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ALPHABETICAL DIET

 ALPHABETICAL DIET Alphabetical diet is one in which one's take one letter diet for 26 days regularly. It starts from A and end in Z. It is basically a cooking and eating challenge and allows a variety of diet in every day life. It is not a weight loss plan. Here we discuss food and drinks available in Pakistan. LETTER 'A' APPLES Pakistan is the 10th largest apple producing country globally. The popular varities included Granny Smith, Golden Delicious, KallaKaku, Pink Lady and Red Delicious. Apples contain pectin, a natural fibre found in plants.It has a cholesterol lowering effect. Apples are low on the glycaemic index (GI) prevents diabetes. Apples are rich in polyphenols ' querctin' lower risk of hearth diseases and respiratory problems.  APRICOTS The apricot's native region is Central Asia. It is a fruit with a firm exterior and a soft interior that is smaller than a peach but looks remarkably similar. Apricots are a great food for supporting eye health sinc...
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RHEOLOGY

 

RHEOLOGY

Rheology is the science that concerns with the flow of liquids and the deformation of solids and describes the interrelation between force, deformation and time. The term comes from Greek “Rheos” meaning to flow.


TYPES OF FLOW
Rheology has developed two classes of liquids: Newtonian and Non-Newtonian fluids.
Newtonian Fluids
Newtonian fluids are those which follow Newton's hypothesis, and they are considered to be perfectly viscous. This is because the ratio between the shear rate and shear stress are constant, or in other words, the viscosity of the liquid remains constant at all possible shear rates for a given temperature.
Examples: Pure water, oils, and organic solvents.
Non Newtonian fluids
Most liquids are non-Newtonian fluids, meaning they do not have a constant ratio between their shear rate and shear stress. As a result, the viscosity of the material is highly variable. 
Examples: mayonnaise, paints and emulsions.
IMPORTANCE OF RHEOLOGY
Study of rheological properties is important in food science due to its utility in food processing operations and sensory characteristics. It gives information about the microstructure of a food. The microstructure of liquid foods has an important impact on its qualitative and quantitative quality attributes.  This microstructure is a function of the physico-chemical bonds and inter/intra-molecular associations between the ingredients in any recipe. In the recent years, rheology has become an increasingly important and demanding tool for food science as well as the food industry.
MIXING
The mixing of fluids in stirred vessels is by far one of the most common processes encountered throughout the industry in many different processes. Correct mixing is needed to ensure homogeneity of materials so as to achieve the desired product.
DISPENSING
Rheology dictates how a material is applied whether by spatula, spray, pump, syringe, cartridge, screen/stencil printing, or pouring. It is influenced by how rapidly viscosity changes once mixed due to the mixture’s chemistry.
FLOW CONTROL
Rheology affects the way a material flows. High flow allows easy entry into intricate spaces versus a low flow which prevents flow into critical areas. Flow control is very important during initial application and during the curing process as well.
SETTLING/ FLOATING
Rheology affects the degree and rate at which fillers settle. Also important is filler type, particle size, shape, and size distribution. Material with different specific gravity either settle or float depending on viscosity of the material.
PUMPING
Liquids or semi-solids are forced through the pipe.  Fluids passing through pipes similarly change viscosity depending on the amount of shear stress produced near pipe walls.
COATING
The “coatability” of food glazes, sauces and dressings is a crucial characteristic for the visual and sensory appeal of the finished product. The requirements are not trivial, however, with a range of behaviours proving desirable depending on the product and its intended presentation. A coating, must be stable during storage, easy to apply using whatever application process is appropriate, and, ideally, the final surface finish should be smooth and drip-free.
MEASUREMENT OF RHEOLOGICAL PROPERTIES
Rheological properties of fluid can be measured by following
  1. SHEAR FORCE: A shear force is a force applied perpendicular to a surface.
  2. COMPRESSION FORCE: Compression force (or compressive force) occurs when a physical force presses inward on an object, causing it to become compacted.
  3. ELONGATION FORCE: Elongation is a measure of deformation that occurs before a material eventually breaks when subjected to a tensile load.
  4. VISCOSITY: Viscosity is the measure of a substance's resistance to motion under an applied force. The formula for measuring viscosity is: 
VISCOSITY = SHEAR STRESS / SHEAR RATE


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