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Summary: The fraudulent practice of beef adulteration is a growing concern, as it violates consumer rights. Electrical impedance spectroscopy (EIS) combined with machine learning has emerged as a widely used approach to identify low‐quality meat. Unlike traditional biochemical methods that require expensive instruments, complex sample preparation, and chemical reagents, EIS is a cost‐effective alternative. However, EIS data are susceptible to temperature fluctuations, requiring a waiting period under consistent temperature conditions for data stabilisation before measurements. This process becomes impractical when dealing with a large number of samples. To overcome this limitation, standardisation, normalisation, and smoothing methods were introduced in the meat quality detection based on EIS data. A recognition model for detecting carrageenan adulteration in beef was established. Under an inconsistent temperature condition, by applying the spectra pre‐processing methods to the prediction dataset, the model accuracy reached 84%, whereas the accuracy of the unprocessed prediction dataset dropped to 54%. This study demonstrates that acquiring EIS data under consistent temperature conditions is unnecessary if proper spectra pre‐processing methods are applied. By eliminating the waiting time for data stabilisation, this practical approach enhances the efficiency and accuracy of meat quality detection. [ABSTRACT FROM AUTHOR]

We describe a catalytic cascade sequence involving directed C(sp3)−H activation followed by β‐heteroatom elimination to generate a PdII(π‐alkene) intermediate that then undergoes redox‐neutral annulation with an ambiphilic aryl halide to access 5‐ and 6‐membered (hetero)cycles. Various alkyl C(sp3)−oxygen, nitrogen, and sulfur bonds can be selectively activated, and the annulation proceeds with high diastereoselectivity. The method enables modification of amino acids with good retention of enantiomeric excess, as well as σ‐bond ring‐opening/ring‐closing transfiguration of low‐strain heterocycles. Despite its mechanistic complexity, the method employs simple conditions and is operationally straightforward to perform. [ABSTRACT FROM AUTHOR]

Astaxanthin is a valuable carotenoid and is used as antioxidant and health care. Phaffia rhodozyma is a potential strain for the biosynthesis of astaxanthin. The unclear metabolic characteristics of P. rhodozyma at different metabolic stages hinder astaxanthin's promotion. This study is conducted to investigate metabolite changes based on quadrupole time‐of‐flight mass spectrometry metabolomics method. The results showed that the downregulation of purine, pyrimidine, amino acid synthesis, and glycolytic pathways contributed to astaxanthin biosynthesis. Meanwhile, the upregulation of lipid metabolites contributed to astaxanthin accumulation. Therefore, the regulation strategies were proposed based on this. The addition of sodium orthovanadate inhibited the amino acid pathway to increase astaxanthin concentration by 19.2%. And the addition of melatonin promoted lipid metabolism to increase the astaxanthin concentration by 30.3%. It further confirmed that inhibition of amino acid metabolism and promotion of lipid metabolism were beneficial for astaxanthin biosynthesis of P. rhodozyma. It is helpful in understanding metabolic pathways affecting astaxanthin of P. rhodozyma and provides regulatory strategies for metabolism. Take‐away: Purine, pyrimidine, and amino acid pathways competed with the carotenoid pathway.Upregulation of lipid metabolism contributed to the carotenoid pathway.Regulators of amino acids and lipids increased astaxanthin by 19.2% and 30.3%. [ABSTRACT FROM AUTHOR]

