Raw material properties
Definition
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Raw materials are substances and products that manufacturers and processors use to create finished goods for human consumption.
Food industries invest in raw materials to produce their final food products that work with raw material producers from all over the world.
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DEFINITION:
A raw material is a condition prior to processing and obtaining the necessary components used to manufacture a product or structure in industry. This term is most often used for materials that are obtained from nature and have not yet been processed or have been processed only slightly. Iron ore, wood, crude oil are materials that can be an example of raw material.
Kinds of raw material properties
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Fruits and vegetables
Grain-seed-nuts
Meat-Seafood and Poultry
Diary products
Aromatic brants
Eggs
Honey
Plant raw material
Animals raw material
Raw material
Kinds of raw material properties
Chemical properties of food cannot be measured without altering the chemical composition of the food, such as: Moisture content and water activity, fat content, pH, acidity, viscosity, nutritional value, enzyme concentration, etc.
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Physical properties
Let’s start with the first set of properties
Physical properties of raw materials are:
The obvious (organoleptic) characteristics, such as : shape, appearance, taste, smell, flavour, texture, color, defects, aroma, size, density, freshness, etc.
In the next slides we will analyze these characteristics
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Shape and appearance
Appearance of raw agriculture materials is a significant quality indication throughout the commercial-use chain, from manufacture through storage, marketing, and lastly to the consumer. Their overall appearance is linked with shape, size, color and lack of visual faults.
The shape of agricultural products is one of the most important aspects of their appearance and it’s one of the most essential factors in the categorization and grading in terms of commercial quality and organoleptic characteristics.
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Color is the most important feature of food appearance. is the first perceived feature and becomes a determining factor in quality selection or evaluation food
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Color measurements
Color measurements can be used to predict visual and chemical changes in foods, an important criterion used to evaluate quality
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Flavour
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TASTE
One of the five senses, by which we perceive the quality of food and fluids in the mouth depending on how they irritate the tongue
There are five main tastes, sweet, bitter, sour, salty and umami.
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The basic taste qualities, sweet, sour, salty, bitter and umami of the foods are governed a number of small molecular compounds, which are in most cases water soluble.
All sugars and sweeteners are ions or dipolar molecules, salts dissociate in their ions. The acid taste is related to proton activity and umami to a number of water-soluble molecules, the most well-known glutamic acid.
Smell and aroma
Smell is a sense that is a result of olfactory nerve in our nasal cavity. All smells, whether good or bad, are called odors.
Each individual food item has a smell all to its own as well.Our primitive ancestors used to smell food to understand whether it was edible or not
Aroma is a word that is used for pleasant smells of aromatic plants, foods, and drinks.
The aroma or aromatic quality of food in each dish is the defining quality and character that separates it from the other dishes.
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DENSITY
The mass density or density of a material is defined as its mass per unit volume. The mass density of a material varies with temperature and pressure. The variance is typically small for solids and liquids.
Bulk density is a property of powders, granules and other solids, particularly used in reference to mineral components (soil, gravel), chemical substances, (pharmaceutical) ingredients, foodstuff or any other masses of corpuscular or particulate matter. It is defined as the mass of many particles of the material divided by the total volume they occupy.
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2.�Chemical properties
Chemical properties of raw materials are:
The properties that cannot be measured without altering the chemical composition of the food material, such as: moisture content and water activity, fat content, pH, acidity, viscosity, nutritive value, enzyme concentration,etc.
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Water moisture of food raw materials
Most foods have a water activity above 0.95 and that will provide sufficient moisture to support the growth of bacteria, yeasts, and mold. The amount of available moisture can be reduced to a point which will inhibit the growth of the organisms. If the water activity of food is controlled to 0.85 or less in the finished product, it is not subject to the regulations of 21 CFR Parts 108, 113, and 114.
The water activity (a w) of a food is the ratio between the vapor pressure of the food itself, when in a completely undisturbed balance with the surrounding air media, and the vapor pressure of distilled water under identical conditions.
A water activity of 0.80 means the vapor pressure is 80 percent of that of pure water. The water activity increases with temperature. The moisture condition of a product can be measured as the equilibrium relative humidity expressed in percentage or as the water activity expressed as a decimal.
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Fat content plays an important role in food sensory quality by
contributing to attributes such as texture, flavor, nutrition, and caloric density. Ioanna Z
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pH-Acidity
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The term pH is a measure of acidity; the lower the value, the more acid in the food.The pH is an indicator of the amount of acid or base present in a food.
For canned foods, a pH of 4.6 or lower would prevent microorganisms το grow if proper sterilization time and temperature are used.
The pH also affects flavor, color and texture.
Viscosity
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Exogenous factors that affect quality of raw materials
Preharvest factors
Post harvest conditions
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Timing and methods of harvesting
Post harvest operations
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Resources
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