Progress 07/01/01 to 09/30/06
Outputs
Minimally-processed fresh-cut produce (FCP) is implicated in foodborne disease outbreaks. Chlorine is currently used by the FCP industry to reduce microbial contamination; however, the use of this sanitizer raises safety and environmental concerns. Ozone could be an alternative to chlorine due to its high sanitization power and environment-friendly attributes. The objective of this study was to design and evaluate a pilot-scale washer that uses ozone to sanitize fresh-cut lettuce. A pilot-scale continuous washing system, allowing adjustments to optimize the mechanics of the process, was designed. The capability of ozone to sanitize fresh-cut lettuce was tested using a two-step washing procedure. Whole lettuce heads (150 lbs) were cut manually into pieces (2x3 cm) and pre-washed with water containing 0.1% tetra-sodium pyrophosphate (TSPP) at 5 lbs-lettuce/min feeding rate and 13.2 gal/min water flow rate. Samples were drained and divided into equal amounts for
subsequent washings using either tap water or ozonated tap water (10 ppm maximum delivered concentration) with sample collections at 5, 10, 15 and 20 min. Processed lettuce was tested for mesophilic aerobic and psychrotropic microbial counts. Results indicated that pre-washing lettuce with TSPP, followed by washing with ozonated tap water effectively decreased an initial population (~105 CFU/g lettuce) of mesophilic aerobic and psychrotrophic microorganisms by >1 log for all treatment times. On the other hand, the initial population of natural microflora in cut-lettuce treated with the TSPP and subsequently washed with tap water alone remained unchanged.
Impacts
These experimental trials satisfactorily simulate an industrial sanitizing procedure and demonstrate the effectiveness of ozone and its potential as an alternative to chlorine.
Publications
- R. Ramaswamy, L. Rodriguez-Romo, M. Vurma, V.M. Balasubramaniam, and A. E. Yousef. 2007. Ozone Technology: Fact Sheet for Food Processors. Ohio State University Extension {http://ohioline.osu.edu}
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Progress 01/01/05 to 12/31/05
Outputs
Raw or minimally processed fresh-cut produce (FCP) are implicated in foodborne disease outbreaks. Varieties of antimicrobial agents have been studied for produce treatment, including chlorine dioxide and ozone. Chlorine is currently used by fresh-cut produce industry in order to reduce microbial contamination; however, use of this sanitizer raises safety and environmental concerns. Ozone is proposed as alternative to chlorine, providing more sanitizing power to inactivate wide range of microorganisms and having more environment friendly attributes. The objective of this study was to design and evaluate a pilot plant washer that uses ozone as a sanitizer for FCP. A pilot plant scale washer was set up for experimental trials. The setup includes corona-discharge ozone generation unit, produce treatment chamber, vibratory draining conveyor, water collection and buffer tank, process water chillers, off-gas exhaust system, flow control valves, recirculation pumps, and
several auxiliary components. Maximum ozone concentration of 10 ppm was achieved in ozone storage tank (200 gal of water). Compared to water treatment, more than a 1-log reduction in natural flora was achieved with wetting agent and ozone treatment in continuous flow processing. These experimental trials satisfactorily simulate industrial sanitizing procedure using aqueous ozone as an alternative to chlorine.
Impacts
A continuous flow pilot-scale washing system was designed to sanitize FCP using aqueous ozone. The system should be useful for implementation in the food industry.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/31/04
Outputs
Raw or minimally processed fresh-cut produce (FCP) are implicated in foodborne disease outbreaks. Varieties of antimicrobial agents have been studied for produce treatment, including chlorine dioxide and ozone. Chlorine is currently used by fresh-cut produce industry in order to reduce microbial contamination; however, use of this sanitizer raises safety and environmental concerns. Ozone is proposed as alternative to chlorine, providing more sanitizing power to inactivate wide range of microorganisms and having more environment friendly attributes. The objective of this study was to design and evaluate a pilot plant washer that uses ozone as a sanitizer for FCP. A pilot plant scale washer was set up for experimental trials. The setup includes corona-discharge ozone generation unit, produce treatment chamber, vibratory draining conveyor, water collection and buffer tank, process water chillers, off-gas exhaust system, flow control valves, recirculation pumps, and
several auxiliary components. Maximum ozone concentration of 10 ppm was achieved in ozone storage tank (200 gal of water). Compared to water treatment, more than a 1-log reduction in natural flora was achieved with wetting agent and ozone treatment in continuous flow processing. These experimental trials satisfactorily simulate industrial sanitizing procedure using aqueous ozone as an alternative to chlorine.
Impacts
Successful completion of the project would lead to safer produce and decrease incidence of foodborne illnesses associated with produce consumption.
