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Original Article
Studies on the quality and flavor of ponkan (Citrus poonensis hort.) wines fermented by different yeasts
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Jian-Shing Leea, Chi-Yue Changa, Tung-Hsi Yua, Shung-Tang Laib,
Li-Yun Lin
a Department of Bioindustry Technology, Da-Yeh University, Changhua, Taiwan, ROC b Department of Food Science and Technology, Hungkuang University, Taichung, Taiwan, ROC
ARTICLE INFO
ABSTRACT
Article history:
Received 25 September 2012 Received in revised form 26 November 2012 Accepted 17 May 2013 Available online 9 August 2013
Keywords:
Aromatic constituents Fermentation Ponkan fruit
Ponkan fruit wine production Yeast
Ponkan (Citrus poonensis hort.) juice and ponkan pulp were used as raw materials for the production of ponkan wines fermented with six different strains of Saccharomyces cer-evisiae. We found that ponkan wines fermented with S. cerevisiae BCRC 22332 and commercial yeast HF-08 had higher alcohol contents (10.70—11.86%), lower contents of residual sugar (0.64—1.14%), lower degrees of browning (OD420 = 0.20—0.34), higher clarity (OD660 = 0.07 —0.17), and higher sensory scores (5.15—6.25 points). Flavor analysis revealed that, in addition to the citrus flavor characters of a-pipene, limonene, and a-terpineol, ponkan wine contained the yeast-generated characteristic aromatic components of iso-amyl alcohol, phenethyl alcohol, 2,3-butandiol, ethyl acetate, diethyl succinate, isoamyl acetate, ethyl 3-hydroxybutyrate, ethyl caproate, ethyl 4-hydroxybutanoate, ethyl capry-late, phenethyl acetate, ethyl caprate, and ethyl 3-methylbutyl butanedioate. The aromatic components of isobutyl alcohol, isoamyl alcohol, diethyl succinate, phenethyl alcohol, ethyl acetate, and isoamyl acetate in the ponkan wine fermented with HF-08 were higher in amounts than that fermented with BCRC 22332. In summary, S. cerevisiae HF-08 produced more types of aroma and higher aroma contents.
Copyright © 2013, Food and Drug Administration, Taiwan. Published by Elsevier Taiwan
LLC. All rights reserved.
1. Introduction
The annual global orange yield is about 80 million tons, with Brazil and USA as the major producing countries, and approximately 34% of the total production is made into fruit juice. Most fruit juices are consumed in European and North American countries [1]. Based on the fact that oranges can be made into orange wines, the types of products
can be diversified. It has been reported that the major yeasts used in the making of commercial fruit wines are Saccharomyces cerevisiae and Saccharomyces bayanus [2]. The ethanol productivity by yeasts is theoretically about 51%, when hexose is used as the fermentation substrate [3]. Furthermore, it has been reported that different yeast strains can produce different organic acids and alcohol contents in wine [4].
* Corresponding author. Department of Food Science and Technology, Hungkuang University, No. 1018, Sec. 6, Taiwan Boulevard, Shalu District, Taichung City 43302, Taiwan, ROC.
E-mail address: lylin@sunrise.hk.edu.tw (L.-Y. Lin). 1021-9498/$ — see front matter Copyright © 2013, Food and Drug Administration, Taiwan. Published by Elsevier Taiwan LLC. All rights reserved. http://dx.doi.org/10.1016/jjfda.2013.07.004
In wine fermentation processes, the consumption of sugar is proportional to alcohol generation [5]. When fruits are used as the raw materials for wine fermentation, the shortage of nitrogen source will retard the growth of yeast [6], whereas nitrogenous nutrients can accelerate fermentation and improve the quality and yield [7,8]. Fermentation temperature also affects the quality and flavor of the wine products [9,10]. The suitable fermentation temperature for most S. cerevisiae strains is in the range of 22-27 °C [2,11]. In addition, the type of strain of S. cerevisiae used is an important factor influencing aroma contents and flavor characteristics of wine [12-18]. Because orange juice squeezed together with peel contained too much oil that consequently influenced yeast fermentation [19,20], Liou [21] has chosen deacidified peeled tangerine orange juice with the addition of 10% raw peel juice to make tangerine orange wine. It was found that the quality of wine fermented with fruit juice without the peel was much better than that of wine fermented with the peel [22]. Beyond this, Li et al [23] found that ethyl acetate, isoamyl acetate, and a-terpineol are the main aromatic constituents of the fruit wine of Glorious Oranges from Chongqing, China. Another research group also indicated that the main aromatic constituents of the fruit wine made from the Turkish oranges of Kozan are isoamyl alcohol, 2-phenethyl alcohol, ethyl hex-anoate, aromatic alcohols, citronellol, terpinene, and eugenol [24]. In this study, we compared the ponkan wines made from ponkan juice and ponkan pulp by fermenting with different S. cerevisiae strains.
