Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2015
Publication Date: 5/1/2015
Publication URL: http://handle.nal.usda.gov/10113/60866
Citation: Fan, X., Felker, P., Sokorai, K.J. 2015. Decontamination of mesquite pod flour, naturally contaminated with Bacillus cereus and formation of furan by ionizing irradiation. Journal of Food Protection. 78(5):954-962.
Interpretive Summary: Mesquite pod flour with unique flavor and high sugar content is often used for gluten-free food formulations. However, the pod can be contaminated with human pathogens during growing and harvesting, resulting in adulteration of the pod flour. A study was conducted to investigate the efficacy of ionizing irradiation in decontaminating two types of mesquite pod flour naturally contaminated with Bacillus cereus (a human pathogenic bacterium), and the effect of irradiation on the formation of furan (a possible human carcinogen). Results showed that irradiation reduced population of the bacterium to a non-detectable level at doses of 6 kilogray or higher. Furan was found in non-irradiated flours and its levels increased with irradiation doses. The information will help regulatory agencies and the industry to consider the technology for the decontamination of sugar-containing dry flour.
Technical Abstract: Mesquite pod flour produced from nitrogen-fixing trees of Prosopis species has a unique aroma and flavor which is preferred by some consumers. Due to the presence of wildlife, grazing domestic animals and insects, the pods have a high potential of being contaminated with human pathogenic bacteria such as Bacillus cereus. Non-thermal processing technologies are helpful to reduce the population of microorganisms in the flour because heating deteriorates the characteristic flavor. A study was conducted to investigate the efficacy of ionizing radiation in decontaminating two types of mesquite pod flours (P. alba and P. pallida) naturally contaminated with B. cereus, and the effects of irradiation on the formation of furan, a possible human carcinogen. Results showed that spores contributed to 94-97% of total native microflora population and 80-90% of spores were B. cereus spores. The populations of B. cereus were 3.8 and 5.4 log CFU/g in non-irradiated P. alba and P. pallida flours, respectively. Populations of microflora, mesophilic spores, B. cereus and B. cereus spores decreased with increasing radiation doses. At 6 kGy, the populations fell below 1 log CFU/g. Non-irradiated P. alba and P. pallida flours contained 13.0 and 3.1 ng/g furan respectively. Furan levels increased with irradiation doses at rates of 2.3 and 2.4 ng/g/kGy in the two flours. The level of 3-methylbutanal was reduced or not affected by irradiation while hexanal level was increased. Our results suggested that irradiation was effective in decontaminating contaminated mesquite flour. The significance of furan formation and possible changes in flavor due to irradiation may need to be further examined.