Studies on physico-chemical characteristics and fatty acid composition of wild apricot (Prunus armeniaca Linn.) kernel oil

Abstract

Some principle characteristics like fruit, stone and kernel weight and kernel and oil recovery as crude oil and physico-chemical characteristics of apricot (Prunus armeniaca Linn.) kernel oils were determined in the stones collected from different locations of Himachal Pradesh. Mean fruit weight of apricot fruits ranged between 8.0-15.1 g with the stone recovery of 12.7-22.2% having stone weight 1.78-1.92 g. Further, the kernel recovery was found ranging between 30.7-33.7% whereas kernels gave oil yield of 45.6-46.3% crude oil. The study further revealed that the colour of apricot kernel oil was yellow whereas acid value; peroxide value; iodine value and saponification value were reported as 2.27-2.78 mg KOH/g; 5.12-5.27 meq/kg; 100.2-100.4 g I2/100 g and 189.8-191.3 mg KOH/g oil, respectively. The fatty acid profile of these oils showed that the oleic (62.07-70.6%); linoleic (20.5-27.76%); linolenic (0.4-1.42%); palmitic (5.0-7.79%) acids are present in major quantity, while palmitoleic acid (0.48-0.70%) in small quantities. Vitamin E contents were present in oil to the extent of 72-107 mg/100 g. Apricot oil was characterized by its high contents of oleic and linoleic acid. The apricot oils because of the fatty acid composition indicates that they may be suitable as edible oils and vitamin E rich contents make these oils suitable for use in preparation of cosmetic and moisturizing creams for dry skins, massaging oils and for industrial use.

Full text

Indian Journal of Natural Products and Resources
Vol. 3(3), September 2012, pp. 366-370
Studies on physico-chemical characteristics and fatty acid composition of wild
apricot (Prunus armeniaca Linn.) kernel oil
Anil Gupta1*, P C Sharma1, B M K S Tilakratne2 and Anil K Verma1
1Department of Food Science and Technology, Dr. Y S Parmar University of Horticulture and Forestry, Nauni, Solan – 173 230,
Himachal Pradesh, India
2Institute of Postharvest Technology, Anuradhapura, Sri Lanka
Received 01 January 2010; Accepted 28 May 2012
Some principle characteristics like fruit, stone and kernel weight and kernel and oil recovery as crude oil and physico-
chemical characteristics of apricot (Prunus armeniaca Linn.) kernel oils were determined in the stones collected from
different locations of Himachal Pradesh. Mean fruit weight of apricot fruits ranged between 8.0-15.1 g with the stone
recovery of 12.7-22.2% having stone weight 1.78-1.92 g. Further, the kernel recovery was found ranging between 30.7-
33.7% whereas kernels gave oil yield of 45.6-46.3% crude oil. The study further revealed that the colour of apricot kernel oil
was yellow whereas acid value; peroxide value; iodine value and saponification value were reported as 2.27-2.78 mg
KOH/g; 5.12-5.27 meq/kg; 100.2-100.4 g I2/100 g and 189.8-191.3 mg KOH/g oil, respectively. The fatty acid profile of
these oils showed that the oleic (62.07-70.6%); linoleic (20.5-27.76%); linolenic (0.4-1.42%); palmitic (5.0-7.79%) acids are
present in major quantity, while palmitoleic acid (0.48-0.70%) in small quantities. Vitamin E contents were present in oil to
the extent of 72-107 mg/100 g. Apricot oil was characterized by its high contents of oleic and linoleic acid. The apricot oils
because of the fatty acid composition indicates that they may be suitable as edible oils and vitamin E rich contents make
these oils suitable for use in preparation of cosmetic and moisturizing creams for dry skins, massaging oils and for
industrial use.
Keywords: Apricot, Prunus armeniaca, Kernels, Crude oil, Fatty acid composition, Vitamin E.
IPC code; Int. cl. (2011.01)—A61K 36/00, C11B 1/04
Introduction
Apricot (Prunus armeniaca Linn.), commonly
known as chulli, chulu, sarha or zardalu is grown in
temperate regions of the world including USA, Spain,
France, Italy, Turkey, Morocco, Iran, Africa and
Australia. In India, apricots are found growing in
Himachal Pradesh, Jammu & Kashmir and Uttarkashi
in Uttarakhand. In Himachal Pradesh, it is grown in
the districts of Shimla, Mandi, Kullu, Chamba,
Sirmour, Kinnaur and Lahaul-Spiti1. Owing to their
short harvest season and highly perishable nature,
apricots are mostly used for preparation of different
value-added products, in processing, in drying and in
preparation of fermented liquor (Ghanti). The
stones/pits left after processing is thrown as a waste,
which otherwise is a good source of edible oil and
considered to be a good source of polyunsaturated
fatty acids like linoleic and linolenic acid and oleic
acid as monounsaturate with a good nutritional and
pharmaceutical importance. Broadly, it contains 13.7%
saturated and 86.0% unsaturated fatty acids2. The oil
has been used in preparation of many cosmetic
products, moisturizing creams for dry skins, baby oil,
massaging oil, face scrub, lip balm, etc3. It is
estimated that Indian varieties are reported to contain
44% oil4. Femenia et al reported that the apricot
kernels contain more oil (53 g/100 g) that of bitter
kernels (43g/100 g)5. Owing to the presence of
unsaturated fatty acids in good proportion, its quality
attributes matches with almond oil. After oil
extraction from apricot kernels, around 60% of
remaining residue called as press cake, contains about
50% of protein thus the press cake can also be utilized
as protein source after its treatment for removal of
bittering component hydrocyanic acid (HCN).
The level of major fatty acids found in apricot
kernel oil range between 3.2-10.7 palmitic, 51.0-83.3
____________
*Correspondent author:
E-mail: pht_anil@sify.com

