L-Ascorbic Acid Stability in Orange
Juice in TetraBrik Cartons
Application Note
Author
Introduction
Linda Lloyd
Agilent Technologies, Inc.
In recent years the value of L-ascorbic acid in human nutrition has become
increasingly apparent to health conscious consumers. This has led to an upsurge
in the manufacture of soft drinks based on fruit juices containing ascorbic acid.
Orange juice in TetraBrik cartons is one such example. In this product the juice is
processed and packed aseptically to reduce thermal loads during manufacture.
This note assesses the instability of L-ascorbic acid in reconstituted single strength
orange juice in TetraBrik cartons stored at different temperatures. The effect of
dissolved oxygen in the juice was also examined. Ion suppression reversed phase
HPLC was used, with PLRP-S columns. PLRP-S is a rigid macroporous styrene/
divinylbenzene HPLC phase which is chemically stable with the acidic eluent.
Materials and Reagents
4
dissolved oxygen conc. (ppm)
The samples were ready to drink commercial orange juice
without artificial flavors, colors, preservatives or added sugar.
Samples were stored at different temperatures for differing
lengths of time. Before analysis all samples were centrifuged
at 10000 g for 45 minutes then filtered through a 0.45 µm
cellulose nitrate membrane.
Conditions
Columns:
Eluent:
Flow rate:
Detector:
Key
4 oC
20 oC
37 oC
x 76 oC
105 oC
2 x PLRP-S 100Å 5 µm, 150 x 4.6 mm (p/n PL1111-3500)
0.2 M NaH2PO4, pH 2.14
0.5 mL/min
UV, 268 nm
3
2
1 x
x
0
Materials and Reagents
L-ascorbic acid conc. (mg/L)
Key
4 oC
20 oC
37 oC
x 76 oC
105 oC
20
30
40
50
L-ascorbic acid conc.
50
60
Key
4 oC
20 oC
37 oC
x 76 oC
105 oC
x
80
x
x
1
2
3
dissolved oxygen conc. (ppm)
Figure 3. Loss of L-ascorbic acid vs dissolved oxygen level.
x x
10
160
0
80
0
30
40
storage period (days)
240
0
160 x
0
20
320
The complete data set and analysis is available in Kennedy et
al. (1992).
240
10
Figure 2. Dissolved oxygen levels vs storage time in TetraBrik cartons at
different temperatures.
Figure 1 shows the degradation of L-ascorbic acid over
time, with concentrations varying from 60.4% after 64 days
at 4 ºC to 3.6% after three days at 105 ºC. The marked fall
in L-ascorbic acid seems to coincide with an initial drop in
dissolved oxygen concentrations (Figure 2). This dramatic
loss of oxygen appeared to correlate with the higher
decomposition rate of the acid at the beginning of storage
(Figure 3). It seems the degradation mechanism is initially
aerobic but continues anaerobically at a lesser rate once the
level of dissolved oxygen has reached equilibrium.
320
x
60
storage period (days)
Figure 1. L-ascorbic acid concentration over time in orange juice in
TetraBrik cartons at different storage temperatures.
2
4
Conclusion
Ion suppression HPLC using PLRP-S columns successfully
revealed the decline in L-ascorbic acid content of
reconstituted orange juice. The amount of dissolved oxygen
at carton filling had a significant effect on the acid’s content.,
and the rate of oxygen consumption depended on the
L-ascorbic acid content. Aerobic and anaerobic decomposition
occurred in the same system.
Reference
Kennedy, JF, Rivera, ZS, Lloyd, LL, Warner, FP, Jumel, K (1992)
L-ascorbic acid stability in aseptically processed orange juice
in TetraBrik cartons and the effect of oxygen. Food Chem., 45,
327-331.
www.agilent.com/chem
This information is subject to change without notice.
© Agilent Technologies, Inc. 2011
Published in UK, May 9, 2011
5990-8161EN