Effect of protein and prebiotic on the survival of encapsulated probiotic during storage

The aim of this research was to investigate the impact of encapsulation system on its protective capability during freeze drying of Lactobacillus casei TISTR 1463 and its storage at 4˚C and 30˚C for 90 and 60 days, respectively. Sericin extract is a kind of protein with gel-like property that could aid in binding and also contains important amino acids. The combinations of sericin and prebiotics, including isomaltooligosaccharide and modified starch were evaluated during microencapsulation of probiotic L. casei TISTR 1463 in alginate beads. The highest encapsulation efficiency was 97.61% with the addition of sericinisomalto-oligosaccharide. Encapsulated probiotic with sericin-modified starch had the lowest specific rate of degradation (k) of 3.74x10-2 day-1 and 1.09x10-1 day-1 at both storage temperatures of 4˚C and 30˚C, respectively. Probiotic property of cell surface hydrophobicity (CSH) was also carried out

Novel and Highly Sensitive Electrochemical Sensor for the Determination of Oxytetracycline Based on Fluorine-Doped Activated Carbon and Hydrophobic Deep Eutectic Solvents

Residues of oxytetracycline (OTC), a veterinary antibiotic and growth promoter, can be present in animal-derived foods; their consumption is harmful to human health and their presence must therefore be detected and regulated. However, the maximum residue limit is low, and consequently highly sensitive and accurate detectors are required to detect the residues. In this study, a novel highly sensitive electrochemical sensor for the detection of OTC was developed using a screen-printed electrode modified with fluorine-doped activated carbon (F-AC/SPE) combined with a novel deep eutectic solvent (DES). The modification of activated carbon by doping with fluorine atoms (F-AC) enhanced the adsorption and electrical activity of the activated carbon. The novel hydrophobic DES was prepared from tetrabutylammonium bromide (TBABr) and a fatty acid (malonic acid) using a green synthesis method. The addition of the DES increased the electrochemical response of F-AC for OTC detection; furthermore, it induced preconcentration of OTC, which increased its detectability. The electrostatic interactions between DES and OTC as well as the adsorption of OTC on the surface of the modified electrode through H-bonding and π–π interactions helped in OTC detection, which was quantified based on the decrease in the anodic peak potential (Epa = 0.3 V) of AC. The electrochemical behavior of the modified electrode was investigated by cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy. Under optimum conditions, the calibration plot of OTC exhibited a linear response in the range 5–1500 μg L–1, with a detection limit of 1.74 μg L–1. The fabricated electrochemical sensor was successfully applied to determine the OTC in shrimp pond and shrimp samples with recoveries of 83.8–100.5% and 93.3–104.5%, respectively. In addition to the high sensitivity of OTC detection, the proposed electrochemical sensor is simple, cost-effective, and environmentally friendly