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        YOGHURT MANUFACTURE TECHNOLOGY

        放大字體  縮小字體 發(fā)布日期:2006-08-26  來源:食品論壇 食品安全衛(wèi)士 提供
         
        LECTURE PLAN
         
         
        HISTORICAL CONSIDERATIONS
        PRESENT SITUATION
        Production data
         
         
         
        I         GENERAL CONSIDERATIONS ON YOGHURTS MANUFACTURE
         
        II         YOGHURTS QUALITY
         
        III         KEY POINTS ABOUT YOGHURTS
        MANUFACTURE PROCESSES
         
        III.1 - MIXES (CULTURE MEDIUM) PREPARATION
         
        III.2 - FERMENTATION PROCESS
         
                    III.3 - COOLING – MECHANICAL TREATMENTS
         
                    III.4 - FROM PACKAGING TO COLD STORAGE
         
        III.5 – CLEANING IN PLACE – PROCESS
                           AUTOMATION
         
        IV         CONCLUSIONS


        -T 3
         
         
         
         
        HISTORICAL CONSIDERATIONS
        _____________________________________________
         
         
         
         
         
        è APPARITION 8 000 TO 10 000 YEARS AGO (MESOPOTANIA, EGYPT, INDIA, NORTH-EAST OF AFRICA)
         
        Ä LINKED TO ANIMALS DOMESTICATION
         
        Ä A WAY OF MILK PRESERVATION
         
        Ä IMPORTANT BENEFITS FOR HUMAN HEALTH
                 AND NUTRITION
         
         
        è CENTURIES AND CENTURIES OF TRADITIONAL HANDICRAFT MANUFACTURE … ACCORDING TO PEOPLE'S TRADITIONS AND ENVIRONNE- MENTAL CONDITIONS
        (MORE THAN 400 GENERIC NANES ;
        NOT ONLY BASED ON LACTIC FERMENTATION)
         
        è LARGE SPREADING OVER ALL THE WORLD


        -T 4
         
         
         
         
        PRESENT SITUATION
         
        __________________________________________________
         
         
         
         
        è INDUSTRIALISATION OF THE YOGHURT MANUFACTURE IS 30 TO 40 YEARS OLD
         
        è LARGE MULTINATIONAL COMPAGNIES ARE INVOLVED
         
        è A LOT OF YOGHURT TYPES AVAILABLE ACCORDING TO CONSUMERS DEMAND
         
        è WELL ESTABLISHED MANUFACTURING
        PROCESSES              ð BETTER QUALITY CONTROL
                                                            ð PROCESS PRODUCTIVITY
                                                                 IMPROVEMENT
         
        è RESPECT OF THE REGULATIONS ESTABLISHED BY EACH DIFFERENT COUNTRY
         


        -T 5
        LACTIC ACID FERMENTATION
        ______________________________

        LACTOSE
         
        STARTER CULTURE
        LACTIQUES
         
        GALACTOSE
        GLUCOSE
         

         
         
         
         
         


                                                             +      

        LACTIC ACID
        +
        AROMA
        COMPOUNDS
        +
        TEXTURING
        COMPOUNDS
         

         
         
         
         
         
         
         


        Þ Symbiotic cultures : Streptococcus
                  thermophilus and Lactobacillus bulgaricus
         
        Þ Galactose accumulation,
                   glucose utilisation
         
        Þ The accumulation of the lactic
                    acid leads to an acidification of
                    the mix (pH decrease)
         
        Þ Milk coagulation when pH ~ 5.2
         
        Þ Production of aroma COMPOUNDS        (acetaldehyde) and of texturing
                    compounds (E.P.S.)


