Water-soluble emulsions of carotenoids

Magistrsko delo je bilo usmerjeno v razvoj stabilnih vodotopnih emulzij karotenoidov za uporabo v industriji pijač. Zanimal nas je vpliv različnih emulgatorjev, proizvodnih postopkov in parametrov na stabilnost emulzij. Naš cilj je bil razvoj vsaj ene stabilne emulzije s vsakim uporabljenim emulgatorjem, saj naročniki pogosto želijo emulzijo s točno določenim emulgatorjem, ki pa ni nujno najbolj učinkovit. Pripravili smo emulzije različnih karotenoidov: β-karotena, oleorezina paprike in luteina. Uporabili smo osem različnih emulgatorjev: Purity gum 2000, Caragum, Eficacia, InstantGum, PS 750, HM P90, SuperCloud in Q-Naturale. Za pripravo emulzij smo uporabili postopek visokotlačne homogenizacije, preverili pa smo tudi vpliv predhodnega mešanja pri visokih obratih (high shear). Kakovost emulzij smo skušali izboljšati s spremembami koncentracije emulgatorja, deleža vode, vrsto olja in tlakom homogenizacije. Kakovost emulzij smo preverjali z meritvami velikosti delcev (D-50, D-90), koncentracije karotenoidov, turbidnosti raztopin (NTU), določitvijo barve (L*a*b) in opazovanjem izgleda pripravljenih raztopin emulzij. Ugotovili smo, da so emulzije β-karotena in luteina bolj kakovostne in stabilne od emulzij paprike. Načeloma je veljalo, da višja koncentracija emulgatorja, večji delež vode, MCT olje namesto sončničnega, višji tlak (vsaj 600 bar) in uporaba mešanja pri visokih obratih pred homogenizacijo, pripomorejo k tvorbi bolj stabilnih emulzij. Izmed vseh emulzij, so bile najbolj kakovostne in stabilne tiste pripravljene z emulgatorji Purity gum 2000, PS 750 in Q-Naturale. S Cargumom smo uspeli pripraviti le stabilno emulzijo β-karotena. Emulzije z ostalimi emulgatorji so bile le pogojno stabilne oziroma popolnoma nestabilne. Mnoge med njimi so bile glede na rezultate analize sicer kakovostne, a so bile njihove raztopine nestabilne. Stabilnost emulzij je bila najbolj očitno povezana z izmerjenim premerov delcev, za večino stabilnih emulzij je ta znašal 0,13 μm (D-50). Nekaterim uspešnim emulzijam smo po dveh mesecih ponovno izmerili premer delcev in ugotovili, da so emulzije prvotno velikost delcev ohranile ali pa se je ta celo nekoliko zmanjšala. Test barvne stabilnosti emulzij z dodatkom različnih antioksidantov je pokazal, da so barvo najbolje ohranile raztopine emulzij, ki so vsebovale 0,5 % tokoferola, 0,5 % inolensa in 1 % askorbinske kisline. Nazadnje smo preverili še stabilnost najbolj uspešnih emulzij v raztopinah pijač po dveh mesecih v temi in na svetlobi. Stabilne raztopine emulzij smo opazili pri emulzijah s Purity gum 2000, Q-Naturale in pri emulzijah β-karotena s Caragumom.This graduation thesis aimed to develop stable water-soluble emulsions of carotenoids for the usage in beverages. The influence of different emulsifiers, production methods and process parameters on the stability of prepared emulsions have been studied. The goal was to develop at least one stable emulsion with each emulsifier, as there is often a demand for the emulsion with a specific emulsifier, that however, is not necessarily the most effective. Emulsions of various carotenoids (β-carotene, pepper oleoresin and lutein) have been prepared. For the preparation of these emulsions, eight different emulsifiers were used: Purity gum 2000, Caragum, Eficacia, InstantGum, PS 750, HM P90, SuperCloud and Q-Naturale. Emulsification was achieved with high-pressure homogenization. In some emulsions, the effect of high shear mixing prior to high-pressure homogenization was also tested. In order to improve the emulsion quality the emulsifier concentration, water content, oil type and pressure during homogenization were changed. Emulsion quality was determined by measuring particle size (D-50, D-90), carotenoids concentration, emulsion solution turbidity (NTU), colour (L*a*b) and appearance. Based on our experiments it was determined that emulsions of β-carotene are generally of better quality and are more stable than emulsions of pepper oleoresin. Higher emulsifier concentration, higher water content, use of MCT oil, the higher pressure during homogenization and high shear mixing all improved the quality and stability of emulsions. Emulsifiers Purity gum 2000, PS 750 and Q-Naturale were the most efficient in stabilizing emulsions. Caragum was semi-efficient as it was only able to stabilize the emulsion of carotene but not paprika oleoresin. Emulsions prepared with other emulsifiers were not stable, even though based on the analysis they were of good quality. Emulsion stability was the most directly influenced by particle size, D-50 being 0,13 μm for most of the stable emulsions. For some of the most stable emulsions, the particle size measurement was repeated after 2 months. D-50 remained the same or even decreased in some emulsions. Colour stability test of emulsions with different combinations of antioxidants added proved the combination of 0,5 % tocopherol, 0,5 % Inolens and 1 % ascorbic acid to be the most efficient. Finally, the stability of several stable emulsions in beverage solutions stored in dark and light was tested after 2 months. Stability was observed in emulsion solutions where emulsifiers Purity gum 2000, Q-Naturale and Caragum (only in the emulsion of carotene) were used