2. Methods
2.1. Sample preparation
Ponkan fruits were purchased from a local market in Taichung, Taiwan. The yeast strains of BCRC 21761, BCRC 21805, BCRC 21823, BCRC 22293, and BCRC 22332 were purchased from the Food Industry Research and Development Institute (Hsinchu, Taiwan). HF-8 (commercial yeast) was purchased from the Eherfon Biotechnology Company (Kaohsiung, Taiwan). Pon-kan fruits were washed and peeled. The peeled ponkan fruits were then crushed with a stainless steel crusher (crushing aperture was 800 mm x 1,350 mm) to prepare ponkan pulp, and squeezed with a barrel basket squeezer (squeezing aperture was 270 mm x 390 mm) to prepare ponkan juice. Ponkan pulp and ponkan juice were separately adjusted to contain 24% sugar, 50 ppm of potassium metabisulfite [22,25], 500 ppm of ammonium sulfate, and 5% activated yeast culture in the 5 L conical glass flasks for wine fermentation [26]. The total volume of each flask was 3000 mL. They were then subjected to fermentation for 30 days at 25 ± 1 °C [10,11]. Samplings were carried out every 5 days to determine pH, residual sugar contents, soluble solid contents, alcohol contents, acidity, clarity, and colors. The ponkan wine made from ponkan juice was later abbreviated as PJW, and ponkan wine made from ponkan pulp was abbreviated later as PPW. Numbers 61, 05, 23, 93, 32, and 08 represented S. cerevisiae BCRC 21761, BCRC 21805, BCRC 21823, BCRC 22293, BCRC 22332, and commercial yeast HF-08 used for wine fermentation, respectively.
2.2. Analytical methods
Enological parameters such as oBrix, pH value, and total acidity (g citric acid/100 mL) were measured according to official Association of Office Analytic Chemists (AOAC) methods [27]. Reducing sugar contents were determined according to Zoecklein et al [28]. Browning indices were determined according to the method of Tien and Chiang [29].
2.3. Determination of ethanol contents
Ethanol contents were determined according to Zoecklein et al [28]. Approximately 1 g of acetonitrile was accurately added as the internal standard for each 10 mL of the sample wines, filtered with a Millipore filter (0.45 mm), and analyzed by gas chromatography with an FID detector (Agilent HP-6890, Wilmington, DC->, USA). The column used was a DB-1 capillary column (60 m, 0.25 mm i.d., 1-mm thickness). Nitrogen gas was used as the carrier gas, and operated at a flow rate of 1 mL/min with a split ratio of 60:1. The gas chromatography (GC) oven temperature was initially held at 40 °C for 10 minutes, then raised from 40 °C to 240 °C at 2 °C/min, and maintained at 240 °C for 10 minutes. The injection port temperature was 200 °C, and the detector temperature was 220 °C.
2.4. Preparation of volatile extracts and gas chromatography-mass spectrometry analysis
The volatile components of the sample wines were analyzed according to Romer and Renner [30]. A wine sample (300 mL) was diluted with distilled water to a concentration of 4% alcohol (Sample A) in an Erlenmeyer flask (2000 mL), with the addition of 5 mL of internal standard (accurately weigh about 0.08 g of dodecane dissolved in 100 mL of dichloromethane). Dichloromethane (300 mL) was added to the above sample wines with vigorous stirring for 2 hours, and allowed to stand for separation of the two layers. The bottom dichloromethane layer was separated and dried with a sufficient amount of anhydrous sodium sulfate. The dichloromethane was transferred to an oval-shaped flask and distilled with a concentration tower at 45 °C. It was firstly concentrated to about 1-2 mL, followed by purging with nitrogen gas at a flow rate of 25 mL/min to a volume of about 0.5 mL (Sample B). Sample B was then analyzed with a gas chromatograph/mass selective detector (GC-MSD; Hewlett-Packard 6890 GC connected to Hewlett-Packard 5973 MSD->). A capillary column (DB-1, J&W Scientific, Folsom, CA, i.d. 0.25 mm x 60 m, 0.25 mm film thickness) was used. The carrier gas, helium, was operated at a flow rate of 1.0 mL/min, with a split ratio of 80:1. The temperature was programmed initially at 40 °C for 5 minutes, raised to 240 °C at 2 °C/min, and maintained at 240 °C for 60 minutes. The injector temperature was 250 °C. The MS source temperature was 230 °C, the EM (electron multiplier) voltage was 2300 V, and the mass (MS) Quad temperature was 250 °C. The qualitative and quantitative determinations of the volatile components were performed according to Majlat et al [31]. Triplicate quantitative determinations were carried out by using the internal standard. The content of a specific component (Cs) was calculated by the following equation:
Table 1 - Changes in ethanol contents and residual sugar of the ponkan wines during the wine fermentation process.
