High Hydrostatic Pressure Combined with Mild Temperature for the Preservation of Comminuted Orange: Effects on Functional Compounds and Antioxidant Activity

Comminuted orange, obtained by grinding of the peel and pulp and mainly used for flavoring soft drinks is a good source of functional compounds. High hydrostatic pressure (HHP) can preserve it without altering its functionality. The effect of HHP combined with mild temperature on the content of vitamin C, phenolic, flavonoids, carotenoids, and antioxidant activity (AOA) of comminuted orange was evaluated. Samples were subjected to 350-550 MPa/41 +/- 2-68 +/- 3 A degrees C/CUT-10 min. Higher vitamin C contents and AOA values than the untreated control were observed for most treated samples (11.4-43.6, 21.2-45.3, and 5.8-18.1 % for total vitamin C, reduced vitamin C, and AOA, respectively) with some effect obtained after the "come up time" (CUT). This behavior suggests that HHP increases the release of vitamin C and some other compounds responsible of AOA probably due to cellular disruption mainly of flavedo, making them more accessible for quantification. There was, however, no clear relationship between the process parameters, and the concentrations obtained, and between vitamin C and AOA. Most treatments did not affect the content of phenolic and flavonoids. Total carotenoids decreased about 15 % at 56 and 68 A degrees C without effect of the CUT, even though the proportions of each individual carotenoid did not change significantly. Although consistent trends were not found in all processing conditions tested, the processing of comminuted orange at pressures between 450 and 550 MPa during 5.5 to 10 min and temperatures from 41 to 56 A degrees C was adequate to obtain products with high content of functional compounds.