The stability of biologically active compounds in Maraska sour cherry dehydrated products during storage

Cilj ovog istraživanja bio je ispitati utjecaj različitih metoda sušenja (liofilizacija, sušenje raspršivanjem) i vrste ambalaže za pakiranje (PET/PPmet/PE i PET/Al/PE) tijekom 52 tjedna skladištenja pri 4, 37 °C i sobnoj temperaturi na stabilnost polifenola (antocijani, flavonol glikozidi, fenolne kiseline), antioksidacijski kapacitet, boju i senzorska svojstva liofiliziranih plodova i instant praha soka višnje Maraske. Postupci liofilizacije i sušenja raspršivanjem su utjecali na degradaciju svih polifenola od 0,68 do 8,3 %, odnosno od 13 do 33 % u odnosu na početne količine u svježoj višnji i soku. Izračunavanjem kinetičkih parametara, konstante brzine kemijske reakcije (k), vremena poluraspada (t1/2), konstanta maksimalne brzine kemijske reakcije (k0) te energije aktivacije (Ea) ustanovljeno je da stabilnost spojeva u obje vrste ambalaže i pri sve tri temperature skladištenja se smanjuje kako slijedi: fenolne kiseline, flavonol glikozidi te antocijani. Stabilnost sve tri grupe polifenolnih spojeva je veća u prahovima soka višnje Maraske nego u liofiliziranim plodovima. U svim skladištenim proizvodima određen je antioksidacijski kapacitet primjenom DPPH metode, promjena boje primjenom CIE L*a*b* kolorimetrijske metode, te statistička analiza senzorskih obilježja analizom glavnih komponenata. Rezultati su pokazali da su najveći antioksidacijski kapacitet, stabilnost boje te poželjna senzorska obilježja skladištenih proizvoda pri 4 °C u obje vrste ambalaže.The objective of this study was to examine the influence of different methods of drying (freeze drying, spray drying) and types of packaging, (PET/PPmet/PE and PET/Al/PE) during 52 weeks of storage time at 4, 37 °C and room temperature on the stability of polyphenols (anthocyanins, flavonol glycosides, phenolic acids), antioxidant capacity, colour and sensory properties of freeze dried cherry fruits and instant powder cherry juice. Related to fresh sour cherries and juice, freeze-drying and spray drying processes affected on polyphenolic degradation from 0.68 to 8.3 % and from 13 to 33 %, respectively. Based on the calculated kinetic parameters, the chemical reaction rate constant (k), half-life (t1/2), maximum chemical reaction rate constant (k0) and the activation energy (Ea) the stability of the polyphenols in both packaging materials and at all three storage temperatures decreased ranked as follows: phenolic acid, flavonol glycosides and anthocyanins. Stability of all three groups of polyphenolic compounds was higher in sour cherry juice powders than in freeze dried fruits. Antioxidant capacity evaluated by the DPPH method, colour changes by CIE L*a*b* colorimetrically method, and statistical analysis of sensory parameters by principal component analysis in all stored samples were determinated. Results showed that highest antioxidant capacity, colour stability and desirable sensory parameters of stored samples were at 4 °C in both types of packaging materials