Pengolahan & Pengawetan Bahan Pangan

Pengolahan Bahan Pangan Kulitas Pangan: Reaksi enzim Deteriorasi oleh mikroba Perubahan oksidatif pada buah dan sayuran Otot (daging) putih vs merah Pasca Panen “Post mortem” Rigor mortis “Post harvest”

Myofibrils are the contractile apparatus of the muscle fibre. White muscle (birds, poultry) - high ratio of myofibrils to sarcoplasm. White fibres are efficient at providing the energy source, adenosine triphosphate (ATP) by anaerobic glycolysis (no O2). Found in muscles that contract quickly for only short bursts and tire quickly. The retail cut of meat, “silverside” contains high amounts of white muscle fibres. Red muscle - poor in myofibrils but rich in sarcoplasm. They contract slowly and long lasting and do not tire. Found in legs of mammals and breasts of birds (except chickens). Sarcoplasm: This is the cytoplasm of muscle fibres. It is the intracellular colloidal substances in which all organelles and inclusions are suspended. Myofibril: Long, thin, cylindrical rods: 1-2 µm in diameter. Long axis of myofibril is parallel to the long axis of the muscle fibre. eg. muscle fibres of meat animals consist of 1000-2000 myofibrils each with diameters of 50 µm. Each myofibril consists of myofilaments that are commonly referred to as thick and thin filaments. Myofibrils are the contractile apparatus of the muscle fibre. Myofibrils are surrounded by the sarcoplasm, and mitochondria.

Metoda Pengawetan Bahan Pangan Asepsis: mencegah masuknya mikroba ke dalam bahan pangan  Menghilangkan mikroorganisme: penyaringan atau pencucian  Destruksi mikroorganisme: Perlakuan kimia, suhu, tekanan atau tekanan osmosa  Pengaturan lingkungan hidup mikroba selama penyimpanan control of temperature, water activity or oxygen content

Contoh pengawetan: Umumnya digunakan kombinasi dari metoda berikut disamping asepsis Pengeringan: Menurunkan kandungan air sehingga aktivitas air dalam pangan Table 1. Minimum water activities for the growth of selected bacteria   Organisms Aw Organisms Aw Molds 0.75-0.90 Micrococcus 0.905-­ Pseudomonas sp.0.94-0.96 Salmonella 0.94 Bacterium 0.945-0.990 Staphylococcus 0.86 Sarcina sp. 0.915-0.930 Yeasts 0.85-0.92  

Metoda (lanjutan) Penyimpanan suhu rendah Destruksi mikroba: Suhu tinggi: Pasteurisasi (pemanasan berulang pada suhu dibawah 100 C) Metoda lain: radiasi, sonikasi, listrik, tekanan, penambahan senyawa kimia (asam, basa, logam & garamnya, H2O2

Beberapa contoh metoda pengawetan pada beberap komoditi Cereal and cereal products -asepsis, reduced moisture content Baked goods   -asepsis, heat, chemical preservatives, low temperature Sugar and sugar products -asepsis, low moisture content, high osmotic pressure Syrups   -asepsis, heat, low temperature storage, surface irradiation by UV light Vegetables and vegetable products -asepsis, washing, heat (canning, blanching), chilling, freezing, drying, preservatives, fermentation Fruit and fruit products -asepsis, washing, low temperature storage, freezing, drying, preservatives Fruit juices   -asepsis, pasteurization, low temperature storage, freezing, preservatives Meats and poultry -asepsis, low temperature storage, freezing, heat, drying, preservatives (salt, spices, etc.) Fish and other seafood -asepsis, heat (canning), low temperature storage, freezing, drying, preservatives, pickling, “germicidal ice” Eggs -asepsis, removal of microorganisms by dry cleaning or washing in a germicidal solution at 90-140°F, pasteurization, freezing, drying, preservatives Milk and milk products -asepsis, pasteurization, sterilization, low temperature storage, drying, fermentation

Aplikasi: Post harvest- Apple: Fruit coating: Reduced respiration & ethylene production rateDelay fruit ripening Delay development of flavor-associated compounds( esters, alcohols, aldehydes, ketone & sesquiterpene Film coating CO2 permeable,but low for H2O(vap) & volatiles Reduced flesh mass loss during cold storage

The effects of harvest-applied coating and shrink-wrap film treatments of apples (Malus xdomestica Borkh. 'Gala' and 'Golden Delicious') on volatile levels, quality attributes, respiration and internal atmospheres after storage at 0C for 1 to 6 months, and during subsequent ripening at 20C were investigated. Over thirty volatiles were detected, most of the identified volatiles were esters, the rest were alcohols, aldehydes, a ketone and a sesqueterpene. Fruit coatings transiently inhibited total volatile levels in 'Golden Delicious' while not affecting those in 'Gala' apples during 6 months of storage in air at 0C. Ripening fruit at 20C for up to three weeks following cold storage increased volatile levels with coated and untreated fruit having similar amounts. Only shellacked 'Golden Delicious' apples accumulated ethanol and ethyl acetate during ripening at 20C. The film treatment had no effect on fruit volatile levels during cold storage or during subsequent ripening at 20C

