Ultrasonic preparation of citral/hydroxypropyl-β-cyclodextrin inclusion complex: Application as a potential antifungal preservative in strawberry storage

In this study, an inclusion complex (IC) of citral (CIT) within hydroxypropyl-β-cyclodextrin (HPβCD) was prepared by ultrasound technique. The structural characterization, thermal stability, phase solubility, antifungal properties and applications of CIT/HPβCD-IC in strawberry storage were investigated. The results showed that CIT/HPβCD-IC was successfully formed and had better thermal stability than CIT only. The apparent stability constant and Gibbs free energy change of the inclusion process was determined to be 142.08 M⁻¹ and −12.87 kJ mol⁻¹, respectively, by the phase solubility method. The in vitro antifungal tests demonstrated that the IC had a certain antifungal effect against Geotrichum citri-aurantii, with a significant inhibitory effect against the growth of Botrytis cinerea and Alternaria alternata at concentrations above 5 mg mL⁻¹. Additionally, the treatment of CIT/HPβCD-IC on strawberry effectively reduced the decay rate and decrease of weight loss, soluble solids, firmness, and pH, thereby extending the shelf life. This research indicated that the ultrasonically synthesized CIT/HPβCD-IC effectively improved the water solubility and stability of CIT and could be utilized as an antifungal preservative for storage and preservation of strawberry, and potentially other fruits and vegetables.     

Development of nucleic acid extraction and real-time recombinase polymerase amplification (RPA) assay integrated microfluidic biosensor for multiplex detection of foodborne bacteria

Rapid and accurate screening of foodborne bacteria is of great significance for food safety, particularly in the areas where health resources for grass-root service are inadequate. In this study, we fabricated a fully integrated micro-platform (named FID-MP) performing nucleic acid extraction, recombinase polymerase amplification (RPA), and signal detection for point-of-care testing (POCT) of multiplex pathogens. After the on-chip nucleic acid extraction, which adopted a filtration membrane, to obtain the DNA template of bacteria, the purified DNA was driven to the detection chip to conduct nucleic acid amplification. The fluorescent images can be read by using a smartphone under the portable signal detector. Using FID-MP, eight foodborne bacteria were detected with 100% specificity and similar sensitivities as compared to standard real-time RPA reactions. The entire process was accomplished within 60 min. Overall, FID-MP eliminates the need for bulk equipment and skilled personnel, holding promise to become a versatile sample-to-answer platform for foodborne bacteria monitoring.