Optimization of spray drying process of sour cherry Marasca (Prunus cerasus var. Marasca) juice

Metoda odzivnih površina korištena je kao baza za optimizaciju procesa proizvodnje praha soka višnje Maraske (PSVM) s najboljim fizikalno-kemijskim parametrima, bojom najsličnijom boji soka te s najvišim sadržajem fenolnih spojeva. Ispitana su tri različita nosača (maltodekstrini MD 4-7 DE i MD 13-17 DE te arapska guma (GA)) dodana u tri koncentracije (20, 30 i 40%) u sok suhe tvari 10, 15 i 20% te je sušenje provedeno na temperaturama 150, 175 i 200 °C. Najbolja fizikalno-kemijska svojstva (iskorištenje, sadržaj vlage, higroskopnost, topljivost, nasipnu gustoću), najstabilniju boju te najveći udio fenolnih spojeva PSVM su imali pri koncentracijama nosača 30 % za MD 4-7 DE, 35 % za MD 13-17 DE i 28 % za GA, suhoj tvari soka 15 % za MD 4-7 DE, 20 % za MD 13-17 DE i 13,5 % za GA te temperaturi sušenja 185 °C za MD 4-7 DE, 165 °C za MD 13-17 DE i 157,5 °C za GA. Pri navedenim uvjetima uz primjenu nosača MD 4-7 DE postignuto je najveće iskorištenje (55,23 %) pri proizvodnji PSVM i najniža higroskopnost (19,98 g/100 g) dok su prahovi proizvedeni s MD 13-17 DE imali najniži sadržaj vlage (1,16 %) i najbolju topljivost (98,66 %), a prahovi s GA najveću nasipnu gustoću (0,35 g/ml). Prah s MD 13-17 DE imao je najtamniju i najintenzivniju boju, visokog udjela crvene boje, te najveću koncentraciju ukupnih antocijana i fenolnih kiselina (93,44 i 79,04 mg/100 g s.tv. soka). U ovim prahovima udio antocijana i fenolnih kiselina iznosio je 72 % u donosu na udio u izvornom soku višnje Maraske prije sušenja. Prah s GA imao je najveći sadržaj flavonol glikozida (21,46 mg/100 g s.tv. soka) koji je odgovarao 73 % početne koncentracije u soku. Prema navedenim fizikalno-kemijskim svojstvima, boji i udjelu fenolnih spojeva, optimalna svojstva prahova soka višnje Maraske postižu se uz upotrebu nosača MD 13-17 DE.Response surface methodology was used as a tool for optimization of spray drying process of sour cherry marasca juice in order to obtain powder with optimal physico-chemical parameters, the most assembling colour to the one of the juice and with the highest concentration of phenolic compounds. Three different carriers were used (maltdextrins MD 4-7 DE and MD 13-17 DE and gum arabic (GA)) in three concentrations (20, 30 and 40%), added to juice with 10, 15 and 20 % dry matter while drying was performed on three different inlet air temperatures, 150, 175 and 200 °C. The optimal physico-chemical parameters (yield, moisture content, hygroscopicity, solubility and bulk density), the most stable colour and the highest amount of phenolic compounds was achieved in powders produced with 30% of MD 4-7 DE, 35 % of MD 13-17 DE and 28 % of GA, with juice with 15 % of dry matter for MD 4-7 DE, 20 % soluble solids for MD 13-17 DE and13,5 % for GA, at inlet air temperature 185 °C for MD 4-7 DE, 165 °C for MD 13-17 DE and 157,5 °C for GA. At these conditions, powder with carrier MD 4-7 DE had the highest recovery (55,23 %) and the lowest hygroscopicity (19,98 g/100 g), powder produced with MD 13-17 DE had the lowest moisture content (1,16 %) and the highest solubility (98,66 %), while powder with GA had the highest bulk density (0,35 g/ml). MD 13-17 DE powder had the darkest colour, the highest rate of red colour and the highest colour intensity which are all related to the highest amount of total anthocyanins and total phenolic acids (93,44 i 79,04 mg/100 g juice dry matter) presenting the 72 % of total anthocyanins and total phenolic acids concentration in sour cherry marasca juice before drying. Powder with GA had the highest concentration of flavonol glycosides (21,46 mg/100 g juice dry matter) which reffers to 73 % of total flavonol glycosides determined in sour cherry marasca juice. According to the best physico-chemical parameters, colour and the highest amount of phenolic compounds, maltdextrin 13-17 DE was considered to be the most suitable carrier for sour cherry marasca juice drying