Film-forming properties and mechanisms of soy protein: Insights from ß-conglycinin and glycinin.

Extensive research has been conducted on soy protein films; however, limited information is available regarding the influence of the major components, ß-conglycinin (7S) and glycinin (11S), on the film-forming properties of soy protein. This study aimed to isolate the 7S and 11S fractions in order to prepare films and investigate the impact of varying 7S/11S ratios on the film-forming solutions (FFS) and film properties. The findings revealed that higher 11S ratios led to increased protein aggregation, consequently elevating the storage modulus (G') of the FFS. Notably, an optimal 7S/11S ratio of 7S1:11S2 (CF3) significantly enhanced the film's water resistance. Specifically, it enhanced the water contact angle by an impressive 17.44 % and reduced the water vapor transmission rate by 27.56 %. These improvements were attributed to intermolecular interactions, involving hydrogen bonds and salt bridges, between the amino acid residues of 7S and 11S. As a result, a more uniform and dense microstructure was achieved. Interestingly, the mechanical and optical properties of the film were maintained by the different protein fractions examined. In summary, this study contributes to the understanding of the film-forming properties of soy protein, particularly the role of 7S and 11S.

Breaking the temperature limitation of zein-rice starch dough by microwave pre-gelatinization: Morphological, structural and rheological properties of the dough.

Zein has gluten-like viscoelasticity, but its use is limited due to high glass transition temperature (Tg). To break the temperature limitation of zein-starch dough, microwave heating was used to pre-gelatinize a partial of the starch with zein, and then the remaining was added and kneaded to form a dough. Pre-gelatinized doughs formed by rice starch (PRS), zein-starch (PUZS), and extruded zein-starch (PEZS) were included in this study. The thermal, morphological, rheological, and secondary structural properties of the dough were investigated. The results showed that zein and starch formed a composite gel network and firmly bound starch granules, which improved the dough properties with a smooth surface and compact internal structure, increased strain tolerance, and decreased stiffness. Unextruded zein was distributed uniformly and had strong interactions with the starch. Extruded zein tended to form large particles and had limited interaction with starch but improved dough extensibility. Microwave pre-gelatinization increased the stability of the secondary structure of zein and maintained the viscoelasticity of dough below zein's Tg, which provided a safe and effective way to break the temperature limitation of zein as a structural protein used in foods.

Identification of Toxicity Forcing Agents from Individual Aliphatic and Aromatic Disinfection Byproducts Formed in Drinking Water: Implications and Limitations.

Recently, a study found that aromatic DBP fractions dominate the overall toxicity of chlorinated drinking water. However, key toxicity drivers have not been reported via comprehensive evaluation based on the formation of aliphatic and aromatic DBPs in drinking water. In this study, the occurrence of 37 aliphatic and 19 aromatic DBPs in drinking samples with different water characteristics collected in a Chinese megacity was explored. According to the individual DBP concentrations and cytotoxicity potencies as well as the "TIC-Tox" method, haloacetonitriles and halonitrophenols were found to be the toxicity drivers among the measured aliphatic and aromatic DBPs, respectively. However, when aromatic and aliphatic DBPs are taken into consideration together, aliphatic DBPs were calculated to present higher toxicity contribution than aromatic DBPs, which is inconsistent with the previous study. TOX showed significant positive correlations with most aliphatic DBPs but no aromatic DBPs, and the overall toxicity of the water sample concentrates is significantly related to the total calculated cytotoxicity and aliphatic DBPs, suggesting that current selected aromatic DBPs are insufficient to represent the overall aromatic DBPs. UV254 and DOC rather than SUVA are better surrogates for predicting DBP formation potential for DOM with a lower humification degree as indicated by fluorescence results.

Assessment of fresh Alpinia galanga (A. galanga) drying techniques for the chemical composition of essential oil and its antioxidant and biological activity.

This study evaluated drying characteristics, structure and essential oil chemical composition, and biological activity of A. galanga by hot air drying (HAD), vacuum drying (VD), freeze drying (FD). The results showed that HAD had the shortest drying time while FD could better maintain the microstructure and showed a higher essential oil yield than HAD and VD. In addition, E-nose, HS-GC-IMS and HS-SPME-GC-MS could effectively distinguish the essential oil chemical composition of the four samples because different drying methods induced the changes in the profile and content of the compounds. HS-SPME-GC-MS detected 43 compounds, of which alcohols, alkenes, and esters were the main substances in fresh and dry samples. In comparison, HS-SPME-GC-IMS detected 80 compounds, including alcohols, aldehydes, ketones, esters, alkenes. Overall, the FD samples showed more outstanding advantages by evaluating antioxidant properties and antibacterial activities. FD was more suitable for A. galanga drying as it maintains appearance and biological activity.

