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PTT 307. SSF : defined as the growth of the micro-organisms on (moist) solid material in the absence or near-absence of free water. Solid substrate fermentation processes in which the substrate itself acts as carbon/energy source, occurring in the absence or near-absence of free water.
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SSF : defined as the growth of the micro-organisms on (moist) solid material in the absence or near-absence of free water Solid substrate fermentation processes in which the substrate itself acts as carbon/energy source, occurring in the absence or near-absence of free water solid-state fermentations fermentation process occurring in the absence or near-absence of free water, employing a natural substrate as above, or an inert substrate used as solid support
Growing Medium Rice straw Wheat straw Coffee pulp Sawdust Cotton waste from textile industry Cotton seed hulls Logs Sawdust-rice bran Corncobs Paper Horse manure (fresh or composted) Crushed bagasse Water hyacinthl Oil palm waste Bean straw Cotton straw Cocoa shell waste Banana leaves Distillers grain waste
Type of bioreactor Type of fennenter Process/product Micro-organism Wooden trays [1923] Koji fermentation Aspergillus oryzae Rotating drum [1962] Cpmposting mixed cultures Rotating drum [1964] Koji fermentation A. oryzae Rotating drum [1969] Enzymes A. oryzae Aluminium pot [1943] Enzymes A. oryzae Horizontal drum [1976] feedlot fugal strains Cement mixer [1977] Corn fennentation fungal and yeast strains
Economically and industrially important advantages of SSF Lower capital and recurring expenditure Lower waste water output / less water need Reduced energy requirement Simplicity Simpler fermentation media Absence of rigourous control of fermentation parameters Easier aeration Economical to use even in smaller scales Applicability of using fermented solids directly Storage of dried fermented matter Lower cost of down stream processing
Factors needs to consider Biological factors: Physico-chemical factors metabolic process and reproduction related with the transport phenomena of momentum, energy and mass transfer these will have impact on strains selection, design of medium for fermentation, substrate conditioning, control criteria, design of reactors.
Physico-chemical factors • water activity and moisture content of the substrate. • temperature and heat transfer. • pH. (it determines the enzyme activities) • aeration. • nutrient diffusion. It affects the nutrient concentration and regulates the actions of enzymes over the solid substrate • Mixing : It helps heat removal, gas exchange, water content, uniformity • and influences the process conditions.
media formulations, biomass composition Cellular biomass presents as average 40-50% C, 30-50% O, 6-8% H 3-12% N. For fungi, C/N ratio is important as it could induce or delay sporulation
Example 1: Determine the ratio of C/N that is needed to obtain biomass from a strain of Aspergillus niger. The empirical formula for this strain is
Solution: Basis of calculation: 1 mol biomass MW C = 12, N= 14 O=16 The weight of C = 12 (1) = 12 N= 14(0.085) = 1.19 C/N = 12 / 1.19 = 10.08 /1
Example 2 Consider a 50% yield of biomass based on sugar consumption (g biomass produced/g sugar consumed), In SSF process with an initial concentration of total reduced sugars of 30% dried basis, determine the amount of (NH4)2SO4 that must be added to the medium to obtain the maximum biomass production of Aspergillus niger. The empirical formula for this strain is
TEMPERATURE T is important because it is related to Protein denaturization, enzymatic inhibition, Promotion or inhibition on the production of a particular metabolite, cells death Extremo-thermophiles 90-250 C Thermophiles 45 -90 Mesophiles 30-45 Psychrophiles 0-30
MOISTURE • In a general sense, it has been established that • Bacteria : > 70%. • yeast, 72-60% • Fungi 70-20%. AERATION AND AGITATION Related to oxygen demand in the aerobic processes, heat and mass transport phenomena in a system. PARTICLE SIZE Determine the surface area Examples of bioreactors
Schematic of a koji-type reactor: (1) water inlet, (2) UV tube, (3) (4) (5) air blowers, (6) (7) air filters, (8)air outlet, (9) humidifier, (10) heater, (11) Air inlet, (12) Trays,
A bioproduct is best described by its chemical composition or structure and its function or application. function or application composition or structure Proteins, Lipids, biopolymers organic acids, food and feed additives, pharmaceuticals, detergents, chemical intermediates, agriculturally used products, Citric acid, Lactic acid, gluconic acid e.g. insecticides and herbicides Milk, Vegetable, Meat Fermentation Products
Why process milk? • There are many reasons to process milk into dairy products, such as the following: • ? Many dairy products can be kept longer than fresh milk, therefore the milk does not have to be consumed immediately. • ? The demand for fresh milk may be limited, and there may be more interest in dairy products. • ? If the daily amount of fresh milk for sale is limited, it may be more economical to process the milk into less perishable products, store them, and sell them later in greater quantities. • ? There may be no market for fresh milk close by, and only preserved products can be sold at markets at a greater distance. • ? Greater financial gain may be obtained.
Yogurt Definition : milk product that is fermented by the action of both Lactobacillus bulgaricus and Streptococcus thermophilus . YOGURT MANUFACTURE The general goal of yogurt production : > to create a semisolid, long shelf-life food from fluid milk
