Effects of high hydrostatic pressure on embryonation of Ascaris suum eggs Alexa C. Rosypal a,1 , Dwight D. Bowman b , Daniel Holliman c , George J. Flick c , David S. Lindsay a, * a Center for Molecular Medicine and Infectious Diseases, Department of Biomedical Sciences and Pathology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, 1410 Prices Fork Road, Blacksburg, Virginia 24061, USA b Department Microbiology and Immunology, College of Veterinary Medicine, Cornell University, C4-119 VMC, Tower Road, Ithaca, New York 14853, USA c Department of Food Science and Technology, Virginia Tech, Blacksburg, Virginia 24061, USA Received 3 August 2006; received in revised form 1 November 2006; accepted 3 November 2006 Abstract High hydrostatic pressure processing (HPP) has been shown to be an effective non-thermal means of inactivating micro- organisms from various food products. Little information is available regarding the effects of HPP on metazoan parasites. Outbreaks of food-borne disease have been associated with importation of food contaminated with fecal material. Ascaris suum is used as a surrogate model metazoan parasite for the human roundworm, Ascaris lumbricoides, to study the effects of treatments on the inactivation of eggs in sludge. The present study was conducted to determine the effects of HPP on A. suum eggs. Unembryonated A. suum eggs were subjected to 138–552 megapascals (MPa) for 10–60 s in a commercial HPP unit. Embryonation was induced after HPP treatments by incubating eggs in 0.01N sulfuric acid at room temperature. After 21 days, 100 eggs were examined per treatment using a light microscope and the percent of embryonated eggs was determined. Embryonation was induced in 38–76% eggs that were subjected to 138 and 270 MPa. No embryonation was observed in eggs exposed to pressures of 241 MPa or more for 60 s or in eggs exposed to 276 MPa for 10–30 s. These results indicate that HPP treatment could be used to protect contaminated food items by inactivating A. suum eggs and may also have potential in reducing food-borne illness resulting from fecal contamination. # 2006 Elsevier B.V. All rights reserved. Keywords: Ascaris suum; Eggs; High hydrostatic pressure; High pressure processing 1. Introduction Food preservation methods have traditionally employed high temperatures to ensure food safety and stability, however, thermal processes such as pasteuriza- tion are known to cause undesirable changes in heat treated products. Consumer demand for ‘‘fresh’’ and ‘‘natural’’ foods is reflected in a preference for products with extended shelf-life that also have similar features to the original product (San Martı ´n et al., 2002). In response to consumer preferences, novel non-thermal technolo- gies are in demand. High hydrostatic pressure processing (HPP) has been shown to be an effective non-thermal means of inactivating non-spore forming bacteria on and in a variety of foods (Tewari et al., 1999; Flick, 2003). www.elsevier.com/locate/vetpar Veterinary Parasitology 145 (2007) 86–89 * Corresponding author. Tel.: +1 540 231 6302; fax: +1 540 231 3426. E-mail address: lindsayd@vt.edu (D.S. Lindsay). 1 Present address: Department of Pathology and Laboratory Med- icine, CB #7525, Room 805 Brinkhous-Bullitt Building, University of North Carolina at Chapel Hill, Chapel Hill, NC 25799-7525, USA. 0304-4017/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.vetpar.2006.11.001