Vol.4, No.9B, 76-80 (2013) Agricu ltural Sciences
http://dx.doi.org/10.4236/as.2013.49B013
Insect oil and protein: Biochemistry, food and other
uses: Review
Abdalbasit Adam Mariod
College of Sciences and Arts-Alkamil, King Abdulaziz University, P.O BOX 110, ALKAMIL 21931 Alkamil, KSA;
Received August 2013
ABSTRACT
In searching for new sources of oil, protein and
gelatin researchers have investigated many wild
plants, but our research group took a different
approach: We looked at insects as oil, protein
and gelatin source for both nutritional and in-
dustrial application s. A cco rding to Sudanese
indigenous knowledge, many insects have food
and medicinal uses. We targeted two of these
insects for our research: Aspongopus vidiuatus
(melon bug) and Agonoscelis pubescens (sorg-
hum bug). The two insects showed 27.0% and
28.2% crude protein, 45% and 60% oil, respec-
tively. The oils contained 46.5% and 40.9% oleic
acid, 3.4% and 34.5% linoleic acid, 44.2% and
12.1% palmitic acid and traces of linolenic acid,
respectively. The tocopherol content of these oils
amounted to 0.3 and 34.0 mg/100g oil, respec-
tively. The total content of sterols in the two oils
was 17 and 450 mg/100g oil, respectively, whe-
reas β-sitosterol was determined as the main
compound in all oils with about 60% of the total
sterol. The oxidative stability of the oils, as meas-
ured by the Rancimat test at 120˚C, was 38 and
5.1 h, respectively. Edible gelatin was extracted
from the two insect using hot water and mild
acid and d istilled wat er. SDS-PAGE patterns of
the insect gelatins had very low molecular weight
chains, and the two gelatins contained 40 kDa as
main component, differential scanning calorime-
try results confirmed the difference between ex-
traction methods concerning the extracted gela-
tin quality. FTIR spectra of melon and sorghum
bug gelatins we re similar and the absorption
bands were situated in more than 6 bands in
melon bug gelatin and only 6 bands in sorghum
bug gelatin. Microstructures of the insect gelatin
examined wit h the scanning electron microscope
sh owed that melon bug exhibited the finest ge-
latin network with very small voids. Melon bug
gelatin showed the finer structure with smaller
protein strands and voids than sorghum bug ge-
latin. Ice cream was made by using 0.5% insect’s
gelatine and compared w it h that made using
0.5% commercial gelatine as stabilizing agent.
The properties of the obtained ice cream pro-
duced using insects gelatine were found to be
acceptable for the panelists, and no significant
differences between ice cream made using in-
sect gelatine when compared with that made
using commercial gelatine in their general pre-
ferences The behavior of the crude Sorghum
bug oil during deep-fr yin g of par-fried potatoes
was studied with regard to chemical, physical,
and sensory parameters, such as the content of
FFA, tocopherols , polar compounds, oligomer TG,
volatile compounds, oxidative stability, and total
oxidation (TO TO X ) value. The results sh owed that
the oil was suitable for deep-fr yi ng of potatoes.
The oxidative stability of sunflower kernel oil
was improved by blending with melon bug oil,
the oxidative stability in the Rancimat test w as
improved from 5% to 68% compared to the con-
trol, with increasing parts of MBO, respectively.
The insect oils were transesterified using me-
thanol or ethanol in the presence of sulfuric acid
to obtain biodiesel. The obtained insect biodiesel
characteristics w ere studied in accordance w it h
the DIN EN 14214 specifications for biodiesel. It
was possible to prepare the methyl and eth yl
esters catalyzed by H2SO4 from the two insect
oils.
Keywords: Agonoscelis pubescens; Aspongopus
vidiuatus; Insects; Biochemistry; Food; Biodeisel;
Melon Bug; Sorghum Bug
1. INTRODUCTION
Grasshoppers, caterpillars, beetles, wing ed termites, bees,
wasps and a variety of aquatic insects are used somewhere

A. A. Mariod / Agricultural Sciences 4 (2013) 76-80
77
in the world as human food. Beetles, termites, caterpil-
lars, grasshoppers, crickets, bees, maggots and butterflies
are considered significant sources of food in Africa, with
varying levels of proteins, fat, minerals and vitamins [1].
