Faculty of Food Technology and Biotechnology, University of Zagreb
Abstract
Gac (Momordica cochinchinensis Spreng.) fruit arils contain an oil rich in carotenoids, especially lycopene and β-carotene, which can be enzymatically extracted in water. Response surface methodology was used to determine the factors influencing the enzymatic extraction of oil from gac fruit arils. A central composite design with four independent variables, namely enzyme mass per volume ratio, time, temperature and the stirring speed of the reaction, was carried out. The results show that all of these four factors have a significant effect on the oil yield recovery, with no significant interaction between these factors. Under the optimum conditions obtained (enzyme mass per volume ratio of 14.6 %, incubation time of 127 min, temperature of 58 °C and stirring speed of 162 rpm), it is estimated that the maximum oil recovery and the total carotenoid extraction per dry mass would be 79.5 % and 5.3 mg/g, respectively. There is a strong correlation between the oil recovery and total carotenoid content. The physicochemical properties of the extracted gac oil were characterised. Finally, the Schaal oven test shows that conservation time of gac oil is comparable to that of other edible oils.Ovojnica sjemenke biljke Momordica cochichinensis Spreng. sadržava ulje bogato karotenoidima, osobito likopenom i β-karotenom, koje se može ekstrahirati pomoću enzima. Metodom su odzivnih površina određeni faktori što utječu na enzimsku ekstrakciju ulja iz sjemene ovojnice. Proveden je centralno složeni plan sa četiri nezavisne varijable: omjer mase enzima i volumena smjese, vrijeme, temperatura i brzina miješanja. Rezultati su pokazali da sva četiri faktora bitno utječu na prinos ulja, a da među njima nema bitne interakcije. Pri optimalnim je uvjetima (omjer mase enzima i volumena od 14,6 %, vrijeme inkubacije od 127 min, temperatura od 58 °C i brzina okretaja od 162 o/min) maksimalni prinos ulja bio 79,5 %, a ukupno je ekstrahirano 5,3 mg β-karotena po g suhe tvari. Utvrđena je znatna korelacija između prinosa ulja i udjela ukupnog β-karotena. Opisana su fizikalno-kemijska svojstva ekstrahiranog ulja. Naposljetku je Schaal-ovim testom utvrđeno da je trajnost ulja dobivenog iz sjemenki biljke Momordica cochichinensis Spreng. slična onoj ostalih jestivih ulja
