Pomegranate seed residue as waste exploitation to augment shelf life stability and neutraceutical prominence in edible oils

Abstract

The present study was aimed to investigate and utilize the pomegranate seed residues that considered as waste after processing. The current study was an attempt to explore the functional and nutraceutical potential of pomegranate seed extracts i.e. pomegranate seed oil (PSO) and defatted pomegranate seed residues (DPSRs) after juice extraction. Three different varieties (Desi, Kandhari, and Bedana) of Pakistani pomegranate varieties were selected and analyzed comparatively. The comparative study of pomegranate seed oil showed the highest lipid contents (15.90±1.40%) in Desi variety followed by Kandhari (11.00±1.25%) and Bedana (8.70±1.10%). The six different fatty acids were found in each variety. The highest contents of conjugated linolenic acid (punicic acid) as 76.66±1.00, 75.50±1.20 and 68.52±1.63% in Desi, Kandhari and Bedana variety, respectively followed by linoleic acid, oleic acid, palmitic acid, stearic acid and myristic acid. Data also showed the significant difference between physico-chemical parameters in all oil samples. The highest antioxidant activity and oxidative stability was observed in Desi seed oil as compared to other varieties. Defatted pomegranate seed extract (DPSE) was prepared in different organic solvents. A significant difference was observed in proximate and mineral contents of defatted residues of all varieties with maximum antioxidant potential in Desi variety extract with promising anti-inflammatory activity with no cytotoxic effect on RAW264.7 macrophages. According to the results of 1st phase of study, Desi variety was selected for further study. The pomegranate seed extracts (PSO + DPSE) were blended with plant-based oils (canola and sunflower oil) at different concentrations and subjected to six month storage and frying study. The treatments and storage showed significant (p≤0.05) effect on physico-chemical attributes of oil blends. The oxidative stability and antioxidant activity decrease with storage. A decrease was observed in unsaturated fatty acids and tocopherol contents with storage. The French fries prepared in TC7 and TS7 treatments showed even oil distribution as compared to other treatments. Oil uptake decreased in French fries by increasing the DPSE in oil blends while increased with storage. Treatments had non-significant (p≤0.05) on sensory attributes. The experimental rats modeling comprised of three segments including normal, diabetic and hypercholesterolemia Sprague Dawley rats. Each study was divided into further 4 groups D1, D2, D3 and D4. The D1 and D3 were normal diets of canola and sunflower oil, respectively while D2 and D4 were experimental diets of canola and sunflower oil with 7% PSO + 800ppm DPSE, respectively. The maximum cholesterol reduction was observed in canola oil groups in all studies as 1.20, 11.38 and 16.30% following 0.80, 9.80 and 12.68% in sunflower oil group. Similarly, significant reduction was observed in LDL and triglycerides level, while an increase was observed in HDL level as 11.26 & 8.02% and 12.84 & 10.05% in study II & III in canola and sunflower oil groups, respectively. As far as, antidiabetic perspectives are concerned, a substantial decrease in serum glucose level was observed as 7.04 & 6.01% and 4.59 & 3.93% in study-II and III of canola and sunflower oil groups while an increase in insulin level was noticed. The percent increase in insulin level was observed as 1.70 & 0.92%, 3.97 & 3.19% and 2.31 & 2.15% in study-I, II and III, respectively. Moreover, for the assessment of the anti-oxidative markers, glutathione level was improved and thiobarbituric acid reactive oxygen substances (TBRAS) level was reduced by utilization of pomegranate seed extract addition. The analysis of liver and kidney functioning tests ensured the safety of pomegranate seed extracts. It is obvious from the data of efficacy study that canola oil with pomegranate extracts as natural anti-oxidants is more effective as compared to sunflower oil. It is inferred from the present exploration that Desi variety of pomegranate is more effective as compared to other varieties available in Pakistan