title: Inactivation of Escherichia coli O157:H7 on Orange Fruit Surfaces and in Juice Using Photocatalysis and High Hydrostatic Pressure.
abstract: Nonpasteurized orange juice is manufactured by squeezing juice from fruit without peel removal. Fruit surfaces may carry pathogenic microorganisms that can contaminate squeezed juice. Titanium dioxide-UVC photocatalysis (TUVP), a nonthermal technique capable of microbial inactivation via generation of hydroxyl radicals, was used to decontaminate orange surfaces. Levels of spot-inoculated Escherichia coli O157:H7 (initial level of 7.0 log CFU/cm(2)) on oranges (12 cm(2)) were reduced by 4.3 log CFU/ml when treated with TUVP (17.2 mW/cm(2)). Reductions of 1.5, 3.9, and 3.6 log CFU/ml were achieved using tap water, chlorine (200 ppm), and UVC alone (23.7 mW/cm(2)), respectively. E. coli O157:H7 in juice from TUVP (17.2 mW/cm(2))-treated oranges was reduced by 1.7 log CFU/ml. After orange juice was treated with high hydrostatic pressure (HHP) at 400 MPa for 1 min without any prior fruit surface disinfection, the level of E. coli O157:H7 was reduced by 2.4 log CFU/ml. However, the E. coli O157:H7 level in juice was reduced by 4.7 log CFU/ml (to lower than the detection limit) when TUVP treatment of oranges was followed by HHP treatment of juice, indicating a synergistic inactivation effect. The inactivation kinetics of E. coli O157:H7 on orange surfaces followed a biphasic model. HHP treatment did not affect the pH, °Brix, or color of juice. However, the ascorbic acid concentration and pectinmethylesterase activity were reduced by 35.1 and 34.7%, respectively.
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea.
authors.forename: Sungyul
authors.initials: S
authors.lastname: Yoo
authors.affiliation: Department of Food Science and Nutrition, King Saud University, P.O. Box 2460, Riyadh 11451, Kingdom of Saudi Arabia.
authors.forename: Kashif
authors.initials: K
authors.lastname: Ghafoor
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea.
authors.forename: Jeong Un
authors.initials: JU
authors.lastname: Kim
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea.
authors.forename: Sanghun
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea.
authors.forename: Bora
authors.initials: B
authors.lastname: Jung
authors.affiliation: Department of Food Science and Technology, Chung-Ang University, Anseong 456-756, Republic of Korea.
authors.forename: Dong-Un
authors.initials: DU
authors.lastname: Lee
authors.affiliation: Department of Biotechnology, Yonsei University, Seoul 120-749, Republic of Korea. foodpro@yonsei.ac.kr.
authors.forename: Jiyong
authors.initials: J
authors.lastname: Park
mesh_terms: D001628:Beverages / Q000382:microbiology*; D002713:Chlorine; D032084:Citrus sinensis / Q000382:microbiology*; D015169:Colony Count, Microbial; D004203:Disinfection / Q000379:methods; D019453:Escherichia coli O157; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D005638:Fruit / Q000382:microbiology*; D006801:Humans; D006874:Hydrostatic Pressure; D050296:Microbial Viability; D010777:Photochemistry; D014025:Titanium; D014466:Ultraviolet Rays
chemical_list: C009495:titanium dioxide; D002713:Chlorine; D014025:Titanium