Effects of high pressure processing (HPP) on antioxidant capacity of apple juices

Jabuka i sok od jabuke smatraju se dobrim izvorom biološki aktivnih spojeva (BAS) s pozitivnim djelovanjem na ljudski organizam. Od BAS-a u jabuci, najzastupljeniji su fenolni spojevi i vitamin C. Izniman doprinos jabuke i sokova od jabuke ističe se sastavom i strukturom fenolnih spojeva, koji se odlikuju visokom biodostupnošću te značajnim antioksidacijskim kapacitetom (AOK). AOK predstavlja sposobnost molekula antioksidansa da inhibiraju oksidacijske procese bilo reakcijom neutralizacije slobodnih radikala, keliranjem metala ili inhibiranjem enzima. Obzirom je u izravnoj vezi sa prisutnim BAS, AOK se značajno mijenja tijekom prerade i skladištenja, stoga je potrebno posebno obratiti pažnju na optimiranje procesa obrade VHT kao i režima skladištenja. Postoje različiti podaci u literaturi o utjecaju VHT parametara na AOK, no većina autora potvrdila je da se AOK bolje očuva primjenom nižih tlakova uz kraće vrijeme tretiranja. Parametri koji tijekom skladištenja negativno utječu na stabilnost BAS-a, uglavnom će se negativno manifestirati i na stabilnost AOK.Apple and apple juice are considered to be good sources of biologically active compounds (BAC) with positive impact on human organism. Phenolic compounds and vitamin C are the most commonly present BAC in apples. Extraordinary contribution of apple and apple juice is seen in composition and structure of phenolic compounds, which are characterized with high bioavailability and significant antioxidant capacity (AOC). AOC is the ability of antioxidant molecule to inhibit oxidation processes, either by neutralizing free radicals, chelating metals or enzyme inhibiting. Considering that AOC is directly connected to BAC, AOC is being significantly changed during processing and storing, so it is necessary to pay attention to optimizing the HPP process as well as storage regime. There are different literature data about the impact of HPP parameters on AOC, but most of the authors claim that AOC is better preserved if lower pressure is applied for a shorter period of time. Parameters that have negative impact on BAC stability during storage are most commonly manifested negatively on AOC stability