Microwave and RF Plasma Microwave Ohmic Heating Why nonthermal processing? • Enhance microbiological safety • Extend shelf life • Low temperature exposure to food products– minimal effect on heat sensitive components • flavor & functional compounds • Fresh like attributes • Shelf stable products can be processed by combining with a moderate heat treatment. High Pressure Processing Pulsed Electric Field Processing Ozone Processing Irradiation HIGH PRESSURE PROCESSING Elevated pressures (up to 120,000 psi or approximately 900 MPa) with or without addition of heat to achieve microbial inactivation or to alter the food attributes in order to achieve desired qualities. • Quality Similar to Fresh Products – Juices, Seafood, Jam, Avocado, Oysters, Purees, Sauces, Coffee drink – Pasteurized and shelf stable high acid food products – Pasteurized low acid products – Shelf stable low acid products • Equipment/processing costs are comparable to similar processes – Typically < $.05/lb Semi-Continuous BATCH Concept from Flow International, Kent, WA Pressure T m Temperature P2 P1 T2 Ts Ps Pf Tf ts t1 Come-Up t2 Hold ing tf Decompression Packaging • Flexible packaging is widely used – At least one interface of the package should be flexible for pressure transfer – Minimize headspace • Air has different compressibility than food Process and products development PRODUCT NEW Process OLD related limitations PROCESS Value added NEW OLD Compete against existing product MICROBIAL SAFETY • HPP treatments are effective in inactivating most of the vegetative microorganisms, with pressures between 200 and 600 MPa at ambient temperatures. • Gram-positive organisms are more resistant than Gram negatives. • There can be variations in pressure resistances between strains. Combined effect of pressure and temperature on C. botulinum spore inactivation • 0 -1 Log (N/No) -2 -3 35oC 40oC -4 45oC 50oC • -5 -6 550 600 650 700 750 800 850 Pressure (MPa) Reddy et al., 1999 • Achieved a 5-log reduction of type E spores in phosphate buffer and model food system such as crab meat blend Spores of nonproteolytic type B strains (17-B and KAP9-B) in both phosphate buffer and crab meat blend offer higher resistance Research is in progress to identify most resistant C. OSU HPP Facilities •HPP pilot plant with kitchen •Custom made equipment for microbial inactivation, in-situ property measurement under pressure High Pressure Research Program at OSU • High pressure processing of low-acid shelf-stable foods • Control of food pathogens and spoilage organisms in food products • Mathematical modeling of high pressure process and food property measurement under pressure • Quality of high pressure processed products • Impact of high pressure processing on packaging materials • Consumer acceptance of high pressure processed foods • High pressure pasteurization of cheese, milk, and meat products Pulsed Electric Field Processing • Application of short burst of high voltage (approx. 30-50 kV/cm) to foods placed between two electrodes – pulses applied at ambient or refrigerated temperatures for short treatment time of seconds or less Potential Food Applications • Juice • Milk • Liquid eggs • Soups • Syrups, sauces • Emulsion • Flavor ingredients Simplified PEF Equipment Layout Power Supply Capacitor Inductor Provide Energy Store Energy Switch Release Energy Treatment chamber Process Food Variables in PEF processing Primary Secondary • Electric field strength • Processing/conditioning temperature • Electrical conductivity / ionic strength • Growth stage of microorganisms / adaptation • pH • gas liquid mix – Average peak field U/d – Uniformity of field • Total treatment time – Resident time in PEF zone – Flow velocity profile – Pulse repetition rate – Number of PEF chambers Microbiological Resistance – Bacteria > Yeasts – Gram (+) > Gram (-) – Bacterial spores & Mold ascospores > Vegetative cells – Stationary or Lag growth phase > Logarithmic phase Mechanism for cell destruction a - Cytoplasm • • • • + b + + + + Medium + + + + + + c d (a) Cell membrane with a potential V’m, (b) membrane compression, (c) pore formation, reversible breakdown, (d) large pores are formed, irreversible dielectric breakdown (cited Zimmermann, 1986) OSU-6 Commercial Scale PEF processing system Aseptic processing system, 0-60kV output, 75kW, 2-8 chambers, up to 2000L/h Food products evaluated using PEF at OSU • • • • • • • • Orange juice Tomato juice Apple cider Peach nectar Yogurt drink Beer Apple sauce Salsa • Salad dressing •Wheat grass juice •Milk •Chocolate milk •Soymilk •Enriched soymilk •Rice pudding •Liquid egg •Liquid egg white •Liquid egg Yolk How can we help you? • • • • • Technology evaluation Lab scale studies Pilot scale product tests Product development technology Evaluation of processing effects on food attributes SUMMARY – Nonthermal processing technologies offer UNIQUE opportunities and challenges. – Nonthermal technologies such as high pressure processing likely to be used commercially before it could be well understood scientifically to exploit its full potential. • Refrigerated products are commercially available. • Shelf-stable low-acid foods require further research and regulatory approval. • Identification of suitable products is critical. …a safer world through food safety and technology research Thank you! High voltage arc discharge http://www.designer-bg.com/tok-v-gazove/en/images/dygov.gif Pulsed light Oscillating magnetic fields Irradiation