Quality evaluation of hot and cold processed virgin coconut oil and VCO capsule

Abstract

Virgin coconut oil (VCO) is a high value product extracted from fresh and mature coconut kernels using mechanical or natural methods, with or without the application of heat. The study entitled “Quality evaluation of hot and cold processed virgin coconut oil and VCO capsule” was carried out with the objectives to assess the physico-chemical properties, antioxidant activity and medicinal properties of virgin coconut oil. The study also envisaged the development of VCO capsule and evaluation of its quality attributes. VCO was extracted from the mature coconuts of West Coast Tall variety (WCT) and Kerasree hybrid using four different methods such as traditional, fermentation, cold centrifugation and enzymatic method using standard procedures. The VCO extracted by the above mentioned methods were subjected to organoleptic evaluation and all the treatments were found to have high sensory qualities. VCO extracted from the WCT variety by cold centrifugation method (T3) had the highest total mean score (8.99) for organoleptic qualities followed by VCO extracted from both WCT variety and Kerasree hybrid by traditional method (T1 and T5 - 8.98). The maximum oil recovery was from the fermentation method (T2 - 54.34 % and T6 - 52.33%) followed by enzymatic method (T4 - 49.60% and T8 - 48.80%) and lowest from the cold centrifugation method (T3 - 38.97% and T7 - 38.82%) in both WCT variety and Kerasree hybrid. The iodine value of VCO ranged from 4.03 to 5.95 I2/100 mg. Peroxide value was low in all the treatments and it ranged from 0.16 to 0.34 MEq/kg. VCO had high saponification value and it ranged from 254.52 to 259.86 mg KOH/g. Moisture content in extracted VCO samples varied from 0.09 to 0.13 per cent with significant difference and the minimum moisture content was noticed in the VCO extracted from the WCT variety by traditional method (T1 - 0.09%) whereas the maximum was found in the VCO extracted from the Kerasree variety by enzymatic method (T8 - 0.13%). These values were within the range specified by CODEX (2009), APCC (2009) and FSSAI (2011) standards.

Tocopherol was present in all the treatments within a range of 14.82 to 27.68 μg/g. The highest tocopherol content was found in the VCO extracted from the WCT variety by cold centrifugation method (T3 - 27.68 μg/g) and oil from the WCT variety by fermentation method (T2 - 27.64 μg/g). VCO prepared by different treatments had total fat in the range of 92.89 to 95.02 per cent. Total phenol content of VCO ranged from 5.28 to 10.87 GAE μg/mg. The highest total phenol content was noted in the VCO extracted from the WCT variety by fermentation method (T2 - 10.87 GAE μg/mg) followed by cold centrifugation method (T3 - 10.63 GAE μg/mg). The concentration of total antioxidants present in the oil ranged from 17.23 to 27.45 μg/mg. The total antioxidant activity was higher in the VCO extracted from the WCT variety by cold centrifugation method (T3 - 27.45 μg/mg) followed by fermentation method (T2 - 27.28 μg/mg). Fatty acid profile showed that VCO was mainly composed of saturated fatty acids (caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid and stearic acid) and 8.57 to 10.79 per cent of unsaturated fatty acids (oleic acid and linoleic acid). Lauric acid (medium chain fatty acid) was the predominant fatty acid present in VCO which ranged from 45.03 to 47.06 per cent. VCO from the WCT variety by cold centrifugation method (T3) had the highest per cent of lauric acid (47.06%) followed by fermentation method (T2 - 46.94%). Viscosity of VCOs ranged from 47.60 to 51.72 cP. The results of colour analysis showed that compared to other treatments, the maximum yellowness was observed in the VCO extracted from the Kerasree variety by traditional method (T5 - 2.72) followed by oil from the WCT variety by traditional method (T1 - 0.72). Bioactive compounds such as hexadecane, heneicosane, octadecane, 1-2- Benzenedicarboxylic acid, butyl 8-methyl nonyl esters, dibutyl phthalate, eicosane, pentacosane, tetracosane, nonacosane, 1-2-benzenedicarboxylic acid, bis[2-methyl propyl] ester, heptadecane were identified in VCO using GCMS analysis. These compounds have various medicinal properties such as antioxidant, antimicrobial, antiproliferatory, antipyretic, analgesic and anti-inflammatory properties.

Organoleptic qualities of VCO samples from all the treatments steadily decreased during the storage period, but were acceptable till the end of six months. The physico-chemical properties such as moisture, free fatty acid value and peroxide values were increased with significant difference and was within the permissible limits till the end of sixth month of storage. The total bacterial population increased during the storage period. Fungi and yeast were not detected in the VCOs till the end of the storage period. Based on the organoleptic evaluation, physico-chemical properties and shelf life studies, VCO extracted from the WCT variety extracted by cold centrifugation method (T3) was selected for further studies. VCO effectively inhibited the growth of human pathogens like Staphylococcus aureus, Bacillus subtilis and Candida albicans. The cell viability of hepatic cancer cells was inhibited by VCO with an IC50 value of 70.60 µg/mL. VCO exhibited the antioxidant activity by its high reducing power and scavenging the DPPH radicals, nitric oxides, superoxides and hydroxyl groups. The projected IC50 value for DPPH, nitric oxides, superoxides and hydroxyl groups were 1236.29 µg/mL, 295.59 µg/mL, 108.71 µg/mL and 120.65 µg/mL respectively.

The developed soft gel VCO capsules containing one mL of oil were highly acceptable with a high score for sensory parameters. During the three months of storage period, the organoleptic mean scores slightly decreased and the physico-chemical properties including moisture content, free fatty acid value and peroxide value of capsules slightly increased with significant difference and was within the specified standards. The colonies of bacteria, fungi and yeast were not detected throughout the storage period. VCO capsules showed good storage stability till the end of three months. The cost of production of VCO varied with the extraction methods. The oil extracted by cold centrifugation method had the highest cost (Rs.115/100 mL) followed fermentation (Rs.100/100 mL), traditional (Rs.93/100 mL) and enzymatic method (Rs.90/100 mL). The estimated cost of production for one mL capsule was Rs. 7.00.

Quality of VCO varied with the coconut variety, hybrid and different extraction methods. VCO extracted by cold centrifugation and traditional methods showed high organoleptic scores than fermentation and enzymatic methods. The presence of lauric acid content, tocopherols, phenols, various bioactive compounds and antioxidant activity contributed to the medicinal properties of VCO. Cold centrifuged oil proved to have antimicrobial activity against human pathogens like Staphylococcus aureus, Bacillus subtilis and Candidia albicans. Antiproliferatory activity was exhibited against hepatic cancer cell lines. VCO capsules were successfully developed with high acceptability scores and storage stability for three months. The beneficial potential of VCO therapy needs to be evaluated clinically through in silico molecular docking and in vivo studies.