Encapsulation of bioactive components from citrus peel by spray and freeze drying

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Date
2018-07
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Sher-e-Kashmir University of Agricultural Sciences and Technology of Jammu, Jammu
Abstract
Encapsulated powder was developed from citrus peel extract (CPE) using maltodextrin (MD) and whey protein concentrate (WPC) as encapsulating agents in the ratios of 100 :: CPE, 85 : 15 :: CPE: MD, 70 : 30 :: CPE: MD, 55 : 45 :: CPE: MD, 85 : 15 :: CPE: WPC, 70 : 30 :: CPE: WPC and 55 : 45 :: CPE: WPC by spray drying and freeze drying techniques. The developed powder was stored for 180 days under ambient conditions to ascertain the changes in physical, hydration, flowability and functional properties. During the study, it was observed that with the incorporation of encapsulating agents in spray dried citrus peel powder, the overall mean values of yield, microencapsulation efficiency, water absorption index, water solubility index, swelling capacity, bulk density and tapped density increased significantly from 12.72 to 82.15 per cent, 0 to 80.35 per cent, 5.54 to 7.83g/g dry solids, 50.40 to 87.78 per cent, 2.42 to 7.13g/g dry solids, 0.34 to 0.72g/ml and 0.49 to 0.85g/ml respectively and overall mean values of moisture, water activity, hygroscopicity, hausner ratio, carr index, decreased significantly from 5.03 to 2.37 per cent, 0.53 to 0.25, 35.23 to 14.51 per cent, 1.78 to 1.25 and 42.82 to 21.01 per cent, respectively. On incorporation of 15 per cent encapsulating agent overall mean values of surface phenolic content, core phenolic content, total flavonoid content and antioxidant activity increased from 3.84 to 5.04 mg/g GAE, 5.64 to 16.65 mg/g GAE, 7.45 to 10.73 mg/g Quercetin and 17.01 to 71.53 per cent and later on beyond 15 per cent addition led to decrease in their mean values. Increase in air inlet temperature of spray drier from 145 to 155°C showed a significant increase in overall mean of water absorption index (6.32 to 7.15g/g dry solids), water solubility index (71.89 to 73.56g/100g dry solids), swelling capacity (5.58 to 5.83g/g dry solids) and microencapsulation efficiency (70.90 to 71.78 per cent) and a significant decrease in overall mean values of bulk density (0.56 to 0.52 g/ml), tapped density (0.66 to 0.64 g/ml), haunser ratio (1.49 to 1.42), car index (31.43 to 27.75 per cent), surface phenolic content (3.93 to 3.36 mg/g GAE), core phenolic content (13.67 to 12.97 mg/g GAE), total flavonoid content (8.91 to 8.21 mg/g Quercetin) and antioxidant activity (61.99 to 60.34 per cent). In freeze dried samples incorporation of encapsulating agent in all treatments increased mean values of yield (17.87 to 87.43 per cent), microencapsulation efficiency (0 to 95.61 per cent), water absorption index (5.01 to 7.24g/g dry solids), water solubility index (44.31 to 81.07g/100g dry solids), swelling capacity (2.17 to 4.31g/g dry solids), bulk density (0.23 to 0.39g/ml) and tapped density (0.26 to 0.39g/ml) and decreased overall mean values of moisture (8.16 to 5.43 per cent), water activity (0.61 to 0.32), hygroscopicity (31.53 to 10.95 per cent), haunser ratio (1.53 to 1.15), car index (34.86 to 13.35 per cent) and surface phenolic content (15.86 to 1.36mg/g GAE). Addition of 15 per cent encapsulating agent led to increase in overall mean values of core phenolic content from 17.07 to 21.22 mg/g GAE, total flavonoid content from 12.91 to 14.06 to mg/g Quercetin and antioxidant activity from 24.93 to 74.49 per cent and later on further addition led to decrease in their mean values. In both techniques, when all the parameters were considered together maltodextrin at 30 per cent concentration i.e., T3 (CPE : MD :: 70 : 30) showed better results for yield, hydration properties (water solubility index, water absorption index & swelling capacity), physical (moisture, water activity and hygroscopicity), flowability (bulk density, tapped density, haunser ratio and car index) at an inlet temperature of 155°C by spray drying technique and was recommended for development of bioactive compound enriched soup sticks. Soup sticks were formulated by blending wheat flour with best developed encapsulated citrus peel powder in the ratios of WF:MPE::100:0; WF:MPE::97:3; WF:MPE::94:6; WF:MPE::91:9; WF:MPE::88:12. Incorporation of encapsulated peel powder led to decrease in moisture content, crude fat, crude protein and crude fiber and an increase in ash content, total phenolic content and total flavonoid content. Among the blends the lowest mean moisture content of 4.82 per cent, crude fat of 13.47 per cent, crude fiber of 0.23, crude protein of 9.04 per cent and highest mean ash content of 1.96 per cent, carbohydrate content of 70.46 per cent, total phenolic content of 13.88mg/GAE/100g, total flavonoid content of 8.86mg Quercetin/100g was recorded in T5 (WF:MPE::88:12). Soup sticks were stored for a period of 180 days during which mean moisture content and carbohydrate content increased from 4.95 to 5.16 per cent and from 69.34 to 69.86 per cent respectively where as there was a significant decline in crude fat, crude protein and crude fiber from 13.84 to 13.74 per cent, 9.23 to 9.15 per cent 0.35 to 0.25 per cent respectively. Organoleptically, T4 (WF:MPE::91:9) was adjudged the best treatment for the development of bioactive enriched soup sticks with sensory score of 7.84, 7.63, 7.49, 7.37 and 7.58 for taste, flavour, texture, color and overall acceptability respectively.
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