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Agricultural Sciences in China

2008, 7(1): 41-47 ScienceDirect January 2008

Physicochemical Characteristics of Orange Juice Samples From Seven

Cultivars

NIU Li-ying, WU Ji-hong, LIAO Xiao-jun, CHEN Fang, WANG Zheng-fu, ZHAO Guang-hua and HU Xiao-
song

College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, P.R. China

Abstract
Some physicochemical parameters of orange juice from seven orange varieties (Pineapple orange, Hamlin, Trovita, Jincheng,
1232 Tangor, Olinda Valencia, and Delta Valencia) were analyzed, special attention was paid to the level of sugars, organic
acids, free amino acids, mineral composition, and color parameters. The results showed that total soluble solids (TSS),
TSShitratable acidity (TA) ratios, sugars, and organic acids were kept within a proper range for juice processing except
that Jincheng had lower TSS than the others. Sucrose was the most dominant sugar in the orange cultivars, followed by
fructose and glucose, while citric acid was the principal organic acid. Serine and proline were the principal amino acids.
Potassium was the most abundant mineral in all of the juice samples, followed by magnesium and calcium. The sodium
content of most varieties was under 10 mg kg-1. Though all of the samples had orange colour, Olinda Valencia and Delta
Valencia had deeper red colour than the others. Statistically significant differences (P<0.05) were found between the
samples in most of the characteristics. The results provided important information on the physicochemical characteristics
of the varieties and on how to make the best use of orange cultivars for different purposes, which is of significance for
both technological research and processing practice.

Key words: physicochemical characteristics, orange cultivars, China

oughly (Park et al. 1983), and have been taken as qual-

INTRODUCTION ity characters and criteria for evaluation of identity and
authenticity (Wallrauch and Faethe 1988a; AIJN 2004).
Oranges (Citrus sinensis L.) constitute by far the most Many reports have been published about the chemical
important class of commercial citrus grown in the composition changes of oranges in relation to season,
world. A large portion of the world orange crop is cultivar, and geographic origin (Barry et al. 2003; Lee
used in the production of orange juice, which are prob- and Castle 2001). But there are few reports on the
ably the most popular fruit juice worldwide with pleas- characteristics of Chinese oranges. Now, with orange
ant flavor and color, and rich in nutritional and biologi- cultivation and orange-processing enterprises develop-
cal active compounds, such as potassium, vitamin c, ing rapidly in China, the physicochemical characteris-
and amino acids. tics of orange juice samples are urgently needed for
The physical and chemical characteristics of most better production and market share.
commercial orange varieties have been studied thor- This investigation aimed at characterizing the juices

Received 8 November, 2006 Accepted 13 September, 2007

NIU Li-ying, Ph D.Tel: +86-10-62737464; Correspondence HU Xiao-song, Professor, Tel: +86-10-62737434,Fax: +86-10-62737434-1, E-mail: huxiaos@gmail.com

Q2W8, CAAS. All rights BWNed. Published by Elsevier Lid.

