SSF : defined as the growth of the micro-organisms on (moist) solid material in the absence or near-absence of free water

Solid substrate fermentationprocesses in which the substrate itself acts as carbon/energy source, occurring in the absence or near-absence of free water

solid-state fermentationsfermentation 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

HISTORY OF SOLID STATE FERMENTATION PERIOD

Bread making by EgyptianCheese making by Penicilium roque/ortiiFish fermentation/preservation with sugar, starch, salt , etc.koji processkoji process from China to JapanVinegar from pomaceUse of gallic acid in tanning, printing, etc.Sewage treatmentProduction of fungal enzymes, kojic acidProduction of fungal enzymes, gluconic acid, citric acid,development of drum-type fermenterPenicillin productionSteriod transformationProduction of mycotoxins, protein enriched feedProduction of various primary and secondary metabolites,development of column type of ferrnenter, work on kineticsand modelling aspects of SSFDevelopments on fundamental aspects of SSF, bioprocessesJproducts developments:

2000 BC1000 BP)2500BP2500BP7th Century18th Century18th Century1860-19001900 19201920-1940

1940-19501950-19601960-19801980-1990

I990-present

Rice strawWheat strawCoffee pulpSawdustCotton waste from textile industryCotton seed hullsLogsSawdust-rice branCorncobsPaper

Horse manure (fresh or composted)Crushed bagasse Water hyacinthlOil palm wasteBean strawCotton strawCocoa shell wasteBanana leavesDistillers grain waste

Growing Medium

Dev of Fermenter design-->

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

ComparisonCharacteristics Solid-state Submerged

Microorganism, substrateWater usageOxygen supply byVolume of fermentation mashLiquid waste producedPhysical energy requirementHuman energy requirementCapital investment

Static. LimitedDiffusionSmallerNegligibleLowHighLow

AgitatedUnlimitedAerationLargerSignificant volumeHighLowHigh

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

related with the transport phenomena of momentum, energy and mass transfer

Biological factors:

metabolic processand reproduction

Physico-chemical factors

strains selection,design of medium for fermentation,substrate conditioning,control criteria,design of reactors.

these will have impact on

•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.

Physico-chemical factors

media formulations, biomass composition

Cellular biomass presents as average 40-50% C,30-50% O, 6-8% H3-12% 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:

MW C = 12, N= 14 O=16

Basis of calculation: 1 mol biomass

The weight of C = 12 (1) = 12N= 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 CThermophiles 45 -90Mesophiles 30-45Psychrophiles 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 SIZEDetermine 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,

Example of bioreactors for SSF

Criteria for production of bioproducts

A bioproduct is best described by its chemical composition or structureand its function or application.

Proteins, Lipids, biopolymers organic acids,

food and feed additives, pharmaceuticals,detergents, chemical intermediates, agriculturally used products,

composition or structure function or application

e.g. insecticides andherbicides

Citric acid, Lactic acid, gluconic acid

Milk, Vegetable,Meat FermentationProducts

DIARY PRODUCTS

Manufacturing of milk into dairy 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

A general scheme for yogurt manufacture

Health Benefit of yoghurt

Industrial production of bakers’ yeast

Manufacture of fermented sausage