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Research Project: New Sustainable Processing Technologies to Produce Healthy, Value-Added Foods from Specialty Crops

Location: Healthy Processed Foods Research

Title: Among different GRAS surface disinfectants, ethanol 70% achieved better efficacy in a single-spray process on inoculated almonds

Author
item Salazar, Fredy - University Of California
item Garcia, Sara - University Of California
item Lagunas-solar, Manuel - University Of California
item Pan, Zhongli
item Cullor, James - University Of California

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2018
Publication Date: 3/10/2018
Citation: Salazar, F., Garcia, S., Lagunas-Solar, M., Pan, Z., Cullor, J. 2018. Among different GRAS surface disinfectants, ethanol 70% achieved better efficacy in a single-spray process on inoculated almonds. Food Control. 227:51-57.

Interpretive Summary: In this study, we validated the use of E. faecium NRRL B-2354 as a surrogate for S. enteritis ATCC 1045 for testing surface disinfectant sprays. Furthermore, it found that using ethanol and a basic two-spray application on nuts was able to significantly reduce E. faecium NRRL B-2354 on almonds. The two-spray process treatment was optimized using 70% alcohol, either ethanol or isopropanol, with an application volume of 4.5% w/w and a contact time of 1-30 min. The research established a simple process treatment using a GRAS surface disinfectant spray in almonds that used inexpensive and easily accessible GRAS disinfectants. It was found that both 70% ethanol and 70% isopropanol had the most potential to achieve a high log reduction. When ethanol and isopropanol were used in a process involving multiple short-timed sprays, a 2-3 log10 CFU/g reduction was achieved. The optimal spray process had the following parameters: (1) Use of 70% ethanol or isopropanol (p<0.05), (2) a spray quantity of 4.5% w/w (p<0.05), (3) contact time of 1-30 min, and (4) use of 2 spray phases (p<0.05). While the current iteration of this process does not meet FDA requirements, further investigation of a heat-spray process may be able to achieve its goal for low moisture content food products.

Technical Abstract: Regulatory standards established by the FDA require almonds destined for consumption in the US to undergo a process treatment that reduces Salmonella by 4 log10 CFU/g. We tested 4 Generally Recognized as Safe (GRAS) surface disinfectants with known antimicrobial properties on almonds inoculated with Enterococcus faecium NRRL B-2354 and Salmonella enteritis ATCC 1045 and validated by use of E. faecium NRRL B-2354 as a surrogate of S. enteritis. One and two factor experiments were performed to quantify the effect of disinfectant concentration on the reduction of two types of bacteria and different parameters for alcohol efficacy. The tested surface disinfectant sprays tested ethanol 70%, hydrogen peroxide 3%, acetic acid 5%, and peracetic acid 500 ppm. Furthermore, we investigated both ethanol and isopropanol, and a combination of spray and mixing processes for disinfection. It was found that both 70% ethanol and 70% isopropanol had the most potential to achieve a high log reduction. When ethanol and isopropanol were used in a process involving multiple short-timed sprays, a 2-3 log10 CFU/g reduction was achieved. The optimal spray process had the following parameters: (1) Use of 70% ethanol or isopropanol (p<0.05), (2) a spray quantity of 4.5% w/w (p<0.05), (3) contact time of 1-30 min (4) use of 2 spray phases (p<0.05). Although it failed to achieve the >4 log10 CFU/g reduction required by the FDA, the study did establish a direction for future research for a treatment process that may meet this requirement.