During the past few years, there has been a new up-
surge of interest in insects as food. One factor that may
be responsible is an increasing awareness in the western
world that insects are traditionally and nutritionally im-
portant foods for many non-western culture s (Fo liart, 1992).
Mariod et al. [2] has reported that insects could be an
important source of edible oil, protein, and gelatin, while
Zhou and Han [3] mentioned that insect’s proteins are of
good quality and high digestibility.
Many vegetable oils are consumed directly, or indirectly
as ingredients in food, they serve a number of purposes
in texture, flavor and flavor base. Oils can be heated and
used to cook other foods . Oils suitable for this objective
must have a high flash point. Such oils include the major
cooking oils—soybean, canola, sunflower, safflower, pea-
nut, cottonseed, etc. Tropical oils, such as coconut, palm,
and rice bran oils, are particularly valued in Asian cul-
tures for high temperature cooking, because of their un-
usually high flash point [4]
(http://www.stonepages.com/news/archives/001708.html).
According to their indigenous knowledge, Sudanese
used many insects as food and medicine. In searching for
new sources of oils, our research group has investigated
two insects: Aspongo pus vidiuatus (Malone bug) and
Agonoscelis pubescens (sorghum bug). The group fo-
cused on insects as an oil source for both nutritional and
industrial applications [5].
The melon bug is an insect belonging to family Penta-
tomidae, is about 20 mm long. It is found in most African
countries, where it causes damage to watermelon and
other cucurbit shoots. The adult bugs can usually be
found by lifting the young melon plants from the ground
and inspecting the undersides of the leaves. The nymphs
pierce the leaves, stems, and yo ung fruits and suck th e
sap, resulting in wilting, fruit drop, and the death of the
plant can be collected in infested fields [6].
The sorghum bug commonly known in Sudan as Dura
andat is belong to family Pentatomidae, shield-shaped,
about 11 - 13 mm long, and 6 - 7 mm wide. Both the
upper- and undersides of its body are covered with a fine
silvery pubescence after which it is named (Agonoscelis
pubescens). In Sudan, the adults infest sorghum during
the plant’s milky stage. In some areas of Sudan, the col-
lected bugs are pressed, and the expressed oil is used for
cooking and some medicinal purposes [7].
2. BIOCHEMIST RY OF INSECT OIL
2.1. Fatty Acids
Edible oils are of nutritional value since they contain
appreciable amounts of the essential fatty acids. Oils
extracted from plants have been used since ancient times
and in many cultures. Mariod et al. [7] exclusively in-
vestigated the oil from melon and sorghum bugs for their
oil content and fatty acids. The oil content of melon and
sorghum bugs was very high which was amounted to 45%
and 60% (dry matter), respectively. The major fatty acids
of the two oils were palmitic, stearic, oleic and linoleic
acids. Compared with oils from cottonseed, peanut, se-
same and sunflower seeds insect oils showed similar
amounts of saturated and unsaturated fatty acids.
The fatty acid composition determined by gas chro-
matography in A. viduatus and A. pubescens oils is oleic
(45.53% and 41.15%), linoleic (4.90% and 35.21%) and
palmitic (31.33% and 11.41%) acid, with 37.9% and
20.5% of saturated fatty acids, respectively [2]. Fo r in-
stance the amounts of saturated and unsaturated fat ty
acids they contain are comparable wi th those of oils com-
monly used in Sudan, su ch as sesame, groundnut, sun-
flower, and cottonseed [8].