Summary: Unscrupulous merchants would sell cheap, low‐nutrition formula milk powder as pasteurised milk, or use it as a raw material in dairy products, for the purpose of making a profit. Currently, biochemical methods are utilised to identify the type of processed milk, which could involve chemical reagents, sample preparation and costly instruments. This paper investigates the utility of electrical impedance spectroscopy (EIS) in distinguishing different types of processed milk. Ultra‐high temperature sterilised milk, pasteurised milk and formula milk powder were studied. The one‐factor analysis of variance revealed that milk type had a significant influence on electrical properties, whereas sensory analysis, pH and total soluble solids showed poor discrimination of milk type. Recognition models were developed using Support Vector Classification, Partial Least Squares‐Discriminant Analysis (PLS‐DA), Gaussian Naive Bayes and Random Forest (RF). The nested cross‐validation and the external validation set (N = 45) indicated the RF model had the highest predicting accuracy of 97.8%; whereas PLS‐DA had a misclassification rate of 33.3% on positive samples and was, therefore, unsuitable for the authentication. The results demonstrated that the EIS data was featured enough for a small sample modelling (N = 75), and the established method was simple, fast and effective for liquid food classification. [ABSTRACT FROM AUTHOR]

Citrus is an important source of flavonoids in our daily diet. Citrus flavonoids have antioxidant, anticancer, anti‐inflammatory, and cardiovascular disease prevention functions. Studies have shown that some pharmaceutical values of flavonoids may be related to their binding to bitter taste receptors, thus activating downstream signal transduction pathways; however, the underlying mechanism has not been systematically elucidated. In this paper, the biosynthesis pathway and the absorption and metabolism of citrus flavonoids were briefly reviewed, and the relationship between flavonoid structure and bitter taste intensity was investigated. In addition, the pharmacological effects of bitter flavonoids and the activation of bitter taste receptors in combating various diseases were discussed. This review provides an important basis for the targeted design of citrus flavonoid structures to make them more biologically active and more attractive as powerful drugs for the effective treatment of chronic diseases such as obesity, asthma, and neurological diseases. [ABSTRACT FROM AUTHOR]

The processing of Traditional Chinese Medicine requires the appropriate parameters, while the specific chemical markers are still absent to obtain the optimized processing. In this study, we used vinegar‐baked Euphorbia kansui as a case to dissect the chemical markers for the baking process using untargeted metabolomics. The robust chemical markers were selected based on the three rules, correlation, significant difference, and controllability. All the differential features were categorized based on their mass defects. After the differential analysis, 310 differential compounds were screened out and could be mainly divided into six categories: diacylglycerols and triacylglycerols demonstrated increasing trends with the baking time in the discriminant model, while ingenane‐type diterpenes, jatrophane‐type diterpenes, fatty acid esters, and fatty acids had decreasing trends. It was unexpected to find that the diterpenes did not correlate with the baking time. Only very few compounds meet the three rules. They were validated with a high‐performance liquid chromatography method. Finally, only 13‐Hydroxy‐9,11‐octadecadienoic acid and its isomer 9‐Hydroxy‐10,12‐octadecadienoic acid could be used further to differentiate the commercial vinegar‐baked Euphorbia kansui. It would be of interest to evaluate whether these two compounds could be utilized as markers to control more processing methods in future studies. [ABSTRACT FROM AUTHOR]

Rationale: Diterpene lactones (DL) in Andrographis paniculata (AP) are known as “natural antibiotics” for their excellent antibacterial activity. During mass spectrometry (MS) analysis, the hydroxyl groups in the AP DL skeleton are prone to neutral loss of H2O, producing high in‐source fragment peaks and affecting the characterization of these components. Methods: Mass tags were applied during the MS data acquisition step, and special adduct ion form was used to guide the data processing and characterization steps. Besides, the total number of characterized AP DLs significantly increased when combining the number of neutrally lost H2O from AP DLs, incorporating information on the diagnostic ions, and adopting molecular networks generated with the Global Natural Products Social Molecular Networking database. Results: Ninety‐nine DLs, comprising 6 monohydroxyl groups, 20 dihydroxyl groups, 27 trihydroxy groups, and 46 DLs with more than 3 hydroxyl groups, were characterized from AP. In addition, based on the characteristic fragments in the product ions (C3H4, Δm/z = 40.03 Da), it could be assumed that 90 DLs had the C19‐OH structure among the identified DLs. The current study provides a new approach for collecting, processing, and characterizing MS analysis of natural DLs prone to in‐source fragmentation. Conclusions: MS characterization of AP DLs was significantly improved, and many potential new compounds were identified in AP. This characterization provides new methods for the purification and identification of AP DLs. [ABSTRACT FROM AUTHOR]

