**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** SUMMARYTHERE HAS BEEN AN INCREASE IN DEMAND FOR MINIMALLY PROCESSED FLUID FOODS. HOWEVER, FLUID FOODS SUCH AS RAW MILK AS WELL AS FRESH FRUIT AND VEGETABLE JUICES HAVE A SHORT SHELF LIFE OF A FEW DAYS UNDER REFRIGERATION IN ADDITION TO THE RISK OF DISEASE OUTBREAKS AND FOOD POISONING. TO REDUCE MICROBIAL CONTAMINATION AND EXTEND SHELF LIFE, MILK AND JUICES ARE PASTEURIZED AND THEN STORED UNDER REFRIGERATION. HOWEVER THERMAL PASTEURIZATION CAUSES OFF FLAVORS, ESPECIALLY IN FRUIT AND VEGETABLE JUICES, AS WELL AS REDUCES NUTRITIONAL CONTENTS. IN THEORY, MILK AS WELL AS FRESH FRUIT AND VEGETABLE JUICES CAN BE FROZEN AT ATMOSPHERIC PRESSURE TO EXTEND SHELF LIFE. HOWEVER, THERE ARE DRAWBACKS TO FREEZING THESE PRODUCTS, SUCH AS PHASE SEPARATION, SIGNIFICANT COLOR CHANGES, LOSS OF AROMA AND TASTE, PRODUCTION OF OFF FLAVORS AND NUTRITIONAL LOSS. IN ADDITION,FREEZING DOES NOT INACTIVATE ALL MICROORGANISMS, SO THESE PRODUCTS NEED TO BE PASTEURIZED OR STERILIZED BEFORE FREEZING. CONSEQUENTLY, FROZEN MILK AND FROZEN FRESH JUICES ARE NOT COMMERCIALLY AVAILABLE.IN THISPROJECT WE WILL DEVELOP A NOVEL ISOCHORIC FREEZING SYSTEM AS A ONE STEP PROCESS TO PRESERVE AND PASTEURIZE FLUID FOODS. ISOCHORIC FREEZING CAN BE USED TO PRESERVE FOODS AT SUBFREEZING TEMPERATURES WITHOUT ICE FORMATION INSIDE THE FOOD. THIS PREVENTS PHASE SEPARATION OF FLUIDS, ESPECIALLY OIL IN WATER EMULSIONS. THE LOW, SUBFREEZING TEMPERATURES SHOULD ALSO PRESERVE THE NUTRITIONAL AND SENSORY PROPERTIES OF THE FLUID FOODS. WE HAVE ALSO FOUND THAT ISOCHORIC FREEZING OF FLUIDS AT -15°C FOR 1 DAY LED TO COMPLETE INACTIVATION OF PATHOGENIC BACTERIA FROM AN INITIAL CONCENTRATION OF 7 LOG CFU/ML. THIS EXTENDS THE SHELF-LIFE AND GREATLY REDUCES FOOD WASTE. PRELIMINARY CALCULATIONS ALSO INDICATE THAT ISOCHORIC FREEZING IS LOWER IN ENERGY THAN TRADITIONAL FREEZING, AND PASTEURIZATION BY ISOCHORIC FREEZING IS LOWER IN ENERGY THAN VAT PASTEURIZATION OF MILK. IN ADDITION, AN ISOCHORIC SYSTEM SIMPLY CONSISTS OF A RIGID CHAMBER AND CAN BE EASILY INTEGRATED INTO COOLING UNITS USED IN INDUSTRY. THIS NOVEL ISOCHORIC SYSTEM PROVIDES A SIMPLE, ONE STEP PROCESS TO PRODUCE SAFE, HIGHER QUALITY FLUID FOODS WITH EXTENDED SHELF LIVES AT REDUCED ENERGY CONSUMPTION.WE PLAN TO EXAMINE THE USE OF ISOCHORIC FREEZING ON SIX FLUID FOODS: MILK, ORANGE JUICE, APPLE JUICE, CARROT JUICE, POMEGRANATE JUICE AND CREAMY TOMATO SOUP.WE WILL OPTIMIZE THE ISOCHORIC CONDITIONS TO PASTEURIZE AND PRESERVE THESE FOOD PRODUCTS WHILE USING THE LEAST AMOUNT OF ENERGY. WE WILL ALSO DESIGN AND BUILD LIGHTER AND LARGER ISOCHORIC CHAMBERS.THE GENERAL GOAL OF THIS FOUR-YEAR PROJECT IS TO DEVELOP THE TECHNOLOGY TO AN ADVANCED LEVEL THAT WILL FACILITATE COMMERCIAL INCORPORATION IN THE FROZEN FOOD INDUSTRY.

Agricultural Research Service

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