Handbook of Solvents - George Wypych - ChemTech - Ventech!

14.10 Food industry 935
Figure 14.10.1a. Flow diagram of oilseed extraction
process from seed to crude oil and
meal.
the extraction solvent, if proper manufacturing practices
are followed. (see Section 14.10.3.3 Processing
crude oil, for more details.) Refining
removes free fatty acids and other non-oil
compounds (e.g., phospholipids, color, and trace
metals); bleaching with acid-activated bleaching
earth or clay (e.g., bentonite), removes color-producing
substances and residual soaps; and
deodorization, the last major processing step in edible
oils refining removes volatile compounds (undesirable
ingredients occurring in natural oils and
those that may be imparted by prior unit processes or
even storage, many of which are associated with undesirable
flavors and odors). 26,27 Most commercial
deodorizers operate at a temperature of 245-275 o C
(475-525 o F) under a negative pressure of 2-10 mm
Hg. 26,27 It has been reported that no hexane residue
remains in the finished oil after processing due to its
high volatility. 28 In addition, animal-feeding studies
with expeller and solvent-extracted meals have not
indicated any adverse health affects related to the
extraction solvent. 29
Hexane has been used since the 1940’s as an
oilseed-extraction solvent on the determination that
it is GRAS and it may also be subject to a prior sanction.
However, like many other food-processing
substances, there is no U.S. FDA regulation specifi-
cally listing hexane as GRAS or prior sanctioned.
GRAS status may be determined by a company (“GRAS self-determination”), an industry,
an independent professional scientific organization (e.g., FEMA GRAS), or the U.S.
FDA. The Federal Food, Drug and Cosmetic Act (FFDCA; 21 U.S. Code 321 et seq.) does
not provide for the U.S. FDA to approve all ingredients used in food, and the U.S. FDA explicitly
recognizes that its published GRAS list is not meant to be a complete listing of all
substances that are in fact GRAS food substances. Although there is no requirement to inform
the U.S. FDA of a GRAS self-determination or to request FDA review or approval on
the matter, the U.S. FDA has established a voluntary GRAS affirmation program under
which such advice will be provided by the agency. Solvents that do not have prior sanction,
a GRAS determination, or a tolerance set, probably should be evaluated for compliance under
food safety requirements, if a facility is considering changing its extracting solvent or
using a solvent for the extraction of the various biological materials for specialty markets.
14.10.3 THE SOLVENT EXTRACTION PROCESS
Three types of processing systems are used to extract oil from oil-bearing materials:
expeller pressing, prepress solvent extraction, and direct solvent extraction. Only prepress
solvent extraction and direct solvent extraction, which remove the oil from the conditioned,
prepared seed with an organic solvent, will be discussed here 1,27 (see Figure 14.10.1).
Oil-bearing materials have to be prepared for extraction to separate the crude oil from the