MICROWAVE ASSISTED ENCAPSULATION OF PUFA RICH PEANUT OIL 3763
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Date
2023-09
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jau junagadh
Abstract
Peanut (Arachis hypogaea L.) is a leguminous crop known for its diverse
nutrient profile. India ranks as the world's second-largest producer of peanuts. Peanut
oil, derived from these legumes, contains approximately 80% unsaturated fatty acids,
including both mono- and polyunsaturated fatty acids (MUFAs and PUFAs). The
higher concentration of MUFAs and PUFAs in peanut oil has been associated with
various health benefits, particularly in reducing the risk of cardiovascular diseases.
However, the elevated percentage of PUFAs in peanut oil makes it highly susceptible
to oxidation during processing and storage. Encapsulation is a protective process that
shields the oil from environmental factors, such as oxygen, light and temperature by
enveloping it with a protective wall material.
Existing encapsulation techniques have drawbacks, such as high temperature
exposure during processing and development of porous structures. These limitations
can be addressed by employing volumetric heating through microwave processing.
Microwaves are particularly suitable for heat-sensitive products like vegetable oil,
offering stability to encapsulated oil. With a view of the importance of preserving
peanut oil quality and recognizing the drawbacks of current encapsulation methods, this
study proposes an investigation into the encapsulation of PUFA-rich peanut oil using a
microwave-assisted technique.
The peanut oils from three cultivars: GG-20, GJG-22 and GJG-32 was extracted
using cold-press method to assess their biochemical properties. Key parameters
examined include free fatty acids (FFA), iodine value, saponification value and
peroxide value ranged from 0.118% to 0.136%, 74.45 to 82.49 mg/100 g, 176.90 to
184.10 mg KOH/g and 4.90 to 5.70 meq/kg oil, respectively for the selected oil samples.
The highest PUFA content (38.17%) was found in the oil extracted from the GJG-32
peanut cultivar, leading to its selection for further encapsulation experiments. The
encapsulation process involved four independent parameters: (A) corn starch:whey
protein isolate (CS:WPI) ratio, (B) emulsifier concentration (%), (C) ultrasonication
time (min) and (D) microwave power (W). A total of 30 runs were generated using the
Central Composite Rotatable Design (CCRD) of Response Surface Methodology
(RSM).
v
The emulsions prepared for encapsulation exhibited stability ranging from
34.52% to 100% and viscosity between 6.90 and 14.40 cP. Physical properties,
including bulk density, angle of repose, Hausner ratio and
516.88 to 638.50 kg/m3
, 46.5° to 58.3°, 1.117 to 1.246 and 10.48% to 22.14%,
respectively. Encapsulation efficiency ranged from 21.82% to 74.25%, with the
maximum achieved at a 2:1 CS:WPI ratio, 1.25% emulsifier concentration, 2.5 minutes
of ultrasonication and 600 W microwave power. Biochemical properties, such as
moisture content, antioxidant activity, peroxide value, free fatty acids (FFA) and total
phenol content, varied from 1.94% to 8.70% (w.b.), 19.82% to 72.62%, 1.789 to 3.723
meq/kg oil, 0.042% to 0.127% and 0.080 to 0.450 mg GAE/100 g, respectively, for the
encapsulated peanut oil. Functional properties of the encapsulated peanut oil, including
wettability (235 to 447 s) and water solubility index (WSI, 2.57% to 9.80%), were also
examined.
The optimal treatment parameters were identified as a 1.33:1 CS:WPI ratio,
0.26% emulsifier concentration, 5.52 minutes of ultrasonication and 300 W microwave
power, resulting in a desirability score of 0.830. A storage study revealed higher
retention of antioxidant activity and total phenol content in encapsulated peanut oil after
180 days, with peroxide value and free fatty acids (FFA) remaining within permissible
limits, unlike non-encapsulated peanut oil.
An economic evaluation of microwave-assisted encapsulation for PUFA-rich
peanut oil showed a co
summary, this study highlights the potential of microwave-assisted encapsulation as a
valuable technique for preserving the quality of cold-pressed PUFA-rich peanut oil,
making it a promising addition to the food processing industr