Strainc dayd
Ethanol content (% v/v)a
Residual sugar (%)b
PPW05 0 2.90 ± 0.10F,e 7.70 ± 0.26e 9.80 ± 0.20C 10.93 ± 0.06B-C 10.90 ± 0.05B 10.93 ± 0.06B-C'D'E 24.00 18.23 ± 0.21B 9.70 ± 0.26d 5.30 ± 0.44d 1.44 ± 0.39e 1.27 ± 0.24e,f 1.37 ± 0.31E
PPW08 0 7.56 ± 0.31A 10.26 ± 0.15A 11.80 ± 0.30A 11.63 ± 0.42A 11.66 ± 0.40A 11.86 ± 0.21A 24.00 11.06 ± 0.15F 3.56 ± 0.20¡ 1.41 ± 0.22H 0.70 ± 0.12g 0.60 ± 0.04H 0.68 ± 0.07g,h
PPW23 0 5.23 ± 0.25d 8.23 ± 0.25d 8.76 ± 0.25e 10.90 ± 0.10B'C 11.13 ± 0.25B 11.23 ± 0.15B 24.00 14.20 ± 0.61C 7.80 ± 0.20F 6.40 ± 0.10C 2.07 ± 0.31D 1.87 ± 0.14d 1.84 ± 0.14d
PPW32 0 4.76 ± 0.23e 7.56 ± 0.21e 9.90 ± 0.20C 10.63 ± 0.15C 10.90 ± 0.10B 10.70 ± 0.17e 24.00 13.90 ± 0.36C 9.23 ± 0.25d 4.50 ± 0.30E 1.63 ± 0.42e 1.34 ± 0.15e 1.14 ± 0.16E'F
PPW61 0 2.63 ± 0.15f 4.46 ± 0.35g 6.96 ± 0.15g 9.03 ± 0.15e 9.33 ± 0.15d 9.43 ± 0.12g 24.00 18.13 ± 0.32B 15.30 ± 0.44a 10.16 ± 0.21A 5.25 ± 0.25B 5.45 ± 0.17B 5.60 ± 0.10B
PPW93 0 6.56 ± 0.21B 9.01 ± 0.20C 10.63 ± 0.23B 10.93 ± 0.15B,C 10.96 ± 0.15B 10.90 ± 0.10C'D'E 24.00 12.16 ± 0.21d 6.86 ± 0.42g 2.33 ± 0.15g 1.26 ± 0.21e,f 1.19 ± 0.18e,f,g 1.13 ± 0.06E'F
PJW05 0 5.46 ± 0.35c,d 8.26 ± 0.21d 9.23 ± 0.25d 10.26 ± 0.21d 11.06 ± 0.21B 11.06 ± 0.25b,c,d 24.00 14.36 ± 0.51C 7.96 ± 0.21e,f 5.53 ± 0.31D 0.92 ± 0.03F'G 0.90 ± 0.03G'H 0.93 ± 0.04f,g
PJW08 0 7.70 ± 0.17A 9.56 ± 0.31B 11.60 ± 0.46A 11.80 ± 0.30A 11.73 ± 0.32A 11.86 ± 0.21A 24.00 10.33 ± 0.20e 4.53 ± 0.35H 2.12 ± 0.16G 0.71 ± 0.03G 0.64 ± 0.04H 0.64 ± 0.04H
PJW23 0 2.96 ± 0.12f 5.16 ± 0.35f 7.50 ± 0.30F 9.36 ± 0.23e 10.06 ± 0.15C 9.73 ± 0.21F 24.00 18.76 ± 0.30B 14.23 ± 0.15B 5.13 ± 0.35d 2.83 ± 0.16C 2.69 ± 0.10C 2.63 ± 0.11C
PJW32 0 5.70 ± 0.26C 7.70 ± 0.20e 10.60 ± 0.20B 10.86 ± 0.15B,C 10.73 ± 0.21B 10.73 ± 0.21e 24.00 12.3 ± 0.43d 8.36 ± 0.32e 2.93 ± 0.15F 1.56 ± 0.20e 1.17 ± 0.20e,f,g 1.21 ± 0.16E
PJW61 0 2.06 ± 0.32g 5.50 ± 0.30F 7.46 ± 0.06F 9.93 ± 0.15d 10.80 ± 0.26B 10.80 ± 0.10D'E 24.00 20.43 ± 0.45A 13.23 ± 0.32C 9.10 ± 0.10B 6.31 ± 0.25A 6.37 ± 0.34a 6.34 ± 0.27A
PJW93 0 6.73 ± 0.21B 8.56 ± 0.21c,d 10.73 ± 0.21B 11.20 ± 0.10B 11.13 ± 0.15B 11.16 ± 0.15B,C 24.00 11.70 ± 0.26d 7.50 ± 0.30F 3.10 ± 0.36F 0.97 ± 0.04f,g 0.97 ± 0.12f,g 0.89 ± 0.08f,g,h
a The ethanol content in the fermentation processes of the ponkan wine fermented with different yeast strains. b The residual sugar content in the fermentation processes of the ponkan wine fermented with different yeast strains.
c The Saccharomyces cereuisiae strain of PPW (ponkan pulp wine) and PJW (ponkan juice wine) is BCRC 21805, HF-08, BCRC 21823, BCRC 22332, BCRC 21761, and BCRC 22293, respectively. d Day of fermentation.
e The means in column with different uppercase alphabets are significantly different at p < 0.05.