Calcium infiltration Delays membrane lipid catabolism  Golden decious’apple Ca infiltrated apple 6mth 0C, 7 d 20C: Cold storage: Phospholipid & acylated steryl glycoside increase Free sterol & sterylglycoside conc. Increase with increasing [Ca]

Honeydew Melon Controlled atmosphere extent shelf life 4% O2, 10% CO2  shelf life incr 20% Reduce respiration rate, ethylene production Retard microbial growth Needs temp control to prevent anaerobic respiration

Pengolahan pangan (Food Biotechnology) Fermentasi tradisional Endogenous enzim &/Mikroorganisme Contoh: “brewing & baking” (keduanya) kecap kedelai (terutama mikroorganisme) Kecap ikan (terutama endogenous enzim) Pengeringan: Sinar matahari Listrik Freeze drying Pemanisan Pengasapan - Pemasaman Pemanfaatan teknologi rekombinan untuk memperbaiki kualitas pangan

Enzim untuk industri Pemanfaatan enzim untuk pengolahan pangan: Enzim amobil Sel amobil Contoh: A. Glycosidases B. Proteases 1. Amylases 1. Meat tenderization 2. Invertase 2. Chill proofing 3. Lactase 3. Rennets 4. Pectic enzymes 4. Cheese ripening 5. Cellulase 5. Baking 6. Hemicellulase 6. Oil extraction 7. a-galactosidase 7 Fish membrane/skin removal 8. a-rhamnosidase 9. Thioglucosidase

Berbagai enzim untuk pengolahan pangan (lanjutan) C. Esterases D. Oxidoreductases 1. Lipases 1. Glucose oxidase -Cheese ripening 2. Catalase -Oil processing 3. Lipoxygenase -Glycoside esters 4. Aldehyde dehydrogenase 2. Phosphatase 5. Butanediol dehydrogenase E. Isomerases 1. Glucose isomerase

Glutenin, makropolymer pada “dough” Artikel: Trends in Food Science & Technology 10 (1999) 247-253

Peningkatan kualitas Pangan dengan teknologi rekombinan Sejarah C. r DNA Technology o 1970's- Discovery of restriction and ligase (cut and join) enzymes and development of rDNA techniques. (More than 600 restriction endinucleases are now known.) DNA polymerases reform the phosphodiester bonds under appropriate conditions.-overhead shows reactions, from Whitaker o 1980's-Transformation of mutant strains of E. coli; 1983 patent for cloning prochymosin gene in E. coli.

o 1980's- First transformation of plant, phaseollin gene into sunflower plant. Many other plants since transformed. More recently, problems with transforming monocots have been overcome. o 1980's- Growth hormone with metallothione promotor put into various livestock and fish. 1990- First approved food additive from rDNA. 1994- First approved transgenic food with improved quality. (shelf life) o 1990's - Intensive interest in safety considerations. Reports of agencies like International Food Biotechnology Council(1990), World Health Organization(1991) and FDA(1992); April 6, 1994 Sac B article on "flavr savr". USDA, FDA, EPA involvement in regulatory processes. Teknik contoh

Teknik

Contoh E.coli/ K.marxianus/ Asp.niger Organisme Strategi Perbaikan Ikan, Babi + gen pengkode hormon pertumbuhan Meningkatkan pertumbuhan, massa otot/daging, menurunkan adipose otot Sapi + -Laktoglobulin Meningkatkan produksi susu, memanipulasi komposisi protein (tahap ide) Ayam + antisens RNA utk gen pengatur (regulatory genes) tertentu, dsb Menurunkan sintesis kolesterol di telur, memanipulasi kandungan senyawa tertentu yg fungsional Kentang, tomat, daun slada (lettuce) + gen thaumatin Meningkatkan rasa & aroma manis Biji tanaman penghasil minyak + antisens RNA utk gen lauryl acyl carrier protein tioesterase Meningkatkan kandungan asam laurat pada biji “canola” E.coli/ K.marxianus/ Asp.niger + antisens RNA/gen chymosin anak sapi Mempercepat produksi chymosin, digunakan pada pembuatan keju

Degradasi sukrosa

Beberapa Efek Samping Pengawetan & Perlakuan Peningkatan Kulitas Bahan Pangan Pengaturan lingkungan hidup mikroba (artikel: N.J Rowan, Trends in Food Science & Technology, 1999) Adaptasi Mutasi ‘New food born disease’ Penambahan zat pengawet & pewarna Pestisida, Insektisida, Fungisida Teknologi Rekombinan XPengaturan lingkungan hidup mikroba Pengawetan bahan pangan dengan mengatur lingkungan hidup mikroba, seperti pengaturan pH bahan, kadar air, kadar oksigen yang tak sesuai akan menyebabkan stress pada mikroba. Agar mikroba dapat bertahan hidup, ia akan memasuki fase pertumbuhan stasioner. Kemampuannya utk dapat bertahan dalam keadaan yg tak sesuai ini karena adanya perubahan enzim/sistem enzim & mekanisme sitem transport yg tentunya karena adanya perubahan ekspresi genetik. Pada enteric bacteria seperti E.coli O157:H7, gen yang berperan dalam fase stasioner adalah gen rpoS yang mengatur expresi protein pelindung. Protein ini menyebabkan sel dapat bertahan pada perubahan kimia atau fisik yang ekstrim. (Booth, 1998)