Effect of nanoencapsulation of purified polyphenolic powder on encapsulation efficiency, storage and baking stability


Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Food Engineering, Turkey

Approval Date: 2012

Student: ALEXANDRU LUCA

Co-Supervisor: SERPİL ŞAHİN, SERVET GÜLÜM ŞÜMNÜ

Abstract:

The primary objective of this study was to obtain nano-emulsion containing polyphenolic compounds extracted from sour cherry pomace and to investigate the effect of degritting of polyphenolic concentrates on the encapsulation efficiency and particle size distribution of capsules and emulsions. It was also aimed to study storage and baking stability of the capsules. Extracted polyphenolic concentrate was degritted at 10,000 rpm for 2 min. Purification reduced Sauter mean diameter (D[32]) of concentrated extract from 5.76 μm to 0.41 μm. Unpurified and purified concentrates were freeze dried for 48 h to obtain extracted phenolic powder (EPP) and purified extracted phenolic powder (PEPP), respectively. Powders were entrapped in two types of coating materials which contain 10% maltodextrin (MD) or 8% MD-2% gum arabic (GA). Samples were prepared by ultrasonication (160 W, 50% pulse) for 20 min. Emulsions containing EPP had D[32] of 1.65 and 1.61 μm when they were entrapped in 10% MD and 8% MD-2% GA coating material solutions, respectively. It was possible to obtain nano-emulsions when purification step was performed. Emulsions prepared with PEPP and coated with 10% MD and 8% MD-2% GA had D[32] of 0.396 and 0.334 μm, respectively. Encapsulation efficiency of the capsules increased significantly from 86.07-88.45% to 98.01-98.29% by means of degritting (p≤0.001). Loss of total phenolic content during storage at 43% and 85% relative humidities was smaller for encapsulated powders when compared to powders not entrapped in coating material. In addition, encapsulation significantly increased retention of phenolic compounds from 15.1-22.2% to 30.4-30.7% during baking (p≤0.05).