Cs = (As/Ai) x Ci
Cs is the concentration (ppm) of the specific component; As is the area of the specific component; Ai is the area of the internal standard; Ci is the concentration (ppm) of the internal standard. The structural determinations were processed by referring to the computerized database of Heller and Miline [32,33] and Toegepast Natuurwetenschappelijk Onderzoek (TNO) [34]. Alternatively, some data were referred to the cited mass spec-troscopic data.
2.5. Sensory analysis
The organoleptic evaluation [35] was performed by 47 students (from the Department of BioIndustry Technology, Da-Yeh University, Changhua, Taiwan). Data were expressed as mean scores (1 = extremely dislike; 5 = mutual; 9 = extremely like).
2.6. Statistical analysis
Samples were analyzed in triplicates. The concentration of volatile components was determined as the mean value of three independent determinations. The data were analyzed by Duncan's multiple range method with a significance of difference of p < 0.05 (SPSS Base 12.0).
3. Results and discussion
3.1. Analysis of general compositions of ponkan wine fermented with different S. cerevisiae strains
3.1.1. Comparison of alcohol content and residua! sugar in ponkan wines during the fermentation processes with different yeast strains
As shown in Table 1, ponkan juice wines, PJW 08 and PJW 93, had better alcohol productivity.
After 15 days of fermentation, the alcohol contents were 11.60 ± 0.46% and 10.73 ± 0.21%, respectively, and the residual sugar decreased to 2.12 ± 0.16% and 3.10 ± 0.36% respectively. The alcohol analysis showed that, after 30 days of fermentation, the alcohol contents increased to 10.5%, except that of PJW 23 and PPW 61 which were <10%. As shown in Table 1, there was a significant difference in the productivities of alcohol between ponkan juice wine and ponkan pulp wine.
The fermentation rate of the ponkan juice was faster than that of the ponkan pulp, and the amount of alcohol content of the ponkan juice wine was 0.5% higher than that of the pon-kan pulp wine. Furthermore, its sugar residue was 1% lower than that of the ponkan pulp wine. Table 1 also showed that the alcohol content made from the ponkan juice and ponkan pulp fermented with HF-08 yeast strain was up to 11.86 ± 0.21%. It demonstrated that HF-08 yeast strain was beneficial to the utilization of sugar and the production of alcohol. Table 1 indicates that ponkan pulp wine fermented with yeast strain BCRC 21823 had a higher alcohol content and lower sugar residue than those of the ponkan juice wine. The alcohol content of PPW 23 was 11.23 ± 0.15%, which was higher than that of PJW 23 with an alcohol content of 9.73 ± 0.25%. This study showed that BCRC 22332 and HF-08 were beneficial for the manufacturing of ponkan juice wine and ponkan pulp wine.
3.1.2. Comparison of acidity of ponkan wines during the fermentation process fermented with different yeast strains Table 2 indicates a variation of acidity in producing PJW and PPW fermented with different yeasts. When ponkan juice and ponkan pulp were fermented with different yeasts, the acidity of mash increased during the initial 15—20 day fermentation period. In general, Table 2 indicates that the acidities of ponkan wines were mainly dependent on the yeasts used for fermentation. The acidities of PPW 08, PPW 32, PJW 08, and PJW -32 were 0.64%, 0.81%, 0.75%, and 0.5%, respectively.
Table 2 — Changes in the acidities of the ponkan wines during the wine fermentation process.
Strainb dayc Acidity (%)a
0 5 10 15 20 25 30
PPW05 0.42 ± 0.02B,d 0.82 ± 0.03B 0.89 ± 0.03A 1.11 ± 0.10A 1.11 ± 0.10A 0.99 ± 0.05a 1.00 ± 0.06A
PPW08 0.41 ± 0.03B 0.64 ± 0.04e 0.55 ± 0.04e 0.70 ± 0.04d,e 0.64 ± 0.03F 0.64 ± 0.03E'F 0.64 ± 0.04f
PPW23 0.43 ± 0.02B 0.90 ± 0.02a 0.81 ± 0.03B 0.90 ± 0.03B 0.94 ± 0.02B 0.91 ± 0.01B 0.94 ± 0.02B,C
PPW32 0.41 ± 0.02B 0.72 ± 0.02c,d 0.73 ± 0.04C 0.82 ± 0.03C 0.84 ± 0.03C'D 0.82 ± 0.03C 0.81 ± 0.01D
PPW61 0.41 ± 0.03B 0.47 ± 0.02g 0.77 ± 0.02B,C 0.82 ± 0.02C 0.91 ± 0.04B,C 0.92 ± 0.05B 0.91 ± 0.03C
PPW93 0.44 ± 0.02a,b 0.55 ± 0.03F 0.62 ± 0.02d 0.68 ± 0.04e 0.62 ± 0.02f 0.60 ± 0.02f 0.62 ± 0.01F
PJW05 0.44 ± 0.02a,b 0.71 ± 0.03C'D 0.61 ± 0.02d 0.72 ± 0.04d,e 0.90 ± 0.04B,C 0.89 ± 0.03B 0.89 ± 0.04C
PJW08 0.49 ± 0.02a 0.73 ± 0.04c,d 0.75 ± 0.03C 0.75 ± 0.02c,d,e 0.75 ± 0.04e 0.76 ± 0.02c,d 0.75 ± 0.01E
PJW23 0.43 ± 0.03B 0.65 ± 0.04e 0.87 ± 0.02a 0.91 ± 0.03B 0.97 ± 0.02B 1.02 ± 0.06A 0.98 ± 0.03A'B
PJW32 0.42 ± 0.04B 0.42 ± 0.02H 0.47 ± 0.04f 0.44 ± 0.04f 0.51 ± 0.03G 0.45 ± 0.05g 0.50 ± 0.03G
PJW61 0.44 ± 0.04a,b 0.68 ± 0.04d,e 0.90 ± 0.05a 0.77 ± 0.02c,d 0.77 ± 0.03D'E 0.73 ± 0.04d 0.74 ± 0.04e
PJW93 0.42 ± 0.04B 0.75 ± 0.02C 0.73 ± 0.03C 0.75 ± 0.04c,d,e 0.72 ± 0.02e 0.70 ± 0.03D'E 0.75 ± 0.02d,e
a The acidity in the fermentation processes of the ponkan wine fermented with different yeast strains.