42 NIU Li-ying et al.

from seven orange varieties (Pineapple orange, Hamlin, Determination of sugars Sugar determination
Trovita, Jincheng, 1232 Tangor, Olinda Valencia, and (glucose, fructose, sucrose) was performed according
Delta Valencia) which are the main varieties in juice to Wang et al. (2006) with KNAUER (Germany) high-
processing. The physicochemical characteristics, such performance liquid chromatography (HPLC) system.
as sugars, organic acids, free amino acids, mineral The column of Waters sugar pak-1 (300 mmx6.5 mm
content, and color parameters, are routinely monitored id)(Waters Co., USA) and RI detector were used for
through every quality control program in the industry. sugar analysis. The mobile phase was de-ionized water
These data of the cultivars will help in the selection of at 90°C with the flow rate of 0.5 mL min-I. Sugars
orange genotypes to improve quality and processing present in each sample were identified and quantified
characteristics in orange processing industry. by external standard method using a commercial stan-
dard of sucrose, glucose, and fructose (Sigma, St.
Louis, MO, USA).
MATERIALS AND METHODS
The fruit juice (10 mL) was centrifuged in a refrig-
erator at 10000 x g at 0°C for 10 min. 0.5 mL superna-
Sample preparation tant was diluted to 10 mL with redistilled water, and
then filtered through a 0.45-pm Millipore filter for cur-
Six varieties of orange (Pineapple orange, Hamlin, rent HPLC analysis of sugars.
Trovita, Jincheng, Olinda Valencia, and Delta Valencia) Determination of organic acids Organic acids were
were collected by Chongqing Three-Gorge Construc- determined by the HPLC system as sugar determina-
tion Co. Ltd., and 1232 Tangor was taken from Citrus tion with the column of PRONTOSIL, 120-10-C1,H
Research Institute, Chinese Academy of Agricultural (10.0 pn, 250mm x4.6 mm id.)and the UV detector
Sciences, Chongqing, China. The oranges were har- K-1205 which was set at 210 nm. The HPLC method
vested in Jan. 2006 except for Delta Valencia and Olinda was according to Lee (1993) with a minor modification.
Valencia, which were harvested in May 2005. Each The mobile phase was ethanol/water (3:97, v/v) con-
fruit was packed with a thin plastic bag and stored in taining 0.01 M K,HPO, *3H,O, and pH was adjusted
cool room at 4 ° C 80-90% relative humidity. to 2.56 with H,PO,. The flow rate was set at 0.5 mL
Twenty oranges of each cultivar were randomly min-'. Organic acids were identified and quantified
selected, peeled, and squeezed by a domestic squeezer. by comparison of retention times and peak heights
The fresh juice was filtered through 2-mm steel sieves with standard solutions of known organic acids. Ac-
to remove the excessive pulp, and deaerated by vacuum ids present in each sample were identified and quanti-
rotating system at 20"C, then pasteurized at 90°C fied by external standard method using a commercial
( 1min). The final juice was heat-filled in PET bottles standard of oxalic, malic, lactic, acetic, and citric acid
and stored at -18°C before analysis. (Beijing Chemical Agent Co., China).
Determination of free amino acids As for amino
Chemical analysis acid analysis, Waters ACCQTAG method (Cohen and
Michaud 1993) was used. Juice samples were centri-
Determination of total soluble solids (TSS), pH, ti- fuged at 10 000 x g at 0°C for 10 min. 2 mL supema-
tratable acidity (TA) The TSS content of juice was tant were placed in 10 mL glass ampoules containing
determined using WAY-2s Abbe digital refractometer 1 mL of internal standard (alpha-aminobutyric acid) and
with automatic temperature compensation (Shanghai 9 mL of 6N HC1. The ampoules were frozen in liquid
Precision & Scientific Instrument Co., Shanghai, China). nitrogen, evacuated, sealed, and then placed in an oven
The pH was determined with a Thermo Orion modle at 110°C for 20 h. After cooling, the ampoules were
868 pH meter with a CNC 060 electronic probe. centrifuged for 10 min to remove acid. Samples were
TA was estimated by titration with 0.1 M NaOH us- resolved in 50 mL 6N HCl and 10 mL aliquots were
ing phenolphthalein as indicator. The results were cal- removed for derivation. Each sample was analyzed in
culated as anhydrous citric acid (g citric acid L-I). duplicate.

62008,CAAS. All rights reserved. Publishedby Elsevier Ltd.

