Module 9-oil seed prosessing

Question 1

what are the steps of oil extraction

Answer 1

The derivation of edible oils from oilseeds involves primary processing of oilseeds, oil extraction, and secondary processing or refining.

Question 2

what is the purpose of primary processing

Answer 2

Primary processing begins with cleaning the seed to remove foreign materials

Question 3

what determines the specific needs of the seed preparation

Answer 3

The specifics of the seed preparation are determined by the nature of the oilseed and the extraction process employed to remove the oil from the seed

Question 4

why are seeds dehulled

Answer 4

Seeds are usually dehulled, at least partially, using an aspiration system to reduce the fibre content of the extracted meal

Question 5

how is dehulling carried out

Answer 5

Dehulling may be preceded by warming and/or increasing the moisture content

Question 6

why is dehulling benifical for oil extraction

Answer 6

Dehulled seed destined for direct solvent extraction is generally flaked to increase the efficiency of extraction by increasing available surface area and the rate of solvent percolation through the bed of material from which the oil is being extracted

Question 7

how is flaking done

Answer 7

Flaking may also be preceded by warming and/or increasing moisture content

Question 8

what happens to oilseeds destined for pressing

Answer 8

Oilseeds destined for pressing are usually flaked and cooked prior to pressing to increase handling properties and increase oil recovery.

Question 9

what is a downfall to cooking oil or meal during processing

Answer 9

Cooking also denatures enzymes that can damage the quality of the oil or meal during processing.

Question 10

what is the final step of the primary processing

Answer 10

Pressing is the final primary processing step

Question 11

what does the presses meal contain

Answer 11

The pressed meal contains a relatively high concentration of oil

Question 12

what are the steps of the primary processing of oil sees

Answer 12

1) cleaning
2) seed preparation
3) dehulling
4) flaking
5) pressing
6) press cake preperation
7) solvent extraction

Question 13

what comes off the pressing process

Answer 13

crude oil

Question 14

what comes off the solvent extraction process

Answer 14

solvent & mean and solvent & oil

Question 15

how are soy means primarily processed

Answer 15

Soybeans prepared for extraction are cracked into four to eight pieces with fluted cracking rolls, separating the hull from the cotyledon chips via aspiration, tempering the chips with steam to 60 to 65°C and flaking the chips to 0.3 mm thickness with smooth flaking rolls. Oil is then removed by direct solvent extraction.

Question 16

what are the three main methods of oil extraction

Answer 16

(1) pressing, (2) solvent (hexane) extraction, and (3) prepress-solvent extraction, a combination of pressing and solvent extraction

Question 17

what is the oil recovered by in prepress-solvent extraction

Answer 17

In prepress-solvent extraction, the bulk of the oil is recovered by pressing and the oil remaining in the presscake is removed with hexane

Question 18

what is the main determinant of what method is used to extract oil

Answer 18

The oil content of the oilseed is the principle determinant of which extraction method will be used

Question 19

how are hard oilseeds usually extracted

Answer 19

Hard oilseeds with oil contents of twenty percent or less (low oil) are usually extracted with solvent only

Question 20

how are softer oilseeds usually extracted

Answer 20

softer oilseeds with higher oil content are typically extracted using prepress-solvent extraction

Question 21

what kind of oilseeds are pressed

Answer 21

Pressing alone is used only for oilseeds such as olives, palm and cacao and oils produced for markets specifying a non-hexane extracted oil.

Question 22

what are something unrefined oils can contain

Answer 22

In addition to triglycerides, unrefined oils can also contain monoglycerides, diglycerides, free fatty acids, phosphatides (diglycerides with a phosphate group or phosphate derivative at one position), waxes (fatty acids esterified to long chain alcohols in place of glycerol), carotenes and chlorophyll.

Question 23

why is refining done

Answer 23

Secondary processing or refining is undertaken to improve the appearance, flavor, odour and stability of extracted fats and oils

Question 24

what are the steps of refining

Answer 24

Following filtration, the oil refining process involves degumming, alkali refining, bleaching, and deodorization

Question 25

why do crude vegetable oils need to be refined

Answer 25

Crude vegetable oils contain a variety of impurities including particulate matter, gums, unesterified fatty acids, pigments and malodorous aromatics that need to be refined out of the oil to improve appearance, flavor, odour and stability

Question 26

what happens when crude oil is recovered from the expeller

Answer 26

Crude oil recovered from the expeller is usually filtered and then degummed and refined.

Question 27

what oils do not undergo any further refining after filtering

Answer 27

Olive oil and cocoa butter do not undergo any further refining after filtering

Question 28

what is degumming

Answer 28

Degumming is the removal of phospholipids (gums) from the crude oil by treating it with hot water or steam

Question 29

what happens to the heated gums

Answer 29

The heated gums are hydrated, lose their oil solubility and separate from the oil when the aqueous (water) layer is removed by centrifugation

Question 30

how are non-hydratable gums removed

Answer 30

Non-hydratable gums are removed by washing the oil with dilute phosphoric or citric acid.

Question 31

what is alkali refining

Answer 31

Alkali refining utilizes a dilute alkali solution (NaOH or KOH) to solubilize free fatty acids.

Question 32

what is the aqueous phase

Answer 32

The aqueous phase separated from the oil by centrifugation will contain most of the free fatty acids in an effluent soapstock stream

Question 33

after the alkali refining how much does the free fatty acid content weight

Answer 33

Following alkali refining, the free fatty acid content of the oil is less than 0.01% by weight

Question 34

how is the soap removed after the alkali refining

Answer 34

The oil is then washed with warm water to remove any residual soap

Question 35

what is the soap stock

Answer 35

The soapstock is a mixture of sodium or potassium salts of fatty acids.

Question 36

what about the soapstock makes a challenge for the oilseed operation

Answer 36

Disposal of the soapstock stream is a challenge for oilseed processing operations

Question 37

what does bleaching do

Answer 37

Bleaching removes coloured impurities from the oil by treatment with bleaching clay or charcoal.

Question 38

how is deodorization accomplished

Answer 38

Deodorization is accomplished by treating the oil with high temperature steam under vacuum

Question 39

what is contained in the deodorization and whats in it

Answer 39

The deodorizer distillate collected from the deodorization unit contains a portion of the sterols and tocopherols naturally present in the oil

Question 40

sterols and tocopherols are collected in deodorization what can they be used for

Answer 40

These products are recovered and processed for use in the manufacture of synthetic hormones and anti-oxidants.

Question 41

what is the end product of the refining process

Answer 41

The end-product of the refining process is refined-bleached-deodorized (RBD) oil

Question 42

The end-product of the refining process is refined-bleached-deodorized (RBD) oil what is it used for

Answer 42

marketed as cooking or salad oil or used in the manufacture of modified oil products or in food processing.

Question 43

what can physical refining replace

Answer 43

Physical refining processes can be used in place of traditional refining methods to eliminate the alkali refining step

Question 44

if you replace alkali refining with physical what do you eliminate

Answer 44

eliminate the effluent soapstock stream

Question 45

why do oils that are physically refined need to be degummed

Answer 45

Oils to be physically refined must be super degummed to minimize the phosphorus content

Question 46

in physical refining what happens in deodorizing process

Answer 46

it uses a modified deodorization step removing the entire free fatty acid content along with malodorous compounds by vacuum steam