b The Saccharomyces cereuisiae strain of PPW (ponkan pulp wine) and PJW (ponkan juice wine) is BCRC 21805, HF-08, BCRC 21823, BCRC 22332, BCRC 21761, and BCRC 22293, respectively. c Day of fermentation.
d The means in column with different uppercase alphabets are significantly different at p < 0.05.
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3.1.3. Comparison of browning and clarity ofponkan wines during the fermentation processes fermented with different yeast strains
Table 3 values determined with spectrum photometer at 420 nm show the variation in browning indices and clarity of PJW and PPW fermented with different yeasts. Table 3 reveals that during the 30-day fermentation period, the browning index of that made from pulp was higher than that made from juice, except that the browning index of PJW 32 was higher than that of PPW 32. The browning index of PPW 32 was 0.22 ± 0.03 (OD 420). The main reason for the browning of PPW might be due to the polyphenols presented in ponkan pulp. Table 3 shows that both browning indices and clarity parameters decreased throughout the entire fermentation process. This might be due to the sedimentation of the colloids presented in the ponkan juice and ponkan pulp, especially in the ponkan pulp.
3.2. Comparison of the results of sensory evaluation of PJW and PPW fermented with different yeast strains
Table 4 shows the results of sensory evaluation of the ponkan wines after fermenting for 30 days. Concerning the color of four of the six ponkan wines, PJW had higher preference scores than PPW. In general, the ponkan juice wines had better sensory evaluation scores, and the bitterness of ponkan pulp wines might lower the sensory evaluation scores. The most preferred ponkan wines were PJW 08 and PJW 32, with the overall preference scores of 6.25 and 6.15, respectively. They also had better colors, flavors, and taste preferences.
3.3. Differences between aromatic constituents in the ponkan wine fermented with BCRC 22332 and HF-08 yeast strains
Based on the data in Table 4, PJW 08 and PJW 32 were the most preferred ponkan wines. Therefore, they were selected for further studies of their flavor components.
Table 4 - Sensory evaluation scores of ponkan wines.a
Wine product
Flavor
Overall preference
PPW05 6.75 ± 0.56B 6.02 ± 0.57a 3.34 ± 0.52B*C 4.58 ± 0.68B*C
PPW08 6.36 ± 0.79B 6.16 ± 0.72a 4.12 ± 0.45a*b 5.15 ± 0.88B
PPW23 4.18 ± 0.64C 5.75 ± 0.74B 3.24 ± 0.43B*C 3.42 ± 0.50D
PPW32 6.50 ± 0.59B 5.82 ± 0.61A*B 3.95 ± 0.70a*b 5.55 ± 0.72a*b
PPW61 6.53 ± 0.65B 4.25 ± 0.57C 2.45 ± 0.77C 4.12 ± 0.80C*D
PPW93 6.15 ± 0.72B 5.52 ± 0.66B 2.72 ± 0.62C 4.98 ± 0.53B*C
PJW05 7.25 ± 0.44a 6.47 ± 0.55a 3.95 ± 0.60A*B 5.49 ± 0.59a*b
PJW08 7.88 ± 0.40a 6.58 ± 0.74a 4.55 ± 0.62a 6.25 ± 0.74a
PJW23 3.63 ± 0.68C 5.43 ± 0.71B 4.64 ± 0.49a 4.98 ± 0.49B*C
PJW32 7.72 ± 0.62a 6.79 ± 0.66a 4.61 ± 0.85a 6.15 ± 0.75a
PJW61 6.93 ± 0.53a*b 4.86 ± 0.65B*C 3.12 ± 0.58B*C 4.36 ± 0.79C
PJW93 7.28 ± 0.45a 5.53 ± 0.58B 3.45 ± 0.65B 5.25 ± 0.67B
a The PPW (ponkan pulp wine) and PJW (ponkan juice wine) of strain is Saccharomyces cerevisiae BCRC 21761, 21805, 21823, 22293, 22332 and HF-08 is 61, 05, 23, 93, 32, and 08, respectively. b Symbols with different uppercase alphabets in the same column are significantly different (p < 0.05, n = 47).