        -T 6
         
         
        FRENCH YOGHURT DEFINITION
        __________________________________________________
         
         
        è THE FRENCH REGULATION FIXED THE CONCENTRATION OF :
         
        ÄLACTIC ACID ³ 7.0 g/l
         
        ÄALIVE THERMOPHILIC LACTIC BACTERIA ³ 107b/g
        (only Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus are allowed)
         
        ÄADDITIVES £ 30% w/w
        (fruits, sugar, flavouring agents)
         
        è OTHERS INDICATIONS MUST BE GIVEN :
         
         
        ÄFAT CONTENT
         
        ÄMILK ORIGIN (ANIMAL)
         
        ÄNATURE OF ALL THE ADDITIVES
         
        Ä STORAGE TEMPERATURE
         
        Ä MAXIMUM STORAGE TIME
         
        è EXCEPT FOR SUGAR, ALL "MIXES" COMPONENTS MUST COME FROM MILK


        -T 7
         
        TYPES OF YOGHURTS AVAILABLE
        ________________________________
         
         
        1)                  TEXTURE
         
        ð SET TYPE YOGHURTS
        ð STIRRED TYPE YOGHURTS
        ð DRINKING YOGHURTS
         
        2)                  FAT CONTENT
         
        ð LOW FAT
        ð MEDIUM FAT
        ð FULL FAT
         
        3)                  FLAVOR
         
        ð PLAIN (NATURAL) YOGHURTS
        ð FRUIT ADDITION
        ð FLAVOURED YOGHURTS
         
        4)                  DIVERSIFICATION IN PRODUCTS AND MANUFACTURING CONDITIONS
         
        ð VEGETABLE OILS ADDITION
        ð HEAT TREATMENT
        ð VITAMIN FORTIFICATION
        ð ENZYME HYDROLYSIS


        -T 9
         
        SIMPLIFIED YOGHURT MANUFACTURE
        FLOW-SHEET
        __________________________________________________
         
         
        3 MAIN STEPS CAN BE DEFINED :
         
         
        1)                  PREPARATION AND PHYSICAL
        TREATMENTS OF THE MIXES
         
        2)                  Ö     INOCULATION OF THE MIX
        Ö       LACTIC ACID FERMENTATION
            (INCUBATION IN CUPS OR IN TANKS)
         
        3)                  COOLING, FILLING, PACKAGING*
        AND COLD STORAGE
         
        -----------------------------------------------------------------
        *FOR SET YOGHURTS FILLING AND PACKAGING
        ARE DONE BEFORE FERMENTATION.
        THEIR INCUBATION IS DONE IN WARM ROOMS


        T 10
         
         
         
        MAIN YOGHURT QUALITY CRITERIA
        ___________________________________________
         
         
        1)                  ORGANOLEPTIC EVALUATION
         
        ð       ACIDITY
        CONSUMERS ARE SELECTING "NON ACID" YOGHURTS
         
        ð        TEXTURE
        Ÿ KEY PARAMETRE (PIECES OF FRUIT
             HOMOGENITY INTO THE BULK)
        ŸON SPOON AND IN MOUTH APPRECIATION
         
        ð        FLAVOR
        THE "YOGHURT TASTE" (BASED ON ACETALDEHYDE) IS VERY COMPLEX
         
         
        2)        OTHERS FACTORS
         
        ð        NO SYNERESIS
               EXUDATION OF WHEY IS BADELY APPRECIATED BY
               THE CONSUMERS
         
        ð        GEL HOMOGENITY
               MICROSTRUCTURE, GRANULARITY
         
        ð        COLOUR
         


         
        -T 11
         
         
        METHODS FOR
        YOGHURT QUALITY
        DETERMINATION
        ______________________
         
         
        ACIDITY
         
        Ÿ pH
        Ÿ LACTIC ACID CONTENT
         
        ð      MEASUREMENT AS A FUNCTION OF :
        * FERMENTATION TIME,
        * STORAGE TIME (POST-ACIDIFICATION)
         
        ACIDIFICATION RATE (STARTER + PROCESS
        PROPERTIES)
         
        Ÿ THE CINAC SYSTEM
         * pH = f (TIME)
         * dpH/dt = f (TIME)
         * KEY DESCRIPTORS :
        - Vm :             MAXIMUM ACIDIFICATION RATE
        - Tm :              TIME TO OBTAIN Vm
        - pHm :           pH CORRESPONDING TO Vm
        - TpHi :           TIME TO REACH A CERTAIN pHi


        -T 12
         
        METHODS FOR
        YOGHURT QUALITY
        DETERMINATION
        _____________________
         
         
        è A LOT OF MORE OR LESS EMPIRICAL METHODS
         
        ·         POSTHUMUS FUNNEL
        ·         BROOKFIELD (LARGE INDUSTRIAL UTILISATION)
        ·         BOSTWICK CONSISTOMETER
         
