Flavonoids in high-pressure processed citrus juices

Abstract

Citrus juice is one of the main sources of dietary flavonoids in the Mediterranean diet, and contains mainly flavanones and flavones whose bioactivity has been proved through multiple mechanisms that demonstrate different health-related characteristics, such as its antibiotic, antioxidant, antiinflammatory, and antibacterial properties. Also flavonoids can modify the appearancet, the taste and the nutritional value of the citrus juice. Flavonoids content of juices depends on the citrus specie, variety and the type of processingt technology used to stabilize the juice. High pressure processing (HPP) is a non-thermal technology efficient enough to destroy microorganisms and to inactivate food enzymes (total or partially) in citrus juice, at levels equivalent to those achieved by pasteurization without affecting greatly the nutritional and health-promoting characteristics and sensory properties. HPP offers the chance of producing functional foods improving the extraction of potentially health related compounds. The main objective of this work is to study the effect of HPP on individual and total flavonoids of citrus juice by HPLC/DAD and HPLC/MS/ES/Q, obtained from oranges (Citrus sinensis L. Osbeck, cv. Navelate) and tangerines (Citrus reticulate, Blanco, cv. Clemenules). HPP has been applied in three different ways: 1) on the whole peeled citrus fruit before juicing (200 MPa/25ºC/1 min) (HP-200); 2) on juice obtained from wholle-pressurized citrus fruit (400 MPa/40ºC/1 min) (HP-200+400) andD, 3) on freshly squeezed juices (400 MPa/40ºC/1 min) (HP-400). This study could facilitate the production of functional orange and tangerine juices with the concentration of flavonoids enhaced. Mainly flavonoids in freshly-squeezed ornage and tangerine juices werel, from higher to lower concentration: Hesperidin > Narirutin > Naringin-7-0-Glucoside > Apigenin-7,8-Di-Glucoside > Dydimin . Total flavonoid content in orange and tangerine juice was 40.05+/-0.73 mg/100 g f.w. and 7'28+/-0'49 mg/100 g f.w., respectively. The three HPP treatments assayed on tangerine juices maintained the total flavonoids of the juice control, whereas HP-200 and HP-200+400 orange juices showes an increase of 24.32% and 11%, respectively, in the total flavonoid content.