Table 5 - Contents of volatile compounds in the ponkan wines fermented with BCRC 22332 and HF-08 strains
Compound RIa Concentration (ppm)
(DB-1) Ponkanb PPW32c PJW32d PPW08e PJW08f
Alcohols
Isobutyl alcohol 632 n.d.B'g n.d.B n.d.B 11.32 ± 4.81a 17.61 ± 6.09a
Butyl alcohol 669 n.d.B n.d.B 1.53 ± 0.90a n.d.B n.d.B
2-Methyl-3-buten-2-ol 685 n.d.B n.d.B n.d.B n.d.B 0.37 ± 0.14a
3-Penten-2-ol 686 n.d.C 0.09 ± 0.05B 0.24 ± 0.08a,b 0.42 ± 0.16A 0.36 ± 0.12a
Isoamyl alcohol 747 0.67 ± 0.12C 9.19 ± 2.02B 6.61 ± 3.50B 57.17 ± 3.67a 79.95 ± 35.37a
Amyl alcohol 755 n.d.C 4.77 ± 1.97a 2.59 ± 0.44B 2.55 ± 0.25B 3.06 ± 0.67a,b
2,3-Butanediol 808 35.63 ± 19.58a 37.78 ± 14.02a 49.04 ± 12.47A 32.35 ± 9.97a 61.39 ± 19.20a
3-Methyl-1-pentanol 882 n.d.C n.d.C n.d.C 3.03 ± 0.50a 0.51 ± 0.14B
Hexanol 895 n.d.C n.d.C n.d.C 0.39 ± 0.04a 0.25 ± 0.11B
Methionol 998 n.d.C n.d.C n.d.C 1.96 ± 0.54a 0.01 ± 0.004B
Phenethyl alcohol 1139 n.d.D 8.40 ± 1.04c,d 10.94 ± 1.78C 60.87 ± 9.52a 36.40 ± 0.70B
4-Hydroxyphenethyl alcohol 1480 n.d.D 0.08 ± 0.03C 0.31 ± 0.04C 21.76 ± 2.80a 16.82 ± 3.98B
Elemol 1596 n.d.C 0.20 ± 0.09B 0.33 ± 0.06B 0.29 ± 0.15B 0.40 ± 0.01A
Farnesol 1611 n.d.C n.d.C n.d.C 0.04 ± 0.01B 0.12 ± 0.06A
2,6-Dimethoxy-4-allylphenol 1634 n.d.D 0.54 ± 0.07B 0.50 ± 0.20B 2.25 ± 0.27a 0.11 ± 0.03C
4-Methyl-2,6-di-tert-butylphenol 1681 n.d.B n.d.B 0.05 ± 0.02a n.d.B n.d.B
2,4-Di-tert-butylphenol 1690 n.d.B n.d.B 0.28 ± 0.05a n.d.B n.d.B
t-Muurolol 1693 n.d.B 1.29 ± 0.26a 1.16 ± 0.23a 1.00 ± 0.61A 1.20 ± 0.35a
ß-Eudesmol 1700 n.d.C 1.42 ± 0.14a 0.20 ± 0.05B n.d.C n.d.C
a-Cadinol 1720 n.d.C n.d.C n.d.C 0.43 ± 0.23B 1.07 ± 0.44a
Subtotal 36.30 ± 19.70 63.76 ± 19.69 73.78 ± 19.82 195.83 ± 33.53 219.63 ± 67.41
Ketones
3-Hydroxy-2-butanone 696 n.d.B 0.48 ± 0.06A n.d.B n.d.B n.d.B
Butyrolactone 898 n.d.C n.d.C n.d.C 0.13 ± 0.05B 0.31 ± 0.12a
Geranyl acetone 1408 0.16 ± 0.02a n.d.B n.d.B n.d.B n.d.B
a-Ionone 1441 0.11 ± 0.02a n.d.B n.d.B n.d.B n.d.B
Farnesyl acetone 1861 0.12 ± 0.04a n.d.B n.d.B n.d.B n.d.B
Subtotal 0.39 ± 0.08 0.48 ± 0.06 n.d. 0.13 ± 0.05 0.31 ± 0.12
Esters
Ethyl acetate 609 24.37 ± 9.10a 10.94 ± 0.81B 9.08 ± 1.15B 7.03 ± 2.79B 11.48 ± 4.19B
Methyl tiglate 638 n.d.B n.d.B 1.11 ± 0.32a n.d.B n.d.B
Methyl lactate 741 n.d.C 0.20 ± 0.02B n.d.C 0.28 ± 0.04a n.d.C
Isobutyl acetate 751 n.d.C n.d.C 11.53 ± 2.36a n.d.C 0.96 ± 0.44B
Ethyl isobutyrate 771 n.d.C n.d.C 0.09 ± 0.02a n.d.C 0.02 ± 0.01B
Ethyl lactate 831 n.d.D 21.83 ± 6.53a 13.70 ± 4.09B 4.52 ± 0.41C 6.82 ± 1.55C
Isoamyl acetate 896 n.d.C 0.16 ± 0.02B 0.21 ± 0.07B 0.35 ± 0.12ab 0.58 ± 0.28a
Ethyl 3-hydroxybutyrate 962 n.d.C n.d.C n.d.C 0.94 ± 0.07a 0.33 ± 0.09B
Ethyl caproate 1029 n.d.C n.d.C n.d.C 0.25 ± 0.05a 0.03 ± 0.02B
Methyl 3-methoxypropionate 1068 n.d.C n.d.C 0.35 ± 0.11B n.d.C 2.53 ± 0.78a
Ethyl 4-hydroxybutanoate 1088 n.d.C n.d.C n.d.C 2.31 ± 0.33B 33.33 ± 2.29a
Ethyl 2-hydroxycaproate 1093 n.d.B 0.09 ± 0.06A n.d.B 0.15 ± 0.04a n.d.B
Ethyl caprylate 1234 n.d.C n.d.C n.d.C 0.23 ± 0.10B 1.55 ± 1.09a
