Microbial quality of edible seeds commercially available in southern Portugal

Abstract

In the present work, the microbiological quality of sesame, flaxseed, chia, pumpkin sunflower seeds, a mix of seeds, as well as flaxseed flour, marketed in southern Portugal, were studied through the counting of aerobic microorganisms at 30 ºC (AM), molds and yeast (M&Y), Escherichia coli (β-glucuronidase positive) (β-GP E. coli), Staphylococcus coagulase positive, and detection of Salmonella spp.. The persistence of AM and M&Y populations were also counted in organic and non-organic flaxseed at 20 ºC for 11 months. The seeds with the highest average of AM were flaxseed (1.3 x 106 CFU/g) followed by flaxseed flour (1.1 x 106 CFU/g) while the lowest level was found in chia (2.9 x 104 CFU/g). This seed also presented the lowest average values of filamentous fungi (9.8 x 102 CFU/g), whereas sunflower seeds had the highest levels (1.7 x 105 CFU/g). Flaxseed flour had the highest yeast counts (1.5 x 104 CFU/g). Although some samples had high levels of AM and fungi, β-GP E. coli and Salmonella were not detected, therefore, they complied with the microbiological criteria of the European Union. The organic flaxseed contained higher numbers of AM and M&Y than the non-organic ones (p < 0.05). In addition, the storage of flaxseed at 20 °C resulted in changes of AM and M&Y, showing that these populations were able to remain viable after eleven months (AM Log 5.4–Log 5.6; M&Y Log 2.8–Log 4.1). The results obtained in the present study, namely those high levels of AM and fungi (>106 and 104 CFU/g respectively), alert to the need of improving processing practices, storage/distribution conditions of edible seeds and derivatives, as well as the requirement of implementing adequate decontamination techniques.