At present, the image encryption algorithm based on the bit‐plane has the problem that the encryption speed and the encryption effect cannot be well balanced. To address the problem, an image layered scrambling encryption algorithm is proposed in this paper. First, a new one‐dimensional Cosine Logistic compound chaotic map (1DCLC) is proposed. Several characteristics of the new chaotic map are analyzed by using various measures, such as bifurcation diagram, Lyapunov exponent, sample entropy etc. And the results show that the novel chaotic map has a better chaotic performance. Second, based on the chaotic map, an image encryption algorithm is proposed. The algorithm first performs an XOR encryption operation on the image. Second, the layered scrambling is applied to the XOR encrypted image. Then the layered and scrambled image is recombined for the second XOR encryption operation. In particular, in the layered scrambling, not only can the position of the pixel be changed but also the value of the pixel can be modified, which improves the security of the algorithm. In addition, in order to defend against various plaintext attacks and increase the security of the overall algorithm, the Hash function is introduced to update the key of the proposed algorithm. Finally, the original algorithm is improved and the improved algorithm's ability to resist differential attacks is analyzed. The experimental simulation and security test results show that the proposed encryption algorithm has a comparable encryption effect and a faster encryption speed. [ABSTRACT FROM AUTHOR]

Phosphate is widely used in surimi products to improve the gel properties. However, excess addition of phosphate occurs, which can harm the consumer's health. This study aimed to evaluate the effects of agar gum and fucoidan on maintaining the gel properties of surimi products instead of phosphate. Interestingly, our results showed that 0.125% of agar gum and fucoidan to replace phosphate could enhance water‐holding capacity and maintain gel strength and textual properties of surimi products well. Especially at frozen storage for 1 year, 0.125% of agar gum reduced the expressible moisture content of surimi products by around 10% (p <.05). Sensory evaluation showed that 0.125% of agar gum and fucoidan instead of phosphate can improve tissue and fondness of surimi products in refrigerated storage for 24 h but not in frozen storage for 1 year. The addition of agar gum and fucoidan at a high concentration >0.50% increased the WHC, but significantly decreased gel strength and springiness of surimi products (p <.05). Particularly, 1.00% of agar gum and fucoidan reduced gel strength by around 20% (p <.05). It might be due to the destruction of the gel network structure of surimi protein following the excess addition of these polysaccharides. It can be concluded that 0.125% of agar gum and fucoidan can replace phosphate to develop high‐quality surimi products, and excessive addition of them have negative effects. [ABSTRACT FROM AUTHOR]

Palladium(II)‐catalyzed C(alkenyl)−H alkenylation enabled by a transient directing group (TDG) strategy is described. The dual catalytic process takes advantage of reversible condensation between an alkenyl aldehyde substrate and an amino acid TDG to facilitate coordination of the metal catalyst and subsequent C(alkenyl)−H activation by a tailored carboxylate base. The resulting palladacycle then engages an acceptor alkene, furnishing a 1,3‐diene with high regio‐ and E/Z‐selectivity. The reaction enables the synthesis of enantioenriched atropoisomeric 2‐aryl‐substituted 1,3‐dienes, which have seldom been examined in previous literature. Catalytically relevant alkenyl palladacycles were synthesized and characterized by X‐ray crystallography, and the energy profiles of the C(alkenyl)−H activation step and the stereoinduction model were elucidated by density functional theory (DFT) calculations. [ABSTRACT FROM AUTHOR]

