Identification of Chinese baijiu from the same brand based on a graphene quantum dots fluorescence sensing array.

The identification of Chinese baijiu is crucial to regulating the international market and maintaining legitimate rights, as the popularity, influence and awareness of baijiu are growing. A graphene quantum dot (GQD) based fluorescence sensor array is designed in this paper. Upon using only GQDs as a single sensing element, combining three different solvents improves the sensing array's detection sensitivity while simplifying material preparation and experimental detection. Adding organic substances creates intermolecular forces between the GQDs and the solvent, causing the fluorescence intensity to change. The sensor array was able to distinguish 21 types of organic matter, different ratios of quaternary mixed organic materials and 17 types of baijiu of the same brand. It also showed excellent performance in the detection of species in blind samples, with the machine learning algorithm successfully distinguishing baijiu from five other distilled spirits. The experiment provides guidance for the practical application of GQDs and provides a simple but effective reference for sensor arrays to detect baijiu.

Probing the mechanism of interaction between capsaicin and myofibrillar proteins through multispectral, molecular docking, and molecular dynamics simulation methods.

The interaction between myofibrillar proteins (MPs) and capsaicin (CAP) was investigated using multispectral, molecular docking, and molecular dynamics simulation methods. The resulting complex increased the hydrophobicity of the tryptophan and tyrosine microenvironment as revealed by fluorescence spectral analysis. The fluorescence burst mechanism study indicated that the fluorescence burst of CAP on the MPs was a static one (Kq = 1.386 × 1012 m-1s-1) and that CAP could bind with MPs well (Ka = 3.31 × 104 L/mol, n = 1.09). The analysis of circular dichroism demonstrated that the interaction between CAP and MPs caused a decrease in the α-helical structure of MPs. The complexes formed exhibited lower particle size and higher absolute ζ potential. Furthermore, hydrogen bonding, van der Waals forces, and hydrophobic interactions were found to be the primary factors facilitating the interaction between CAP and MPs, as suggested by molecular docking models and molecular dynamics simulations.

Effects of replacement partial sodium chloride on characteristic flavor substances of bacon during storage based on GC×GC-MS and non-targeted metabolomics analyses.

Comprehensive 2D gas chromatography-mass spectrometry (GC × GC-MS) and non-targeted metabolomics were employed to investigate the differences in key volatile flavor substances between bacon salted with alternative salt and traditional bacon during storage. The GC × GC-MS analysis revealed that among 146 volatile compounds in both types of bacon, alcohol, aldehydes, ketones, phenols, and alkenes were the most abundant. Additionally, non-targeted metabolomics indicated that the changes in amino acids and the oxidation degradation of lipids could be the main reasons for the flavor differences among the two kinds of bacon. Furthermore, the acceptability scores of both bacon types showed a general upward trend as the storage time increased, indicating that the metabolic of substances occurring during bacon storage significantly impact its overall quality. By partially substituting sodium chloride with 22% potassium chloride and 11% calcium ascorbate, coupled with appropriate storage conditions, the quality of bacon can be improved.

Conformational Changes in Proteins Caused by High-Pressure Homogenization Promote Nanoparticle Formation in Natural Bone Aqueous Suspension.

As a natural calcium resource, animal bone needs to be miniaturized to the nanoscale to improve palatability and absorption capacity. To explore the mechanism of high-pressure homogenization (HPH) in preparing natural bone aqueous nanosuspensions, the relationships between the changes in protein conformation, solubility and quality characteristics of rabbit bone aqueous suspensions (RBAS) prepared by different HPH cycles were studied. The results showed that the improvements in particle size, stability and calcium solubility of RBASs could be mainly attributed to the improvement of protein solubility induced by the changes in protein conformation. HPH treatment led to the denaturation and degradation of protein in rabbit bone, generating soluble peptides and improving the stability of the suspensions by enhancing the surface charge of the particles. When collagen as the main protein was partially degraded, the hydroxyapatite in the bone was crushed into tiny particles. The increase in the particle-specific surface area led to the release of calcium ions, which chelated with the peptides to produce peptide calcium. However, excessive HPH treatment caused the production of protein macromolecular aggregates and affected the quality of RBASs. This study is helpful to promote the application of HPH technology in animal bone nanoprocessing.

