FST 508 FERMENTED FOODS (3 units) By Dr. Olusegun Obadina

Know Your Lecturers Prof. Olusola OyewoleDr. Olusegun Obadina

Part 1Introduction to fermentation processes Type of products resulting from fermentation processes – biomass – enzymes – metabolites (primary + secondary) – recombinant products – transformation processes

Part 2Microbial growth kinetics Batch culture x = biomass concentration (g/l) t = time (h) µ = specific growth rate (h -1 ) µ = µ max during exponential phase when nutrients are in excess Exponential phase :

Part 2Microbial growth kinetics Transition phase before stationary phase: – Growth rate decreases - by exhaustion of a nutrient - by accumulation of a toxin – Y dependent of strain, growth rate, pH, T, kind of limited substrate, other media compounds At which x: concentration biomass produced (g/l) Y: yield (g biomass/ g substrate) SR: initial substrate concentration (g/l) s: residual substrate concentration

Part 3Isolation, 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 CONTINUOUS CULTURE SHAKE FLASKS K S van A > K S van B 1.µ max A > µ max B 2.µ max A < µ max B Selection on µ max or K S 1.Several times subculturing µ max A > µ max B Selection on µ max

Part 3Isolation, 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, O 2,…) – 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 4Media 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 5Sterilization Sterilization by : heat moist – 121°C 15min dry – 160°C 2h tyndallization – 100°C 3x filtration depth absolute radiation UV, ,  wave, X disinfectant peroxides, alcohols, aldehydes, quats

Part 6Fermenter 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, O 2,anti-foam,….. control 5.Sampling facilities 6.Extras : automatisation labour cost easy cleaning smooth surfaces good geometry H/D dimensions easy maintenance