EFFECTS OF PULSED ELECTRIC FIELDS ON PHYSICOCHEMICAL PROPERTIES AND MICROBIAL INACTIVATION OF CARROT JUICE BOB XIANG 1 , SRIJANANI SUNDARARAJAN 1 , KEVIN MIS SOLVAL 1 , LUIS ESPINOZA-RODEZNO 1 , KAYANUSH ARYANA 2 and SUBRAMANIAM SATHIVEL 1,3,4 1 Department of Food Science, Louisiana State University Agricultural Center, Baton Rouge, LA 2 School of Animal Sciences, Louisiana State University Agricultural Center, Baton Rouge, LA 3 Department of Biological and Agricultural Engineering, Louisiana State University Agricultural Center, Baton Rouge, LA 70803-4300 4 Corresponding author. TEL: (225)-578-0614, FAX: 225-578-5300; EMAIL: ssathivel@agcenter.lsu.edu Received for Publication July 5, 2012 Accepted for Publication February 12, 2013 doi:10.1111/jfpp.12115 ABSTRACT Carrot juice samples treated with pulsed electric fields (PEF) of electric field intensity of 25 kV/cm and treatment time of 144.6 ms (PEF1) and 433.8 ms (PEF2) and thermal pasteurization (TP) treatment of 90C for 1 min were evaluated for physicochemical properties and microbial inactivation. The PEF1 and PEF2 treated carrot juice retained higher amounts of ascorbic acid, a-carotene, b-carotene and lutein than the TP-treated carrot juice. The PEF-treated carrot juices were not significantly (P > 0.05) different in pH and °Brix compared to the control, while the TP-treated juices were significantly different in °Brix and total acidity compared to the control. The PEF2 was comparable with the TP for inacti- vation of aerobic bacteria and mold in carrot juice. PRACTICAL APPLICATIONS Pulsed electric field (PEF) can be used as a nonthermal pasteurization method to inactivate microorganisms and enzymes in liquid food and it preserves the physio- chemical and sensory properties, and nutritional value of liquid food. Our study showed that PEF treatment was more efficient in preserving some physico- chemical and quality properties of carrot juice compared to conventional heat pasteurization. INTRODUCTION Carrot juice is an excellent source of a-carotene, b-carotene and ascorbic acid, and a good source of dietary fiber and minerals (Senti and Rizek 1975; Marx et al. 2000). The pH of carrot juice is approximately 6.0 results in a high risk of bacterial growth. Thus, carrot juice requires a thermal pas- teurization (TP) treatment (90 to 121C) for inactivation of microbial growth (Chen et al. 1995; Park et al. 2002). TP treatments prevent spoilage due to microbial growth in fruit juice; however, they may cause undesirable biochemical and nutritious changes (Park et al. 2002; Alwazeer et al. 2003; Zerdin et al. 2003; Aguilar-Rosas et al. 2007). Heat treat- ment may also cause color change, separation of particles and a change in flavor of juice products (Qin et al. 1995). If heat treatment is not performed rapidly or at a reasonably low temperature, the juice will begin to separate due to the destruction of pectin (Goodman et al. 2002). The formation of sediment and change in flavor of carrot juice are the major reasons for some consumers rejecting TP-treated carrot juice (Beveridge 2002; Alklint et al. 2004). Therefore, an alternative processing method, such as a nonthermal method, is needed for carrot juice processing. An increase in the demand for minimally processed fresh products has raised interest in the development of new techniques for food processing such as pulsed electric fields (PEF; Vega-Mercado et al. 1997; Aguiló-Aguayo et al. 2008). PEF treatment applies intense electric pulses which develop pores in the cell membranes of microorganisms either by enlargement of existing pores or by creation of new ones. These pores may be permanent or temporary, depending on the condition of PEF treatment. This process is known as electroporation, which increases membrane permeability, allowing loss of cell contents. The electroporation leads to Journal of Food Processing and Preservation ISSN 1745-4549 Journal of Food Processing and Preservation 38 (2014) 1556–1564 © 2013 Wiley Periodicals, Inc. 1556