Phenethyl acetate 1280 n.d.C n.d.C n.d.C 0.39 ± 0.14a 0.03 ± 0.01B
Trans-2-hexenyl butyrate 1431 n.d.B n.d.B n.d.B n.d.B 1.46 ± 0.53a
Ethyl caprate 1439 n.d.C n.d.C n.d.C 0.06 ± 0.01B 1.45 ± 1.01A
Ethyl 3-methylbutyl butanedioate 1460 n.d.C n.d.C n.d.C 0.33 ± 0.12B 11.90 ± 7.23a
Diethyl succinate 1471 n.d.D 2.58 ± 0.98B 0.15 ± 0.08C 64.95 ± 10.84a 58.73 ± 3.16A
Ethyl 2-hydroxy-3-phenylpropanoate 1478 n.d.C 0.16 ± 0.03B 0.18 ± 0.09B 0.43 ± 0.18a n.d.C
Ethyl 2-hydroxypentanedioate 1656 n.d.C n.d.C n.d.C 0.04 ± 0.01B 0.41 ± 0.18a
Methyl linoleate 2030 0.74 ± 0.42a n.d.B n.d.B n.d.B n.d.B
Methyl linolenate 2036 2.59 ± 1.18a n.d.B n.d.B n.d.B n.d.B
Methyl oleate 2042 1.11 ± 0.45a n.d.B n.d.B n.d.B n.d.B
Methyl trans-8-octadecenoate 2047 3.24 ± 1.43a n.d.B n.d.B n.d.B n.d.B
Ethyl linolenate 2103 4.25 ± 2.35a n.d.B n.d.B n.d.B n.d.B
Ethyl oleate 2112 17.97 ± 1.19a n.d.B n.d.B n.d.B n.d.B
Methyl linolelaidate 2167 0.29 ± 0.14a n.d.B n.d.B n.d.B n.d.B
Subtotal 54.56 ± 16.26 33.38 ± 8.45 36.4 ± 8.29 82.26 ± 15.25 131.61 ± 22.86
Acetic acid 644 13.27 ± 2.66BC 20.17 ± 0.65C 22.34 ± 5.22B,C 35.60 ± 12.40B 97.10 ± 34.20a
Hexanoic acid 1045 n.d.C n.d.C n.d.C 0.50 ± 0.06B 0.89 ± 0.34a
Benzoic acid 1270 n.d.C n.d.C n.d.C 0.13 ± 0.04B 0.58 ± 0.30A
Caprylic acid 1271 n.d.B n.d.B n.d.B 0.16 ± 0.08a 0.26 ± 0.05a
Table 5 - (continued)
Compound RIa Concentration (ppm)
(DB-1) Ponkanb PPW32c PJW32d PPW08e PJW08f
Nonoic acid 1331 n.d.B n.d.B n.d.B 0.07 ± 0.01A n.d.B
Capric acid 1424 n.d.B n.d.B n.d.B 0.13 ± 0.07a 0.21 ± 0.07a
Lauric acid 1576 0.40 ± 0.22B n.d.C n.d.C 0.48 ± 0.17B 3.89 ± 1.19a
Myristic acid 1726 1.54 ± 0.86a n.d.C 0.25 ± 0.05B n.d.C n.d.C
9-Hexadecenoic acid 1899 2.55 ± 1.48a n.d.B n.d.B n.d.B n.d.B
Palmitic acid 2015 61.38 ± 34.65a 0.40 ± 0.26B 0.25 ± 0.04B 0.28 ± 0.15B 0.11 ± 0.03B
Octadecanoic acid 2108 8.9 ± 1.91a n.d.B n.d.B n.d.B n.d.B
Linoleic acid 2112 94.39 ± 62.08a n.d.B n.d.B n.d.B n.d.B
Oleic acid 2145 80.19 ± 45.88a n.d.B n.d.B n.d.B n.d.B
Subtotal 262.62 ± 149.74 20.57 ± 0.91 22.84 ± 5.31 37.35 ± 12.98 103.04 ± 36.18
Terpenes and terpene alcohol
a-Pipene 955 0.05 ± 0.02B n.d.C 0.11 ± 0.04B n.d.C 1.46 ± 0.29a
g-Terpinene 1037 0.15 ± 0.03A n.d.B n.d.B n.d.B n.d.B
Limonene 1073 2.14 ± 0.28a 0.19 ± 0.06B 3.42 ± 0.36A 0.38 ± 0.08B 2.06 ± 0.70a
a-Terpineol 1220 2.54 ± 0.35B 0.28 ± 0.11D 1.34 ± 0.59C 0.48 ± 0.19c,d 3.42 ± 0.39a
5-Cadinene 1574 n.d.C 0.02 ± 0.01B 0.20 ± 0.09a n.d.C n.d.C
a-Calacorene 1594 n.d.C 0.05 ± 0.04B 0.06 ± 0.03B 0.07 ± 0.04B 0.51 ± 0.17a
Cadina-1,4-diene 1685 n.d.C 0.17 ± 0.04B n.d.C n.d.C 0.72 ± 0.33A
a-Cubebene 1695 n.d.B 0.27 ± 0.06A n.d.B n.d.B n.d.B
g-Elemene 1705 n.d.C n.d.C n.d.C 1.52 ± 1.03A 0.31 ± 0.13B
a-Cedrene 1904 n.d.B n.d.B 0.03 ± 0.01A n.d.B n.d.B
a-Copaene 2024 n.d.B n.d.B 0.31 ± 0.03A 0.40 ± 0.29a n.d.B
Subtotal 4.88 ± 0.68 0.98 ± 0.32 5.47 ± 1.11 2.85 ± 1.63 8.48 ± 2.01
Total 358.75 ± 186.46 119.17 ± 29.43 138.49 ± 34.53 318.42 ± 63.44 463.07 ± 128.58
n.d. = not detected.
