3. DEFINITION
FOOD PRESERVATION IS THE PROCESS TO HANDLE AND
TREAT A FOOD IN ORDER TO CONTROL ITS SPOILAGE BY
STOPPING THE ATTACK AND GROWTH OF FOOD BORNE
DISEASES CAUSING MICROBES; TO AVOID OXIDATION OF
FATS (RANCIDITY) AND TO MAINTAIN THE NUTRITIONAL
VALUE, TEXTURE AND FLAVOR OF THE FOOD.
EXAMPLE:
EXAMPLES OF PRESERVED FOODS INCLUDE PROPERLY
PACKAGED REFRIGERATED, FROZEN, CANNED, AND DRIED
PRODUCTS
4. METHODS OF PRESERVATION
PHYSICAL METHODS:
MOSTLY TEMPERATURE CONTROL METHODS LIKE LOW OR HIGH TEMPERATURES.
CHEMICAL METHODS:
IT INCLUDED CERTAIN ANTIMICROBIAL CHEMICALS SUCH AS SORBATE,
BENZOATES, NITRATES.
5. HIGH TEMPERATURE METHODS
PASTEURIZATION
STERILIZATION
ULTRA-HEAT TREATMENT (UHT)
COOKING
OHMIC HEATING
CANNING
6. PASTEURIZATION
PASTEURIZATION:
IT IS A PROCESS OF HEAT PROCESSING A LIQUID OR A FOOD TO KILL
PATHOGENIC BACTERIA TO MAKE THE FOOD SAFE TO EAT. IT INVOLVES
HEATING THE FOOD TO KILL MOST HARMFUL MICROORGANISMS.
EXAMPLE:
MILK IS A FOOD PRODUCT THAT IS PASTEURIZED WORLDWIDE, BUT
SOME OTHER FOODS ARE NORMALLY PASTEURIZED IN CERTAIN PARTS OF THE
WORLD
LIMITATIONS:
DUE TO LOSS OF CERTAIN ENZYMES IN FOOD DURING PASTEURIZATION
PROCESS, SOME PEOPLE BELIEVE THAT RAW MILK IS A BETTER OPTION TO
PASTEURIZED MILK.
IT IS BELIEVED THAT MILK PASTEURIZED WITH HTST METHOD MAY LOSE
1/3RD OF THE THIAMINE PRESENT IN THE MILK AND HALF OF VITAMIN B12.
8. STERILIZATION
STERILIZATION:
IT IS A METHOD OF DESTRUCTION OF ALL MICROORGANISMS USING
TEMPERATURES ABOVE 100°C. FOR COMPLETE STERILIZATION OF FOODS, THE TIME
AND TEMPERATURE REQUIRED ARE MUCH INFLUENCED BY A NUMBER OF FACTORS LIKE
THE TYPE OF MICROORGANISMS FOUND ON THE FOOD, THE SIZE OF THE CONTAINER,
THE ACIDITY OR PH OF THE FOOD AND THE METHOD OF HEATING.
EXAMPLE:
AUTOCLAVING, DRY HEAT, GAS
LIMITATIONS:
IT IS RELATIVELY SLOW (CAN TAKE A COUPLE HOURS)
MANY OBJECTS CANNOT WITHSTAND THE VERY HIGH TEMPERATURES REQUIRED FOR
DRY HEAT STERILIZATION (EX: SOME PLASTICS WOULD MELT)
10. ULTRA-HEAT TREATMENT (UHT)
DEFINITION:
THE UHT PROCESSING INVOLVES THE USE OF HIGH TEMPERATURES (135–150°C) FOR
SHORT TIMES (A FEW SECONDS) TO ACHIEVE A PRODUCT THAT IS COMMERCIALLY
STERILE.
APPLICATION OF HIGH HEAT DURING THE UHT PROCESS CAN CAUSE MILLARD
BROWNING AND CHANGE THE TASTE AND SMELL OF DAIRY PRODUCTS BUT NOT
SIGNIFICANTLY.
EXAMPLE:
THE MOST COMMON UHT PRODUCT IS MILK, BUT THE PROCESS IS ALSO USED FOR
FRUIT JUICES, CREAM, SOY MILK, YOGURT, WINE, SOUPS AND HONEY.