GUPTA et al: PHYSICO-CHEMICAL & FATTY ACID COMPOSITION OF WILD APRICOT KERNEL OIL
367
oleic and 9.6-45.9% linoleic acid5. The oil obtained
from Indian bitter apricot kernels had the fatty acid
composition as 1.1 myristic, 3.5 palmitic, 2.0 stearic,
73.4 oleic and 20.0% linoleic acid, the lipid profile in
apricot oil also reported as 3.8 myristic, 4.37 palmitic,
0.12 palmitoleic, 0.46 stearic, 66.29 oleic, 28-64
linoleic and 0.12% linolenic acid6,7. A diet rich in
palmitoleic and linolenic acid is known to
significantly decrease the level of total cholesterol and
triacylglycerol concentration in the blood plasma. The
essential fatty acids (EFA) are those which are
required for growth, maintenance and proper
functioning of many physiological processes and are
not biosynthesized in the human body. Linoleic,
linolenic and arachidonic acids are generally
considered to be essential fatty acids for human
beings8. Tocopherols are important dietary
constituents as they are essential in maintaining the
stability and integrity of the cell membrane, which is
associated with high concentrations of unsaturated
fatty acids present in these membranes. The
tocopherol content in apricot oil ranged from
268.5-436.0 µg/g, while, in almond oil, the vitamin E
is present in fairly large concentration i.e. 4 mg/g of
oil9,10. However, detailed literature on fatty acid
composition with proximate composition of apricot
press cake is scarce. Therefore, present investigations
were carried out to study the physico-chemical
characteristics of apricot fruits, stones, kernels and
kernel oil. The fatty acid composition with proximate
composition of apricot press cake were undertaken for
apricots seeds collected from different areas of
Himachal Pradesh.
Materials and Methods
Apricot stones/pits collected from different
locations in Himachal Pradesh were utilized for these
studies. The kernels were separated from the mass of
stones/pits by using specific gravity separation
method after breaking the stones with mechanical
decorticator. On semi-pilot scale, the oil was extracted
by passing the apricot kernels through table oil
expeller and after filtration through a filter press; the
oil was analyzed for different physico-chemical
characteristics.
Chemical and statistical analysis
Standard analytical procedures were followed for
estimation of iodine value, saponification value, acid
value and peroxide value in the extracted oils11. The
fatty acid composition of the apricot kernel oil was
determined by using standard method and converting
them in respective fatty acid methyl esters and by
using gas liquid chromatography (GLC)11,12. Vitamin E
contents were determined by using HPLC13. The data
on physico-chemical characteristics were statistically
analyzed by using CRD-Factorial design14. Triplicate
determinations were made for each attribute.
Results and Discussion
Physico-chemical characteristics of apricot fruits, stones and
kernels
Broadly, mean fruit and stone weight ranged
between 8.0-15.1 g and 1.78-1.92 g, respectively with
stone recovery of 12.7-22.2% in apricot fruits.
Further, the kernel recovery was 30.7-33.7% (on
stone basis) and 3.9-7.5% (on fruit basis) having a
kernel weight of 0.58-0.60 g (Table 1). Further oil
recovery ranged between 45.6-46.3% as crude oil
(extracted through Soxhlet apparatus). The moisture
contents in kernels ranged between 4.0-4.1% with
2.2-2.4% ash contents, whereas in oils the moisture
contents ranged between 0.25-0.26%. The bitter
apricot kernels are reported known to contain bittering
component HCN (hydrocyanic acid). In confirmation
to these results, the kernel recovery in apricot stones
was reported as 35-45% and 22-38% in sweet and
bitter apricots. Further, the apricot oil yield of 35-45%
was reported6,15.
Quality characteristics of apricot kernel oil
The visual appearance of extracted oil was
observed to be yellow in colour (Table 2). The
specific gravity of apricot kernel oil was found to
range between 0.914-0.915 with the refractive index
and butyro- refractometer reading (40°C) of
1.4720-1.4729 and 69.6-70.3, respectively. The kernel
oil from apricots exhibited low acid value (2.27-2.78
mg KOH/g); peroxide value (5.12-5.27 meq/kg);
iodine value (100.2-100.4 g I2/100 g and
saponification value of 189.8-191.3 mg KOH/g oil.
The quality characteristics of apricot oil extracted
from kernels collected from different locations are at
par and all the values were found well within the
standards specified by PFA for almond oil16. Further,
the vitamin E contents in oils ranged between
72-93.7 mg/100 g and total carotenoids ranged
between 262-267 µg/100 g. Earlier, the vitamin E
content in apricot oil was reported in the range of
268.5 to 436.0 µg/g oil9.

