date, the fates of hidden ZEN under different extraction methods of zein have not been clarified. In this study, the effect of zein extraction methods on conversion of free ZEN with hidden ZEN and its corresponding mechanism were studied. Results showed that the acid extraction condition promoted the formation of hidden ZEN (up to 92.03%), which was closely related to increased hydrophobic cavity of zein. However, alkaline extraction condition caused the conversion of hidden ZEN (from 58.82% to 13.33%) into free ZEN (from 41.18% to 86.67%), which was attributed to the great denaturation of zein. This study is of great significance for controlling hidden ZEN during zein extraction and maize processing. [ABSTRACT FROM AUTHOR]

• Hidden ZEN and free ZEN could transform into each other during food processing. • Zein-bound ZEN can be conversed to free ZEN by heat or alkaline treatment. • Free ZEN can be changed to zein-bound ZEN under the acid condition. • The binding of ZEN with zein enhanced the thermal stability of ZEN. Food processing might induce the transformation of hidden ZEN (zein-bound ZEN) in maize. The objective of this study was to assess the effect of processing factors on free ZEN and hidden ZEN. After zein was treated under different temperature and pH, ZEN was quantified in samples before and after in vitro digestion. The ratios of hidden to total ZEN in zein are decreased from 54.25% to 40.74% after thermal treatment and from 54.25% to 0 after alkaline treatment, respectively. Conversely, acid treatment increased the ratio of hidden to total ZEN from 54.25% to 100%. Thus, it can be concluded that thermal or alkaline condition induced the conversion of hidden ZEN to free ZEN while acid condition promoted the ZEN-zein interactions to form the hidden ZEN. Overall, temperature and pH values played a vital role in the conversion of hidden ZEN during food processing. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mechanism of the presence of hidden ZEN in maize is proposed. • Binding of ZEN to zein can result in the "hidden" phenomenon of ZEN in maize. • ZEN binds with zein through hydrophobic interaction and hydrogen bonds. • ZEN-zein interaction affects ZEN migration and transformation during food processing. Hidden mycotoxins have been reported to be "protected" by macromolecular substances to escape routine determination, but release to free mycotoxins under gastrointestinal conditions. Nowadays, the hidden zearalenone (ZEN) that binding with macromolecular zein has been found in maize. However, the binding mechanism of ZEN with zein in maize has not been clarified. In this study, the formation of ZEN-zein complex was investigated applying ultrafiltration, multi-spectroscopic and molecular modeling techniques. The steady-state and transient fluorescence analysis suggested the ZEN could interact with zein to form the complex driven by hydrophobic force and hydrogen bonds, which is in accordance with the molecular modeling studies. The conformational changes of zein induced by binding with ZEN were revealed by Fourier transform infrared spectroscopy (FTIR) and circular dichroism (CD). Elucidating the binding mechanism between zein and ZEN could help the development of detecting hidden ZEN and guarantee the safety of maize products. [ABSTRACT FROM AUTHOR]