Formation of metabolites:(citric, lactic) Acid, alcohol, enzymes.//Factors affecting ferm.: Acids (spoil + diseas m/os, still need fridge for acid-tolerant psychotriphoc yeasts/moulds) , Alcohol(>20%), Starter cultures, temp (control type of m/o), O2(good+bad), Salt (inhibit spoilage m/os, acid+salt more effective, draws moisture away) CHEESE:3 uses of biotech in cheese prod.: genetically engineered starter cultures (resistance to virus, improved enzyme activity)--recombinant chymosin (m/os genetically engineered to include gene for producing enzyme chymosin or rennin,which are from 4th stom. Of calves or lambs. Approved food additive for enzyme. Chymosin comes from a gene from calves that encodes for this enzyme. This gene is added to specific m.o.s for enzyme production. Then the chymosin that is created is sold for cheese making. Bovine chymosin->milk-clotting enzyme. CHEESE PROD.: 1.setting milk: lactic-acid producing culture added to pasteurized milk. Rennetadded to acidic milk to coagulate.2.cut curds to cubes to remove whey 3. cook curds 38 C to get out whey and for lactic acid production 4. draining whey and curd matting. Curd shrinks turns to matted rubbery slab. Cheddaring: cut into blocks + turned every 15 secs. 5. salting: prevent bad m/os. Cheese ripening. 6. pressing and then curing: mending together 7. ripening: 2 C for 6-365days. Vacuum packed and cool room for 3-4 days after pressing. CHEESE TYPES: swiss: hard. Propionibacterium shermanni bacterial culture. Eye holes from Co2 during againg.//blue veined: semi soft. Blue, stilton, gorgonzola, roquefort. Penicillium roquefortii mould: colour and sharp flavour->Mycelia mould.// Cemembert (brie): soft. Penicillium camembertii spores. Mycelia grows outside. Creamy, hydrolysis of casein, mild flavour: good quality.// Cheese preservation: moisture, Aw, acid, lactic acid bacteria->micorbial antagonism, antimocrobials, salt. Ionizing radiation(non-thermal): energy emmited:MeV energy absorbed:kGy. wavelength short. Energy high. Penetrability high. Xrays (\<5meV, gamma rays(radioactive isotopes, colbalt-60/cesium137), electrons \<10meV max energy output is 5-10MeV.. Radioactive when exposed to >15MeV, split the nucleus.// Direct effects: directly hits m/os may break DNA bonds. Damage dpends on dose and m/o.//Indirect effects: ionizing energy intereacts w water. Electrons knocked out of water molecules->release of ions+free radicals: reactive, damages proteins,lipids. exist in our body.// Doses and food application: low dose, 1kGy->inhibit potato sprouting, inactivates parasites, slows ripening of fruit. Radiation pasteurization: dose: 1-10kGy. Radicaidation: <10kGy kills/inhibits pathogens. Requires frigde b/c some spoil. m/os survive. Ex. chicken, ground beef, veggies. Radurization: below 10kGy. kill majority of spoil. m/os and parasites. Ex. kill mould in fresh strawbs.