PENGENDALIAN MIKROBIA DENGAN PEMANASAN

PENGELOMPOKAN MIKOBIA ATAS DASAR RENTANG SUHU PERTUMBUHANNYA [˚C] KELOMPOK MINIMUM OPTIMUM MAKSIMUM THERMOPHILES MESOPHILES PSYCHROPHILES PSYCHROTROPH 40 - 45 5 – 15 (- 5) – 5 (- 5) - 5 55 – 75 30 – 45 12 – 15 25 - 30 60 – 90 35 – 47 15 – 20 30 - 35

PENGARUH SUHU TERHADAP WAKTU GENERASI DASAR PENGENDALIAN PENGARUH SUHU TERHADAP WAKTU GENERASI psychrophile mesophile

HEAT INDUCED CHANGE IN THE CELL SURFACE AND MEMBRANE*) INNER MEMBRANE OUTER MEMBRANE CYTOPLASM BLEBS The bar in ea The bar in each micrograph represents 0.5µm *) Katsui, et al, 1982

PENYEBAB KEMATIAN SEL KARENA PEMANASAN – RUSAKNYA SISTEM METABOLISME  KEHILANGAN KEMAMPUAN UNTUK MEMPERBANYAK DIRI KERUSAKAN MEMBRAN SEL : sifat permiabilitasnya hilang “leakage” senyawa intraseluler kehilangan ion Mg  degradasi RNA dan ribosoma kehilangan ensim periplasmik (alkali fosfatase) kehilangan ensim sitoplasmik (glukosa 6 fosfat dehidrogenase) PERUBAHAN FUNGSI SENYAWA SELULER  DENATURASI PROTEIN ( inaktivasi ensim) KERUSAKAN DNA

FAKTOR-FAKTOR YANG MEMPENGARUHI KETAHANAN PANAS BAKTERI Sifat yang melekat pada individu sel Kondisi pertumbuhan Suhu Medium Recovery medium (minimal or enriched medium) Lingkungan selama pemanasan Kompoisis makanan Bentuk pangan (padat, cairan) Aktivitas air Ukuran bahan yang dipanaskan pH bahan  Low Acid food (pH above 4.6) didasarkan pada ketidakmampuan C. Botulinum untuk tumbuh pada pH 4.6 atau lebih rendah dari 4,6  Acid food

Mechanism the dead of cell subjected to heat Damage in cell membrane and cell wall Leakage of cell component Denaturation of protein ( enzymes )  cell metabolism stopped Denaturation of one gene essential to reproduction (Rahn, 1929) 8 7 The Rate of Dead of Bacteria Logaritmic Log Number of cells 6 5 1 2 3 4 5 6 7 Heated ( min) at t˚C

BEBERAPA PENYIMPANGAN YANG MUNGKIN TERJADI 8 Activation 7 Dead of cells Logaritmic Log Number of cells 6 Consist of two strains 5 1 2 3 4 5 6 7 Heated ( min) at t˚C

D > D > D RATE OF DESTRUCTION 8 7 6 5 D D D Nilai Dt : waktu pemanasan (menit) yang diperlukan untuk mengurangi populasi sebanyak 90% pada suhu t˚C 7 D > D > D Log Number of cells 6 5 D D D 1 2 3 4 5 6 7 Heated ( min) at t˚C Graphical illustration of decimal reduction time D

Graphical illustration of Thermal Death Time curve 8 z value = ˚C required for thermal death time curve to transfer one log cycle 10 D VALUE (MINUTE) D80 = 10 minutes D93 = 1.0 minute 1 z value 0.1 80 90 100 TEMPERATURE (˚C) Graphical illustration of Thermal Death Time curve

PROBABILITY OF SURVIVAL t = D (log a – log b) t = time, in minutes, of heating at a constant lethal temperature D = time, in minute, to kill 9)% of the cells in the population a = initial number of viable cells in the population b = number of viable cells in the population after time t Examples : assume that there is 1 spore of C.botulinum in each of 1012 containers, and D 250 is 0.21 . Time temperature combinations is 2.52 minutes at 250˚F. If all container are given the same process, how many should spores be expected survive?  2.52 = 0.21(log 1012 - log b) log b= 0  b = 1 Tell us that 1 container of the should not be sterillized by the process.

Approximate resistance of some bacterial spore to heat*) Bacterial species Food class D value 120˚C 100˚C 80˚C Z value (˚C) Thermophilic anaerob Clostridium thermosachariliticum C. Nigricans Thermophilic aerob Bacillus stearothermophilus B. coagulans LA A 3-4 2-3 4-5 0.1 - 3000 12-18 7 Mesophilic anaerob C. sporogenus(include.PA3679) C. botulinum (type A and B) C. perfringens C. histolyticum C. pateurianum C. subterminate 0.1-1.5 0.1-0.2 50 0.3-20 3 0.1-0.5 115 30 9-13 10 Mesophilic aerob Bacillus cereus B. licheniformis B. megaterium B. subtilis B. macerans 5 13 1 11 6 9 *)The International Commission on Microbiological Specifications for Foods (ICMF)

LOW-HEAT PROCESSING (Pasteurization) To destroy all vegetative cells f the pathogen and a large number of associative (spoilage) microorganisms LTLT (low temperature long time); HTST ( high temperature short time)? HIGH-HEAT PROCESSING (heating at or above 100ºC) pH>4,6  12D concept (Cl. butulinum tipe A dan B) the most resistant spores of pathogen. For spoilage studies: Bacillus stearothemophylus. pH < 4,6 spore forming B. coagulans, aciduric non- spore forming : lactobacillus dan Leuconostoc UHT : 150ºC for 2 to 3 sec. MICROWAVE HEATING Can not considered safe from pathogen  is not heated uniformly and some areas remain cold

A two-way regeneration system used in juice processing Automatic valve 88˚C -0.5˚C 13˚C 21˚C 53˚C Silo tank 5 4 3 2 1 73˚C 88˚C 38˚C Heating section Regeneration section Cooling with water Cooling with chilled water Cooling with glycol Balance tank