title: Encapsulation of thyme (Thymus serpyllum L.) aqueous extract in calcium alginate beads.
abstract: BACKGROUND
  Encapsulation of Thymus serpyllum L. aqueous extract within calcium alginate beads was studied in order to produce dosage formulations containing polyphenolic compounds. Electrostatic extrusion was applied for encapsulation of thyme aqueous extract in alginate gel beads. In addition to hydrogel beads, heat-dried and freeze-dried forms of beads were examined.
  
  
  METHODS
  Encapsulation systems were examined and compared in order to choose the optimal one with respect to entrapment efficiency, preservation of antioxidant activity and thermal behaviour under heating conditions simulating the usual food processing.
  
  
  RESULTS
  The beads obtained with approximately 2 mg g⁻¹ of gallic acid equivalents encapsulated in 0.015 g mL⁻¹ of alginate were spheres of a uniform size of about 730 µm. Encapsulation efficiency varied in the range 50-80% depending on the encapsulation method. Besides, the analysis reveals that the encapsulation process and the material used did not degrade the bioactive compounds, as the total antioxidant content remained unchanged. This was verified by Fourier transform infrared analysis, which proved the absence of chemical interactions between extracted compounds and alginate. Addition of a filler substance, such as sucrose and inulin, in the dried product reduced its collapse and roundness distortion during drying process.
  
  
  CONCLUSIONS
  This study demonstrates the potential of using hydrogel material for encapsulation of plant poplyphenols to improve their functionality and stability in food products.
authors.affiliation: Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11000 Belgrade, Serbia.
authors.forename: Radoslava
authors.initials: R
authors.lastname: Stojanovic
authors.forename: Ana
authors.initials: A
authors.lastname: Belscak-Cvitanovic
authors.forename: Verica
authors.initials: V
authors.lastname: Manojlovic
authors.forename: Drazenka
authors.initials: D
authors.lastname: Komes
authors.forename: Viktor
authors.initials: V
authors.lastname: Nedovic
authors.forename: Branko
authors.initials: B
authors.lastname: Bugarski
mesh_terms: D000464:Alginates / Q000737:chemistry*; D000975:Antioxidants / Q000737:chemistry*; D019422:Dietary Sucrose / Q000737:chemistry; D019587:Dietary Supplements; D005520:Food Preservatives / Q000032:analysis / Q000737:chemistry; D005524:Food Technology; D005527:Food, Fortified; D005612:Freeze Drying; D005782:Gels; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006358:Hot Temperature; D020100:Hydrogels; D007444:Inulin / Q000737:chemistry; D008863:Microspheres; D010316:Particle Size; D010936:Plant Extracts / Q000737:chemistry*; D055771:Serbia; D017550:Spectroscopy, Fourier Transform Infrared; D017365:Spices / Q000032:analysis; D055672:Static Electricity; D046930:Thymus Plant / Q000737:chemistry*
chemical_list: D000464:Alginates; D000975:Antioxidants; D019422:Dietary Sucrose; D005520:Food Preservatives; D005782:Gels; D006603:Hexuronic Acids; D020100:Hydrogels; D010936:Plant Extracts; D020723:Glucuronic Acid; D007444:Inulin