Introduction

What is the main chemical constituent of fats and oils?
The main chemical constituent of fats and oils are triacylglycerols (TAGs).

What fatty acids are animal fats primarily made up of?
Animal fats are primarily made up of saturated fatty acids (SFAs).

What fatty acids are vegetable oils primarily made up of?
Vegetable oils are primarily made up of varying proportions of saturated and unsaturated fatty acids (SFAs and UFAs) tied to their TAG molecules.

What are the two types of unsaturated fatty acids?
The two types of unsaturated fatty acids are monounsaturated (MUFAs) and polyunsaturated (PUFAs).

What are the physico-chemical properties of TAGs dependent on?
The physico-chemical properties of TAGs are dependent on what fatty acids they're made of.

How many different types of fatty acids are in the molecules of simple TAGs?
Simple TAGs have the same fatty acid in their molecules.

How many different types of fatty acids are in the molecules of mixed TAGs?
Mixed TAGs have two or three different fatty acids in their molecules.

Oilseed pretreatment

What is the first step of seed oil extraction regardless of the method used?
The first step of seed oil extraction regardless of the method used is oilseed pretreatment.

What steps make up oilseed pretreatment?
The steps that make up oilseed pretreatment include:

  • Dehulling.
  • Pod or seed coat removal.
  • Winnowing.
  • Sorting.
  • Cleaning.
  • Grinding or milling.
  • Preheating.

What are the two reasons for grinding or crushing oilseeds prior to solvent extraction?
The two reasons for grinding or crushing oilseeds prior to solvent extraction is:

  1. To ensure oil-bearing minute cells embedded in fibrous structures are ruptured to release the oil.
  2. To increase the surface area for solvent penetration.

What is the purpose of heat treatment prior to solvent extraction?
The purpose of heat treatment prior to solvent extraction is to reduce moisture content and harden the interior of the oilseed to facilitate oil release.

Oil extraction methods

What are the three major methods of extracting oil from oil-rich parts of plants?
The three major methods of harvesting oil from oil-rich parts of plants are:

  1. Wet extraction (hot water or steam).
  2. Solvent extraction.
  3. Mechanical expression.

What is the ultimate verdict on traditional methods of seed oil extraction?
The ultimate verdict on traditional methods of seed oil extraction are that it is:

  • Crude.
  • Largely unscientific.
  • Inefficient.
  • Poor quality.

What are the conventional methods for seed oil extraction?
The conventional methods for seed oil extraction are the well-known and widely practiced methods of solvent extraction, mechanical expression, or both.

For what type of oilseed is solvent extraction used?
Solvent extraction is used on oilseeds with low oil content (<20%).

How is the choice of solvent determined?
The choice of solvent is determined by the:

  • Leaching characteristics of the desired solute substrate.
  • High solvent-solute ratio.
  • Relative volatility of solvent to oil.
  • Oil viscosity and polarity.
  • Cost and market availability.

What solvents are commonly used?
Solvents commonly used are:

  • Hexane.
  • Diethyl ether.
  • Petroleum ether.
  • Ethanol.

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What is mechanical expression?
Mechanical expression is the application of pressure to force oil out of an oil-bearing material.

For what type of oilseed is mechanical expression used?
Mechanical expression is used on oilseeds with a high oil content (>20%).

What are the two types of mechanical press methods?
The two types of mechanical press methods are:

  1. Cold-press (below 50ºC).
  2. Hot-press (elevated temperature and pressure).

Of the two types of mechanical press methods, which results in safer oil?
Of the two types of mechanical press methods, cold-press mechanical expression results in safer oil.

What is preserved with cold-press mechanical expression?
Cold-press mechanical expression preserves:

  • Oil purity.
  • Natural properties of seed oils.
  • Valuable nutraceuticals like phytosterols and tocopherols.

What are the adverse effects of using hot-press mechanical expression?
The adverse effects of using hot-press mechanical expression are:

  • Decreased oxidative stability.
  • Degradation of valuable oil components.
  • Reduced oil keeping quality.

What are the innovative and alternative methods of seed oil extraction aside from the traditional and conventional methods?
The innovative and alternative methods of seed oil extraction aside from the traditional and conventional methods are:

  • Microwave-assisted extraction (MAE).
  • Ultrasonic-assisted extraction (UAE).
  • Supercritical fluid extraction (SFE).
  • Soxtec extraction.

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