        è TEXTURE (FIRMNESS CARACTERISATION)
         
        ·         PENETROMETRY
        ·         ROPINESS ASSESSEMENT
         
        è RHELOGICAL BEHAVIOUR
         
        ·         OSCILLATORY MEASUREMENTS ON A CONE/PLATE INSTRUMENT
        ·         OBTENTION OF THE CHANGE OF COMPLEX VISCOSITY VERSUS STRESS INCREASE
         


        -T 13
         
        METHODS FOR
        YOGHURT QUALITY
        DETERMINATION
        _________________________________________
         
        ANALYSIS OF FLAVOUR COMPOUNDS
         
        ·      GAS CHROMATOGRAPHY
        (+ MASS SPECTROMETRY)
        ·      LIQUID CHROMATOGRAPHY
        ·      COLORIMETRIC TESTS
         
        è4 MAIN CATEGORIES OF COMPOUNDS :
         
        ·      CARBONYL COMPOUNDS (ACETALDEHYDE, ACETON, ACETOÏN, DIACETYL)
        ·      NON-VOLATILE ACIDS (LACTIC, PYRUVIC, OXALIC)
        ·      VOLATILE ACIDS (FORMIC, ACETIC, PROPIONIC)
        ·      SOME AMINO ACIDS
         
        è ACETALDEHYDE IS THE KEY COMPOUND
        (2 TO 75ppm)
         
        ·      INCREASE IN MIXED CULTURES
        ·      DECREASE DURING STORAGE
        ·      MOST OF THE OTHER COMPOUNDS MUST BE PRESENT


        -T 14
         
         
         
         
         
        METHODS FOR
        YOGHURT QUALITY
        DETERMINATION
         
         
        SOME OTHER QUALITY CRITERIA
         
        è MICROBIOLOGICAL COMPOSITION
         
        ·         GOOD AMOUNT OF ALIVE LACTIC BACTERIA
        ·         AVOID CONTAMINANT FLORA
         
        è COLOUR – COLORIMETRY
         
        ·         WHITE COLOUR (NATURAL YOGHURTS)
        ·         "FRUIT" COLOUR/FLAVOUR COLOUR
         
        è GEL HOMOGENITY
         
        ·         AVOID BUBLES AND GRANULAR COAGULUM
         
        è SYNERESIS = VOLUME OF WHEY OBTAINED AFTER SOME DAYS
         
        ·         LIMIT WHEY EXUDATION AND INCREASE WATER-BINDING CAPACITY
         


        -T 15
         
         
        METHODS FOR
        YOGHURT QUALITY
        DETERMINATION
         
         
         
        SENSORY ANALYSIS
         
        ·         EXPERTS TRAINED PANEL (10-20 PEOPLE)
        ·         CONSUMERS TRAINED PANEL (100 PEOPLE)
         
        è VERY TIME CONSUMING AND EXPANSIVE
         
        è AGREEMENT AND TRAINING ON TEST METHODS AND SPECIFIC TERMINOLOGY (YOGHURT ATTRIBUTES)
         
        è HOW TO SELECT ONLY A FEW NUMBER OF KEY ATTRIBUTES


        -T 16
         
         
        CULTURE MEDIUM (MIX) PREPARATION
        ___________________________________________
         
         
         
        1)                  COMPOSITION OF THE MIXES
         
        Ü GENERAL RULE
         
        ð         UTILISATION OF A MILK BASE
        ð         FAT CONTENT STANDARDISATION
        ð         PROTEIN ENRICHMENT
        Ÿ MILK AND/OR CASEINE POWDER ADDITION
        Ÿ CONCENTRATION (EVAPORATION, U.F.)
        Ÿ NON-MILK PROTEINS ARE NOT ALLOWED
        IN ALL COUNTRIES
         
        Ü FRUIT/FLAVOURED YOGHURTS
         
        ð             ADDITION OF PIECES OF FRUIT
        ð              ADDITION OF SUGAR OR SWEETENING AGENTS
        ð              ADDITION OF FLAVOURING AGENTS


        -T 17
         
         
        CULTURE MEDIUM (MIX) PREPARATION
        ___________________________________________
         
         
         
