Fermentation

Fermentation

The controlled action of selected microorganisms

For:–   
   Treat waste
–   Production of new products
–   Helps preserve foods
–   Alter texture of foods

Main advantages

• Lower energy consumption 
• Generally simple technology
• High efficiency
• Environmental friendly

Microorganisms used in fermentation

•Bacteria 
•Molds 
•Yeasts

Bacteria

•Acetobacter
•Pediococcus 
•Lactobacillus
•Leuconostoc
•Streptococcus

Molds

•Aspergillus 
•Mucor 
•Penicillium

Yeasts

•Saccharomyces
•Kluyveromyces

Factors that control the growth of MO in food fermentation


Intrinsic factors

•Parameters that are an inherent part of the medium and can alter MO growth

Extrinsic factors

•Properties of the storage environment that affect the growth of MO

Intrinsic factors

•Nutrient content 
•Substrate pH 
•Antimicrobials 
•Redox Potential 
•Water activity

Extrinsic factors

•Storage temperature 
RH of environment 
•Atmosphere 
•Presence of other MO

Bioreactors

• A bioreactor is a reactor system used for the culture of microorganisms.
•They vary in size and complexity from a 10 ml volume in a test tube to computer controlled fermenters with liquid volumes greater than 100 m3.

Types of Bioreactors

•Continuous fermentations•Batch fermentations


Some examples for bioreactors 


•Standing cultures
Shake flasks
•Stirred tank reactors 
•Bubble column and airlift reactors
•Fluidized bed reactors 

Standing cultures

•Large Pyrex flasks are used for the small  scale production of fermented products. 

Standing cultures - Surface cultures

•The Aspergillus niger mycelia are grown on the surface of liquid media in large shallow trays.
•The solids may be continuously or periodically turned over to improve aeration and to regulate the culture temperature. One example of a commercial scale, solid substrate fermentation is the production of koji by Aspergillus oryzae on soya beans which is part of the soya sauce process.

Shake flasks

•Shake flasks are commonly used for small scale cell cultivation. Through continuous shaking of the culture fluid, higher oxygen transfer rates can be achieved as compared to standing cultures. Shaking continually breaks the liquid surface and thus provides a greater surface area for oxygen transfer. Increased rates of oxygen transfer are also achieved by entrainment of oxygen bubbles at the surface of the liquid.





•Although higher oxygen transfer rates can be achieved with shake flasks than with standing cultures, oxygen transfer limitations will still be unavoidable particularly when trying to achieve high cell densities.

Bio fuels

  Bio fuel is defined as solid, liquid or gaseous fuel obtained from lifeless or living biological material and is similar to fossil fuels, which are derived from long dead biological material.

  • Bio fuel has the added advantage of bio sequestration of atmospheric C02 and so assisting to re mediate greenhouse gas and climate change problems.
  • Globally, bio fuels are most commonly used to power vehicles, heat homes, and for cooking. 
  •  Bio fuel industries are expanding in Europe, Asia, and America. 

    What  are  AGROFUELS?


   Agrofuels are Eco friendly fuels  which are produced from specific crops, rather than from waste processes such as landfill off-gassing or recycled vegetable oil.

   There are two common strategies of producing liquid and gaseous agrofuels.

  •       One is to grow crops high in sugar (sugar cane, sugar beet, and sweet sorghum) or starch (corn/maize), and then use yeast fermentation to produce ethyl alcohol (ethanol).

  •      The second is to grow plants that contain high amounts of vegetable oil, such as oil palm, soybean, algae, jatropha, or pongamia pinnata

  •      When these oils are heated, their viscosity is reduced, and they can be burned          directly in a diesel engine, or they can be chemically processed to produce fuels such as biodiesel
  •       Wood and its byproducts can also be converted into bio fuels such as woodgas, methanol or ethanol fuel. It is also possible to make cellulosic ethanol from non-edible plant parts, but this can be difficult to accomplish economically.

