|HSU, HSIN YUN - National Taiwan University|
Submitted to: Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2014
Publication Date: 12/11/2014
Citation: Hsu, H., Sheen, S., Sites, J.E., Cassidy, J.M., Scullen, B.J., Sommers, C.H. 2014. Effect of high pressure impact on the survival of Shiga Toxin-producing Escherichia coli ('Big Six' and 0157) in ground beef. Food Microbiology. doi:10.1016/j.fm.2014.12.002.
Interpretive Summary: High pressure processing (HPP), is a green and sustainable non-thermal means to reduce harmful bacteria in foods, and has been demonstrated to be an effective method for inactivating Shiga Toxin-producing Escherichia coli (STEC) in ground beef. In recent years, new types of harmful E. coli, which are not the well known O157:H7 type, have caused numerous foodborne illness outbreaks. In this study the ability of HPP to inactivate the O157:H7 STEC versus the new non-O157:H7 STEC was compared. At moderate operation conditions (e.g. 450MPa, 4 degree C, 15 min), five log microbial counts reduction (100000 per gram of food) of both type of STEC is achievable in meats (e.g. ground beef). This may provides a regulatory agencies and the food processing industry valuable information for the control of these emerging foodborne pathogens, the non-O157:H7 STEC, in meat.
Technical Abstract: High pressure processing (HPP) is a safe and effective technology for improving food safety while maintaining food quality attributes. Non-O157:H7 Shiga Toxin-producing Escherichia coli (STEC) have been increasingly implicated in foodborne illness outbreaks and recalls, and the USDA Food Safety Inspection Service have designated them as adulterants in meat (e.g. ground beef). In this study we compared the inactivation of a multi-isolate (five isolates) cocktail of E. coli O157:H7 versus a six-isolate cocktail of the non-O157:H7 STEC ‘Big Six’ (i.e. O26, O45, O103, O111, O121, and O145) suspended in ground beef (83% lean) using HPP. The HPP operation was designed to exclude potential thermal impact on STEC lethality. A greater than 5-log CFU/g inactivation at 450 MPa (15 min, 4 degree C) was observed for both the O157:H7 and ‘Big Six’ cocktails. A multiple-cycle HPP may have slightly higher impact on both O157: H7 and non-O157:H7 STEC inactivation versus the single-cycle having same total time applications. The HPP (350 and 250 MPa) may not completely eliminate the STEC and the survivals were able to recover following storage at mild abuse temperature (10 degree C) for 8 days. Our results indicate that HPP inactivation parameters which are effective for O157:H7 STEC can be used for the non-O157:H7 ‘Big Six’ isolates in ground beef. The ‘Big Six’ was slightly more sensitive to high pressure processing than O157 under high pressure stress under identical treatment conditions.