Physicochemical Characteristics of Orange Juice Samples From Seven Cultivars 43

Aliquots were dried in a centrifuge, and then derived as no reflection, and was calibrated with a white refer-
with ACCQ . Fluor derivatization buffer (Waters) and ence tile (white ceramic tile for o/d reflectance from
ACCQ.Fluor reagent (Waters) at 56°C for 15 min. The 380 to 780 nm). Color was recorded using the CIE-L*,
ACCQTAG system (Waters) was used for quantitative a*, b’ uniform color space, the a* scale ranges from
determination of the amino acid composition. 5 pL negative values for green to positive values for red, and
aliquot of each sample was injected onto a column the b* scale ranges from negative values for blue to
(Waters ACCQTAG18 column, 150 mmx 4.6 mm id., positive values for yellow. Numerical values of a* and
5 p)for analysis of individual amino acids. A Waters b* were converted into hue angle (Hue= tan-lb*/a*)and
2475 fluorescence detector was used, with a mobile chroma (chroma = [(a*)2+ (b*)2]”2),which quantifies
phase consisting of special mobile phase (Waters the intensity or purity of the hue. The value of hue is
Company)/acetonitrile (93:7, v/v) with a flow rate of the angle in a 360 color wheel, where 0, 90, 180, and
1.O mL m i d . 270 represent the red-purple, yellow, bluish-green, and
Quantification was carried out by the internal stan- blue hues, respectively.
dard method using commercial standard L-amino acid
and alpha-aminobutyric acid (Sigma, St. Louis, MO, Statistical analysis
USA).
Determination of mineral metals About 20.00 g of Juice samples from the individual cultivar were consid-
juice was accurately weighed in an acid washed glass ered as a source of variation. The results were statisti-
digestion tube. The digestion liquid (DL) was a mix- cally evaluated by one-way analysis of variance
ture of redistilled concentrated nitric acidlperchloric acid (ANOVA). Statistical differences with P-values under
(4:1, v/v). 12 mL DL was added, and the tube was set 0.05 were considered significant and means were com-
in a temperature control digestion oven (modle KXL- pared by 95% Tukey’s HSD multiple range test.
1010, Beijing Tongrunyuan Machine & Electronic Tech-
nology Co. Ltd.) at room temperature overnight. Then,
the tube was heated and more DL was added if the
RESULTS
digest was not completely clear. This digest was trans-
ferred into a 50-mL acid washed volumetric flask and TSS, pH, and TA
conditioned. This solution was diluted with deionized
water for determination of potassium, magnesium, and Studies on fruit quality have often found good relation-
calcium, and the remaining undiluted digest was used ships between TSS levels or TSS/TA ratios and con-
to determine other elements. Three water blanks were sumer acceptability of fruits (Fellers 1991; Jodan et al.
run with each batch of samples. 2001; Marsh et al. 2004). The TSS and TSSlTA ratios
The analysis was done with atomic absorption spec- were generally taken as a basic characteristic of juice
trophotometers (AAS) (model TAS-986, Beijing Purkinje quality (USDA 1983; AIJN 2004). Table 1 showed
General Instrument Co. Ltd., China), mixed (multi- these values in the juices were significantly different
element) working standard solutions were made from (P c 0.05). 1232 Tangor, Trovita, and Olinda
stock solutions (1 mg mL-I, 3% HNO,) supplied by Vanlencia got the highest TSS with 10.8, and Jincheng
National Research Center for CRMs (certified refer- the lowest TSS with 8.7. Pineapple orange and Delta
ence materials), China. Three concentrations covering Valencia had medium TSS of the samples, with 9.8
the range of metal concentrations in the orange juice and 9.7, respectively.
digest were prepared for AAS (at mg L-’ levels). The pH values of the juices were within the normal
Color parameters assessment The color parameters range (3.81-4.31). As one would expect, the pH val-
were determined using an automatic colorimeter (model ues are lower in the juices with more acidity. Trovita
SC-8OC, Beijing Kangguang Instrument Co., Beijing, and Delta Valencia got higher pH values than the others,
China) ordinates from the reflectance spectrum. 4.3 1 and 4.21, respectively. Olinda Valencia and 1232
The instrument was calibrated with a black cuvette Tangor had the highest content of TA, followed by Pine-

02008,C M S . All rights reserved.Publishedby Elsevier Ltd.