Aspongubus viduatus and A. pubescens have 37.9%
and 20.5% of saturated fatty acids (SFA), 56.8% and
43.0% of monounsaturated fatty acids and 5.3% and
36.5% of polyunsaturated fatty acids (PUFA), respec-
tively. The balanced ingestion of foods containing PU-
FAs reduces cardiovascular disorders. The PUFA: SFA
ratio in the oil of A. viduatus is relatively lower (about
0.14), while it is relatively high (about 1.78) in the case
of A. pubescens. This ratio is recommended to be 0.45
for a healthy diet; so A. viduatus oil seems to be healthier
than that of A. pubescens. In addition, the two insect oils
have a n-6/n-3 fatty acids ratio (10.8 and 27.5 for A. vi-
duatus and A. pubescens, respectively) that should be
smaller than 4.0 as suggested by the UK Department of
Health [2].
The low amounts of polyunsaturated fatty acids such
as linoleic and linolenic acid in insect oils give them high
oxidative stability. The fatty acid composition has a much
higher influence on the stability of these oils than the
minor components of antioxidants present in the oil.
Blending sunflower oil with melon bug oil resulted in
an increase of oleic and a decrease of linoleic acid and
improved the oxidative stability of sunflower oil. This
stability increased with an increase of the percentage of
melon bug oil in blends [9]. When melon and sorghum
bug oils stored at 30˚C ± 2˚C in the dark for 24 months,
their fatty acid compositions remained almost unaltered.
The two oils showed slight changes in their oxidative
stability as indicated by the peroxide value (PV), and
when this stability was measured by Rancimat method as
an induction period, melon bug oil showed a slight de-
crease with loss of 10% of its induction period during
two years of storage. Sorghum bug oil showed a gradual
increase in the PV and a gradual loss of stability as

A. A. Mariod / Agricultural Sciences 4 (2013) 76-80
78
measured by induction period IP during storage [9].
No change in the fatty acid composition of insect oils
was observed during processing using laboratory refining
equipment [10].
2.2. Tocopherols and Sterols
The tocopherol content of foods is important to protect
food lipids against autoxidation and, thereby to increase
their storage life and their value as wholesome foods [11].
Acting as chain-breaking antioxidants, tocopherols react
with lipid radicals to convert them into more stable
products (Wagner and Elmadfa, 1999). The sorghum bug
oil had higher amounts of tocopherol content (Table 1)
which was 34.0 mg/100g while melon bug oil had low
amounts of tocopherols about 0.30 mg/100g, respective-
ly.
The amount of sterols (Table 1) in the oils ranged
from 17.5 (MBO) to 449.9 mg/100g (SBO) as general
saying the amounts of both tocopherols and sterols of
insects oil were lower th an most edible oils.
3. BIOCHEMSI TRY OF INSECT PROTEIN
3.1. Protein
The protein concentrations of Aspongubus viduatus
and A. pubescens were reported to 27.0% and 28.2%,
Table 1. Tocopherol and Sterol Content (mg/100g oil) of two
Insects Oil*.
Type of tocopherol Melon bug oil (MBO) Sorghum bug oil (SBO)
α-T 0.17 0.88
β-T 0.00 0.00
γ -T 0.13 32.16
P8 0.00 0.21
δ-T 0.00 0.78
Total 0.30 34.03
Type of sterol
Cholesterol 1.4 2.2
Campesterol 1.8 11.6
Stigmasterol 0.8 25.4
ß-sitosterol 10.6 268.8
∆5-avenasterol 0.5 16.3
∆7-avenasterol 0.0 1.6
∆7-stigmasterol 0.9 2.8
*Others 1.5 121.2
Total 17.5 449.9
*Data are means of triplicate results. *Others include 24-methylcholesterol,
campestanol, chlerosterol, sitostanol, 5,24-stigmastadienol. Source: rede-
signed from Mariod et al. [12].
respectively, on a dry-matter basis). The total amino ac-
ids were 360.5 and 268.8 mg/g crud e protein, respective-
ly, which was less than the 864.2 mg/g crude protein in
chicken egg that is considered as a main protein source
in the human diet [2].
