Microbiological Profile, Incidence, and Behavior of Salmonella on Seeds Traded in Mexican Markets

Abstract

Seed consumption has increased in recent years because the high nutrient content of seeds. However, the number of outbreaks caused by Salmonella associated with the consumption of low water activity food items has also increased, although these food items do not support microbial growth. The main goal of this study was to quantify microbial indicators and to determine the prevalence and content of Salmonella spp. in chia, amaranth and sesame seeds obtained from Mexican retail outlets. In addition, the behavior of this pathogen on seeds was also evaluated. One hundred samples of each product (chia, amaranth and sesame seeds) were collected from Queretaro City markets. Aerobic plate count (APC), coliforms and Escherichia coli were quantified, and the presence and number of Salmonella were also determined. Chia, amaranth and sesame seeds (1 kg each) were inoculated with a cocktail containing five Salmonella strains (~6 log CFU mL -1 ) and were stored at ambient temperature and populations of Salmonella were quantified. The median APC contents in chia, amaranth, and sesame seeds were 2.1, 2.4, and 3.8 log CFU g -1 , respectively, and the content of coliforms on the seeds ranged from 0.48 to 0.56 log MPN g -1 . E. coli was present at low concentrations in the three types of seeds. Salmonella was detected in chia (31%), amaranth (15%), and sesame (12%) seeds, and the population ranged from 0.48 to 0.56 Log MPN g -1 . Salmonella spp. decreased through 240 days of storage, showing inactivation rates of 0.017, 0.011 and 0.016 log CFU h -1 in chia, amaranth, and sesame seeds, respectively. The high prevalence of Salmonella in the seeds highlights potential risks for consumers, particularly giving that seeds are generally consumed without treatments guaranteeing pathogen inactivation.

Microbial and Qualitative Traits of Quinoa and Amaranth Seeds from Experimental Fields in Southern Italy

“…The seed samples recorded very low Aw values, ranging from 0.427 ± 0.024 (sample Q3) to 0.514 ± 0.024 (sample A3). Our results are similar to those reported by other authors for amaranth, chia, and sesame seeds [41].…”

“…Other authors also found yeasts and moulds with similar microbial load in different seeds from Mexico and Portugal [41]. Spore-forming bacteria were also found in spices from the United States (with values from 2.0 ×10 2 to 8.3 ×10 7 CFU/g) [48] and in Australian wheat (10 4 CFU/g) [49].…”

“…The low Aw of seeds is a characteristic of non-perishable foods, and is one of the most important parameters for the preservation of dry products [41].…”

Quality Attributes of Sesame Butter (Tahini) Fortified with Lyophilized Powder of Edible Mushroom (Agaricus blazei)

“…For the food industry and regulatory organizations, the microbiological safety of tahini and its derivative products has increased in importance. However, Salmonella is a great hazard joined with sesame infection bacteria worldwide [ 46 ]. Tahini is thought to be shelf stable due to its low water activity; however, due to its high fat content, it may cause cross-protection against negative environmental factors, which might prolong the survival of pathogens such as Salmonella under different storage conditions [ 47 ].…”