44 NIU Li-ying er al.

apple orange (6.18 g L-l). Delta Valencia, Trovita, and riety for development in 1985. 1232 Tangor is a citrus
Hamlin had relatively low TA values (5.12-5.74 g L-'). fruit hybrid of Vanlencia orange (Citrus sinensis) and
The TSS/TA values of the samples were between 14.91 Red Tangerine (Citrus reticulutu) (Wu et ul. 1991) cul-
and 20.23, and all of the values meet the requirement of tivated by Citrus Research Institute, Chinese Academy
the USDA standard (10.5-23.0). of Agricultural Sciences. Compared with the other
cultivars, much fewer reports are available about the
Composition of sugars physicochemical characteristics of Jincheng and 1232
Tangor for juice processing, so more study should be
The sugar profile of orange juice is an important com- done on their characteristics for juice quality evaluation
ponent of chemical composition tables and provides and authentic identification.
valuable information regarding the authenticity of fruit
juices. It also has an effect on the sensory properties Composition of free amino acids
and nutritional value of fruit products. Sucrose,
fructose, and glucose were identified as the principal Organic acids contribute to the particular flavor and
sugars in them (Table 2). Sucrose level (29.65-69.61 palatability of orange juice. The acids composition and
g L-') was always higher than fructose (18.74-24.13 content vary depending on the origin, climate, variety,
g L-') and glucose (1 3.95-22.16 g L-I) levels. The pro- and degree of maturity (Vandercook 1977). Just as
portion of sucrose, glucose, and fructose in fresh the report by Lee (1993), the organic acids profile
Florida orangejuice is about 2: 1: 1 (Villamiel et ul. 1998). (Table 3) of orange juice subject to our analysis showed
The sucrose:total sugar ratio and the total sugar con- that citric acid was the most abundant (5.99-8.40 g LA'),
tent are naturally subject to large variations, but the followed by malic (0.35-2.09 g L-l). Oxalic was found
g1ucose:fructose ratio is practically constant which in much lower quantities (0.23-0.37 g L-I). Ascorbic
should not exceed the value of 1.00 and is generally acid or vitamin C is hypothesized to prevent cancer
higher than 0.85 (AIJN 2004). The proportions of by inhibiting the formation of N-nitroso compounds
sucrose, glucose, and fructose in the samples studied in the stomach and by stimulation of the immune sys-
(Table 2) agreed with the guideline of AIJN except tem (Byers and Perry 1992). Orange juice with high
that Jincheng and 1232 Tangor had relatively low val- ascorbic acid content would be appreciated by
ues with 0.74 and 0.76, respectively. Jincheng is one consumers. The content of ascorbic acid in all of the
of the most popular orange varieties in China, it has juice samples analyzed had met the requirement of
been introduced to the US by USDA as an orange va- AIJN (min. 0.2 g L-I).

Table 1 pH, TSS, TA, and TSS/TA in juice samples from seven orange cultivars
~ ~~

Parameters Pineapple orange Hamlin Trovita Jincheng 1232 Tangor Olinda Valencia Delta Valencia Average Range
PH 3.91 i0.19 b 4.02i0.04 b 4.31 kO.02 a 4.00*0.02 b 3.81 20.02 c 3.9520.04 b 4.21 i0.03 a 4.03 3.81-4.31
TSS 9.8i0.2 b 10.2i0.2b 10.8*0.1 a 8.7 i 0 . 2 c 10.8i0.3a 10.5i 0 . 2 a 9.7i0.2 b 10.1 8.7-10.8
TA(g L-1) 6.18i0.05 b 5 . 3 4 i 0 . 0 4 ~ 5 . 1 8 i 0 . 0 4 ~ 5.74i0.02~ 6.93i0.05 a 7.04*0.08a 5.12*0.04 c 5.93 5.12-7.04
TSS/TA 15.53i0.34 d 20.24i0.46 a 18.52i0.03 b 15.16*0.30d 16.13iO.18 d 14.91*0.11 d 18.95k0.24 b 17.01 14.91-20.23
Values followed by different letters within each row indicate significant differences for each parameter at Pc0.05.n = 3.