Rational construction of a robust metal-organic framework nanozyme with dual-metal active sites for colorimetric detection of organophosphorus pesticides.

While nanomaterials with enzyme-mimicking activities are emerging as promising candidates in the colorimetric detection of organophosphorus pesticides (OPs), the catalytic activities and recognition ability to analyte of most nanozymes are inherently deficient. In this work, we introduced manganese ions into a typical iron based MOF (Fe-MIL(53)) via a one-pot hydrothermal reaction strategy, which brought out a catalytically favorable bimetallic Mn/Fe-MIL(53) MOF nanozyme. The catalytic performance of Mn/Fe-MIL(53) is superior to that of pure Fe-MIL (53) and the mechanism for superior catalytic activity of material is revealed by active species scavenging experiments and X-ray photoelectron spectroscopy (XPS). Besides, the introduction of manganese endows the material with the characteristic of being specially destroyed by choline, which motivates the establishment of a simple, selective and sensitive colorimetric strategy for OPs detection. The proposed colorimetric strategy could quantify the methyl parathion and chlorpyrifos in the concentration range of 10-120 nM and 5-50 nM, respectively. The low detection limit of 2.8 nM for methyl parathion and 0.95 nM (3 S/N) for chlorpyrifos were achieved. Good recoveries were obtained when applied in the real sample detection. Our work paves the way to boost catalytic performance of MOF nanozymes, which will be useful in biosensing.

Species and formation characteristics of halogenated DBPs in chloramination of tannic acid after biodegradation.

Tannic acid is widely found in source water and wastewater, and it is also a typical degradation precursor of natural organic matter. In this study, focused on chloramination, the formation characteristics of halogenated DBPs from tannic acid biodegradation products were examined. Fifty-nine polar emerging DBPs (including four nitrogenous DBPs) were detected and forty of them were identified for the first time; meanwhile, their formation pathways were tentatively proposed. In general, much more polar emerging DBPs were formed at the early biodegradation stage than those at the later stage, while commonly observed aliphatic DBPs presented an exactly inverse trend, because initially-formed emerging DBPs can be transformed to those aliphatic DBPs by residual chloramine. Interestingly, while the relative formation level of brominated species in overall halogenated polar emerging DBPs maintained at high level at the later biodegradation stage during chlorination, it decreased significantly later during chloramination. The discrepancy may be due to that hydrolysis effects became dominant at this period in chloramination, whereas DBP formation from the reactions between slow reactive sites and hypohalous acids prevailed in chlorination. In addition, the calculated toxicity drivers among the 21 aliphatic DBPs were found to be haloacetonitriles, although they contribute mildly to the total concentration.

Application of (LC/)MS/MS precursor ion scan for evaluating the occurrence, formation and control of polar halogenated DBPs in disinfected waters: A review.

Water disinfection can result in the unintended formation of halogenated disinfection byproducts (DBPs), which have been the subject of intensive investigation over the past 40 years. Robust methods for evaluating and characterizing the formation of halogenated DBPs are prerequisites for ultimately controlling the formation of DBPs and ensuring quality and safe disinfected water. Only a fraction of the total organic halogen (TOX) formed during disinfection has been chemically identified or even well characterized by the classical (derivatization-)gas chromatography/mass spectrometry (GC/MS) method. Such a method may not be amenable to the detection of polar halogenated DBPs, which constitute a major portion of the TOX that is still unaccounted for. Accordingly, a novel precursor ion scan (PIS) method using (liquid chromatography/) electrospray ionization-triple quadrupole mass spectrometry was developed for the rapid selective detection of all polar halogenated DBPs-no matter whether the DBPs are known or unknown-in water. This article reviews recent literature on the application of the PIS method for evaluating the occurrence, formation and control of polar halogenated DBPs in disinfected waters. The challenges in developing the PIS method were briefly summarized. Application of the powerful method pinpointed >150 previously unknown DBPs and revealed the formation, speciation and transformation of halogenated DBPs in disinfected drinking water, wastewater effluents, and swimming pool water. For the same source water, positive correlations were found between the total ion intensity (TII) levels in the PIS spectra of m/z 35/79/126.9 and the total organic chlorine/bromine/iodine levels in the disinfected water sample, and a disinfected sample with a higher TII level generally showed a higher toxic potency. Accordingly, the TII value can be used as a surrogate to comparatively reflect the water quality and assess the efficiency of a DBP control approach. To achieve a more comprehensive and systematic understanding of the DBP compositions in different waters and thus better control the DBP formation and reduce their overall toxicity, topics for future work were discussed.