LIMITATIONS:
MOST OF PEOPLE BELIEVE THAT ENZYMES IN RAW MILK AID DIGESTION AND CALCIUM
ABSORPTION AND THEIR SPECIFIC HEALTH BENEFITS ARE DEBATED WITHIN THE
SCIENTIFIC COMMUNITY. IT IS TRUE THAT THE UHT AND HTST PASTEURIZATION
12. COOKING
DEFINITION:
THIS METHOD IS USUALLY USED TO IMPROVE PALATABILITY RATHER THAN
TO IMPROVE STORAGE QUALITY OF FOOD. IT IS ALSO CALLED BOILING, IS
THE PROCESS OF USING HEAT TO WATER UNTIL THE TEMPERATURE
REACHES ABOUT 100°C.
BOILING OF FOODS IN WATER CANNOT COMPLETELY DESTROY ALL
MICROBES, BUT THE ACTIVELY GROWING (VEGETATIVE) CELLS OF
BACTERIA AND FUNGI (YEASTS AND MOLD) ARE GENERALLY QUICKLY
DESTROYED AT THIS TEMPERATURE IF MAINTAINED FOR A SUFFICIENTLY
LONG PERIOD OF TIME, HELPS THE HEAT TO COMPLETELY PENETRATE THE
FOODS AND KILL THE MICROORGANISMS.
LIMITATIONS:
COOKING DESTROYS THE SPOILAGE CAUSING MICROBES AND REDUCES
THE POSSIBLE RISK OF DISEASE TRANSMISSION BUT IT CAN DAMAGE THE
FOOD’S QUALITIES (I. E. APPEARANCE, TEXTURE AND FLAVOR ETC.) AND
MAY ALSO DESTROY SOME IMPORTANT VITAMINS.
13. OHMIC HEATING
DEFINITION:
AN OHMIC HEATER (ALSO KNOWN AS A JOULE
HEATER) CAN BE USED IN WHICH ELECTRICAL HEATING
DEVICE THAT USES A LIQUID’S OWN ELECTRICAL RESISTANCE
TO GENERATE THE HEAT. PRACTICALLY, OHMIC HEATERS ARE
VERY EFFICIENT WITH OVER 94% OF THE APPLIED ELECTRICAL
POWER CONVERTED TO HEAT AND HAVE BEEN REVEALED TO
IMPROVE THE COLOR AND VITAMIN RETENTION OF FOODS
AND PROVIDE AN EXTENDED SHELF LIFE FOR PASTEURIZED
PRODUCTS WHEN COMPARED TO HOT SURFACE HEATING
DEVICES.
14. CANNING
DEFINITION:
(USING HEAT TO APPROPRIATE TEMPERATURE AND FOR A PRESCRIBED TIME
TO DESTROY MICRO-ORGANISMS, INCLUDING CLOSTRIDIUM BOTULINUM SPORES),
AND SEALED IN AN AIRTIGHT CONTAINER. CANNING PROCESS WAS DEVELOPED BY
NICOLAS APPERT.
STEPS:
STERILIZING THE FOOD PRODUCTS TO BE CANNED.
ASEPTIC PACKING (IN STERILE, AIR-TIGHT STAINLESS METAL, GLASS OR PLASTIC
CONTAINERS) AND FOOD MICROBIOLOGY PRESERVATION OF FOODS BY
PHYSICAL METHODS LOW AND HIGH TEMPERATURE.
HERMETICALLY SEALING (WITH A COMPLETE, AIRTIGHT SEAL).
16. FOOD PROCESSING JUICE PRODUCTION
PROCESS
DEFINITION:
FOOD PROCESSING GENERALLY INCLUDES
THE BASIC PREPARATION OF FOODS, THE ALTERATION
OF A FOOD PRODUCT INTO ANOTHER FORM (AS IN
MAKING PRESERVES FROM FRUIT), AND PRESERVATION
AND PACKAGING TECHNIQUES.
EXAMPLE:
CANNING.
17. TECHNIQUES FOR FOOD PROCESSING
DRYING: DRYING REDUCE THE WATER CONTENT IN THE PRODUCT, WHICH IN
RETURN REDUCE THE RISK OF BACTERIAL GROWTH.
PRESERVATION: THIS INCLUDE DESTRUCTION OF MICROORGANISMS AND OTHER
HARMFUL PATHOGENS BY HEATING, DRYING, OSMOTIC INHIBITION AND FREEZING.
