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Duck is often used in meat fraud as a substitute for more expensive meats. Rapid detection of duck ingredient in meat products is of great significance for combating meat fraud and safeguarding the interests of consumers. Therefore, we aim to develop duck-specific recombinase polymerase amplification (RPA)-based assays for the rapid detection of duck ingredient in animal-derived foods. Using Cytb gene as target, the real-time RPA and RPA combined with lateral flow strips (LFS RPA) were developed successfully for the rapid detection of ducks in 20 min at 39 °C and 40 °C, respectively. The assays did not show cross-reactions with 6 other livestock and poultry. The developed RPA assays could detect 10 pg duck genomic DNA per reaction and 0.1 % (w/w) duck ingredient in duck and mutton mixed powder within 30 min, including a rapid nucleic acid extraction. Furthermore, duck ingredient could be detected in 30 different actual foods including heat-processed meats and blood products. Therefore, duck-specific real-time RPA and LFS RPA assays were successfully developed with good specificity and sensitivity, which could enable rapid detection of duck ingredient in the field and provide technical support for combating the meat fraud.

Objective To establish a real-time recombinase-aid amplification (RAA) method for rapid detection of Pseudomonas aeruginosa. Methods Specific primers and exo probes based on ecfX gene of P. aeruginosa were designed in this study, and the validity of the method was evaluated by sensitivity, specificity and suspected strains detection. Results Real-time RAA was performed successfully at 39℃ for 20 min. Only the P. aeruginosa strains but not other bacteria were amplified, showing the good specificity. The limit of detection was 3.0×103 fg genomic DNA per reaction, and 1.0×103 CFU P. aeruginosa pure culture per reaction. The developed real-time RAA was further evaluated on 36 suspected of P. aeruginosa, which were identified successfully to be P. aeruginosa.The detection result were the same with those of a real-time PCR assay and the VITEK 2 Compact. Conclusion The developed real-time RAA assay is a rapid, simple and reliable tool for accurate detection of P. aeruginosa of diverse origins.

Okra is widely used as vegetable, food ingredient, and traditional medicine in China for various applications. The main healthy properties are accepted to originate from the high polysaccharide content of okra. In this study, a homogenous pectic polysaccharide WOP-2 was extracted, isolated, and purified from okra by DEAE-cellulose and Sepharose CL-6B column, and its molecular weight was estimated to be 580 kDa. Monosaccharide composition was analyzed to be Rha (21.4%), GalA (34.9%), Gal (29.6%), GlcA (4.5%), Glc (5.9%), and Ara (3.7%) by HPLC with PMP derivatization. Combined with NMR analysis, WOP-2 was elucidated to be a rhamnogalacturonan I backbone with type-II arabinogalactan side-chains substituted partly at O-4 of Rhap. WOP-2 exhibits significant anti-hyperglycemic activity on STZ-induced diabetic mice by inhibiting the lipid peroxidation chain reaction probably. Overall, these results provide new insight into structure–activity relationships of polysaccharide from okra and provide impetus towards the development of polysaccharide-based therapeutics on diabetes.