Rimutu Ji

This study investigated microbial and metabolite dynamics in raw camel milk stored at 4°C. Physicochemical and microbial monitoring identified d 3 as a critical transition point, with samples from d 0, 1, 3, and 6 subjected to 16S rRNA sequencing and metabolomic analysis. The dominant genera shifted from Lactococcus to Pseudomonas. Metabolomic analysis showed that non-volatile metabolites were primarily composed of esters, lipids, and organic acids, with 9 of these metabolites exhibiting a continuous increasing trend. Similarly, the levels of volatile metabolites, including ketones, esters, and alcohols also increased gradually throughout refrigeration. Correlation analysis linked Lactococcus to organic acid production, while Pseudomonas was associated with esters and lipids. These findings highlight microbial succession and metabolite shifts as key determinants of refrigerated camel milk quality, providing theoretical support for improved quality control and product development.

Camel milk often faces quality control problems because it is vulnerable to adulteration with inferior dairy sources or plant-derived additives. Many existing DNA-based detection methods rely on suitable endogenous reference genes. This study aimed to develop an absolute quantification strategy based on real-time quantitative polymerase chain reaction using TaqMan probes. A recombinant plasmid standard containing camel-specific cytochrome b ( Cytb ) genes was designed. The resulting standard curve revealed high linearity ( R ² = 0.9982) across six orders of magnitude, enabling precise quantification of copy numbers. The primers and probes demonstrated high specificity for camel DNA, and the plasmid standards met quality criteria (A260/280 = 1.82; concentration deviation <2%). The method achieved a sensitivity of 6.39 × 10² copies/μL. For samples containing 5%–100% of camel milk, the coefficient of variation ranged from 0.99% to 5.20%, and the recovery rates for spiked products ranged from 97.5% to 107.5%. By providing absolute quantification without requiring a reference gene, this method offers a robust solution for detecting camel milk adulteration in dairy products.

Aflatoxin M1 (AFM1) is known to be carcinogenic, mutagenic, and teratogenic and poses a serious threat to food safety and human health, which makes its surveillance critical. In this study, an indirect competitive ELISA (icELISA) based on a nanobody (Nb M4) was developed for the sensitive and rapid detection of AFM1 in dairy products. In our previous work, Nb M4 was screened from a Bactrian-camel-immunized phage-displayed library. It exhibits VH-like features, possesses higher thermal stability than monoclonal antibody (mAb 1E6) and tightly binds to AFM1–BSA with a K_D value of 2.5 nM. Under the optimal conditions, its half-maximal inhibitory concentration was 0.338 ng/mL, the limit of detection was 0.051 ng/mL, and linearity was noted in the range of 0.168–0.679 ng/mL. Nb M4 displayed almost no cross-reactivity with other mycotoxins. No matrix effect was observed in milk and milk powder samples, and the matrix effect in yogurt samples could be weakened by 2-fold dilution. Furthermore, validation studies in spiked samples (milk, yogurt, and milk powder) resulted in good recoveries of 95.40–111.33%, with a low coefficient of variation (2.89–6.78%). High-performance liquid chromatography was used to evaluate the accuracy and reliability of the developed icELISA, which indicated a satisfactory consistent correlation (R² = 0.9722). This study highlights the potential of Nb M4 as a promising component for detecting AFM1 in dairy products.