Effect of frozen and refrozen storage of beef and chicken meats on inoculated microorganisms and meat quality.

The objective of this study was to investigate the effects of repeated freeze-thaw cycles on microorganisms, amino acid composition profile, chemical composition, mineral concentrations, water mobility, and fat of beef and chicken meats. Pure cultures of specific fungi and bacteria were separately injected into the minced meat. Apart from Pseudomonas, the total count of microorganisms significantly increased (P < 0.05) during refreezing treatment with the increase of storage period in both beef and chicken meats. During freezing treatment, the total count of Staphylococcus aureus, spore forming bacteria, and lactic acid bacteria were meat-type dependent. In conclusion, freeze-thaw cycles increased the microbial counts and decreased the water holding capacity, amino acids, and mineral concentrations of beef and chicken meats.

Tannins inhibit SARS-CoV-2 through binding with catalytic dyad residues of 3CLpro : An in silico approach with 19 structural different hydrolysable tannins.

Coronavirus epidemic 2019 (COVID-19), instigated by SARS-CoV-2 virus, is recently raising worldwide and inspiring global health worries. The main 3-chymotrypsin-like cysteine protease (3CLPro ) enzyme of SARS-CoV-2, which operates its replication, could be used as a medication discovery point. We therefore theoretically studied and docked the effects of 19 hydrolysable tannins on SARS-CoV-2 by assembling with the catalytic dyad residues of its 3CLpro using molecular operating environment (MOE 09). Results discovered that pedunculagin, tercatain, and castalin intensely interacted with the receptor binding site and catalytic dyad (Cys145 and His41) of SARS-CoV-2. Our analyses estimated that the top three hits might serve as potential inhibitor of SARS-CoV-2 leading molecules for additional optimization and drug development process to combat COVID-19. This study unleashed that tannins with specific structure could be utilized as natural inhibitors against COVID-19. PRACTICAL APPLICATIONS: The 3CLPro controls SARS-CoV-2 copying and manages its life series, which was targeted in case of SARS-CoV and MERS-CoV coronavirus. About 19 hydrolysable tannins were computed against 3CLpro of SARS-CoV-2. Pedunculagin, tercatain, and castalin interacted with Cys145 and His41 of SARS-CoV-2-3CLpro . Pedunculagin-SARS-CoV-2-3CLpro remain stable, with no obvious fluctuations. We predicted that the understandings gained in the current research may evidence valued for discovering and unindustrialized innovative natural inhibitors for COVID-19 in the nearby future.

A novel strain of acetic acid bacteria Gluconobacter oxydans FBFS97 involved in riboflavin production.

A novel bacterial strain of acetic acid bacteria capable of producing riboflavin was isolated from the soil sample collected in Wuhan, China. The isolated strain was identified as Gluconobacter oxydans FBFS97 based on several phenotype characteristics, biochemicals tests, and 16S rRNA gene sequence conducted. Furthermore, the complete genome sequencing of the isolated strain has showed that it contains a complete operon for the biosynthesis of riboflavin. In order to obtain the maximum concentration of riboflavin production, Gluconobacter oxydans FBFS97 was optimized in shake flask cultures through response surface methodology employing Plackett-Burman design (PBD), and Central composite design (CCD). The results of the pre-experiments displayed that fructose and tryptone were found to be the most suitable sources of carbon and nitrogen for riboflavin production. Then, PBD was conducted for initial screening of eleven minerals (FeSO4, FeCl3, KH2PO4, K2HPO4, MgSO4, ZnSO4, NaCl, CaCl2, KCl, ZnCl2, and AlCl3.6H2O) for their significances on riboflavin production by Gluconobacter oxydans strain FBFS97. The most significant variables affecting on riboflavin production are K2HPO4 and CaCl2, the interaction affects and levels of these variables were optimized by CCD. After optimization of the medium compositions for riboflavin production were determined as follows: fructose 25 g/L, tryptone 12.5 g/L, K2HPO4 9 g/L, and CaCl2 0.06 g/L with maximum riboflavin production 23.24 mg/L.

Nitroso-hemoglobin-ginger conjugates effects on bacterial growth and color stability in a minced beef model.

This study aims to enhance the color and microbiological qualities of a raw beef using natural ingredients. Nitroso-hemoglobin (NO-Hb) integrated with vitamin C (VC), calcium lactate, and ginger complexation were used as natural inhibitors against the growth of aerobic and pathogenic bacteria, namely (Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Salmonella. NO-Hb inhibited E. coli, S. aureus, and Salmonella, and enhanced the color stability more than nitrite in the minced beef model. After the multiexponential analysis of relaxation decays, the water component (T2b) was analyzed using the low-field NMR. The results indicated that, at the 7th d of cold-storage the third component (T2) was detected. Significant correlations were observed between T21 and T22 relaxation times and water-holding capacity in minced beef, implying that the LF-NMR measurements could be an efficient method for the determination and prediction of beef freshness. NO-Hb- ginger mixture, as a novel ingredient, could be used instead of nitrite in terms of meat safety.