Question

Assignment
1,industrial biochem
:Discuss biophotolysis(10mks)1 page
:Explain types of biopolymers(5mks)1 page
:Discuss yogurt production process and the
microorganisms involved.(20mks)2 pages
:Explain bioextractive mettalurgy.

Answer 1

Biophotolysis is the action of light on biological systems that results in dissociation of water into molecular hydrogen and oxygen,

H2O → H2 + ½ O2.

This review focuses on biophotolysis-based hydrogen production by green microalgae and cyanobacteria.

Biophotolysis - the Process
Photochemical reactions are initiated by the absorption of energy in the form of radiation (infrared, visible or ultraviolet). The process by which a photochemical reaction is carried on is designated photolysis. Photochemical processes are sometimes extremely efficient in the conversion of light energy into chemical energy. In photosynthesis in green plants, light energy is converted into stored chemical energy by the production of cellular constituents from carbon dioxide and water. The process is initiated with the breaking of the stable bond between hydrogen and oxygen in the water molecule by radiant energy in the primary photochemical reaction
[1] H 0 ~ 2 H+ + 2 e- + 1h 0 2 2
The water molecule can not - under usual conditions - be cleaved directly into H- and OH radicals by the action of sunlight. A photodissociation of this type requires a high-energy radiation of at least 114 kcal per Einstein. This corresponds to a wavelength of 260 nm. Photodissociation requires this or even shorter wavelengths if no suitable sensitizer is present. Radiation of these
wavelengths is, because of their high energy content fatal for living cells. Light energy is a flow of photons whose energy content is inversely related to the wavelength of the radiation. Photosynthetically active organisms have acquired appropriate pigments to enable them to use the biologically less dangerous part of the solar spectrum for the cleavage of water. The energy of effective red quanta amounts to about 40 kcal per Einstein. In this case, more than one quantum is required to split one molecule of water, in contrast to the photodissociation of water by ultraviolet radiation. The various kinds of photosynthesis among higher plants and microorganisms show common fundamental features. The structural and functional basis of the physiological process has been
intensively studied. The series of events takes place in a lipid bilayer membrane - the thylakoid. Special pigment-protein complexes known as antennae are situated on the surface of or in the membrane and capture light energy. By resonance, the energy is transferred to reaction centers where the energetically decisive photochemical reactions take place

2)

Biopolymer Classification

There are four main types of Biopolymers. These are

Sugar based Biopolymers

Starch or Sucrose is used as input for manufacturing Polyhydroxibutyrate. Sugar based polymers can be produced by blowing, injection, vacuum forming, and extrusion. Lactic acid polymers (Polyactides) are created from milk sugar (lactose) that is extracted from potatoes, maize, wheat, and sugar beet. Polyactides are resistant to water and can be manufactured by methods like vacuum forming, blowing and injection molding.

Starch-based Biopolymers

Starch acts as a natural polymer and can be obtained from wheat, tapioca, maize and potatoes. The material is stored in tissues of plants as one way carbohydrates. It is composed of glucose and can be obtained by melting starch. This polymer is not present in animal tissues. It can be found in vegetables like tapioca, corn, wheat and potatoes.

Biopolymers based on Synthetic materials

Synthetic compounds that are obtained from petroleum can also be used for making biodegradable polymers such as aliphatic aromatic copolyesters. Though these polymers are manufactured from synthetic components, they are completely compostable and bio-degradable.

Cellulose-based Biopolymers

These are used for packing cigarettes, CDS and confectionary. This polymer is composed of glucose and is the primary constituent of plant cellular walls. It is obtained from natural resources like cotton, wood, wheat, and corn.

The production of biopolymer may be done either from animal products or agricultural plants.

3)

Production

1. Adjust Milk Composition & Blend Ingredients

Milk composition may be adjusted to achieve the desired fat and solids content. Often dry milk is added to increase the amount of whey protein to provide a desirable texture. Ingredients such as stabilizers are added at this time.

2. Pasteurize Milk

The milk mixture is pasteurized at 185°F (85°C) for 30 minutes or at 203°F (95°C) for 10 minutes. A high heat treatment is used to denature the whey (serum) proteins. This allows the proteins to form a more stable gel, which prevents separation of the water during storage. The high heat treatment also further reduces the number of spoilage organisms in the milk to provide a better environment for the starter cultures to grow. Yogurt is pasteurized before the starter cultures are added to ensure that the cultures remain active in the yogurt after fermentation to act as probiotics; if the yogurt is pasteurized after fermentation the cultures will be inactivated.

3. Homogenize

The blend is homogenized (2000 to 2500 psi) to mix all ingredients thoroughly and improve yogurt consistency.

4. Cool Milk

The milk is cooled to 108°F (42°C) to bring the yogurt to the ideal growth temperature for the starter culture.

5. Inoculate with Starter Cultures

The starter cultures are mixed into the cooled milk.

6. Hold

The milk is held at 108°F (42°C) until a pH 4.5 is reached. This allows the fermentation to progress to form a soft gel and the characteristic flavor of yogurt. This process can take several hours.

7. Cool

The yogurt is cooled to 7°C to stop the fermentation process.

8. Add Fruit & Flavors

Fruit and flavors are added at different steps depending on the type of yogurt. For set style yogurt the fruit is added in the bottom of the cup and then the inoculated yogurt is poured on top and the yogurt is fermented in the cup. For swiss style yogurt the fruit is blended with the fermented, cooled yogurt prior to packaging.

9. Package

The yogurt is pumped from the fermentation vat and packaged as desired.

Bacterial Cultures

The main (starter) cultures in yogurt are Lactobacillus bulgaricus and Streptococcus thermophilus. The function of the starter cultures is to ferment lactose (milk sugar) to produce lactic acid. The increase in lactic acid decreases pH and causes the milk to clot, or form the soft gel that is characteristic of yogurt. The fermentation of lactose also produces the flavor compounds that are characteristic of yogurt. Lactobacillus bulgaricus and Streptococcus thermophilus are the only 2 cultures required by law (CFR) to be present in yogurt.

Other bacterial cultures, such as Lactobacillus acidophilus, Lactobacillus subsp. casei, and Bifido-bacteria may be added to yogurt as probiotic cultures. Probioticcultures benefit human health by improving lactose digestion, gastrointestinal function, and stimulating the immune system

There is nothing called bioextractive mettalurgy. If you have typed wrong just change it and we will answer it