In this study, we systematically evaluate different ambiphilic organohalides for their ability to participate in anti‐selective carbo‐ or heteroannulation with non‐conjugated alkenyl amides under PdII/PdIV catalysis. Detailed optimization of the reaction conditions has led to protocols for synthesizing tetrahydropyridines, tetralins, pyrrolidines, and other carbo/heterocyclic cores via [n+2] (n=3–5) (hetero)annulation. Expansion of scope to otherwise unreactive ambiphilic haloketones through PdII/amine co‐catalysis is also demonstrated. Compared to other annulation processes, this method proceeds via a distinct PdII/PdIV mechanism involving Wacker‐type directed nucleopalladation. This difference results in unique reactivity and selectivity patterns, as revealed through assessment of reaction scope and competition experiments. [ABSTRACT FROM AUTHOR]

SUMMARY: Malvids is one of the largest clades of rosids, includes 58 families and exhibits remarkable morphological and ecological diversity. Here, we report a high‐quality chromosome‐level genome assembly for Euscaphis japonica, an early‐diverging species within malvids. Genome‐based phylogenetic analysis suggests that the unstable phylogenetic position of E. japonica may result from incomplete lineage sorting and hybridization event during the diversification of the ancestral population of malvids. Euscaphis japonica experienced two polyploidization events: the ancient whole genome triplication event shared with most eudicots (commonly known as the γ event) and a more recent whole genome duplication event, unique to E. japonica. By resequencing 101 samples from 11 populations, we speculate that the temperature has led to the differentiation of the evergreen and deciduous of E. japonica and the completely different population histories of these two groups. In total, 1012 candidate positively selected genes in the evergreen were detected, some of which are involved in flower and fruit development. We found that reddening and dehiscence of the E. japonica pericarp and long fruit‐hanging time promoted the reproduction of E. japonica populations, and revealed the expression patterns of genes related to fruit reddening, dehiscence and abscission. The key genes involved in pentacyclic triterpene synthesis in E. japonica were identified, and different expression patterns of these genes may contribute to pentacyclic triterpene diversification. Our work sheds light on the evolution of E. japonica and malvids, particularly on the diversification of E. japonica and the genetic basis for their fruit dehiscence and abscission. Significance Statement: Malvids is one of the largest clades of rosids and include 58 families, and its phylogenetic position is still contested. Euscaphis japonica, an early‐diverging species within malvids, is mainly distributed in Southeast Asia with deciduous or evergreen and two types: deciduous and evergreen. We assembled a high‐quality chromosome level genome of E. japonica, and found that E. japonica experienced a unique whole genome duplication event approximately 53 Mya. Genome‐based phylogenetic analysis suggests that the unstable phylogenetic position of E. japonica may result from incomplete lineage sorting and hybridization event during the diversification of the ancestral population of malvids. By resequencing 101 samples from 11 populations, we speculate that the temperature has led to the differentiation of the evergreen and deciduous of E. japonica and the completely different population histories of these two groups. Candidate positively selected genes related to the flower and fruit development in the evergreen were detected. We found that reddening and dehiscence of the E. japonica pericarp and long fruit‐hanging time promoted the reproduction of E. japonica populations, and revealed the expression patterns of genes related to fruit reddening, dehiscence, and abscission. The key genes involved in pentacyclic triterpene synthesis in E. japonica were identified, and different expression patterns of these genes may contribute to pentacyclic triterpene diversification. In summary, the present study has important scientific significance because it describes the phylogeny of the malvids, how the ancestor E. japonica differentiates into the evergreen and deciduous, and the evolutionary significance of the fruit. [ABSTRACT FROM AUTHOR]

Wine‐processed Angelica Sinensis is a widely used Chinese medicinal decoction piece in China. However, there are hardly any robust markers indicating the processing procedure of wine‐processed Angelica Sinensis, including the amount of rice wine and processing degree. A strategy integrating untargeted metabolomics and chemometric analysis for deducing robust markers was provided and applied to the discrimination of processing procedure. First, 86 compounds were tentatively identified in wine‐processed Angelica Sinensis by ultra‐high‐performance liquid chromatography coupled with quadrupole‐time of flight mass spectrometry. Second, 93 potential chemical markers were selected using multivariate analysis, among which nine robust chemical markers were selected by verification with commercial samples. Finally, the effects of processing temperature, time, and amount of rice wine on the three selected chemical markers were investigated through a rapid analytical method. It was demonstrated that both m/z 258.1097 and 238.1189 were positively correlated with the amount of rice wine and processing degree. In summary, this study introduced two candidate processing markers as robust markers for discriminating the processing procedures of wine‐processed Angelica sinensis. It also proposed a strategy to provide the reference for the research of other decoction pieces. [ABSTRACT FROM AUTHOR]

