Changes in Physicochemical, Free Radical Activity, Total Phenolic and Sensory Properties of Orange (Citrus sinensis L.) Juice Fortified with Different Oleaster (Elaeagnus angustifolia L.) Extracts

Abstract

In Iran and other parts of Western Asia, the oleaster (Elaeagnus angustifolia L.) fruit is processed in the dried powdery form, and in recent times, increasingly applied/sprinkled in fruit juices such as those made from oranges (Citrus sinensis L.). To our best knowledge, the effectiveness of oleaster fruit extract in fortifying the orange juice has not yet been reported and the knowledge of this will greatly benefit the consumers, particularly those around the Western Asia region. This current work, therefore, investigated the changes in physicochemical, free radical activity, total phenolic compounds, and sensory properties of orange juice fortified with different oleaster fruit extracts. The orange juice mix formulation comprised different concentrations (5, 10, 15, 20, and 25%) of oleaster (alcoholic, aqueous, and hydro-alcoholic) extracts. The control comprised orange concentrate (4% w/v), sugar (8.5% w/v), and citric acid (0.1% w/v) brought to the desirable volume with water. As the free radical activity depicted the antioxidant properties, the physicochemical aspects of this work involved the determinations of Brix, density, ash, pH, total acidity, sucrose, and total sugar, whereas the sensory aspects involved the determinations of color and taste. Whilst the aqueous oleaster 20 and 25% extracts produced notable physicochemical differences in the orange juice mix, both free radical activity, and phenolic compounds significantly increased (p < 0.05) after 30 days despite resembling (p > 0.05) those of control at day 1. More so, the increases in aqueous, alcoholic, and hydro-alcoholic oleaster extracts would decrease (p < 0.05) the sensory color and taste of the orange juice mix in this study.

Keywords: Citrus sinensis; Elaeagnus angustifolia; extraction solvent; natural antioxidant; physicochemical properties.

Figure 1

Changes in Brix (a), density (b), and ash (c) values of the orange juice subject to different oleaster extracts ((1) control, (2) aqueous extract 5%, (3) aqueous extract 10%, (4) aqueous extract 15%, (5) aqueous extract 20%, (6) aqueous extract 25%, (7) alcoholic extract 5%, (8) alcoholic extract 10%, (9) alcoholic extract 15%, (10) alcoholic extract 20%, (11) alcoholic extract 25%, (12) hydro-alcoholic extract 5%, (13) hydro-alcoholic extract 10%, (14) hydro-alcoholic extract 15%, (15) hydro-alcoholic extract 20%, (16) hydro-alcoholic extract 25%). Different letters (a–e) indicate significant changes occurred at p < 0.05.

Figure 2

Changes in total acidity (a), pH (b), total sugar content (c), and sucrose (d) values of orange juice subject to different oleaster extracts ((1) control, (2) aqueous extract 5%, (3) aqueous extract 10%, (4) aqueous extract 15%, (5) aqueous extract 20%, (6) aqueous extract 25%, (7) alcoholic extract 5%, (8) alcoholic extract 10%, (9) alcoholic extract 15%, (10) alcoholic extract 20%, (11) alcoholic extract 25%, (12) hydro-alcoholic extract 5%, (13) hydro-alcoholic extract 10%, (14) hydro-alcoholic extract 15%, (15) hydro-alcoholic extract 20%, (16) hydro-alcoholic extract 25%). Different letters (a–g) indicate significant changes occurred at p < 0.05.

Figure 3

Changes in total phenolic compounds (a) and DPPH free radical activity (b) values of orange juice subject to different oleaster extracts ((1) control, (2) aqueous extract 5%, (3) aqueous extract 10%, (4) aqueous extract 15%, (5) aqueous extract 20%, (6) aqueous extract 25%, (7) alcoholic extract 5%, (8) alcoholic extract 10%, (9) alcoholic extract 15%, (10) alcoholic extract 20%, (11) alcoholic extract 25%, (12) hydro-alcoholic extract 5%, (13) hydro-alcoholic extract 10%, (14) hydro-alcoholic extract 15%, (15) hydro-alcoholic extract 20%, (16) hydro-alcoholic extract 25%). Different letters (a–e) indicate significant changes occurred at p < 0.05.

Figure 4

Changes in sensory color (a) and taste (b) values of orange juice subject to different oleaster extracts ((1) control, (2) aqueous extract 5%, (3) aqueous extract 10%, (4) aqueous extract 15%, (5) aqueous extract 20%, (6) aqueous extract 25%, (7) alcoholic extract 5%, (8) alcoholic extract 10%, (9) alcoholic extract 15%, (10) alcoholic extract 20%, (11) alcoholic extract 25%, (12) hydro-alcoholic extract 5%, (13) hydro-alcoholic extract 10%, (14) hydro-alcoholic extract 15%, (15) hydro-alcoholic extract 20%, (16) hydro-alcoholic extract 25%). Different letters (a–e) indicate significant changes occurred at p < 0.05.

Figure 5

A schematic overview of experimental program, indicating the major stages of this current work, from the collection of oleaster and orange fruit samples, the development of oleaster fruit extract and orange fruit concentrate, the incorporation of oleaster fruit extract into orange juice, to the analytical measurements.

Figure 6

A pictorial representation of the samples of oleaster fruits (a) and a view of one when opened (b), as well as the samples of orange fruits (c) and views of a sectioned slice (d).