INDIAN J NAT PROD RESOUR, SEPTEMBER 2012
368
Fatty acid composition of apricot kernel oil
The fatty acids present in apricot kernel oils from
Mandi, Kinnaur and Shimla areas are significantly at
par, whereas the lower linoleic acid contents and high
monounsaturated fatty acid contents present in oils
from Mandi and Kinnaur areas helps in longer shelf-
life as compared to kernel oil from Shimla (Table 3).
Further, it was found that apricot oil possessed an
appreciable proportion of unsaturated fatty acids
which comprised of 62.5-71.2% monounsaturates and
21.2-29.2% polyunsaturates. While the saturates were
only 6.5-8.7%, thus the ratio between unsaturates and
saturates (U/S) were recorded as 10.51-14.24. Among
the unsaturated fatty acids, oleic and linoleic were the
predominant acids in apricot kernel oil. The oils rich
in polyunsaturated fatty acids have been shown to
Table 1—Physico-chemical characteristics of apricot fruits, stones, kernels and kernel oil from different locations in
Himachal Pradesh
Location→
Parameters
Mandi
Shimla Kinnaur
Mean CD0.05
(n=3)
Weight of fruit (g) 8.0 15.1 12.8 12.0 0.24
Pulp weight (g) 6.2 13.2 10.9 10.1 0.24
Pulp, % 77.8 87.3 85.6 84.3 -
Stone weight, g 1.78 1.92 1.85 1.88 0.03
Stone recovery, % 22.2 12.7 14.4 16.4 0.23
Pulp/stone ratio 3.5 6.9 5.5 5.1 -
Kernel weight, g 0.60 0.59 0.58 0.59 0.01
Kernel recovery, %
(on stone basis)
33.7 30.7 31.4 31.9 0.32
Kernel recovery, %
(on fruit basis)
7.5 3.9 4.5 5.3 0.08
Stone/kernel ratio 3.0 3.2 3.1 3.1 -
Kernel moisture, % 4.1 4.0 4.1 4.1 -
Crude oil, % 45.6 46.3 46.3 46.1 0.57
Moisture in oil, % 0.25 0.26 0.26 0.26 -
HCN in kernels* + + + - -
Crude ash,% 2.4 2.2 2.4 2.3 -
Karsog, Mandi (930-935 m amsl.); Jubbal, Shimla (1850-2000 m amsl); Kalpa, Kinnaur, (2190-2250 m amsl); *Qualitative test shows
presence of HCN in kernels; HCN= Hydrocyanic acid
Table 2—Qualitative characteristics of kernel oil from stones of apricots grown in different locations of Himachal Pradesh
Parameters Mandi Shimla Kinnaur Mean CD0.05
(n=3)
PFA Standards
Tintometer Colour Units
Yellow 6.9 6.7 6.4 6.7 -
Red 0.1 0.3 0.1 0.2 -
Blue 0.0 0.0 0.0 0.0 -
Specific gravity, g/cc 0.915 0.914 0.914 0.914 -
Refractive index, 40°C 1.4729 1.4729 1.4720 1.4726 -
Butyrorefractometer reading, 40°C 70.3 70.3 69.6 70.1 0.84 54-57
Acid value, mg KOH/ g oil 2.27 2.78 2.69 2.58 1.02 Not more than 6
Peroxide value, meq/ kg oil 5.26 5.27 5.12 5.22 0.01 Not more than* 125
Iodine value, g I2/100 g oil 100.4 100.2 100.2 100.3 2.23 90-109
Saponification value, mg KOH/ g oil 190.8 189.8 191.3 190.6 0.99 186-195
Visual appearance Yellow Yellow Yellow - - Clear, free from rancidity
Vitamin E, mg/100 g 72 93.7 90.7 - -
Polar material, % PM 5.6 5.8 5.7 5.7 -
Total carotenoid , µg/100 g 262 265 267 264
Karsog, Mandi (930-935 m amsl.); Jubbal, Shimla (1850-2000 m amsl); Kalpa, Kinnaur, (2190-2250 m amsl). *Jacobs, 195818