3.2. Gelatin
Gelatine is a product obtained by the partial hydrolysis
of collagen derived from the skin, w hite connective tis-
sue and bones of animals. It is a gelling protein, which
has widely been applied in the food and pharmaceutical
industries. Most of commercial gelatine (95%) is made
from hide of porcine and bovine and the remaining part
(5%) comes from bones of porcine and bovine [13]. The
study of gelatine from fish by-products, such as skin and
bone (Gudmundsson, 2002) and from insects of melon
and sorghum bugs [14] has increased for the replacement
of mammali a n resources.
Gelatin was extracted from the dried adult insects us-
ing hot, distilled water and mild acid. Extraction of insect
gelatin using hot water gave high yield (3.0%) follow e d
by mild acid and distilled water (2.5% and 0.66%) ex-
traction, respectively. SDS-PAGE pattern showed low
molecular weight chains, and the two gelatins contained
protein with molecular we ight of 40 kDa as main com-
ponent. The differential scanning calorimetry thermo-
grams results confirm no difference between extraction
methods concerning the extracted gelatin quality. FTIR
spectra of melon and sorghum bug gelatins were similar
and the absorption bands were situated in more than 6
bands in melon bug gelatin and only 6 bands in sorghum
bug gelatin. Amide II bands of gelatins from both melon
and sorghum bug appeared at around 1554 cm−1, while
Amide I bands (1734 - 1632 cm−1) appeared only in me-
lon bug method 2 (MB2) and melon bug method3 (MB3)
[14].
Microstructures of the insect gelatin ex amined with
the scanning electron microscope showed that melon bug
exhibited the finest gelatin network with very small voids.
Melon bug gelatin showed finer structure with smaller
protein strands and voids than s orghum bug gelatin [14].
4. FOOD USES OF INSECTS
In Mexico about s eventy eight edible insect species are
used as food, the nutrient composition of these species
were reported and the protein content was found ranging
from 15% to 81%, fat content from 4.2% to 77.2%, with
carbohydrates up to 77.7% on a dry-matter basis [15].
Seventeen species of edible insects representing nine
families were analyzed for their nutrient composition.
These insect species constitute a significant component
of diet among the people of southwestern Nigeria [16].
These insects were found contained high crude protein

A. A. Mariod / Agricultural Sciences 4 (2013) 76-80
79
(27% - 30%). In Thailand, over 50 species of insects are
edible and can be consumed throughout the year; these
include silk worm pupae, bamboo caterpillars, locusts,
beetles and crickets [17].
Mariod et al. [9] improved the oxidative stability of
sunflower kernel oil by blending with 10%, 20%, 30%
and 40% of melon bug oil, respectively. The improved
oil showed good performance, color and flavor. The same
author in the same year repor ted that sorghum and melon
bug oils were suitable for deep-frying only for 6 to 12 h.
After that, the oil and the potatoes fried in it did not meet
the requirements with regard to the sensory assessment
or chemical parameters [18].
Crude melon and sorghum bugs oil were refined using
a laboratory refining experiments their phosphatide, pe-
roxide, tocopherol, and sterol contents as well as oxida-
tive stability fell during refining process, while their free
fatty acids were almost totally removed. The amounts of
total volatiles as well as the amounts of hexanal were
decreased during the different processing steps. The color
decre ased throughout the processing steps up to bleaching,
then in the deodorization step it darkened sharply in all
samples. No change in the fatty acid composition was
observed [10].
5. INDUSTRIAL USES OF INSECT OIL
Melon an d sorghum bugs oils were transes terif ied us-
ing methanol and ethanol in the presence of sulfuric acid.
The resultant fatty acid esters were compared with the
DIN 51606 specifications for biodiesel. Most of the in-
sect oil biodiesel characteristics met the DIN specifica-
tions (water content, iodine number, phosphorus). How-
ever, the kinematic viscosity values of all samples were
much higher than those for biodiesel standards. These
can be reduced by blending with other low-viscosity bio-
diesels [19].
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