SMOKING: MANY FOODS SUCH AS MEAT, FISH AND OTHERS ARE PROCESSED,
PRESERVED AND FLAVORED BY USING SMOKE.
FREEZING: THIS IS THE MOST COMMON TECHNIQUES IN THE WORLD OF TODAY TO
PRESERVE THE FOOD BY FREEZING.
SALTING: THIS IS THE TECHNIQUE USED FOR FOOD PROCESSING BECAUSE SALT
SUCKS OUT THE MOISTURE OF THE FOOD.
VACUUM PACKS: IN THIS METHOD OXYGEN IS EXTRACTED FROM THE BOTTLES OR
BAGS AND THE FOOD IS PACKED IN AIRTIGHT BAGS OR BOTTLES.
18. IMPORTANCE OF FOOD PROCESSING
FOOD PROCESSING IS VERY IMPORTANT IN FOOD INDUSTRY DUE TO ITS SOCIAL,
PHYSICAL AND HEALTH FACTORS.
INCREASE THE SHELF LIFE OF FOOD.
INCREASES FOOD SUPPLY.
RETAIN THE QUALITY OF FOOD.
ADD VARIETY OF FOOD.
DECREASES WASTAGE OF FOOD.
MAKE FOOD AVAILABLE THROUGHOUT THE YEAR.
ENHANCE COLOR, TEXTURE AND FLAVOR OF FOOD.
INCREASE QUALITY AND HYGIENE OF FOOD.
19. CANNING INDUSTRIAL
CANNING
DEFINITION:
CANNING, METHOD OF PRESERVING FOOD FROM
SPOILAGE BY STORING IT IN CONTAINERS THAT ARE
HERMETICALLY SEALED AND THEN STERILIZED BY HEAT.
THE PROCESS WAS INVENTED AFTER PROLONGED RESEARCH
BY NICOLAS APPERT OF FRANCE IN 1809, IN RESPONSE TO A
CALL BY HIS GOVERNMENT FOR A MEANS OF PRESERVING
FOOD FOR ARMY AND NAVY USE.
EXAMPLE:
WHEN YOU CUT UP CUCUMBERS AND MAKE THEM
INTO PICKLES THAT YOU PRESERVE IN A JAR TO EAT
THROUGHOUT THE WINTER, THIS IS AN EXAMPLE OF
CANNING.
20. AUTOCLAVING
DEFINITION:
AUTOCLAVING IS A STERILIZATION METHOD THAT USES HIGH-PRESSURE STEAM. THE
AUTOCLAVING PROCESS WORKS BY THE CONCEPT THAT THE BOILING POINT OF WATER (OR
STEAM) INCREASES WHEN IT IS UNDER PRESSURE.
STRUCTURE:
AN AUTOCLAVE IS BASICALLY A PRESSURE CHAMBER USED TO CARRY OUT ANY PROCESS
THAT REQUIRES HIGHLY ELEVATED TEMPERATURE AND PRESSURE, SUCH AS MEDICAL WASTE
DISPOSAL, AND/OR MEDICAL EQUIPMENT STERILIZATION.
EXAMPLE:
CANNED FOODS ARE STERILIZED IN AN AUTOCLAVE AT ABOUT 121°C FOR 20MIN. HIGHER
TEMPERATURES AND SHORTER TIMES MAY HAVE SIMILAR EFFECTS, E.G. 134°C FOR 3MIN.
21. PRESERVATION OF FOOD BY CANNING
• CANNING IS THE PROCESS OF APPLYING HEAT TO FOOD THAT’S SEALED IN A JAR
IN ORDER TO DESTROY ANY MICROORGANISMS THAT CAN CAUSE FOOD
SPOILAGE. PROPER CANNING TECHNIQUES STOP THIS SPOILAGE BY HEATING THE
FOOD FOR A SPECIFIC PERIOD OF TIME AND KILLING THESE UNWANTED
MICROORGANISMS.
• YOU MAY HEAR OF MANY CANNING METHODS, ONLY TWO ARE APPROVED BY
THE UNITED STATES DEPARTMENT OF AGRICULTURE (USDA). THESE ARE WATER-
BATH CANNING AND PRESSURE CANNING.
