The Effect of Low Dose Irradiation and Grapefruit Extract on C. perfringens Growth from Spores in sous vide Processed Pork-Based Mexican Entrée

Authors: MIGUEL-GARCIA, DENISE - CIAD; Juneja, Vijay; VALENZUELA, MARTIN - CIAD; DIAZ-CINCO, MARTHA - CIAD; THIPPAREDDI, H. - UNIV. OF NEBRASKA

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2009
Publication Date: 6/1/2009
Citation: Miguel-Garcia, D.Y., Juneja, V.K., Valenzuela, M., Diaz-Cinco, M., Thippareddi, H. 2009. The Effect of Low Dose Irradiation and Grapefruit Extract on C. perfringens Growth from Spores in sous vide Processed Pork-Based Mexican Entrée. Journal of Food Science. 74(4):172-176.

Interpretive Summary: Concerns have been expressed by risk assessors and food safety managers about the public-health risks associated with sous vide processed foods because the mild heat treatment required to retain the sensory attributes may not ensure proper destruction of pathogenic and spoilage organisms, particularly spore-formers. The safety of sous vide foods cannot rely on only a single “chilled storage” factor. Since one of the most common types of food poisoning in the United States is caused by the spore-forming bacterium, Clostridium perfringens, there was a need to determine the fate of this pathogen in sous vide processed foods. The results suggest that 800 ppm of a commercial grapefruit extract, Citricidal, added to sous vide processed meat products can control C. perfringens outgrowth from spores and can provide an extra degree of safety in temperature abused products. These findings will be of immediate use to the retail food service operations and regulatory agencies to ensure the safety of the sous vide foods.

Technical Abstract: Sous vide, a common cooking method for meat and poultry products is widely used for providing ready-to-eat meals. Traditionally, these products have limited shelf life, ranging from 2 to 3 weeks. However, similar products may be stored for longer periods in the U.S. and other countries, requiring additional safety measures to control germination and outgrowth of spore forming pathogens such as Clostridium perfringens. Inhibitory effect of Citricidal, a grapefruit extract on C. perfringens was evaluated in a Mexican style sous vide product in combination with low dose irradiation. Mexican style sous vide product was prepared with either 200 or 800 ppm of Citrucidal along with a control (no added Citrucidal). The product was inoculated with C. perfringens spore (3 log spores/g) separately and vacuum packaged. A set of product (treatments) was frozen and subjected to low dose irradiation (2 kGy). All the products were cooked to an internal temperature of 71C, chilled and stored at 4, 15 and 25C. At specific time intervals, the product was removed from refrigeration (4C) and placed at 25C to simulate temperature abuse conditions. Thermal destruction of C. perfringens vegetative cells in the product was also evaluated. Irradiation of the product or inclusion of Citrucidal did not show any effect on the spore populations and C. perfringens spore germination and outgrowth at 4 or 15C. However, a 4 log CFU/g increase in C. perfringens population was achieved after 26 h at 25C regardless of the irradiation or the added Citrucidal. However, in refrigerated samples abused for 13 hours at 25C a reduction in C. perfringens population was observed as a result of the combined application of 2 kGy of gamma irradiation and 800 ppm of Citricidal. The D-values at 60C of C. perfringens vegetative cells in temperature (25C) abused meat samples with or without added Citricidal were ca 12 min. Citricidal (800 ppm) can have significant bacteriostatic activity against C. perfringens under certain temperature abuse conditions and may provide sous vide processed marinated pork a protection against this pathogen.