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Z. Xiao et al.
as a-linolenic acid and unsaponifiable matter were better preserved. The SCW oil is
similar to the CP oil in composition and the similarity reached up to nearly 96%. For
all SCW oils, there is a minimal degree of hydrolysis of the triglycerides. Subcritical
water extraction proved to be an alternative and greener method for simultaneous
separation and production of oil and tea saponin.
2.6.2 Aqueous Enzymatic Extraction of Castor (Ricinus
communis) Seeds Oil
Ricinus communis (Castor), a member of Euphorbiaceae, is an important non-food
oilseed crop predominantly grown in subtropical and tropical regions worldwide. The
high oil yield (contains 37.2–60.6% oil) and unique fatty acid composition (the ricinoleic acid constitutes around 90% of the total fatty acids) of the castor seeds make
it widely be used for lubricating oil and bioenergy production. Castor oil is mainly
extracted by pressing or solvent extraction (SE), sometimes seeds are mechanically
pre-pressed followed by SE. Unfortunately, severe heat treatment during conventional processing not only affects the oil quality but also denatures the protein in the
meal which is ultimately used as fertilizer. On the other hand, the flammability, possible contamination of the oil, and air pollution caused by solvent residues made it
urgent to find a nonhazardous and environmental-friendly way to solve the problem.
Alternatively, aqueous enzymatic extraction (AEE) has been regarded as a promoting method for simultaneous extraction of oil and protein, which based on enzymatic hydrolysis of cellulose and hemicellulose to weaken oilseeds tissue defenses
by digesting the cell walls promote the efficiency of algae lipid extraction, and help
to release the desired compounds into the extracting solution. It is thought to be
environmentally-friendly, cheap, and safe, which avoids serious damage to the oil
and proteins of the seed and has been extensively applied for the extraction of oils
from seed crops such as sesame, sunflower, pumpkin, soybean, camellia, and peanut.
And the effects of solvent extraction (SE) and aqueous enzymatic extraction (AEE)
on the oil’s physicochemical properties were compared. The enzyme of nutrase was
found to be the best one in extracting free oil compared to other enzymes (cellulase, hemicellase, pectinase, and amylase), and the highest oil recovering rate of
77.53% was achieved under optimal experimental conditions of hydrolysis temperature (47 °C), enzyme concentration (3%), ratios of material to water was (1:3.7)
(w/v), and hydrolysis time (4.5 h). Compared with SE oil, AEE oil was more acidic
and had a higher hydroxyl value but did not affect the fatty acids composition. SEM
results illustrated that the nutrase mainly breaks down the seed cells and oil bodies’
membranes structure of castor, which resulted in more free oil releasing from seeds
cell. The results demonstrated that AEE is a promising environmentally friendly
technology for oil extraction of castor seeds in the oil industry.
Z. Xiao et al.
as a-linolenic acid and unsaponifiable matter were better preserved. The SCW oil is
similar to the CP oil in composition and the similarity reached up to nearly 96%. For
all SCW oils, there is a minimal degree of hydrolysis of the triglycerides. Subcritical
water extraction proved to be an alternative and greener method for simultaneous
separation and production of oil and tea saponin.
2.6.2 Aqueous Enzymatic Extraction of Castor (Ricinus
communis) Seeds Oil
Ricinus communis (Castor), a member of Euphorbiaceae, is an important non-food
oilseed crop predominantly grown in subtropical and tropical regions worldwide. The
high oil yield (contains 37.2–60.6% oil) and unique fatty acid composition (the ricinoleic acid constitutes around 90% of the total fatty acids) of the castor seeds make
it widely be used for lubricating oil and bioenergy production. Castor oil is mainly
extracted by pressing or solvent extraction (SE), sometimes seeds are mechanically
pre-pressed followed by SE. Unfortunately, severe heat treatment during conventional processing not only affects the oil quality but also denatures the protein in the
meal which is ultimately used as fertilizer. On the other hand, the flammability, possible contamination of the oil, and air pollution caused by solvent residues made it
urgent to find a nonhazardous and environmental-friendly way to solve the problem.
Alternatively, aqueous enzymatic extraction (AEE) has been regarded as a promoting method for simultaneous extraction of oil and protein, which based on enzymatic hydrolysis of cellulose and hemicellulose to weaken oilseeds tissue defenses
by digesting the cell walls promote the efficiency of algae lipid extraction, and help
to release the desired compounds into the extracting solution. It is thought to be
environmentally-friendly, cheap, and safe, which avoids serious damage to the oil
and proteins of the seed and has been extensively applied for the extraction of oils
from seed crops such as sesame, sunflower, pumpkin, soybean, camellia, and peanut.
And the effects of solvent extraction (SE) and aqueous enzymatic extraction (AEE)
on the oil’s physicochemical properties were compared. The enzyme of nutrase was
found to be the best one in extracting free oil compared to other enzymes (cellulase, hemicellase, pectinase, and amylase), and the highest oil recovering rate of
77.53% was achieved under optimal experimental conditions of hydrolysis temperature (47 °C), enzyme concentration (3%), ratios of material to water was (1:3.7)
(w/v), and hydrolysis time (4.5 h). Compared with SE oil, AEE oil was more acidic
and had a higher hydroxyl value but did not affect the fatty acids composition. SEM
results illustrated that the nutrase mainly breaks down the seed cells and oil bodies’
membranes structure of castor, which resulted in more free oil releasing from seeds
cell. The results demonstrated that AEE is a promising environmentally friendly
technology for oil extraction of castor seeds in the oil industry.