Food preparations techniques

1
Food preparations techniques

• Textbook chapter 6

2
Do you know why ?

• meat turns pink or brown when it is cooked
• meat turns brownish or greenish in refrigerator
• cake rises when it is placed in oven
• grains or nuts can be stored at room temperature
  while fish or meat in refrigerator or freezer
• a canned food can be toxic even when it looks
  normal

3
FOOD SCIENCE IS

• the study of physical and chemical phenomena
• occurring during preparation of food based on
  
• a knowledge of chemical and physical
  properties of food
• the environmental conditions temperature,
  light, oxygen
• the nature of chemical reaction caused by these
  factors
• the effects on food of added substances

4
Food is a mixture of complex chemical substance
s such as proteins, fats, polysaccharides,
fibre, minerals.
5
The objective of food preparation include

• Palatability flavor, texture, size, shape,
  temperature
• variety size, shape and color
• safety microbial contamination, food toxicants
• nutrient retention

6
The preparation of food is both a science and
an art
7
Science of food preparation includes

• Knowledge of interactions between proteins, fats,
  sugars, flavor substances, pigments
• effect of environmental factors on the
  palatability

8
An art of food preparation includes

• Arrangement
• size
• color
• combinations
• variety
• texture

9
The purpose of food cooking is

• to make its maximum nutritive value available in
  a palatable form
• to develop, enhance or alter its flavor
• to increase its palatability by improving or
  retaining its color or texture
• to improve its digestibility
• to destroy pathogenic organisms

10
HEAT is the energy in transit due to a
tempe- rature difference between two regions and
is always transferred from the region of
higher temperature to the region of
lower temperature.
11
HEAT MAY BE TRANSFERRED BY

• Conduction
• Convection
• Radiation

12
CONDUCTION
Transmission of energy due to direct
molecular interaction without appreciable
displacement of the molecules
13
CONVECTION
Transport of energy from one point of fluid to
another point by actual movement of fluid itself
14
Radiation
Transport of energy in the form of
electro- magnetic waves between materials
across the space.
15
QUESTIONS ?