Ohmic heating can feature a higher energy efficiency, rapidity and uniformity in heating pattern, and cleanability. Novel ohmic heating technique is gaining more interests from real sites due to its successful inhibition of typical side effect, electrochemical reactions at the interface. The potential application could be thermal process of meat products, dairy processing, pasteurization/sterilization of liquid foods, tomato peeling, and fermentation.
Pulsed Electric Field Treatment
The PEF treatment is an emerging technique for food preservation which is based on exposing foods to an electric field. The microbial effect of PEF treatment is due to the membrane electrocompression as a result of the induced transmembrane potential. I have experienced on designing the prototype PEF system with 10 kV to inactivate bacteria in milk. The application of PEF treatment as a non-thermal process can be more effective to reduce microbial load while maintaining food qualities when combined with other processing/techniques.
Fouling on Heat Exchanger Surfaces
Because of milk fouling, dairy industries still keep doing with CIP (cleaning-in-place) process every 5-10 hours, which requires frequent shut down and warm up of system, and use of tremendous amount of water and chemicals. It would be beneficial and timely to rationally address and minimize the problem of fouling in the dairy industry, and by extension to the juice and liquid food industries. Ohmic heating and surface treatment such as coating with specialized materials, i.e. Teflon, carbon powder, and carbon nanotubes would be considered as promising methods to minimize the milk deposits.
Nanotechnology – CNT Application
The CNTs have excellent anti-fouling properties via minimization of the surface energy including desirable attributes – strength, flexibility, and conductivity. We have been engaged in an innovative research of hydrophobic surface coating with carbon nanoparticulates in tube form to effectively address the fouling problem in milk pasteurizers. The CNTs can be adaptable not only to thermal processes but also non-stick and biosensor approach in food industries, i.e. CNT modified electrode.
Detection of the chemical and microbial status of fluid foods has been done using surface plasmon resonance (SPR) biosensors. The SPR biosensor for detection of pathogens such as Salmonella and Listeria in eggs, meat, juice, and milk. Fiber optic fluorescence based biosensors will be applied to monitor pathogens in food and health sectors.
Food borne disease caused by pathogenic microbes that are internalized in vegetable leaves is one of the most important, current food safety issues. A rapid detection method for pathogens was designed, optimized, and determined based on electric field, capillary force, and immunofluorescence reaction. The internalized Esterichia coli cells in spinach were concentrated and captured by the innovative system, and a field emission scanning electron microscopy (FESEM) was used to validate the quantified results.
Potential application areas include followings: Continuous pasteurization & sterilization process of fluid foods, measurement of dielectric properties of microwave foods, thawing of frozen meat products, and design of microwave-assisted extraction and microwave- assisted evaporation systems.
Supercooling is defined as the process of lowering the temperature of a food material below its equilibrium freezing point without the formation of ice crystals. There has been continuous interest in applications of the supercooling technology for food preservation since it promises an extended shelf-life while avoiding ice crystal formation and maintaining fresh textural integrity. Current research has shown clear benefits of supercooling preservation over the conventional cold storage methods. As supercooling was found to have a sizable improvement over refrigeration on a perishable product’s shelf life, the implementation of supercooling areas in household and commercial refrigeration units would help in diminishing food waste. (Color changes in tuna after 8 days supercooling)
Videos show the behaviors of a water droplet on the developed CNT-PTFE nanocomposite (middle picture) and the stainless steel 316 (control) (right picture) surfaces. Nanocomposite coating can prevent water droplet from being absorbed into the surface. The water repellent phenomenon observed in a nature which is so called "lotus effect" led to the development of a self-cleaning surface in which the surface impurities (or fouling) will be swept away from surface by mean of flowing water.
Fresh fruits are susceptible to microbial contamination after harvest due to their high water and nutrient contents. Due to regulatory restrictions on the post harvest use of chemicals, there is a renewed interest in alternative physical decontamination techniques. The concept of 'selective heating' can deliver a certain lethal energy only to microorganisms without damaging adjacent food components. The photothermal effect selectively destroys targeted cells without affecting the nearby cells or tissues by tuning the wavelength of the CO2 laser to the maximum absorption peaks of targeted cells where most biological entities will not respond.