|KONSTANCE, RICHARD - RET.,CHEM.ENG.,USDA-DPPRU
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/13/2004
Publication Date: 7/3/2004
Citation: Tomasula, P.M., Gregg, D.A., Baxt, B., Rodriguez, L.L., Kozempel, M.F., Konstance, R.P. 2004. Effect of pasteurization on elimination of foot-and-mouth disease virus (FMDV) in naturally infected cow's milk. (abstract).International Food Technologists Meeting. Paper No. 46-3.
Interpretive Summary: n/a
Technical Abstract: Previous studies made using laboratory simulation of High Temperature Short Time pasteurization (LabHTST) to eliminate foot-and-mouth disease virus (FMDV) in milk have shown that it is not completely inactivated at the legal minimum (71.7 C/15 sec) but is inactivated at times > 20 minutes and temperatures > 100 C. Some of the virus may be resistant to thermal inactivation because it is encapsulated by milk fat. However, LabHTST is a batch heating operation which over or under predicts the delivered thermal process; is difficult to quantify accurately for short holding times; and, does not achieve the rapid come-up and cool-down times encountered in continuous flow HTST. The purpose of this study was to determine the effect on FMDV infectivity of pasteurizing whole milk obtained from FMDV-infected cows in a laboratory-scale continuous flow (HTST) pasteurizer equipped with a plate and frame heat exchanger and holding tube. Additional goals were to determine if the flow component enhances pasteurization and to quantify holding time for the process. Residence time distribution studies were carried out first using tracer to establish holding times. Milk samples containing FMDV at levels up to 4 log 10 pfu/ml were pasteurized at 72C and 80C at nominal holding times of 15 and 45 sec using a 2 x 2 experimental design. Virus was not detectable by tissue culture in milk after all pasteurization conditions. However, residual infectivity was demonstrated in pasteurized milk samples when inoculated into steers. The animals developed full-blown FMD symptoms. Results indicate that the outcome of continuous flow HTST at all temperature-time combinations studied is similar to that of LabHTST with 4 log of the virus eliminated in milk. However, using laboratory-scale continuous flow HTST instead of LabHTST allows simulation of the flow patterns and residence time distribution of milk that occurs in commercial HTST so that the lethality of the entire pasteurization process may be determined.