Effect of vacuum steam treatment of hard red spring wheat on flour quality and reduction of Escherichia coli O121 and Salmonella enteritidis PT 30

Authors: SNELLING, JANE - North Dakota State University; MALEKMOHAMMADI, SAHAR - North Dakota State University; BERGHOLZ, TERESA - North Dakota State University; Ohm, Jae-Bom; SIMSEK, SENAY - North Dakota State University

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2020
Publication Date: 4/22/2020
Citation: Snelling, J., Malekmohammadi, S., Bergholz, T.M., Ohm, J., Simsek, S. 2020. Effect of vacuum steam treatment of hard red spring wheat on flour quality and reduction of Escherichia coli O121 and Salmonella enteritidis PT 30. Journal of Food Protection. 83(5):836-843. https://doi.org/10.4315/JFP-19-491.
DOI: https://doi.org/10.4315/JFP-19-491

Interpretive Summary: There is a demand in the milling industry for a process that reduces pathogens in wheat kernels. Vacuum steam pasteurization (VSP) is a promising technology for pasteurization of low moisture foods including wheat kernels. However, VSP methods can compromise wheat functional quality due to high processing temperature. Heat treatment of wheat kernels substantially degrades processing and product quality of milled flour. The objectives of this study were to identify optimum temperature level of VSP to treat wheat kernels without degrading flour quality; and to evaluate efficacy of the VSP to reduce pathogens on wheat kernels in hard red spring (HRS) wheat. In the first part of the study, HRS wheat samples were pasteurized by VSP at 65, 70, 75, and 85°C for 4- and 8-min. Significant degradations in dough and baked product quality was observed when the pasteurization temperature was over 70°C and the optimum temperature was identified to be 65°C. In the second part, HRS wheat was inoculated with two pathogens, Escherichia coli O121 and Salmonella Enteritidis PT30, and processed at 65°C for 0, 2, 4, 6, or 8 min periods. The VSP treatments achieved significant reduction in populations of pathogens showing that longer treatment times significantly increased reductions of pathogen populations. VSP shows potential as an effective pasteurization method for the flour milling industry. This information will be a very valuable reference to improve safety of flour products.

Technical Abstract: Recent outbreaks traced to contaminated flour have created demand in the milling industry for a process that reduces pathogens in wheat while maintaining its functional properties. Vacuum steam pasteurization (VSP) is a promising technology for pasteurization of low moisture foods. Traditional pasteurization methods can compromise wheat functionality due to high temperatures, thus maintaining the functional quality of the wheat protein was critical for this research. The objective of this study was to evaluate the effect of VSP on Hard Red Spring (HRS) wheat kernels on final flour quality and overall efficacy of VSP to reduce pathogens on HRS wheat kernels. In the first part of the study, HRS wheat samples were pasteurized at 65, 70, 75, and 85°C for 4- and 8-min. Significant changes in dough and baked product functionality were observed for treatments > or = 70°C. For all of the quality tests performed, treatment time had no significant effect. After determining that VSP processing at 65°C best preserved product quality, HRS wheat was inoculated with Escherichia coli O121 and Salmonella Enteritidis PT30, and processed at 65°C for 0, 2, 4, 6, or 8 min periods. The treatments achieved a maximum average reduction of 3.57 ± 0.33 log CFU/g for E. coli 0121 and 3.21 ± 0.27 log CFU/g for Salmonella. VSP shows potential as an effective pasteurization method for the flour milling industry.