22. WATER-BATH CANNING
• THIS METHOD, SOMETIMES REFERRED TO AS HOT WATER CANNING, USES A LARGE
KETTLE OF BOILING WATER. FILLED JARS ARE SUBMERGED IN THE WATER AND HEATED
TO AN INTERNAL TEMPERATURE OF 212 DEGREES FOR A SPECIFIC PERIOD OF TIME.
• USE THIS METHOD FOR PROCESSING HIGH-ACID FOODS, SUCH AS FRUIT, ITEMS MADE
FROM FRUIT, PICKLES, PICKLED FOOD, AND TOMATOES.
ADJUSTMENTS FOR HIGH-ALTITUDE CANNING
• GENERALLY, RECIPES ARE WRITTEN FOR WATER BATH CANNING AT ALTITUDES LESS
THAN 1000 FEET. IF YOU LIVE HIGHER THAN 1,000 FEET ABOVE SEA LEVEL, FOLLOW
THESE GUIDELINES:
FOR PROCESSING TIMES OF LESS THAN 20 MINUTES: ADD 1 ADDITIONAL MINUTE FOR
EACH ADDITIONAL 1000 FEET OF ALTITUDE.
FOR PROCESSING TIMES OF MORE THAN 20 MINUTES: ADD 2 ADDITIONAL MINUTES FOR
EACH 1000 FEET OF ALTITUDE.
23. PROCEDURE OF WATER-BATH CANNING
• GATHER SUPPLIES AND EQUIPMENT; KEEP JARS HOT.
• PREPARE FOOD.
• FILL YOUR JARS, LEAVING PROPER HEADSPACE AND RELEASING AIR
BUBBLES. PUT ON LIDS AND HAND-TIGHTEN SCREW BANDS.
• PLACE JARS IN WATER-BATH CANNER.
• BRING WATER TO BOIL AND ALLOW TO BOIL FOR AMOUNT OF TIME
SPECIFIED IN RECIPE.
• AT END OF PROCESSING TIME, REMOVE JARS AND ALLOW TO COOL
COMPLETELY.
• TEST SEALS.
• STORE!
24. PRESSURE CANNING
• PRESSURE CANNING USES A LARGE KETTLE THAT PRODUCES STEAM IN A
LOCKED COMPARTMENT. THE FILLED JARS IN THE KETTLE REACH AN INTERNAL
TEMPERATURE OF 240 DEGREES UNDER A SPECIFIC PRESSURE (STATED IN
POUNDS) THAT’S MEASURED WITH A DIAL GAUGE OR WEIGHTED GAUGE ON THE
PRESSURE-CANNER COVER.
• USE A PRESSURE CANNER FOR PROCESSING VEGETABLES AND OTHER LOW-ACID
FOODS, SUCH AS MEAT, POULTRY, AND FISH.
ADJUSTMENTS FOR HIGH-ALTITUDE CANNING
PRESSURE CANNING RECIPES ARE GENERALLY WRITTEN FOR ALTITUDES OF LESS
THAN 2000 FEET. IF YOU LIVE HIGHER THAN 2000 FEET ABOVE SEA LEVEL, MAKE
THIS ADJUSTMENT: INCREASE POUNDS OF PRESSURE BY 1/2 POUND FOR EACH
ADDITIONAL 1,000 FEET.
25. PROCEDURE OF PRESSURE CANNING
• GATHER SUPPLIES AND EQUIPMENT; KEEP JARS HOT.
• PREPARE FOOD.
• FILL YOUR JARS, LEAVING PROPER HEADSPACE AND RELEASING AIR
BUBBLES. PUT ON LIDS AND HAND-TIGHTEN SCREW BANDS.
• PLACE JARS IN PRESSURE CANNER.
• CLOSE AND LOCK THE CANNER.
• PROCESS JARS AS OUTLINED IN THE RECIPE.
• AT END OF PROCESSING TIME, ALLOW PRESSURE TO RETURN TO 0.
• REMOVE JARS FROM CANNER AND ALLOW TO COOL COMPLETELY.
• TEST SEALS.
• STORE!
