Rapid, accurate and visual point-of-care testing (POCT) methods for pathogenic bacteria detection are essential for avoiding foodborne diseases caused by pathogens or their toxins. In this study, we proposed a rapid and visual detection method that we named “Cas12aVIP”. By combining recombinase polymerase amplification (RPA), a CRISPR/Cas12a system and a cationic-conjugated polythiophene derivative (poly[3-(3′-N,N,N-triethylamino-1′-propyloxy)-4-methyl-2,5-thiophene hydrochloride] (PMNT) mixed with single-stranded DNA (ssDNA)), the solution turned red in the absence of the target DNA based on conformational modifications of the conjugated backbone of PMNT, whereas it displayed yellow, thus realizing the colorimetric detection of DNA. The Cas12aVIP method yielded high specificity and no interference from other nontargeted bacteria. The detection was accomplished in 40 min and the signal could be observed by the naked eye under natural light, presenting great potential for a variety of rapid nucleic acid detection applications without requiring technical expertise or ancillary equipment.

In order to seek high profit, businesses mix beef and mutton with cheap meat, such as duck, pork, and chicken. Five pairs of primers were designed for quintuple droplet digital PCR (qddPCR) of specific genomic regions from five selected species and specificity and amplification efficiency were determined. The mixed DNA template with an equal copy number was used for detecting the accuracy and limit of multiplex PCR. The results showed that the primers and probes of the five selected species had good specificity with the minimum number of detection copies: 0.15 copies/µL beef (Bos taurus), 0.28 copies/μL duck (Anas platyrhynchos), 0.37 copies/μL pork (Sus scrofa), 0.39 copies/μL chicken (Gallus gallus), and 0.41 copies/μL mutton (Ovis aries), respectively. The five sets of primers and probes could quickly judge whether the specified meat components existed in the food commodities.

To study the differences in meat quality and nutritional components between the local Shanghai pig breeds Meishan pig (MS), Shawutou pig (SWT), Fengjing pig (FJ), and the commercial Duroc × Landrace × Yorkshire (DLY) crossbred pigs, and to provide data support for the selection and breeding of superior pig breeds, this study selected 30 piglets each of three local pig breeds and DLY with similar birth ages and weights around 25 kg, fed them the same daily ration with uniform nutritional components, and slaughtered ten of them at around 100 kg weight for evaluation of differences in meat quality indicators (primarily intramuscular fat content, tenderness value, texture, etc.) and amino acid content among the varieties. The results indicated significant differences among the four pig breeds in intramuscular fat content, with MS having the highest content and significant differences in tenderness value compared to the other three breeds (p < 0.05). In terms of texture indicators, MS and SWT differed significantly from FJ and DLY in terms of hardness and fracturability indicators (p < 0.05), with certain differences existing among the four breeds in other indicators. In amino acid content, the differences in total amino acid content among the three Shanghai local pig breeds were not significant (p > 0.05), but all were significantly higher than DLY. Further analysis revealed significant differences in amino acid content between Shanghai local pig breeds and DLY, with Shanghai local pigs showing markedly higher levels of serine, proline, isoleucine, leucine, and histidine compared to DLY (p < 0.05). Regarding nucleotides, the cytidine monophosphate (CMP) indicator of MS differed significantly from the other three breeds (p < 0.05), SWT’s uridine monophosphate (UMP) indicator differed significantly from FJ and DLY, and FJ and DLY’s inosine monophosphate (IMP) indicator was significantly higher than MS and SWT (p < 0.05), while SWT’s adenosine monophosphate (AMP) indicator was significantly higher than the other three breeds (p < 0.05). The results of this study suggest that the meat quality and nutritional composition of Shanghai local pigs are significantly superior to DLY, with MS exhibiting significantly better meat quality and nutrition compared to SWT and FJ among the three local pig breeds.