SPRAY DRYING OF DOUBLE-EMULSION-ENCAPSULATED DIPEPTIDYL PEPTIDASE-IV (DPP-IV) INHIBITORY PEPTIDES FROM Κ-CASEIN
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Date
2022
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ICAR-NDRI, KARNAL
Abstract
Diabetes is a metabolic disorder characterized by increase in blood glucose level resulting from lower insulin secretion or action. One way of controlling type 2 diabetes is inhibition of the enzyme DPP-IV. Many food or milk-derived peptides, including those from κ-casein, naturally exhibit DPP-IV inhibitory activity. Bioactive peptides are sensitive to the surrounding environmental stresses like pH, temperature and GI transit conditions. These can be overcome by their encapsulation by several means such as double emulsion. Spray drying of double emulsion with suitable filler matrix can improve stability of encapsulates and increase product specific application. Based on these aspects, the current study was carried out for spray drying of double emulsion containing DPP-IV inhibitory peptides. Gum arabic (GA), maltodextrin (MD) and β-cyclodextrin (β-Cd) were selected as materials for carrier matrices and used in seven combinations. Average protein content (%), oil content (%) and ash content (%) of powders were 1.0342±0.12%, 34.12±0.86% and 5.76±0.14%, respectively. Powder containing β-Cd-30% showed highest encapsulation efficiency of peptides (89.32±1.91%), while the GA-30% containing powder had the highest encapsulation efficiency (EE) of oil, solubility, dispersibility and wettability, of 65.1±2.47%, 82.17±0.81%, 48.08±0.80% and 4.42±0.5 s, respectively. According to Carr index and Hausner ratio, all powders possessed poor to very poor flow properties. The optimized double emulsion powder was selected on the basis of hygroscopicity, dispersibility, wettability, solubility, EE of peptides/proteins and EE of oil, which were assigned appropriate weightages. The powder containing 30% gum arabic in carrier matrix solution was found the best among the seven on the basis of the weighted scores. This optimised powder (GA-30%) was stored for 60 days at 30 °C and analysed for changes in physicochemical and functional properties at 15 days intervals. During storage, moisture content, water activity, particle size, bulk density, tapped density, particle density and peroxide value increased significantly. Storage affected functional, flow, reconstitution and microbial properties negatively and significantly. Hygroscopicity, bulk porosity, EE of peptides and EE of oil decreased significantly. κ-casein hydrolysates from milk of Gir cows showed IC50 value of 84.70 μg of protein per ml of solution for DPP-IV enzyme inhibition. The optimised double emulsion and spray dried double emulsion showed maximum respective DPP-IV inhibition of 79.92±0.81% and 71.99±1.62% in intestinal phase of simulated in vitro gastro-intestinal digestion. Stage of digestion and samples had significant effect on controlled release of peptides. On the basis of the present investigation, it can be inferred that the matrix material had significant effect on powder properties and that spray drying is suitable for drying of double emulsion with peptides. Stability of double emulsion was acceptable after spray drying and the peptides were still functional after the drying process.