Influence of hot water dipping on phenolic compounds in cherries (Prunus avium L.)

Namen magistrskega dela je bilo testiranje vpliva toplotne obdelave z vodo na obstojnost in kakovost češenj sorte Van. Češnje smo potapljali v vročo vodo s temperaturo 45 °C, 52 °C in 60 °C, 5 min, 2 min in 0,5 min in jih nato skladiščili 14 dni na +4 °C. Izvedli smo naslednje fizikalnokemijske meritve: meritve barvnih parametrov L*, a* in b*, vsebnost askorbinske kisline, fenolnih spojin, skupnih fenolov, flavonoidov, antioksidativni potencial (AOP), encimsko aktivnost fenilalanin amonijak liaze (PAL). Rezultati so pokazali, da potapljanje v vročo vodo vpliva na vsebnost naštetih fenolnih spojin v češnjah - cianidin-3-glukozid (Cy3G), cianidin-3-rutinozid (Cy3R), peonidin-3-rutinozid (P3R), neoklorogenska kislina (NeochlAC), 3-p-kumaroilkinska kislina (C3p), katehin, klorogenska kislina (ChlorAC), procianidin B2 (PB2), epikatehin, kvercetin-3-glukozil-rutinozid (Q3GR), izoklorogenska kislina (IsochAC) in kvercetin-3-rutinozid (Q3R). Vsebnost AOP, skupnih fenolov, flavonoidov in antocianinov se z višanjem temperature, znižujejo – višja kot je temperatura tretiranja, nižja je vsebnost naštetih komponent v vzorcih. Vsebnost fenolnih spojin se je med skladiščenjem povečevala. Po koncu skladiščenja so vzorci (z izjemo antocianinov), ki smo jih tretirali s T vode 52 °C, vsebovali najvišje vsebnosti posameznih fenolnih spojin. Dokazali smo pozitivno korelacijo med encimsko aktivnostjo PAL in vsebnostjo antocianinov (r2=0,99) – višja kot je encimska aktivnost PAL, višja je vsebnost antocianinov. Potapljanje v vročo vodo je povečalo vsebnost antocianinov. Parametri L*, a*, b*, relativna nasičenost barve C in kot barvnega odtenka so se med skladiščenjem zniževali. Do najmanjših sprememb v obarvanosti (⠆E) je prišlo pri vzorcih obdelanih pri T vode 52 °C. Iz vidika spremembe barve in nastanka fenolnih spojin, bi bilo potapljanje plodov češenj najbolj optimalno pri T vode 52 °C za 2 min.The aim of this master thesis was to test the effect of hot water dipping as a physical treatment to prolong storage life and maintain quality of cherries cv. Van. Cherries were dipped to water with temperature 45 °C, 52 °C and 60 °C for 5, 2 and 0,5 min respectively and stored for 14 days at +4 °C. The following physiochemical analyses were carried out: colour parameters L*, a*, b*, the contents of ascorbic acid, phenolic compounds, total phenols and flavonoids, antioxidant potential (AOP) and phenylalanin ammonia lyase (PAL) enzyme activity. Results showed that hot water dipping significantly effects the contents of the following phenolic compounds – cyanidin-3-glucoside (Cy3G), cyanidin-3-rutinoside (Cy3R), peonidin-3-rutinoside (P3R), neochlorogenic acid (NeochlAC), 3-p-coumaroylquinic acid (C3p), catechin, chlorogenic acid (ChlorAC), procyanidin B2 (PB2), epicatehin, quercetin-3-glucosyl-rutinoside (Q3GR), isochlorogenic acid (IsochAC) and quercetin-3-rutinoside (Q3R). The values of AOP, total phenols, flavonoids and anthocyanins were decreasing with increasing temperature of treatment – higher temperature means lower content of compounds. During storage, the contents of phenolic compounds were increasing. After storage, the individual phenolic compounds (except anthocyanins) were the highest in samples treated with water at 52 °C. There is positive correlation (r2=0,99) between enzyme activity PAL and content of anthocyanins – higher enzyme activity, higher content of anthocyanins. During storage, parameters L*, a*, b*, relative saturation and hue angle were decreasing. The smallest change of color was in samples treated with water at 52 °C. The most optimal temperature for treating cherries would be 52 °C for 2 minutes