Table 2 Parameters of sugars of orange juice samples from seven orange cultivars (g L-')
~

Cultivars Sugars Ratio

Sucrose Glucose Fructose SUm Sucrose/Glucose Glucose/Fructose
Pineapple orange 39.12io. 1 1 21.90 k0.03 23.76 ~ 0 . 0 4 84.79 20.18 1.79 0.92
Hamlin 38.48 *O.16 18.62k0.16 20.98 iO.20 78.09i0.52 2.07 0.89
Trovita 42.30*0.75 22.16iO.22 24.13 i0.23 88.60 i 1.20 1.91 0.92
Jincheng 32.41 i0.18 13.95io.12 18.74+O.15 65.10 i 0.45 2.32 0.74
1232 Tangor 29.65 i0.23 17.57i0.16 23.1 1 i 0 . I6 70.33i0.54 I .69 0.76
Olinda Valencia 39.61 i0.64 19.15 i 0 . 5 2 21.78 20.54 *
80.55 1.70 2.07 0.88
Delta Valencia 38.52i0.22 16.81i0.04 20.15 i0.13 75.48 i0.40 2.29 0.83
Average 37.16 18.59 21.81 77.56 2.02 0.89
Range 29.65-69.6I 13.95-22.16 18.74-24.13 65.10-88.60 1.69-2.32 0.74-0.92
Results were expressed as mean i SEM of triplicate measurements.

Q2008, CAAS.All rights reserved.Published by ElsevierLtd.

Phvsicochemical Characteristics of Orange Juice Samoles From Seven Cultivars 45

Composition of free amino acids Mineral composition

The spectrum of free amino acids has been widely taken Most analytical efforts were devoted to the determina-
as characteristic of fruit juice quality and authenticity tion of elements in fruits because of their nutritional
(Wallrauch and Faethe 1988b; AIJN 2004). importance or because of these elements being indica-
Table 4 lists the free amino acids content of the juices. tive of a geographical locality (Nagy 1977; Bayer et at.
The major amino acids were serine (5.08-7.88 g kg-I), 1980; Nikdel et al. 1988; Simpkins et al. 2000). We
arginine (3.00-9.66 g kg-I), and proline (3.94-8.32 g had determined eight mineral compositions of the seven
kg-I). They accounted for some 79.0% of total amino orange juices, i.e., potassium, calcium, sodium,
acids. The content of amino acids varies with the magnesium, iron, manganese, copper, and zinc.
varieties. Olinda Valencia contained the highest amount As Table 5 showed, potassium is the most abundant
of total amino acid (31.78 g kg-I), followed by Trovita compound in all of the juice samples (1 233.75-1 565.80
(25.35 g kg-') and Delta Valencia (24.95 g kg-I). mg kg-I), followed by magnesium (78.57-167.20 mg

Table 3 Organic acids of iuice samples from seven orange cultivars (g L-')
~ ~ ~~ ~~

Acids Pineapple orange Hamlin Trovita Jincheng I232 Tangor Olinda Valencia Delta Valencia Average Rangc
Oxalic 0.33i0.02 0.23i0.01 0.37i0.00 0.26i0.01 0.25i0.01 0.35 iO.00 0.36i0.01 0.3 I 0.23-0.37
Malic 1.73k0.09 2.09i0.06 1.55iO.01 1.54i0.03 0.41 i0.06 0.35i0.00 0.36iO.O I 1.15 0.35-2.09
Ascorbic 0.25 iO.01 0.59*0.01 0.32i0.00 0.30i0.00 0.56i0.02 0.50 iO.0 I 0.38t0.01 0.4 I 0.25-0.59
Citric 8.40i0.01 5.99k0.19 6.97i0.38 7.31 i0.09 7.44i0.22 6.99t0.18 5.30k0.18 6.91 5.99-8.40
Results were expressed as mean i SEM of triplicate measurements.