26. TIPS FOR SUCCESSFUL AND SAFE CANNING
USED RECIPES MADE FOR MODERN-DAY CANNING (ABOUT 2000 OR NEWER) AND FOLLOW
THEM EXACTLY. DON’T INCREASE OR DECREASE YOUR INGREDIENTS, PROCESSING TIME, OR
PRESSURE LEVEL (FOR PRESSURE CANNING).
DON’T DOUBLE RECIPES. IF YOU WANT MORE THAN ONE RECIPE, PREPARE THE RECIPE MORE
THAN ONCE.
USE THE PROPER INGREDIENTS: ONLY UNBLEMISHED AND NOT OVERLY RIPE FRUIT OR
VEGETABLES, AND WHEN A RECIPE CALLS FOR SALT, USE ONLY CANNING OR PICKLING SALT.
USE JARS AND TWO-PIECE LIDS APPROVED FOR CANNING, AND NEVER REUSE LIDS.
ALWAYS LABEL AND DATE YOUR FINISHED PRODUCT AND USE WITHIN ONE YEAR OF THE DATE
OF PROCESSING.
PERIODICALLY CHECK YOUR JARS FOR ANY SIGNS OF SPOILAGE AND, IF IN DOUBT ABOUT THE
QUALITY OR SAFETY OF A PRESERVED PRODUCT, DISPOSE OF IT WITHOUT TASTING.
TOOLS AND EQUIPMENT FOR CANNING AND PRESERVING.
27. TIPS FOR SUCCESSFUL AND SAFE CANNING
TONGS: HAVE TONGS READY FOR LIFTING HOT FOODS OUT OF BOILING OR
SIMMERING WATER
CANDY THERMOMETER: FIND A GOOD QUALITY THERMOMETER, WITH A CLIP FOR
ATTACHING IT TO THE SIDE OF A POT. THIS ITEM IS SO USEFUL; IT IS A GOOD IDEA
TO HAVE A BACKUP IN CASE ONE BREAKS WHILE YOU ARE USING IT.
JAR LIFTER: THIS TOOL IS A SPECIALIZED SET OF TONGS. ITS RUBBERIZED ENDS FIT
SECURELY AROUND ANY SIZE CANNING JAR, TO LIFT THEM IN AND OUT OF YOUR
CANNER.
CANNING FUNNEL: USED FOR CANNING FOODS, THIS WIDE MOUTH TOOL KEEPS THE
RIMS OF JARS CLEAN. IT CAN ALSO BE USED TO FILL ZIP LOCK BAGS NEATLY.
CANNING JARS: CANNING JARS ARE MADE FROM TEMPERED GLASS TO WITHSTAND
THE HIGH HEAT AND PRESSURE OF YOUR CANNER.
WATER-BATH AND/OR PRESSURE CANNER. IF YOU’RE GOING TO CAN, YOU MUST USE
THE APPROPRIATE CANNER. FOR CANNING HIGH-ACID FOODS (FRUITS, JELLIES,
RELISHES, AND PICKLES), GET A WATER-BATH CANNER.
28. CANNING STEPS
THE MAIN STEPS IN CANNING ARE:
1. PACKING THE PRODUCT INTO THE CONTAINER.
2. HERMETICALLY SEALING THE CONTAINER. HERMETICALLY SEALED CONTAINER MEANS A CONTAINER
THAT IS DESIGNED AND INTENDED TO BE SECURE AGAINST THE ENTRY OF MICROORGANISMS AND
THEREFORE MAINTAINS THE COMMERCIAL STERILITY OF ITS CONTENTS AFTER PROCESSING.
SEALING GLASS JARS
SEALING METAL CANS
3. THERMALLY PROCESSING THE PRODUCT AND THE CONTAINER TOGETHER.
HIGH-ACID FOODS ARE PROCESSED AT 212° F, 100° C IN WATER BATH CANNER.
LOW-ACID FOODS MUST BE PROCESSED AT 240 - 250° F, 116 - 121° C IN PRESSURE CANNER.
4. COOLING FOODS WHICH WERE PROCESSED IN WATER BATH CANNER IS EASY: REMOVE THE JARS
FROM THE WATER BATH CANNER AND LET THEM SIT UNDISTURBED TO COOL AT ROOM TEMPERATURE
FROM 12-24 HOURS. AS THE TEMPERATURE OF THE PRODUCT DROPS, A VACUUM FORMS INSIDE AND
PULLS DOWN THE LID.