GUPTA et al: PHYSICO-CHEMICAL & FATTY ACID COMPOSITION OF WILD APRICOT KERNEL OIL
369
reduce the risk of cardiovascular diseases17 and
linoleic and linolenic acids are essential fatty acids
and are important for maintenance of skin, hair
growth, regulation of cholesterol metabolism and
maintenance of cell membrane integrity8. Thus,
apricot oil possesses special dietary importance and
can be used for both edible and pharmaceutical
purposes.
Moisture content of kernels ranged between 4.0-4.1
and 4.9-7.5% in apricot press cake (Table 4). The
crude protein contents were found to be 24.4% in
kernels and 34.3-44.5% in press cake. The crude
lipids were recorded as 45.6-46.3% in apricot kernels
and in range of 5.4-9.7% press cake and crude fibres
of 5.4 in kernels and 7.0-10.8% in press cake, whereas
calorific value (K cals/100 g) was found in the range
of 324-357 in press cake. Further, the bittering toxic
compound HCN was found to be 148-173 mg/100 g
in kernels and 90.5-92.0 mg/100 g in press cake.
Thus, the preliminary study showed that the stones
left after preparation of different value-added
products from pulp contained an oil of good
nutritional and pharmaceutical properties. The fatty
acid profile showed that there is predominance of
unsaturated fatty acids comprising of major proportion
of oleic and linoleic acids besides vitamin E and
carotenoid.
Conclusion
The apricot kernel oil can be considered as good
edible oil and can also be utilize for other industrial
purposes. Extraction of such oils may also open an
avenue for their utilization in various preparations
such as pharmaceutical, cosmetics, facial creams and
lip balms besides its use in the food industry. The
proximate composition of bitter apricot kernels and
press cake showed that the press cake can also be
successfully utilized for preparation of protein isolate.
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Table 3—Fatty acid composition of apricot kernel oil
Per cent composition (% w/w) Fatty acid
Mandi Shimla Kinnaur
Palmitic acid C16:0 5.0 7.8 5.1
Palmitoleic acid C16:1 0.6 0.5 0.7
Stearic acid C18:0 1.5 0.9 2.0
Oleic acid C18:1 70.6 62.1 69.7
Linoleic acid C18:2 21.0 27.8 20.5
Linolenic acid C18:3 0.4 1.4 0.7
Σ SFA 6.5 8.7 7.1
Σ MUFA 71.2 62.6 70.4
Σ PUFA 21.4 29.2 21.2
Σ UFA 92.6 91.8 91.6
U : S ratio 14.24:1 10.51:1 12.90:1
Σ SFA-Saturated fatty acid; Σ MUFA-Mono unsaturated fatty
acid; Σ PUFA-Polyunsaturated fatty acid; Σ UFA-Unsaturated
fatty acid; Karsog, Mandi (930-935 m amsl.); Jubbal, Shimla
(1850-2000 m amsl); Kalpa, Kinnaur, (2190-2250 m amsl)
Table 4—Proximate composition of bitter apricot kernels and
press cake
Press cake Parameter Bitter
apricot*
kernels
Mandi Shimla Kinnaur
Moisture, % 4.0-4.1 4.9 7.2 7.5
Crude protein, % 24.4 44.5 34.3 40.9
Crude lipids, % 45.6-46.3 5.4 9.7 7.0
Total ash, % 2.2-2.4 4.9 5.1 4.9
Crude fibre, % 5.4 10.2 10.8 7.0
Total CHO, % 8.2 30.1 27.5 32.7
Hydrocyanic acid,
mg/100 g
148-173 90.5 92.0 90.5
Calorific value -
347
324
357
Karsog, Mandi (930-935 m amsl.); Jubbal, Shimla (1850-2000 m
amsl); Kalpa, Kinnaur, (2190-2250 m amsl);
CHO= Carbohydrates. *Range of values as given in Table-1

INDIAN J NAT PROD RESOUR, SEPTEMBER 2012
370
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