Table 4 Content of free amino acids in iuice samples from seven orange cultivars (g kg-')
Free amino acids Pineapple orange Hamlin Trovita Jincheng 1232 Tangor Olinda Valencia Delta Valencia Average Range
Asparagine 0.79i0.01 a 0.73i0.01 a 0.61 i0.02 b 0.28i0.01 d 0.78i0.01 a 0.84i0.02 a 0.46i0.01 c 0.64 0.28-0.79
Serine 5 . l l i O . 3 3 ~ 5 . 0 8 i O . 1 6 ~ 8.92i0.47 a 5.41 i0.33 c 7.88i0.16 a 7.53i0.32 b 5.35i0.29 c 6.47 5.08-7.88
Glutamine 0.67i0.01 a 0.65i0.01 a 0.22i0.02 c 0.36i0.02 b 0.69i0.01 a 0.49i0.02 b 0.35i0.01 b 0.49 0.22-0.69
Glycine 0.1 I iO.01 b 0.09i0.09 b 0.16?~0.05ab 0.12iO.01 b 0. I3 iO.00 b 0.20i0.03 a 0.18i0.02 a 0.14 0.09-0.20
Histidine 0.53i0.02 c 0.72k0.02 bc 1.1 1 i0.06 a 1.26i0.07 a 0.82k0.00 b 1.01iO.04 a 0.62i0.05 c 0.87 0.53-1.26
Arginine 4.90i0.01 c 5 . 1 9 i O . 0 9 ~ 6.39i0.94 b 3.00i0.02 c 4.19io.01 c 9.66i0.12 a 7.46i0.1 I b 5.83 3.00-9.66
Threonine 0.22i0.05 a 0.20i0.06 a 0.28k0.03 a 0.2OiO.01 a 0.22i0.02 n. d. n. d, 0.22 n. d.-0.28
Alanine 0.54i0.01 bc 0.46i0.01 c 0.70i0.02 b 0.43i0.01 c 0.73i0.00 d 1.36i0.03 a 1.33i0.02 a 0.71 0.13-1.36
Proline 4.4OiO.14~ 5.17i0.15 c 6.15i0.02 b 3.94i0.07 c 4.85i0.04 8.32i0.16 a 7.35i0.17 a 5.74 3.94-8.32
Cysteine 0.08*0.01 a 0.05i0.01 b n. d. 0.01 iO.01 a 0.07i0.00 n. d. n. d. 0.05 n. d.-0.08
Tyrosine 0.20i0.00 c 0.16iO.00 c 0.30i0.01c 0.30i0.00 bc 0.19 kO.00 0.54i0.00 a 0.38i0.00 b 0.30 0.16-0.54
Valine 0.15i0.00 b 0.13*0.00 b 0.17i0.07 b 0.15i0.01 b 0.13 io.00 0.28i0.01 a 0.26i0.00 a 0.18 0.13-0.28
Methionine 0.05i0.00b 0.05i0.00b 0.03 iO.00 b 0.05 iO.00 b 0.04i0.00 0.43i0.01 a 0.46k0.00 a 0.16 0.03-0.46
Lysine 0.13i0.00 b 0.16i0.00 b 0.05i0.07 c 0.19iO.00 ab 0.29i0.00 0.16i0.02 b 0.14i0.00 b 0. I6 0.05-0.29
lsoleucine 0.05 i0.00 b 0.05 iO.00 c 0.06i0.00 b 0.06i0.00 b 0.07 iO.00 0.09i0.00 a 0.07t0.00 a 0.06 0.05-0.09
Leucine 0.05i0.00 b 0.04i0.00 b 0.04t0.01 b 0.05 iO.00 b 0.06t0.00 0.09i0.00 a 0.08i0.00 a 0.06 0.04-0.09
Phenylalanine 0.17i0.01 c 0 . 2 0 i 0 . 0 0 ~ 0.24i0.01 bc 0.35 i0.02 b 0.38i0.01 0.77i0.02 a 0.43iO.OI b 0.36 0.17-0.77
Total amino acids 18.17i1.63 c 1 8 . 1 0 i 1 . 0 6 ~ 25.35 i I .98 b 18.OOi1.35 c 23.52i2.45 b 31.78i3.21 a 24.95 r 1.66 b 22.84 18.00-3I .78
Values followed by different letters within each row and each cultivar indicate significant differences for each parameter at P<0.05. n=3. n.d., not detected.