Catalytic efficiency and thermostability are the two most important characteristics of enzymes. However, it is always tough to improve both catalytic efficiency and thermostability of enzymes simultaneously. In the present study, a computational strategy with double‐screening steps was proposed to simultaneously improve both catalysis efficiency and thermostability of enzymes; and a fungal α‐l‐rhamnosidase was used to validate the strategy. As the result, by molecular docking and sequence alignment analysis within the binding pocket, seven mutant candidates were predicted with better catalytic efficiency. By energy variety analysis, A355N, S356Y, and D525N among the seven mutant candidates were predicted with better thermostability. The expression and characterization results showed the mutant D525N had significant improvements in both enzyme activity and thermostability. Molecular dynamics simulations indicated that the mutations located within the 5 Å range of the catalytic domain, which could improve root mean squared deviation, electrostatic, Van der Waal interaction, and polar salvation values, and formed water bridge between the substrate and the enzyme. The study indicated that the computational strategy based on the binding energy, conservation degree and mutation energy analyses was effective to develop enzymes with better catalysis and thermostability, providing practical approach for developing industrial enzymes. [ABSTRACT FROM AUTHOR]

The expansion of deformation‐induced crystallization of polypropylene (PP) pipes was studied. The crystal structure and melting characteristics of the samples after expanding at different expansion strains and expansion temperatures were analyzed. The results showed that the crystallinity was improved when the PP pipes were expanded, and the expansion effect made the crystal structure more perfect while the expanding temperature did not exceed the crystallization temperature. However, once expanding temperature exceeded crystallization temperature, some β lamellae crystal were stretched and transformed into α crystals structure. It showed that the expansion effect could cause the crystal phase transformation of the sample. In addition, when the expanding strain was less than 15%, the β crystal diffraction peak intensity of the sample decreased, but the α crystal diffraction peak intensity increased, and the original sparse distribution lamellae structure gradually became compact. With the expanding strain continued to increase, the oriented molecular chains underwent stress relaxation, which hindered the conversion of β crystals to α crystals. The oriented crystal structure formed by the crystal phase transformation made the PP pipe have excellent tensile and impact strength. As a result, the hoop tensile strength is increased by 13%, and the impact strengths are increased by 36%. [ABSTRACT FROM AUTHOR]

The presence of sulfate groups in agar compromises the agar quality by affecting the crosslinking during gelling process. Some arylsulfatases can catalyze the hydrolysis of sulfate bonds in agar to improve the agar quality. Immobilized arylsulfatases prove beneficial advantages for their industrial applications. Here, a previously characterized mutant arylsulfatase K253H/H260L was immobilized on the synthesized magnetic Fe3O4 nanoparticles after functionalization by tannic acid (MNPs@TA). The surface properties and molecular structures of the immobilized arylsulfatase (MNPs@TA@ARS) were examined by scanning electron microscopy and Fourier transform infrared spectroscopy. Enzymatic characterization showed that MNPs@TA@ARS exhibited shifted optimal temperature and pH with deviated apparent Km and Vmax compared to its free counterpart. The immobilized arylsulfatase demonstrated improved thermal and pH stability and enhanced storage stability with modest reusability. In addition, MNPs@TA@ARS displayed enhanced tolerance to various inhibitors and detergents. The utilization of the immobilized arylsulfatase for agar desulfation brought the treated agar with improved quality. [ABSTRACT FROM AUTHOR]

