Shelf-life extension of Pacific white shrimp (Litopenaeus vannamei) using sodium alginate/chitosan incorporated with cell-free supernatant of Streptococcus thermophilus FUA 329 during cold storage.

Seafood is highly perishable and has a short shelf-life. This study investigated the effect of chitosan and alginate (CH-SA) coating combined with the cell-free supernatant of Streptococcus thermophilus FUA329 (CFS) as a preservative on the quailty of white shrimp (Litopenaeus vannamei) refrigerated at 4° for 0, 3, 6, 9, 12, 15 days. Freshly shrimps were randomly divided into four groups: the CFS group (400 mL); the CH-SA group (1% chitosan/1% alginate); the CFS-CH-SA group (1% chitosan/1% alginate with 400 mL CFS) are treatment groups, and the control group (400 mL sterile water). The CFS-CH-SA coating effectively suppressed microbial growth total viable count and chemical accumulation (pH, total volatile basic nitrogen, thiobarbituric acid reactive substance) compared with the control. Additionally, the CFS-CH-SA coating improved the texture and sensory characteristics of shrimp during storage. The coated shrimp exhibited significantly reduced water loss (p < 0.05). The combination of CH-SA coating with CFS treatment can extend the shelf life of shrimp. PRACTICAL APPLICATION: Recently, edible films have received more consideration as a promising method to enhance the shelf life of seafood. The presence of Lactic acid bacteria metabolites in edible films reduces spoilage and improves consumer health. Our findings encourage the application of edible coating incorporated with cell-free supernatant of Streptococcus thermophilus FUA 329 to design multifubctional foods and preserve the qualities of shrimp.

Genomic and phenotypic-based safety assessment and probiotic properties of Streptococcus thermophilus FUA329, a urolithin A-producing bacterium of human milk origin.

Streptococcus thermophilus FUA329, a urolithin A-producing bacterium, is isolated from human breast milk. The complete genome sequence of FUA329 did not contain any plasmids and at least 20 proteins were related to extreme environment resistance. Phenotypic assay results demonstrated that FUA329 was susceptible to 12 kinds of antibiotics and did not exhibit any hemolytic or nitrate reductase activity. Three free radical scavenging assays revealed that FUA329 have high antioxidant capability. FUA329 exhibited a cell surface hydrophobicity of 52.58 ± 1.17% and an auto-aggregation rate of 18.69 ± 2.48%. Moreover, FUA329 demonstrated a survival rate of over 60% in strong acid and bile salt environments, indicating that FUA329 may be stable colonization in the gastrointestinal tract. Additionally, we firstly found 3 potential proteins and 11 potential genes of transforming ellagic acid to urolithins in FUA329 genome. The above results indicate that FUA329 has credible safety and probiotic properties, as well as the potential to be developed as a new generation of urolithin A-producing probiotics.

Genetic and Probiotic Characteristics of Urolithin A Producing Enterococcus faecium FUA027.

Enterococcus faecium FUA027 transforms ellagic acid (EA) to urolithin A (UA), which makes it a potential application in the preparation of UA by industrial fermentation. Here, the genetic and probiotic characteristics of E. faecium FUA027 were evaluated through whole-genome sequence analysis and phenotypic assays. The chromosome size of this strain was 2,718,096 bp, with a GC content of 38.27%. The whole-genome analysis revealed that the genome contained 18 antibiotic resistance genes and seven putative virulence factor genes. E. faecium FUA027 does not contain plasmids and mobile genetic elements (MGEs), and so the transmissibility of antibiotic resistance genes or putative virulence factors should not occur. Phenotypic testing further indicated that E. faecium FUA027 is sensitive to clinically relevant antibiotics. In addition, this bacterium exhibited no hemolytic activity, no biogenic amine production, and could significantly inhibit the growth of the quality control strain. In vitro viability was >60% in all simulated gastrointestinal environments, with good antioxidant activity. The study results suggest that E. faecium FUA027 has the potential to be used in industrial fermentation for the production of urolithin A.

Comparison of three second-order multivariate calibration methods for the rapid identification and quantitative analysis of tea polyphenols in Chinese teas using high-performance liquid chromatography.

Retention time shifts in second-order calibration-assisted chromatographic analysis seriously impact the modeling and quantitative accuracies in complex systems. In this work, three second-order methods, i.e. alternating trilinear decomposition (ATLD) algorithm, multivariate curve resolution-alternating least squares (MCR-ALS), alternating trilinear decomposition-assisted multivariate curve resolution (ATLD-MCR), were compared their performance to process liquid chromatographic data in the presence of retention time shifts and overlapped peaks. Firstly, the validation samples contain five tea polyphenols at three concentrate levels within the calibration ranges, helped to understand, visualize and interpret these features of three second-order multivariate methods. Secondly, experimental data were studied concerning the determination of polyphenols in Chinese tea samples by HPLC-DAD. The results showed that all three second-order multivariate methods realized satisfactory quantification for five targeted analytes in Pu-Er ripe tea samples and Green tea samples even with the interference of slight retention time shifts, average recoveries were 91.23% -113.16% for ATLD, 89.96%-115.96% for ATLD-MCR, 90.64%-117.60% for MCR-ALS, respectively. However, ATLD was disappointing in the case of larger time shifts (approx. 4.00 s and 6.40 s) occurring for the quantitative analysis of Black tea and Clinacanthus nutans tea, the average recoveries were just 67.33-84.05%. Relatively, MCR-ALS and ATLD-MCR were more significantly excellent, satisfactory results still can be obtained, the average recoveries for MCR-ALS and ATLD-MCR were in the range of 86.04-117.60% and 89.96-115.96%, respectively.

[Fast high-performance liquid chromatography quantification of ten phenolic acids in honey using chemometric second-order calibration method].

This study aims at the determination of ten phenolic acids in honey using high-performance liquid chromatography-diode array detection (HPLC-DAD) combined with a chemometric second-order calibration method. First, the accuracy of the model was investigated by analysis of the calibration samples and validation samples. Satisfactory results were obtained; the ten phenolic acids exhibited good linearity, and the correlation coefficient (R) was in the range 0.9982-0.9999, with average recoveries of 97.6% to 101.1%, which proved that the model was stable and reliable. Second, the types and operating conditions of the SPE columns were determined by experiments using simulated honey; HLB column was selected, washed with 0.1%(v/v) formic acid aqueous solution, and eluted with methanol. Finally, the phenolic acid contents in jujube flower honey were determined under the optimum conditions for simulated honey. The recoveries of the analytes were 62.1%-93.8%, which met the requirements considering the variety of target analytes and the complexity of the honey substrate. In addition, the efficiency of the method was validated by figures of merit and statistical parameters, including sensitivity (SEN), selectivity (SEL), root-mean-square error of prediction (RMSEP), limit of detection (LOD), and limit of quantification (LOQ); the obtained results were satisfactory. This method is simple, fast, and accurate, and it can be used for the quantitative analysis of the target analytes in complex substrates.