Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/3/2006
Publication Date: 6/27/2006
Citation: Jin, Z.T., Zhang, H.Q., Boyd, G. 2006. Thermal inactivation kinetics of e. coli in liquid egg white determined by aluminum thermal-death-time cans. IFT Annual Meeting, June 24-28, 2006, Orlando, FL. Paper No. 0780-44.
Technical Abstract: Accurate determination of kinetic data for liquid egg is important for thermal processing design to ensure food safety or shelf-life. Liquid egg is sensitive to thermal processing and prone to pathogenic contamination. At present capillary tubes and TDT glass tubes are in general use. However, those methods have disadvantages such as limit to low viscous liquid samples, inability to monitor temperature or long come-up time. The objective of this study was to adapt a new type of TDT cans in determination of kinetics of inactivation of E. coli in liquid egg white (LEW). E. coli ATCC 23716 was inoculated in LEW. One mL of inoculated LEW was placed inside a TDT can. The TDT can was submerged completely in a water bath at a preset temperatures. At various time intervals, duplicate cans were removed from the water bath and immediately immersed in an ice bath. The center temperature of the TDT can was monitored and recorded. Heat-treated samples were plated on tryptic soy agar and incubated at 37C for 24 h. The log numbers of the survivors at each temperature and time were used to determine D values and z value by linear regression. Temperature profiles showed that target temperature at the center of TDT can was reached in 60s. The come-up time was much shorter than glass TDT tubes. The D values at 52C, 54C, 56C, 58C and 60C were 5.24 min, 1.72 min, 0.86 min, 0.35 min, and 0.16 min, respectively. The z value was 5.37 C. The kinetic data from this study could be used to properly design a thermal pasteurization or no-thermal process with combination of mild heat treatment for liquid egg.