Laminarin and its derived oligosaccharides have diverse bioactivities. The β‐1,3‐glucanase in marine bacteria can be employed as a tool to digest laminarin in the cell wall of brown algae. Here, we cloned, expressed and characterised a β‐1,3‐glucanase (laminarinase), MaLamNA, from the previously characterised marine bacterium Microbulbifer sp. ALW1, phylogenetically distinct from the glycoside hydrolase families of characterised laminarinases. The recombinant laminarinase was heterologously expressed and purified from Pichia pastoris GS115 cells with a molecular mass of 57.3 kDa. MaLamNA exerted its hydrolytic activity specifically against laminarin, with the highest activity at 45 °C and pH 4.5–5.5, respectively, and demonstrated high stability against extreme acidic and alkaline pH exposure. The addition of reducing agent dithiothreitol could significantly enhance the activity of MaLamNA. The hydrolytic products of laminarin by MaLamNA exhibited more effective antioxidant activities than the undigested laminarin. These characteristics of MaLamNA provide clues to its industrial application for laminarin bioresource development. [ABSTRACT FROM AUTHOR]

Monofluorinated alkyl compounds are of great importance in pharmaceuticals, agrochemicals and materials. Herein, we describe a direct nickel‐catalyzed monofluoromethylation of unactivated alkyl halides using a low‐cost industrial raw material, bromofluoromethane, by demonstrating a general and efficient reductive cross‐coupling of two alkyl halides. Results with 1‐bromo‐1‐fluoroalkane also demonstrate the viability of monofluoroalkylation, which further established the first example of reductive C(sp3)‐C(sp3) cross‐coupling fluoroalkylation. These transformations demonstrate high efficiency, mild conditions, and excellent functional‐group compatibility, especially for a range of pharmaceuticals and biologically active compounds. Mechanistic studies support a radical pathway. Kinetic studies reveal that the reaction is first‐order dependent on catalyst and alkyl bromide whereas the generation of monofluoroalkyl radical is not involved in the rate‐determining step. This strategy provides a general and efficient method for the synthesis of aliphatic fluorides. [ABSTRACT FROM AUTHOR]

White tea is a famous Chinese tea that is cooked at boiling point before drinking. The simultaneous distillation‐extraction (SDE) was used to collect volatile compounds during tea cooking. The SDE extract was dominated with green, floral, roasted and woody notes, and weak sweet note. There were 32 volatile compounds identified via gas chromatography–mass spectrometry analysis, and 19 of them had strong fragrance based on the gas chromatography‐olfactometry analyzed results. Hexanal, 2‐hexenal, cis‐3‐hexen‐1‐ol, and camphene were the main contributors to the green note. The floral note was mainly contributed by 2‐hexanone, benzeneacetaldehyde, trans‐linalool oxide, and linalool, and the sweet note was induced by trans‐β‐damascenone. The roasted note was mainly contributed by 2‐pentyl‐furan. The woody note was mainly contributed by trans‐α‐ionone and trans‐β‐ionone. Four putative reaction pathways, including amino acid degradation, carotene degradation, Maillard reaction, and glycosides hydrolysis, were figured out to explain the generation of aromatic‐active volatiles at high temperatures. This study added our knowledge on tea aroma under cooking as well as other thermal treatments. [ABSTRACT FROM AUTHOR]

A tyrosinase inhibitor was separated from camellia pollen with the aid of solvent fraction, macroporous adsorptive resin chromatography, and high‐speed countercurrent chromatography. The inhibitor was identified to be p‐coumaric acid ethyl ester (p‐CAEE) by nuclear magnetic resonance and mass spectrum. Its inhibitory activity (IC50 = 4.89 μg/ml) was about 10‐fold stronger than arbutin (IC50 = 51.54 μg/ml). The p‐CAEE inhibited tyrosinase in a noncompetitive model with the KI and Km of 1.83 μg/ml and 0.52 mM, respectively. Fluorescence spectroscopy analysis showed the p‐CAEE quenched an intrinsic fluorescence tyrosinase. UV‐Vis spectroscopy analysis showed the p‐CAEE did not interact with copper ions of the enzyme. Docking simulation implied the p‐CAEE induced a conformational change in the catalytic region and thus changed binding forces of L‐tyrosine. Our findings suggest that p‐CAEE plays an important role in inhibiting tyrosinase and provides a reference for developing pharmaceutical, cosmetic, and fruit preservation products using pollen. [ABSTRACT FROM AUTHOR]

