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To develop a laboratory scale ultrasonic treatment for milk and apple cider. The processing technique will be designed to minimize temperature changes that occur with ultrasonic treatment. The developed system will also be constructed so that it can be used independently for ultrasonic treatment and in a combined process using a mild heat treatment; to use ultrasonic processing on milk and apple cider to reduce populations of Listeria monocytogenes and Escherichia coli O157:H7 inoculated into milk and apple cider; to investigation of the impact of ultrasound treatment on microbiological properties of raw milk and apple cider; and on component interactions in milk; and to evaluate the effects of ultrasound treatment on the appearance of milk and apple cider.
NON-TECHNICAL SUMMARY: Food industry is looking for alternative treatments for heat sensetive materials, e.g., milk and apple cider to avoid side-effects of conventional treatment. The proposal herein seeks to determine if ultrasound can be used as an alternative processing treatment to reduce pathogen levels in milk and apple cider without causing major compositional and structural changes.
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APPROACH: The following experiments will be carried out to assess the effect of various ultrasonic treatments: 1) Effect of ultrasound treatment for one min on total plate count of both milk and apple cider at different temperatures (0, 20 and 55oC); 2) Effect of ultrasound treatment for one min on total plate count of both milk and apple cider at different ultrasound intensity outputs (amplitude) (0, 50, 75, and 100%; 3)Effect of ultrasound treatment at 75% amplitude at 20 or 55oC on total plate count of both milk and apple cider as function of time (1, 3, and 5 min). The effects of ultrasound treament and combination of ultrasound and mild heating on total plate count and pathegenics. Microstructure of milk after treated by ultrasound will also be examined by TEM. The apperance of treated milk and cider will analyzed by a coloremeter and tasted by a trained panel.
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PROGRESS: 2002/10 TO 2005/09<BR>
Outbreaks of foodborne illness associated with apple cider and dairy products have prompted research on the survival of Escherichia coli 0157:H7 and Listeria monocytogenes in these food systems, respectively. Current processing methods utilize heat for bacterial inactivation, and although effective, these applications may cause undesirable changes in the nutritional and sensorial properties of foods. Non-thermal processing technologies are emerging as promising alternatives. Ultrasound induced cavitation is lethal to many bacteria, especially when combined with other microbial reduction strategies such as heat. A 400W ultrasound generator was used to evaluate the effects of batch and continuous flow ultrasonic treatments on the natural flora and Listeria monocytogenes in milk as well as E. coli 0157:H7 in apple cider. Continuous flow ultrasound treatment, when combined with mild heat (57C), for 18 minutes resulted in a 99.999% reduction of L. monocytogenes in UHT milk, 99.999% reduction in total aerobic bacteria in raw milk, and a 99.999% reduction in E. coli 0157:H7 in pasteurized apple cider. Microstructural analysis revealed reduction of fat globule size as well as protein lipid interactions, which may be favorable.
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IMPACT: 2002/10 TO 2005/09<BR>
The results show that ultrasonic treatment coupled with mild heating might be a promising alternative method for milk treatment and apple cider pasteurization to preserve nutrients.