5. STORAGE.
30. CANNED FOOD
CANNED FOODS ARE PRESERVED BY HEAT STERILIZATION IN HERMETICALLY
SEALED CONTAINERS AND KNOWN AS COMMERCIALLY STERILE FOODS. A
HERMETIC SEAL OF A CONTAINER EXCLUDES THE PASSAGE OF GAS OR
MICROORGANISMS. HIGHLY HEAT-RESISTANT AND NONTOXIC THERMOPHILIC
MICROBIAL SPORES REMAIN DORMANT IN COMMERCIALLY STERILE CANNED
FOODS UNDER PROPER HANDLING AND STORAGE CONDITIONS.
31. CLASSIFICATION OF CANNED FOODS BASED
ON ACIDITY:
LOW-ACID CANNED FOODS (PH >5.2). MEAT PRODUCTS, MILK, SEAFOOD, CERTAIN
VEGETABLES, CORN, AND PEARS ARE EXAMPLES OF THIS GROUP.
• MEDIUM-ACID CANNED FOODS (PH 5.2–4.6). MEAT PRODUCTS AND VEGETABLE
MIXTURES ARE EXAMPLES OF THIS GROUP. THESE FOODS CAN BE SPOILED BY
THERMOPHILIC ANAEROBIC BACTERIA
• ACID CANNED FOODS (PH 4.6–4.0). TOMATOES, PEARS, FIGS, PINEAPPLES, OLIVES,
CUCUMBERS, AND OTHER FRUITS ARE CATEGORIZED IN THIS GROUP. THESE FOODS
CAN BE SPOILED BY MESOPHILIC SPORE-FORMING BACTERIA.
• HIGH-ACID CANNED FOODS (PH 4.0). PICKLES, GRAPEFRUIT, CITRUS JUICES,
KETCHUP, ACID VEGETABLES, PINEAPPLES, PEACHES. ICE TEA AND OTHER
CATEGORIZED IN THIS GROUP. THESE FOODS ARE GENERALLY SPOILED BY YEASTS,
MOLDS AND LACTIC ACID BACTERIA.
32. SPOILAGE OF CANNED FOODS
SPOILAGE OF CANNED FOOD PRODUCTS RESULTS FROM
THREE MAIN REASONS:
(1) INADEQUATE HEAT APPLICATION ALLOWS SURVIVAL
AND GROWTH OF MESOPHILIC MICROORGANISMS.
(2) INADEQUATE COOLING AFTER HEATING OR HIGH-
TEMPERATURE STORAGE ALLOWS GERMINATION AND
GROWTH OF THERMOPHILIC SPORE FORMER.
(3) LEAKAGE CONTAMINATION OF CANS.
33. MICROBIAL SPOILAGE
• MICROBIOLOGICAL FOOD SPOILAGE IS CAUSED BY THE GROWTH OF
MICROORGANISMS WHICH PRODUCE ENZYMES THAT LEAD TO OBJECTIONABLE BY-
PRODUCTS IN THE FOOD. CHEMICAL FOOD SPOILAGE OCCURS WHEN DIFFERENT
COMPONENTS IN THE FOOD REACT WITH EACH OTHER OR WITH SOME ADDED
COMPONENT WHICH ALTER THE FOOD'S SENSORY CHARACTERISTICS.
TYPES OF MICROBIAL SPOILAGE
• FLAT-SOUR SPOILAGE (PH 5.3) PRODUCT
• THERMOPHILIC ANAEROBES (PH CAN: SWELLS, MAY BURST BY GAS PRODUCTION
(CO2, H2). PRODUCT
• SULFIDE SPOILAGE (PH 5.3) CAN: FLAT, PRODUCT
34. QUESTIONS
1: HOW CAN YOU DEFINE FOOD PRESERVATION?
2: DOES PASTEURIZATION EFFECT THE TASTE AND
NUTRITIONAL FOOD?
3: WHAT IS FOOD PROCESSING?
4: WHY WE SEAL THE FOOD IN CANNING?
5: WHAT IS THE PURPOSE OF PASTEURIZATION?
6: WHAT ARE THE HIGH TEMPERATURE METHODS?
7: DEFINE MICROBIAL SPOILAGE?
8: DESCRIBE TIPS FOR SUCCESSFUL AND SAFE
CANNING?