Tag: #processing

YOGURT- a fermented milk product

Yogurt is a basic fermented milk product that usually contains the basic bacterial starter cultures of Lactobacillus bulgaricus and Streptococcus thermophillus.
Although the composition of different types of yogurts changes but there is some fixed composition of fats present in them. It is important to note that all yogurts must contain at least 8.25% of solid which is not fat. The fat composition changes with the type of yogurt like full fat yogurt must contain not less than 3.25% of milk fat whereas low fat yogurt must not contain more than 2% milk fat. Also there is a category of non fat yogurt where the fat composition is even less than 0.5%.
The yogurt is basically a mixture of milk and cream which is then fermented by using a culture of Lactic acid producing bacteria. The types of milk which can be used are whole, reduced-fat, low-fat or non-fat depending on which the type of yogurt is decided. The lactic acid produced by the starter culture bacteria is basically responsible for lowering the pH of the yogurt making it acidic and tart. This finally causes the milk protein to thicken. These bacteria ferment the milk which results in the production of yogurt leads to partial digestion of the milk making it more easily digestible. In addition, these bacteria also act as a beneficial microorganisms for the human body as they act as oral-antibiotic therapy and helps in eliminating the pathogenic-bacteria from the gut and replenishing the non-pathogenic bacteria.


Ingredients of yogurt –
Milk
Cream
Sweeteners (e.g. sugar, honey, aspartame, etc)
Flavorings (e.g. vanilla, coffee, etc)
Other ingredients (e.g. fruits, preserves, stabilizers such as gelatin)

Types of yogurt –

  1. Set yogurt – This type of yogurt has a jelly-like structure and texture and is incubated and cooled in a final package.
  2. Stirred yogurt – This type is less firm than set yogurt. It is incubated in a tank and final coagulum is broken by stirring before cooling.
  3. Drinking yogurt – It also has coagulum broken before cooling though very little reformation of coagulum will occur.
  4. Frozen yogurt – This type of yogurt is incubated in the same way the stirred yogurt is incubated. It has an ice-cream like texture.
  5. Flavored yogurt – In this type of yogurt, flavors are added just before yogurt is poured into pots and the sugar content present in this type of yogurt is about 50%.

General processing of yogurt –

  1. Adjusting milk composition and blending all the ingredients
  2. Pasteurization of milk (at 85 degrees celcius for 85 minutes)
  3. Homogenization of milk (2000-2500psi)
  4. Cooling of milk to 42 degree celcius
  5. Inoculation with bacterial starter cultures into the cooled milk
  6. pH reduction by waiting for sometime
  7. Again cooling to 7 degree celcius
  8. Addition of fruits and flavors
  9. Packaging of prepared yogurt.

Health benefits of yogurt:
• Yogurt is comparably easier to digest than milk.
• It is rich in variety of vitamins.
• It is a rich source of protein.
• As it is source of protein, it may help in losing weight and gain muscles.
• It acts as a booster for immune system
• It is also important and useful for digestive system. It destroys the pathogenic microorganisms from the gut.
• It is good for bones especially for kids and elderly
• It may also be useful in lowering the blood pressure.

PULSES- STRUCTURE, COMPOSITION AND PROCESSING

WHAT ARE PULSES?
Pulses are basically a fruit part of leguminous crops that are harvested solely for the seeds. Dried beans, lentils, and peas are the most common known and consumed pulses. Pulses do not include crops which are harvested green – these are the vegetable crops. Also excluded are those crops used mainly for oil extraction and leguminous crops that are exclusively used for sowing purposes.
Generally, all pulses have a similar structure, but differ in color, shape, size and thickness of the seed coat.
Mature seeds have three components – Seed Coat, Cotyledons and Embryo.
The seed coat or hull accounts for 7-15% of whole seed mass, cotyledons accounts for 85% of total seed and embryo for 1-4%.

STRUCTURE
The external structures of the seed are testa (i.e. seed coat), hilum, micropyle and raphe.
• The testa is the outer most part of the seed and covers almost all of the seed surface.
• The hilum is an oval scar on the seed coat where the seed was attached to the stalk.
• The micropyle is a small opening in the seed coat next to the hilum.
• The raphe is a ridge on the side of the hilum opposite to the micropyle.
When the seed coat is removed from the grain, the remaining part is the embryonic structure. The embryonic structure of the pulse consists of two cotyledons (or seed leaves) and a short axis above and below them These two cotyledons are not physically attach to each other except at the axis and a weak protection is provided by the seed coat to these cotyledons. Thus, the seed is usually vulnerable to breakage. The outermost layer of the seed coat is the cuticle, and it can be smooth or rough.
• Both the micropyle and the hilum are related to the permeability of the testa and to water absorption.

COMPOSITION
Carbohydrates – 55-65%
Proteins – 18-25%
Fat – 1-4%
Minerals – 1-3%
Fibers – 1-5%

PROCESSING OF PULSES

There are various steps involved in processing of pulses:

  1. SOAKING – Soaking in water is the first step in preparing pulses for consumption. It reduces the oligosaccharides of the raffinose family. It also reduces the amount of phytic acid in pulses.
  2. GERMINATION – It improves the nutritive value of food pulses. The ascorbic acid content of pulses increase manifold after 48 hours of germination. The germination process decreases or eliminates most of the anti nutritional and toxic factors in several pulses.
  3. DECORTICATION – It is a simple method to soak the seeds for a short time in water, the husk takes up more water than the seeds and may be easily separated by rubbing while still moist. In the alternative, the soaked grains may be dried and the husk is removed by pounding and winnowing. Roasting also renders the husk easier to separate.
  4. COOKING – It destroys the enzyme inhibitors and thus improves the nutritional quality of food pulses. It also improves the palatability of the pulse.
  5. FERMENTATION – This process increases the pulse digestibility, palatability and nutritive value. It also improves the availability of essential amino acids and thus, the nutritional quality of protein of the blend.
  6. PULSE MILLING – The removal of the outer husk and splitting the grain into two equal halves is known as milling of pulses.