A nickel‐catalyzed direct trifluoroethylation of aryl iodides with an industrial raw material CF3CH2I has been developed, demonstrating high efficiency, excellent functional‐group compatibility, especially with large sterically hindered groups. The key to success is the combination of nickel with readily available nitrogen and phosphine ligands. The powerful potential of this strategy is further demonstrated by the late‐stage modification of several derived bioactive molecules. [ABSTRACT FROM AUTHOR]

Ischemic stroke is a global disease with high disability and mortality rates. Cognitive impairment is one of the major clinical features of ischemic stroke, and microglia-mediated inflammation has been shown to be an important contributor to the pathogenesis of ischemic stroke. Kellerin, extracted from Ferula sinkiangensis, was previously shown to inhibit microglial activation and exert a strong anti-neuroinflammatory effect. However, there is no report of the potential therapeutic effect of kellerin on ischemic stroke by targeting microglial cells. In this study, we wanted to examine the effects of kellerin on ischemic stroke in the bilateral common carotid artery occlusion (BCCAO) model and the lipopolysaccharide (LPS)-activated microglia model. We found that kellerin alleviated cognitive impairment, decreased neuronal loss, suppressed microglial activation, and transformed microglia from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype in BCCAO mice. Moreover, in in vitro studies, we found that kellerin regulated microglial polarization and inhibited the NLRP3 and MAPK signaling pathways after LPS treatment. These findings provide a new understanding of the function of kellerin in ischemic stroke, and suggest that kellerin could be a potential therapeutic agent for the treatment of ischemic stroke. [ABSTRACT FROM AUTHOR]

Abstract: A combinatorial nickel‐catalyzed monofluoroalkylation of aryl halides with unactivated fluoroalkyl halides by reductive cross‐coupling has been developed. This method demonstrated high efficiency, mild conditions, and excellent functional‐group tolerance, thus enabling the late‐stage monofluoroalkylation of diverse drugs. The key to success was the combination of diverse readily available bidentate and monodentate pyridine‐type nitrogen ligands with nickel, which in situ generated a variety of readily tunable catalysts to promote fluoroalkylation with broad scope with respect to both coupling partners. This combinatorial catalysis strategy offers a solution for nickel‐catalyzed reductive cross‐coupling reactions and provides an efficient way to synthesize fluoroalkylated druglike molecules for drug discovery. [ABSTRACT FROM AUTHOR]

The effects of two crude enzymes from Aspergillus niger on the aromas of instant green tea have been investigated. The crude enzymes from tea stalk (ETS) and potato dextrose (EPD) were respectively prepared by fermentation. Both enzyme extracts significantly changed the volatile composition and aroma profile. ETS treatment increased the content of 2-ethylfuran, ethyl 2-methylbutyrate and decanal and decreased the content of trans-limonene oxide and 2-heptanone; EPD treatment increased the concentrations of 2-ethylfuran and ethyl 2-methylbutyrate and decreased the concentrations of octanal, methyl salicylate and trans-limonene oxide. After ETS treatment, the floral and fermented notes increased, while green, woody and sweet notes decreased. EPD treatment decreased green and floral notes. These results indicate that both ETS and EPD contain some novel enzymes, which could modulate the aroma of instant green tea, and thus provide potential enzyme resources for modulating the aroma of tea products. [ABSTRACT FROM AUTHOR]

