Mold and mycotoxin contamination in cooked nuts and seeds in China

ObjectiveThe aim of this study was to investigate the mold and mycotoxin contamination status of cooked nuts and seeds in China in 2021 and to understand the correlation and risk of mold and mycotoxin contamination in such foods.MethodsSamples of commercially available cooked nuts and seeds were tested for mold contamination. Internal transcribed spacer （ITS） sequencing was used to identify the genus of the contaminating mold in the samples.ResultsOut of the cooked nut and seed samples analyzed， 19.32% （560/2 912） had mold counts > 25 colony-forming units （CFU）/g. The proportion of mold counts > 25 CFU/g was lower in single nuts and seeds （14.74%， 321/2 178） than in mixed nuts and seeds （32.56%， 239/734， P < 0.05）. Among the single nut and seed samples， walnuts （24.10%， 47/195） had the highest proportion of mold counts > 25 CFU/g， followed by almonds， spartan wood， and peanuts at 17.44% （15/86）， 16.81% （20/119）， and 16.22% （73/450）， respectively. All other nuts and seeds had proportions below 15%. Mycotoxin analysis was performed on 26 samples with mold counts > 25 CFU/g， and beauvericin was detected at 16.37 μg/kg in one peanut sample collected from Yunnan Province. ITS amplicon sequencing revealed that the main contaminating genera in cooked nuts and seeds were Aspergillus， Alternaria， and Candida. The detected molds had a certain correlation with mycotoxins.ConclusionHigh levels of mold contamination were detected in cooked nuts and seeds， resulting in a risk of mycotoxin production in the detected foods. Thus， it is necessary to strengthen the genus and species identification and mycotoxin analysis in these types of food to understand the contamination route and the regularity of toxin production and to provide a scientific basis for risk assessment and effective prevention and control measures.