Types of Biofuels


1.First Generation Biofuels

Vegetable oil

Biodiesel

Bioalcohol

Bioether

Biogas

Syngas

Soild Biofuels
 
2. Second Generation biofuels
3. Third Generation bio fuels
4. Ethanol from Living Algae
5. Helioculture

  First Generation Biofuels

 'First-generation biofuels' are biofuels made from sugar, starch, vegetable oil, or animal fats using conventional technology.

       The basic feed stocks for the production of first generation biofuels are often seeds or grains such as wheat, which yields starch that is fermented into bioethanol, or sunflower seeds, which are pressed to yield vegetable oil that can be used in biodiesel.


(i) Vegetable oil

Edible vegetable oil is generally not used as fuel, but lower quality oil can be used for this purpose.
Used vegetable oil is increasingly being processed into biodiesel, or (more rarely) cleaned of water and particulates and used as a fuel.


(ii) Biodiesel

 —     Biodiesel is the most common bio fuel in Europe.
It is produced from oils or fats using trans-esterification and is a liquid similar in composition to fossil/mineral diesel.
biodiesel include animal fats, vegetable oils, soy, rapeseed, jatropha, mahua, mustard, flax, sunflower, palm oil, hemp, field pennycress, pongamia pinata and algae.


(iii) Bioalcohol

      Biologically produced alcohols, most commonly ethanol, and less commonly propanol and butanol, are produced by the action of microorganisms and enzymes through the fermentation of sugars or starches (easiest), or cellulose (which is more difficult).


(iv) Bioethers

      Bio ethers are cost-effective compounds that act as octane rating enhancers.They also enhance engine performance, whilst significantly reducing engine wear and toxic exhaust emissions.Greatly reducing the amount of ground-level ozone, they contribute    to the quality of the air we breathe.


(v) Biogas

  •      Biogas is produced by the process of anaerobic digestion of organic material     by anaerobes.

  •     —It can be produced either from biodegradable waste materials or by the use of  energy crops fed into anaerobic digesters to supplement gas yields.
  •      Landfill gas is a less clean form of biogas which is produced in landfills through naturally Occurring anaerobic digestion. If it escapes into the atmosphere it is a potent greenhouse gas.

(vi) Syngas

    Syngas, a mixture of carbon monoxide and hydrogen, is produced by partial  combustion of biomass, that is, combustion with an amount of oxygen that is not sufficient to convert the biomass completely to carbon dioxide and water.


(vii) Solid biofuels

Examples include wood, sawdust, grass cuttings, domestic refuse, charcoal,                 agricultural waste, non-food energy crops and dried manure. It can burn directly in a stove or furnace to provide heat or raise steam.

Second Generation biofuels

  •       Second  generation (2G) biofuels use biomass to liquid technology, including cellulosic biofuels from non food crops.

  •        Many second generation biofuels are under development such as biohydrogen, biomethanol, Fischer-Tropsch diesel, bio hydrogen diesel, mixed alcohols and wood diesel.

Third Generation biofuels

  •      Algae fuel, also called oilgae or third generation biofuel, is a biofuel from algae. Algae are low-input, high-yield feedstock to produce biofuels.

  •      Based on laboratory experiments, it claimed that Algae can produces up to 30 times more energy per acre than land crops such as soybeans .

Ethanol from Living Algae

  •       An alternative approach relies on the fact that some algae naturally produce ethanol and this can be collected without killing the algae.

  • —     The ethanol evaporates and then can be condensed and collected.

Helioculture

  •       Helioculture is a newly developed Technology which is claimed to be able to produce 20,000 gallons of fuel per acre per year, and which removes carbon dioxide from the air as a feedstock for the fuel.
  •       The process of Helioculture can develop many different fuels and petroleum-derived chemicals all while not using any fresh water or agriculture.

Advantages of Bio fuels


1. Bio-fuels lessen the burden on gradually-vanishing  fossil fuels

             As fossil energy resources are in decline and the need to become less reliant on energy imports is becoming more and more relevant and alternative energy sources are needed. Biofuels are one possible replacement for fossil fuels. Although biofuels still cost more than fossil fuels, their share in terms of use is increasing worldwide. The global production of biofuels is now estimated to be about 5 billion litres per year.          