A new lipolytic enzyme gene was cloned from a thermophile Geobacillus sp. JM6. The gene contained 750 bp and encoded a 249-amino acid protein. The recombinant enzyme was expressed and purified from Escherichia coli BL21 (DE3) with a molecular mass of 33.6 kDa. Enzyme assays using p-nitrophenyl esters with different acyl chain lengths as the substrates confirmed its esterase activity, yielding the highest activity with p-nitrophenyl butyrate. When p-nitrophenyl butyrate was used as a substrate, the optimum reaction temperature and pH for the enzyme were 60 °C and pH 7.5, respectively. Geobacillus sp. JM6 esterase showed excellent thermostability with 68% residual activity after incubation at 100 °C for 18 h. A theoretical structural model of strain JM6 esterase was developed with a monoacylglycerol lipase from Bacillus sp. H-257 as a template. The predicted core structure exhibits an α/β hydrolase fold, and a putative catalytic triad (Ser97, Asp196, and His226) was identified. Inhibition assays with PMSF indicated that serine residue is involved in the catalytic activity of strain JM6 esterase. The recombinant esterase showed a relatively good tolerance to the detected detergents and denaturants, such as SDS, Chaps, Tween 20, Tween 80, Triton X-100, sodium deoxycholate, urea, and guanidine hydrochloride. [ABSTRACT FROM AUTHOR]

Resin adsorption and naringinase treatment represent two major methods for debittering naringin in citrus juices, but their effects on the aroma profiles of citrus juices have not been intensively investigated yet. In this study, the volatiles of the fresh, naringinase-treated and resin-absorbed juices of pummelo were investigated by gas chromatography coupled with a mass spectrometer (GC-MS) and sensory evaluation. The fresh juice was analyzed to have 24 volatiles, among which ( E)-3-hexen-1-ol and 1-hexanol had the highest concentrations. After the naringinase treatment, the juice showed 32 volatiles, among which ( Z)- and ( E)-linalool oxides were the most dominant in concentration; while the resin adsorption captured most of the volatiles. Principal component analysis (PCA) showed that naringinase treatment led to an increase in some compounds, particularly aldehydes, whereas resin adsorption decreased the amounts of a lot of volatile compounds. The sensory evaluation demonstrated the fresh and naringinase-treated juices had similar aroma profiles, whereas the resin-adsorbed juice had a much weaker aroma intensity than its counterparts. These results indicated that the naringinase treatment is more desirable than the resin adsorption for debittering citrus juice because the naringinase treatment could maintain the aroma profile close to the original, fresh juice. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT Volatile extracts were prepared from the peel of pummelo by cold pressing (CP), water distillation (WD), simultaneous distillation and extraction (SDE), microwave-assisted extraction (MAE), ultrasonic-assisted extraction (UAE) and supercritical CO2 fluid extraction (SFE). They were analysed by sensory evaluation and gas chromatography-mass spectrometry (GC-MS). The former technique showed that the CP essential oil (CP-EO), MAE and UAE extracts possessed similar odour profiles to the natural pummelo odour, whereas the SDE extract and WD essential oil (WD-EO) presented the fermented/overripe and alcohol/pungent notes, and the SFE extract had a sweet note. Although the GC-MS analyses revealed the six extracts had a certain degree of differences in their compositions, they had similar major volatiles, including limonene (301 476-497 028 µg/ml), β-myrcene (86 400-230 400 µg/ml), β-pinene (1370-7129 µg/ml), linalool (1916-4482 µg/ml) and germacrene D (1165-2327 µg/ml). Analyses of odour activity values (OAVs) and cluster analysis revealed the fermented/overripe and alcohol/pungent notes of the SDE extract and WD-EO were attributed to nerol, geraniol and linalool oxide. The sweet note of the SFE extract was ascribed to citronellal and limonene oxide. Besides, a lack of limonene, neral and geranial resulted in a light green aroma of the SFE extract. This information might be valuable for further development of aromatically desirable products from citrus fruits. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]