Microbial analysis of the production line for roasted seaweed snacks

Roasted seaweed snacks are getting popular worldwide. To reveal the main origins of microorganisms present in the roasted seaweed snacks, samples of raw materials, finished products, and environment (both food-contact and nonfood-contact surfaces) were collected from four plants. The total aerobic plate (APC), coliform, and mold counts of these samples were analyzed and the selected samples were also used for 16S rRNA sequencing. Results showed that dried laver contained the highest levels of APC among all raw ingredients, ranging from 2.72 to 6.95 Log CFU/g. Crushed pumpkin seeds and almond flakes had the highest coliform (up to 5.57 Log CFU/g) and mold counts (up to 2.16 Log CFU/g). The addition of seasoning to seaweed sandwich snacks increased the total microbial loads. The roasting process decreased the APC, coliforms, and mold counts of seaweed snacks by 0.22–1.73 Log CFU/g, >0.18- >2.46 Log CFU/g, and >0.18- >0.88 Log CFU/g respectively. The 16S rRNA sequencing analysis showed that the microbiota of roasted seaweed snacks was closely correlated with that of dried laver and the microbial load of roasted sandwich seaweed was primarily from the dried laver while less from microorganisms present in the processing plant environment and line workers.