An HPLC-MS/MS Method Using a Multitoxin Clean up Column for Analysis of Seven Mycotoxins in Aquafeeds.

BACKGROUND: In Guangdong Province of China, the climate is very wet, so there are many different fungi living in aquatic feeds, which produce mycotoxins. These compounds contaminate agricultural products worldwide and present a great threat to human health. It is necessary to determine their contamination level in aquatic feeds. OBJECTIVE: A high performance liquid chromatography (HPLC) tandem mass spectrometry (MS/MS) method was developed for the quantitative analysis of aflatoxin B1, aflatoxin M1, T-2 toxin, HT-2 toxin, deoxynivalenol, ochratoxin, and zearalenone in fish and shrimp feed. METHODS: Samples were extracted with acetonitrile-water (3+1, v/v), and degreased with acetonitrile-saturated hexane. The extract was cleaned up with a multitoxin column. The target compounds were separated on a C18 chromatographic column and analyzed simultaneously by electrospray ionization mass spectrometry in both positive and negative ion mode. Detected compounds were quantified using the matrix-matched external standard method. RESULTS: Under the optimized conditions, good linearities for the analytes in the corresponding concentration range were obtained, with correlation coefficients (r2) higher than 0.9948. LODs ranged from 1.83 to 12.63 µg/kg, and LOQs ranged from 5.49 to 37.89 µg/kg. Average recoveries for the target mycotoxins at three spiked levels ranged from 80.5 to 116.5% with RSD ranging from 2.4 to 10.4%. Twenty-three real aquafeed samples were determined by this method, and seven kinds of toxins were detected. CONCLUSION: The results show that the developed method can be successfully applied for the simultaneous determination of mycotoxins in aquatic feeds. HIGHLIGHTS: Multitoxin purification columns proved to be a powerful technique for determining seven mycotoxins simultaneously. This method ensured simple sample pretreatment and less operation time. The established method was successfully applied to the analysis of seven mycotoxins species in aquatic feeds.

Effect of nanoprocessing on the physicochemical properties of bovine, porcine, chicken, and rabbit bone powders.

The chemical composition and hardness of bovine bone, porcine bone, chicken bone, and rabbit bone were compared, as well as the influence of nanoprocessing on the physicochemical characteristics of these bone powders. A series of nanofabrication processes led to an increase in bone minerals and the loss of protein and fat. The hardness of softened bovine bone was still the largest, whereas chicken and rabbit bones were relatively soft. There were no significant differences in the functional groups between nanoscale bone powders. Overall, nanomachining significantly reduced and homogenized the bone particle size and improved the color and release rate of calcium ions of bone powders at the same time; these effects were different for several bones. Nanoscale rabbit bone had higher comminution efficiency, as well as satisfactory nutritional value, color, and product yield, which supports its strong development potential.

Processing milk causes the formation of protein oxidation products which impair spatial learning and memory in rats.

This study explored the effects of protein oxidation during milk processing on spatial learning and memory in rats. Increasing the heating time, fat content, and inlet air temperature during processing by boiling, microwave heating, spray-drying, or freeze-drying increases milk protein oxidation. Oxidative damage done to milk proteins by microwave heating is greater than that caused by boiling. Dityrosine (DT), as a kind of tyrosine oxidation product, is the most important marker of this process, especially during spray-drying. Rats received diets containing either SWM (spray-dried milk powder diet), FWM (freeze-dried milk powder diet), FWM + LDT (freeze-dried milk powder + low dityrosine diet, DT: 1.4 mg kg-1), or FWM + HDT (freeze-dried milk powder + high dityrosine diet, DT: 2.8 mg kg-1) for 6 weeks. We found that the SWM group, the FWM + LDT group, and the FWM + HDT group appeared to have various degrees of redox state imbalance and oxidative damage in plasma, liver, and brain tissues. Further, hippocampal inflammatory and apoptosis genes were significantly up-regulated in such groups, while learning and memory genes were significantly down-regulated. Eventually, varying degrees of spatial learning and memory impairment were demonstrated in those groups in the Morris water maze. This means that humans should control milk protein oxidation and improve the processing methods applied to food.