         
        Ü OTHER YOGHURTS
         
        ð             ADDITION OF OTHERS ADDITIVES (WITH POSSIBLE
         RESTRICTIONS COUNTRY BY COUNTRY)
         
        Ÿ STABILIZERS/EMULSIFIERS (POLYSACCHARIDES)
        Ÿ VITAMINS (A, C ….)
        Ÿ VEGETAL FAT, FATTY ACIDS
        Ÿ PRESERVATIVES (SORBIC AND BENZOIC ACIDS,
        SULFUR DIOXYDE)
        Ÿ MINERAL CONTENT MODIFICATION (Mg2+, Fe2+, Ca+)
        Ÿ FOOD COLOURANTS (10 - 15 COLOURANTS)


        -T 18
         
         
         
        CULTURE MEDIUM (MIX) PREPARATION
        ___________________________________________
         
         
        2)                  PHYSICAL TREATMENTS OF THE MIXES
         
        2.1 – HOMOGENISATION
         
        ð      TO OBTAIN A FAT-IN-WATER EMULSION
         (NO FAT LAYER AT THE TOP OF THE YOGHURT)
         

        CONDITIONS
         
        CONSEQUENCES ON YOGHURT
         
         
         
         
         
        VISCOSITY
         
         
        ARE IMPROVED
        150 - 200 bars
         
         
        SYNERESIS
        60 - 70 °C
         
         
        WHITE COLOUR
         
        MICRO STRUCTURE

         


        T 19
         
         
         
        CULTURE MEDIUM (MIX) PREPARATION
        ___________________________________________
         
         
         
         
        2.2 – HEAT TREATMENT
         
        ð      "HIGH PASTEURISATION" (95°C – some minutes)
         
        ð      "LOW PASTEURISATION" (80°C <) AND UHT TREATMENT ARE LESS EFFICIENT
         
        ð      EFFECTS : Ÿ DESTRUCTION OF MICROORGANISMS
         Ÿ WHEY PROTEINS DENATURATION
         Ÿ INCREASE GEL CONSISTENCY AND
        STABILITY
         
        ð      THE FERMENTATION TEMPERATURE (40-45°C) IS FIXED AT THE OUTSIDE OF THE HEAT EXCHANGER


        T 19b
         
         
         
         
        EFFECT OF HOMOGENISATION AND HEAT TREATMENT ON THE CONSISTENCY/VISCOSITY OF YOGHURT
         
         
         
         Heat treatment of milk for 30 min at

        Measurement of consistency/visco
        sity of yoghurt
         
        70°C
         
        78°C
         
        86°C
         
        95°C
         
        H
         
        NH
         
        H
         
        NH
         
        H
         
        NH
         
        H
         
        NH
        Falling sphere a (depth, cm)
        Posthumus FUNNEL b
        (time, s)
         
        3.0
         
        >15.0
         
        1.5
         
        10.5
         
        1.2
         
        6.0
         
        1.2
         
        2.7
         
        9.0
         
        5.0
         
        14.0
         
        7.5
         
        17.0
         
        8.5
         
        18.7
         
        9.0

         
         
         
        a) Falling sphere : the deeper the sphere sinks into
               the yoghurt, the thinner is the product.
        b) Posthumus funnel : the longer the time required for
        the yoghurt to pass through the funnel, the more viscous is the product.
         
        h : HOMOGENISED MILD – NH : NON-HOMOGENISED MILK
                                                                                                                     (From TAMIME, 1999)
         


         
        -T 21
         
        FERMENTATION PROCESS
        _______________________
         
         
         
        3) MIXED CULTURES PROPERTIES
         
         

        ·    IMMEDIATE ACIDIFICATION
        ·    IMPORTANT AND FAST BACTERIA GROWTH
        ·    RAPID AND LONG-TIME ACIDIFICATION
         
         
        CONTROL OF FERMENTATION LENGTH
         
        ·    SMALL (OR NONE) POST ACIDIFICATION (COOLING, PACKAGING, STORAGE)
        ·    SUITABLE TEXTURE AND VISCOSITY
        ·    GEL RESISTANCE TO MECHANICAL DESTRUCTURATION
        ·    APPROPRIATE FLAVOUR
         
         
         
        CONTROL YOGHURT QUALITY
         

         


        -T 22
         
        FERMENTATION PROCESS
        _______________________
         
         
         
