<p>Post-harvest spoilage of fresh whole and cut produce is a significant challenge that impacts sustainability, economics and nutritional aspects of fresh produce. Despite significant advances in hurdle technologies including combinations of produce washing and cooling, chemical sanitation and fumigation, refrigerated storage and modified atmospheric packaging, currently over 30% of the fresh produce in North America is wasted and microbial spoilage is one of the leading factors influencing the shelf-life of fresh produce. To address this critical challenge, this proposal evaluates a synergistic interaction of US with (a) sonocatalytic materials to develop novel food-contact surfaces that can minimize or eliminate the risk of cross-contamination and biofilm formation, and (b) microbubbles combined with sonocatalytic food-grade materials to improve inactivation of spoilage microorganisms on fresh produce and wash water while maintaining the quality of fresh produce by avoiding mechanical damage.</p><p> The specific objectives of this proposal are: </p><p><ol><li> Develop sonocatalytic coatings for a low-frequency sonochemical process for enhanced inactivation of spoilage microorganisms on food contact surfaces.</li><li> Develop food-grade microbubble assisted high-frequency sonochemical process for enhanced inactivation of spoilage microorganisms in fresh and cut produce. </li><li> Evaluate the shelf-life of produce and risk of cross-contamination from the proposed technologies and perform cost-benefit analysis.</li></ol></p>
Post-harvest spoilage of fresh produce is a critical challenge. Despite advances in hurdle technologies, over 30% of the fresh produce in North America is wasted, largely due to microbial spoilage that results from- limitations of the current washing and sanitation procedures in achieving a significant inactivation of spoilage microorganisms, cross-contamination, and adaptability of microflora to grow under refrigerated and modified storage conditions. To address these challenges, this proposal evaluates two distinct ultrasound (US) based sonochemical approaches. The aim 1 will focus on a synergistic interaction of low-frequency (<50 kHz) US with sonocatalytic coating on food-contact surfaces to reduce the risk of cross-contamination. We hypothesize that food-grade sonocatalytic materials such as zinc oxide and titanium dioxide will generate sufficient ROS (reactive oxygen species) upon exposure to US to efficiently inactivate spoilage microbes on these surfaces, thus reducing the risk of biofilm formation and cross-contamination. The aim 2 will focus on microbubbles assisted high-frequency (1-10 MHz) US process to inactivate spoilage microorganisms on fresh produce and wash water while maintaining the produce quality. We hypothesize that controlled cavitation from exposure of food-grade microbubbles to high-frequency US (1- 10 MHz) will trigger ROS generation from food-grade sonocatalytic compounds in wash water. Together, they will effectively inactivate microorganisms while minimizing the mechanical damage to fresh produce commonly associated with conventional low-frequency US (~ 50 kHz) . These hypotheses are supported from literature and preliminary work. In aim 3, we will evaluate extension of shelf-life of produce by proposed approaches and perform preliminary cost-benefit analysis.