2. Bio-fuels are environment-friendly. They help reduce carbon emissions into the atmosphere

       Fossil fuels generate huge amounts of pollution. Bio-fuels are comparatively safer. Bio Fuel contribute to climate protection. As bio fuels are usually considered to be CO neutral, their use helps to reduce greenhouse gas emissions. Fossil fuels, on the other hand, are a major source of CO       


3. Fossil fuels are created over millions of years while biofuels can be made very quickly.

        Because of their regeneration time, biofuels are considered much more ‘renewable’.
        

4. The use of biofuels as transport fuels

  Biofuels are usually used for transport fuels, but they are also applicable for electricity and heat generation. In relation to reducing dependency on fossil fuel imports, bio fuel is particularly effective.
Biodiesel can be used in pure form (B100) or may be blended with petroleum diesel at any concentration in most modern diesel engines.Bio diesel is widely used  for:
As a heating oil
Aircraft  
Railway usage

5. Cost Effectiveness

             
Bio-fuels, especially, bio-diesel prove to be very cost-effective for consumers.


Are Bio fuels Cost Competitive?

In 2005, neither biofuel was cost-competitive with petroleum – but as petroleum prices increased the gap closed.

Ethanol:
     
Estimated ethanol production cost in 2005 was $0.46 per gasoline 

energy equivalent Wholesale gasoline prices averaged $0.44/L in 2005

Soy biodiesel

Estimated soybean biodiesel production cost in 2005 was  $0.55 per 

diesel EEL,  Diesel wholesale prices averaged $0.46/L in 2005

Recent price effects unfavorable for biofuels:
  
Lower fossil-fuel price Higher corn prices


 6.Invasive crop species can be used in Bio fuel making to reduce their impact on other food crops.

 

Disadvantages relating to biofuels


1."Food vs. fuel" debate

Regarding the risk of diverting farmland or crops for biofuel production in detriment of the food supply on a global scale.

Biofuel production has increased in recent years. Some commodities like maize, sugar cane or vegetable oil can be used either as food, feed or to make biofuels.

This result in higher food prices.

Efforts are currently being put into the production of second generation biofuels from non-food crops, crop residues and waste.


2.Emission of hazardous gases

  •      Can contribute as much or more to global warming by nitrous oxide emissions.

  •      Crops with higher requirements for nitrogen fertilizers, are highly  responsible for these emissions.

  •       Burning biodiesel also emits aldehydes and other potentially hazardous aromatic compounds which are not regulated in emissions laws.


3. Indirect land use change impacts of bio fuel


  •      —  Release more CO2 when farmers elsewhere in the world clear rainforests and other pristine lands to grow grain to produce ethanol, translating in a net increase in CO2 emissions.

  •       —“Biofuel carbon debt” -Biofuel release 17 to 420 times more CO2 than the annual greenhouse gas (GHG) reductions, these biofuels provide by displacing fossil fuels. (mostly corn based ethanol)

       

  4.Soil erosion, deforestation, and biodiversity


  •       —Demand for biofuel has led to clearing land for Palm Oil plantations.

  •        Large-scale deforestation contributes to un-sustainable global warming, atmospheric greenhouse gas level increment, loss of habitat, and a reduction of valuable biodiversity.

  •       —A portion of the biomass should be retained onsite to support the soil resource.

      

  5.Impact on water resources

—    Increased use of biofuels puts increasing pressure on water resources in at least two ways:

1.water use for the irrigation of crops used as feedstocks for biodiesel production;  

2. water use in the production of biofuels in refineries, mostly for boiling and cooling


6.Biofuels and solar energy efficiency


Photovoltaics  are 100 times more efficient than corn ethanol and 10 times more efficient than the best biofuel.


                          

 FOR YOU TO THINK……….


Biofuels are not the answer to sustainable energy, but biofuels may be part of the answer .

Biofuels may offer advantages over fossil fuels, but the magnitude of these advantages 

depends on how a biofuel crop is grown and converted into a usable fuel.