Table 5 Mineral content in orange juice samples from seven cultivars ( m g kg-')
Mineral
Pineapple orange Hamlin Trovita lincheng 1232 Tangor Olinda Valencia Delta Valencia Average Raiige
content
.. ~. .

Potassium 1 3 1 0 . 1 9 ~ 8 . 5 01328.06k5.44~
~ 1419.90i11.31b I500.44i7.58a l233.75k 1 0 . 9 5 ~ I297.51i12.21~1565.80t5.20a I 379 1233.75-1565.80
Calcium 41.03*0.31 c 20.64i0.77d 33.76i0.77d 98.83i17.08h 125.30i6.71 a 49.22i0.34 c 43. I O i 0 . 8 4 ~ 58.84 20.64-125.3
Sodium 6.29k0.89 b 6.60i3. I9 h 12.85k?.70a 6.43i0.08b 7.63i0.18 b 2.70i0.03 c 2.43i0.03 c 6.41 2.43- 12.85
Magnesium 100.7-cO.04b 82.32i0.42d 90.04i0.25~ 78.57k 1.45d 79.21 i 11.21 d 167.2i3.56a 129.9020.33h 103.80 78.57-167.2
Iron 1.04+0.10a 1.09i0.05a 0.96i0.10 a 1.01i0.11a 0.77iO.12b 0.70i0.08 b 0.68kO 07 h 0.89 0.68-I .09
Manganese 0.14tO.01 a Tr. 0.0 I io.00 c 0.17iO.02a 0.02i0.00 c 0.1OiO.00 b 0.09i0.01 h 0.08 Tr.-O.I7
Copper 0.27t0.10d 0.28k0.02d 0.24i0.02 d 0.36i0.05~ 0.19iO.04 e 0.78i0.01 a 0.5 I kO.00 h 0.38 0.19-0.78
Znic 0.72*0.02 a 0.32i0.02~ 0.80i0.03 a 0.05i0.00d 0.30i0.02 c 0.56k0.01 b 0.51k0.01 b 0.47 0.0.5-0.80
Different letters indicate significant differences within each row and each cultivar at P <0.05. n=3. tr., trace