        B - FERMENTATION IMPROVEMENT
         
        è MODIFICATION OF THE STRAINS INVOLVED IN THE STARTER
         
        ·         INTRODUCTION OF NEW STRAINS WITH KNOWN PROPERTIES
        ·         OTHER RATIO OF THE SAME STRAINS
         
        è MODIFICATION OF THE STARTER PRESENTATION AND/OR INOCULATION AMOUNT
         
        è OPTIMISATION OF THE YOGHURT MANUFACTURE CONDITIONS


        -T 23
        FERMENTATION PROCESS
        _______________________
         
         
        PROCESS MONITORING
         
        è TEMPERATURE CONTROL IS QUITE IMPOSSIBLE :
         
        ·         FIXED BY THE OUTSIDE TEMPERATURE OF HEAT TREATMENT
        ·         A VERY "HEAT SENSIBLE" PROCESS
         
        è pH AND ACIDIFICATION RATE ARE KEY PARAMETERS
         
        ·         pH ON-line MEASUREMENT IS NOT AVAILABLE
        ·         THE CONCEPT OF ACIDIFICATION RATE IS NOT YET POPULAR
         
        è FERMENTATION END-TIME INITIATE THE COOLING STEP
         
        ·         STRONG EFFECT ON YOGHURTS QUALITY
        ·         DEFINED FROM pH MEASUREMENTS AFTER SAMPLING


        -T 24
         
         
        FERMENTATION PROCESS
         
         
        FUTURE INNOVATIONS IN PROCESS MONITORING
         
        1)                  INDIRECT pH MEASUREMENT
         
        ·            pH CLASS PROBES ARE NOT ALLOWED
        ·            ELECTRICAL CONDUCTIVITY METHOD
        ·            THERMAL METHOD
         
        2)                  PREDICTION OF FERMENTATION
        END-TIME
         
        ·            PREDICTION OF pH DECREASE VERSUS FERMENTATION TIME
         
        3)                  OPTIMISATION OF YOGHURT QUALITY
         
        SEE CONCLUSION


        T 25
        COOLING
        _____________________________
         
         
        è TWO TYPES OF PROCESSES FOR :
         
        ÄSET YOGHURT
         
        ÄSTIRRED YOGHURT
         
        è SET YOGHURT
         
        ÄSMALL UNITS : WATER BATH OR CABINETS
         
        ÄLARGE UNITS : ROOMS INCUBATION TEMPERATURE,
        AND TUNNELS (WARM AND CHILLED)
        ·        AIR TEMPERATURE CONTROL, AIR CIRCULATING
        CONDITIONS, AND COOLING CAPACITY ARE IMPORTANT
         
        è STIRRED YOGHURT
         
        ÄAGITATION IN TANK AND CONTINOUS COOLING
        (HEAT EXCHANGERS)
         
        ·   RAPID COOLING
         

        IMPORTANT SHEAR STRESS
        (MIXER, PIPES, PUMPS, EXCHANGER…)
         
         
        COAGULUM
        DESTRUCTURATION (LOSS OF VISCOSITY)
         
         

         
         
         
         
         
         



        -T 26
         
         
        PACKAGING
        ______________________________
         
         
         
        1)            MAIN FUNCTIONS OF PACKAGING :
         
        ë                PROVIDE PROTECTION
         
        ë                BRING A MESSAGE TO THE BUYER
         
        ë                FACILITATE THE HANDLING
         
         
        2)           TWO STAGES FOR PACKAGING :
         
        ë                 SET YOGHURT : BEFORE FERMENTATION
        (LOW VISCOSITY)
         
        ë                 STIRRED YOGHURT : AFTER FERMENTA-
        TION AND PRECOOLING (HIGH VISCOSITY)
         


        -T 27
         
         
        PACKAGING
        ___________________________
         
         
         
        3)            TWO KINDS OF PACKAGING EQUIPMENT :
         
        ë                 FILL – SEAL TECHNIQUE (FS)
         
        ë                  FORM – FILL – SEAL TECHNIQUE (FFS)
         
         
        4)            PACKAGING EQUIPMENT CHARACTERISTICS:
         
