FST 508 FERMENTED FOODS (3 units)
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FST 508 FERMENTED FOODS (3 units) By Dr. Olusegun Obadina Know Your Lecturers Prof. Olusola Oyewole Dr. Olusegun Obadina Part 1 Introduction to fermentation processes • Type of products resulting from fermentation processes – biomass – enzymes – metabolites (primary + secondary) – recombinant products – transformation processes Part 2 Microbial growth kinetics Batch culture x= biomass concentration (g/l) t = time (h) µ = specific growth rate (h-1) µ = µmax during exponential phase nutrients are in excess Exponential phase : dx dt µ.x xt x0 .e µ.t ln xt ln x0 µ.t when Part 2 Microbial growth kinetics • Transition phase before stationary phase: – Growth rate decreases - by exhaustion of a nutrient - by accumulation of a toxin x Y S R s At which •x: concentration biomass produced (g/l) •Y: yield (g biomass/ g substrate) •SR: initial substrate concentration (g/l) •s: residual substrate concentration – Y dependent of strain, growth rate, pH, T, kind of limited substrate, other media compounds Part 3 Isolation, preservation and improvement of industrially important m.o. • Isolation of micro organisms * ISOLATION from: - COLLECTIONS: ATCC, LMG,… - NATURE: soil, water,… * ENRICHMENT LIQUID CULTURES : - e.g. • drying raw material • heating raw material Selection on µmax or KS Selection on µmax CULTURE CONTINUOUS K van A > K van B 1. µ A > µ B 2. µ A < µ B S S max max max max SHAKE FLASKS 1. Several times subculturing µ A>µ B max max Part 3 Isolation, preservation and improvement of industrially important m.o. • Improvement of output of the micro organisms – Step 1: optimization of the culture medium and growth conditions (T, pH, O2,…) – Step 2: - productivity of a micro organism is determined by the genome so improvement by changing genome - 3 possible routes * Natural mutants * Induced mutants * Recombinant micro organisms Part 4 • Media Fermentation media – Important parameters for industrial fermentations: 1. Cost and availability 60-80% of the cost 2. Ease of use holding on temperature 3. Ease of sterilization denaturation, browning 4. Ease of formulation, mixing 5. Output/ Productivity 6. Impurities downstream processing 7. Public health Part 5 Sterilization Sterilization by : heat filtration radiation moist – 121°C 15min dry – 160°C 2h tyndallization – 100°C 3x depth absolute UV, g, mwave, X disinfectant peroxides, alcohols, aldehydes, quats Part 6 • Fermenter Design Fermenter Design – Basic Functions 1. Capability to operate aseptically (days-week) 2. Adequate aeration and agitation metabolic requirements mo 3. Power consumption as low as possible 4. A system of T, pH, O2 ,anti-foam,….. control 5. Sampling facilities 6. Extras : automatisation labour cost easy cleaning smooth surfaces good geometry H/D dimensions easy maintenance