Publications
- Vurma,M. 2004. Control of barotolerant Listeria monocytogenes by combinations of phenolic compunds and high-pressure processing. M.S. Thesis. Ohio State University
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Progress 01/01/03 to 12/31/03
Outputs
We successfully acquired a new ozone system for treating produce at the Ohio State University food microbiology research facility. The new system includes: Generator: DEL 8 lb/day, corona discharge, uses external Oxygen tank. Buffer tank: 200 gallon capacity. Accessories: Venturi, contactor, two destruct columns, pumps, etc. Two water chillers. The new system was connected to existing produce treatment chamber, tested, and these are some of the results. Maximum ozone concentration in the buffer tank was 10 ppm. Water temperature now can be maintained at <10C, with a goal of cooling processing water to 4C. Ozone level in collection tank, without produce treatment, was at least 5 ppm. When cut lettuce was introduced in the treatment chamber, residual ozone was at least 0.5 ppm. Trials on the decontamination of produce are planned. Once these trails succeed, produce processors (e.g., Dole) will be invited to test the equipment for suitability of commercial application.
Impacts
Successful completion of the project would lead to safer produce and decrease incidence of foodborne illnesses associated with produce consumption.
Publications
- Kim, J.-G., Yousef, A. E., and Khadre, M. H. 2003. Ozone and its current and future application in the food industry, p. 167-218. In S. Taylor (ed.) Advances in food science and nutrition, Vol 45. Elsevier Sci. Ltd., London, UK
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Progress 01/01/02 to 12/31/02
Outputs
For most industries, and especially food, consumption of large quantities of water is an integral part of processing. However, in recent times, water is increasingly becoming scarce and the cost of fresh water has considerably increased. Although ozone has been used in recycling of several food process waters including poultry chiller water (Waldroup et al., 1993.; Diaz et al., 2002), wine-distillery wastewaters (Beltran et al., 2001), tomato wastewater (Beltran et al., 1997), alkaline fruit cannery effluent (Sigge et al., 2001) and table olive industrial wastewaters (Beltran et al., 1999), little or no studies on salad process waters have been reported in the literature. The present study reports results of our trials to reduce chemical oxygen demand (COD) of salad process waters using ozone and hydrogen peroxide single or in combination at acidic and alkaline pH. Samples of salad process waters were obtained from Dole company salad processing plants. Samples were
treated with (i) filtration, (ii) ozone, (iii) alkali to raise the pH, (iv) hydrogen peroxide, or (v) various combinations of the former processes. Treated and untreated water was analyzed for chemical oxygen demand (Eaton et al., 1995). Results show that raising water's pH and treating with a combination of hydrogen peroxide and ozone decreased COD content by up to 65%. Therefore, the study demonstrated the feasibility of recycling salad process waters by treating with a combination of high pH, H2O2 and ozone. References Beltran, F.J., Ecinar, J.M., Gonzalez, J.F. Industrial wastewater advanced oxidation, Part 2. Ozone combined with hydrogen peroxide or UV radiation. Water Res. 31(10):2415-1428 (1997). Beltran, F.J., Garcia-Araya, J.F., Alvarez, P.M. Ph sequential ozonation of domestic and wine-distillery wastewaters. Water Res. 35(4):929-936 (2001). Diaz, M.E., Law, S.E., Birt, D.M. Microbiological benefits of removing foam formed after UV-enhanced ozonation of poultry-processing
chiller water for recycling. J. Food Sci. 67(3):1036-1042 (2002). Eaton, A.D., Clesceri, L.S., and Greenberg, A.E., eds. Standard Methods for the Examination of Water and Wastewater, 19th edition (1995). American Public Health Association, American Water Works Association, Water Environment Federation.Publisher APHA Washington, DC. Sigge, G. O.; Britz, T. J.; Fourie, P. C.; Barnardt, C. A.; Strydom, R. Use of ozone and hydrogen peroxide in the post-treatment of UASB treated alkaline fruit cannery effluent.Water Sci. Technol. 44(5):69-74 (2001). Waldroup, A.L., Hierholzer, R.E., and Forsythe, R.H. Recycling of poultry chill water using ozone. J. Appl. Poultry Res. 2:330-336 (1993).
Impacts
This research proves the feasibility of water recycling in vegetable processing plants. It is likely the food industry will make best use of the proposed COD reduction method.
Publications
- Kim, J.-G., A. E. Yousef and M. H. Khadre. 2003. Ozone and its current and future application in the food industry, p. 167-218. In Advances in food science and nutrition, Vol 45. Elsevier Sci. Ltd., London, UK
- Khadre, M.A., and Yousef, A.E. 2002. Susceptibility of human rotavirus to ozone, high pressure, and pulsed electric field. J. Food Prot. 65: 1441-1446
- Lado, B. H. and Yousef, A.E. 2002. Alternative food preservation technologies: Efficacy and mechanisms. Microbes and Infection 4: 433-440
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