        ë                 MECHANICALLY SOPHISTICATED
         
        ë                 FULLY AUTOMATION
         
        ë                 CLEAN, ULTRACLEAN OR ASEPTIC
        MACHINES
         
        ë                 VERSATILY (FLAVOR, SIZE, PRODUCT
         PRESENTATION)
         
        ë                 IMPORTANT INVESTMENT


        -T 28
         
        OVER PACKAGING – PALLETISATION –
        COOLING – STORAGE
        _____________________________________
         
         
        è OPERATIONS FULLY AUTOMATED IN LARGE PLANTS
         
        è FIVE STEPS :
         
        ·         PLACEMENT OF YOGHURT CUPS IN CARDBOARD TRAYS
         
        ·         PALLETISATION OF THE TRAYS
         
        ·         COOLING OF THE PALLETISED YOGHURTS (CHILLED TUNNEL)
         
        ·         PLASTIC OVERWRAPPING OF THE COOLED PALLETISED YOGHURTS
         
        ·         COLD STORAGE (4°C) BEFORE DISTRIBUTION AND RETAILING
         
        è THE LOW TEMPERATURE CHAIN MUST BY RESPECTED TO OBTAIN HIGH QUALITY AND SAVE YOGHURTS


        -T 29
         
         
        CLEANING – IN – PLACE (C.I.P.)
         
         
        è  GENERALISED PROCEDURE : MANUAL WASHING HAS DISAPPEARED
         
        è PLANTS AND MACHINES ARE DESIGNED TO ALLOW C.I.P.
         
        è MAIN AGENTS/ACTIONS
         
        ·         HEAT TREATMENT (STEAM)
         
        ·         CHEMICAL AGENTS (DETERGENTS, SURFACE ACTIVE, STERILISING…)
         
        ·         MECHANICAL ACTION (PRESSURE, FLOW RATE)
         
        ·         WATER (ONLY FOR RINCING).


        -T 30
         
        PROCESS AUTOMATION
         
         
         
        è INDUSTRIAL PLANTS ARE LARGELY AUTOMATED
         
        ·         CONTROL LOOPS (TEMPERATURE, FLOW RATE, WEIGHT…)
         
        ·         SEQUENTIAL MONITORING (INCLUDING C.I.P.)
         
        ·         PROCESS SUPERVISION WITH KEY DATA
         
        è OPTIMAL QUALITY CONTROL DOES NOT EXIST : SOME STRATEGIC DECISIONS ARE ON THE OPERATOR RESPONSABILITY
         

        BENEFITS
        DRAWBACKS
         
        ð      SECURITY
        ð      PRODUCT TRACEABILITY
        ð      LABOR COST REDUCTION
        ð      CENTRALISED
                                  INFORMATION
         
         
        ð      EXPENSIVE
        ð      SPECIFICITY
        ð      POOR FLEXIBILITY

         


        -T 31
         
        CONCLUSION
         
         
        MANUFACTURING A HIGH QUALITY YOGHURT IS EASY
         
        YOU REQUIRE FOLLOWING TAMIME AND ROBINSON ADVICE (1999)
         
        ·        MILK OF GOOD QUALITY AND ADEQUATE FORTIFICATION
        ·        CORRECT HEAT TREATMENT,
        ·        AN ACTIVE, WELL-BALANCED AND CONTAMINANT-FREE STARTER CULTURE,
        ·        A CLEAN AND WELL-MAINTAINED PLANT,
        ·        CORRECT INOCULATION RATE
        ·        CORRECT INCUBATION TIMES AND TEMPERATURES,
        ·        AVOIDANCE OF ROUGH HANDLING OF SET YOGHURTS,
        ·        THE USE OF HIGH QUALITY FRUIT OR OTHER INGREDIENTS
        ·        CORRECT STORAGE OF RETAIL PRODUCT BELOW 5°C
         
        A PERTINENT GOOD MANUFACTURING PRACTICE


        -T 32
         
         
         
        CONCLUSION
         
         
         
        è THE OPTIMISATION OF YOGHURT QUALITY STAYS AN INDUSTRIAL CHALLENGE
         
         
        è IT NEEDS AN INTEGRATED APPROACH OF THE PROCESS, FROM CULTURES SELECTION AND MIXES PREPARATION TO COOLING AND MECHANICAL OPERATIONS
        更多翻譯詳細信息請點擊:http://www.trans1.cn
         
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