82008, CAAS All nghts reserved Publishedby Elsevier Ltd

46 NIU Li-ying et al.

kg-I) and calcium (20.64-125.30 mg kg-I). The sodium DISCUSSIONAND CONCLUSION

content of most varieties were below 10 mg kg-' except
Trovita (12.85 mg kg-I). Olinda Valencia and Delta
The physicochemical characteristics can vary signifi-
Valencia had more magnesium and copper than the
cantly depending on a number of factors, such as or-
others. Hamlin had the lowest level of calcium (20.64 ange variety, environmental factors (climate, soils,
mg kg-I) and manganese (n.d.). 1232 Tangor had the maturity at harvest, irrigation, fertilization, etc.), dif-
highest content of calcium (125.30 mg kg-') and low- ferent processing procedures, and analytical methods.
est content of copper (0.19 mg kg-'). But the orange variety has a major influence on the
The contents of magnesium, potassium, and sodium characteristics of the juice.
of the seven varieties were all in the range of the AIJN The cultivars under our analysis were the major com-
reference (2004).
mercial orange varieties cultivated in China, and the or-
anges were harvested at their commercial maturity. Re-
Color parameters sults showed that the parameters of Brix, B r i f l A ratios,
sugars, and organic acids of them were all within a
Color is one of the most important attributes of orange proper range for juice processing. While significant
juice in the United States; and the color of citrus juices difference in most physicochemical characteristics can
is one of the parameters that are evaluated for the com- be found between the samples.
mercial classification of the product in relation to its Valencia orange is the dominant orange variety for
quality. Previously the Hunter ah quotient was used to juice processing in USA and Brazil, and it is believed to
quantify color objectively, as this index is also corre- be able to provide the best of orange juice, especially
lated with the sensory appreciation of color in orange for NFC (not from concentrate) orange juice (Spreen
juice and its acceptance by the consumer. et al. 2001). Valencia orange has a better and deeper
In the measurements of the color of juice analyzed, color than many other varieties, but orange juice from
it was observed that in each of the indices (CIEL", a*, Hamlin has relatively poor color, flavor, and overall qual-
b*, and Hue) there were significant difference between ity in California, USA (Lee and Castle 2001). The re-
the juice samples (Table 6). The juice with the highest sults of physicochemical characteristics in the present
values of a* (reddest hue) were Olinda Valencia and study agreed with their reports. The juice of Olinda
Delta Valencia, indicating they were with more redness. Valencia contained more total amino acids and minerals.
Jincheng got the highest L" value and lowest a* value, Olinda Valencia and Delta Valencia had better deeper
which meant the juice had bright yellow colour distin- reddish color. Hamlin and Jincheng had relatively low
guished from the others. Trovita had the highest b' amino acids and light yellow color. Pineapple orange
value (56.38) with significant difference with the other had the characteristics similar to those of Trovita and
samples. The Hue values of all the varieties were higher Hamlin.
than 70 (Table 6), indicating they all had orange color. The juice quality and authenticity are usually evalu-
Olinda Valencia and Delta Valencia showed lower Hue ated by a comprehensive study of physicochemical char-
values than the other three, being 73.85 and 76.02, acteristics (AIJN 2004). An accurate analysis of them
respectively, indicating that they had deeper red color. enables the observation of the differences in various
Trovita and Olinda Valencia had brighter and pure color orange cultivars. In consideration of the total qualities
with higher Chroma value (54.74 and 53.04). demanded in orange juice (nutrition, taste, appearance,

Table 6 Color parameters of the oranges juices from seven cultivars

Color parameter Hamlin Pineapple orange Trovita Jincheng 1232 Tangor Olinda Valencia Delta Valencia
L' 54.35i0.75 a 53.26i0.24 b 52.02i0.23 bc 54.25i0.48 a 52.47i0.36 c 51.45iO.31 c 51.43i0.27 c
a' 11.64i1.29~ 11.32iO.31 c 1I . 11 i 1.24 c 8.04i0.56 d 11.21 i 0 . 5 5 c 14.06iO.38 a 12.81 i 1.22 b
b' 47.94i1.58 c 50.17i0.19 b 56.38i0.38 a 45.64i1.60 c 47.42i0.79 c 48.56i0.73 b 51.46i1.18 b
Hue 78.45i0.90 a 77.29i0.31 ab 78.85i1.19 a 80.01 i0.88 a 76.7 i 0 . 4 2 b 73.85 i 0 . 3 2 c 76.02 i 1.59 bc
Chroma 48.93i1.63 b 51.43i0.24 b 54.74i0.51 a 46.34 i 1.53 c 48.73 iO.89 b 53.04i0.78 a 50.55i0.86 b
Different letters indicate significant differences within each row and each cultivar at P <0.05. n = 3 .

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Physicochemical Characteristics of Orange Juice Samples From Seven Cultivars 41

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