120 Proc. Fla. State Hort. Soc. 127: 2014. Proc. Fla. State Hort. Soc. 127:120–123. 2014. Handling and Processing Section/RefeReed ManuscRipt The Effect of Chlorine Dioxide and Chitosan/Essential Oil Coatings on the Safety and Quality of Fresh Blueberries XiuXiu Sun 1,2 , Kequan Zhou 1 , Jan narciSo 2 , chriStopher Ference 2 , and Jinhe Bai 2 * 1 Department of Nutrition and Food Science, Wayne State University, Detroit, MI 48202 2 USDA, ARS, USHRL, 2001 S. Rock Rd, Ft. Pierce, FL 34945 additional index woRds. Carvacrol, trans-cinnamaldehyde, frmness, decay Blueberries are high-value fruit having strong antioxidant capacity and health-promoting benefts. Controlled-release of ClO 2 pads and chitosan coating incorporated with 0.5% of carvacrol (CAR) or trans-cinnamaldehyde (ECIN) were applied to fresh blueberries to preserve their quality and ensure microbial safety during postharvest storage. Fruit frmness and microbial populations were monitored during storage. There were approximately a 2 log reduction in the population of bacteria and yeasts/molds in the blueberries after eight days of storage at 10 °C when comparing any of treated fruit with the control. Controlled-release ClO 2 pads and chitosan coating incorporated with 0.5% of CAR or ECIN also maintained the frmness of blueberries. Our results suggest that controlled-release ClO 2 and chitosan- essential oil coatings are effective in extending the shelf life of fresh blueberries. Mention of a trademark or proprietary product is for identifcation only and does not imply a guarantee or warranty of the product by the U.S. Department of Ag- riculture. The U.S. Department of Agriculture prohibits discrimination in all its programs and activities on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or family status. *Corresponding author; phone: (772) 462-5880; email: jinhe.bai@ars.usda.gov Blueberries have become a leading berry crop in the United States, and their high antioxidant potential and high oxygen radical scavenging capacity have been receiving increased at- tention (Ortiz et al., 2013). Blueberries are rich in favonoids and phenolic acids, which exhibit a wide range of biological effects, including antioxidant and anticarcinogenic properties (Zheng and Wang, 2003), and a protective effect against chronic diseases, especially cardiovascular diseases (Fracassetti et al., 2013). However, blueberries are perishable after harvest. Fresh blueberries typically have a shelf life of 1–8 weeks depending on the genetic background, region of production, harvest maturity, harvest methods, presence of disease, and storage conditions (Almenar et al., 2010). Physical damage from mishandling may result in loss of frmness and microbial decay, both negatively affecting postharvest storage and marketing of blueberries (Con- nor et al., 2002; Li et al., 2011). Pre- and postharvest applications of fungicides have been widely used in commercial practice in addition to low temperature storage (Gallo et al., 2007). Neverthe- less, there is consumer demand for the use of natural products, perceived to be environmentally-friendly and safe. Microbial safety of fresh blueberries has been an increasing concern, since any recall or outbreak can negatively affecting the entire industry. An outbreak of hepatitis A, an RNA virus associated with consumption of fresh blueberries, was investigated in New Zealand in which the blueberries were likely contaminated from polluted water or by infected food handlers (Calder et al., 2003). Similarly, an outbreak of six cases of illness due to Salmonella Newport on blueberries occurred in Minnesota in 2010 (Miller et al., 2013). Because of foodborne illnesses associated with blueberries, retailers of blueberries are now beginning to test for foodborne pathogens, including Listeria monocytogenes, Esch- erichia coli and Salmonella spp., as well as yeasts and molds, such as Colletotrichum spp. and Penicillium spp. (Popa et al., 2007). Many new chemical treatments have been tested on fruit and vegetables, including blueberries for improving their quality and safety. Chlorine dioxide (ClO 2 ), as an alternative sanitizer, was approved by the U.S. Environmental Protection Agency (EPA) and U.S. Food and Drug Administration (USDA) for postharvest application for fruit and vegetables in 2006 (Zhu et al., 2013). Chlorine dioxide has 2.5 times the oxidation capacity in compari- son with chlorine, a most widely used sanitizer in the produce industry (Han et al., 2000). Because ClO 2 is less reactive with organic compounds than chlorine, its application as a sanitizer in the food industry is of greater signifcance than chlorine (Wu and Kim, 2007). Moreover, unlike chlorine, chlorine dioxide does not react with nitrogen-containing compounds or ammonia that results in carcinogenic byproducts (Chen et al., 2011). Numer- ous studies have demonstrated the bactericidal and fungicidal properties of ClO 2 (Zhu et al., 2013). The inactivation of E. coli O157:H7 on radish seeds and surface-injured green peppers was increased signifcantly after treatment with ClO 2 (Kim et al., 2010). The growth of fungi could also be inhibited by ClO 2 at very low concentrations (Morino et al., 2007). Zhu (Zhu et al., 2013) showed that the mechanism of action of ClO 2 was by increasing ion leakage in bacterial cell membrane, inhibition of key enzyme activities of bacterial metabolic pathway, and alteration of cell structure. As ClO 2 gas has greater penetration ability than liquid, one particularly promising microbial reduc- tion strategy is the use of ClO 2 gas as an effective disinfectant for fruit surface sanitation (Du et al., 2003). Chitosan is a versatile biopolymer which exhibits antimicrobial activity against a range of foodborne microorganisms and consequently has attracted at- tention as a potential preservative (Ganan et al., 2009). Chitosan has a broad range of applications in the food industry (Gao et al., 2013), one of which is its application as an edible coating material. The chitosan coating creates a semi-permeable barrier