a RI = GC retention index calculated on DB-1 column by using c5-c25 paraffins as standards. b Ponkan = ponkan (Citrus poonensis hort.) peeled and pressed into juice. c PPW32 = fermented ponkan pulp wine using BCRC 22332 as starter. d PJW32 = fermented ponkan juice wine using BCRC 22332 as starter. e PPW08 = fermented ponkan pulp wine using HF-08 as starter. f PJW08 = fermented ponkan juice wine using HF-08 as starter.
g The means in row with different uppercase alphabets are significantly different at p < 0.05.
3.3.1. Comparisons of aroma components between PJW and PPW
Table 5 shows the aroma components of the ponkan wines in this study. The ponkan wines contained high amounts of a-pipene, g-terpinene, limonene, and a-terpineol, similar to those of other studies [33,34]. The main volatile components of the ponkan juice were fatty acids such as palmitic acid (61.38 ± 34.65 ppm), linoleic acid (94.39 ± 62.08 ppm), oleic acid (80.19 ± 45.88 ppm), and esters such as ethyl acetate (24.37 ± 9.10 ppm) and ethyl oleate (17.97 ± 1.19 ppm). The main difference of volatile composition between ponkan juice and ponkan wine was that ponkan juice contained more fatty acids, fatty acid esters, and fruity aroma of ethyl acetate, whereas ponkan wine contained high amounts of alcohols such as isoamyl alcohol, amyl alcohol, phenethyl alcohol, elemol, 2,6-dimethoxy-4-allylphenol, and esters such as ethyl lactate, isoamyl acetate, and diethyl succinate.
Ethyl acetate, acetic acid, isoamyl alcohol, a-terpineol, 2,3-butanediol, limonene, and palmitic acid in ponkan wines were also found in ponkan juice. The result was similar to that of a previous report [35]. The data revealed that, after the yeast fermentation, the ponkan wine retained the original aroma components of citrus fruits. Selli et al [27] found that the characteristic aroma of citrus wine was ethyl acetate and phenethyl alcohol. This study also showed that
ethyl acetate and phenethyl alcohol, respectively, had fruity [36], sweet, and honey [37,38] flavor characteristics. The volatile components of PJW were mainly isobutyl acetate (fruity), ethyl isobutyrate, methyl 3-methoxypropionate, and a-pipene (fruity, piney) [39]. These aroma components were not present in PPW. The main volatile components of the PPW were methyl lactate and ethyl 2-hydroxycaproate. Compared with Table 4, the sensory evaluation results showed that PJW had better preference. This might be due to PJW having higher main aroma components than PPW, such as 2,3-butanediol (PJW 49.04 ± 12.47 > PPW 37.78 ± 14.02), phenethyl alcohol (PJW 10.94 ± 1.78 > PPW 8.40 ± 1.04), limonene (PJW 3.42 ± 0.36 > PPW 0.19 ± 0.06), a-terpineol (PJW 1.34 ± 0.59 > PPW 0.28 ± 0.11), and higher contents and varieties of esters. PJW contained phenethyl alcohol (sweet, honey), ethyl acetate (fruity) and isoamyl acetate (fruity). In addition to the aforementioned aroma components, PPW also contained a large amount of isoamyl alcohol, amyl alcohol, and a-pipene.
3.3.2. Comparisons of the aroma components of ponkan wines fermented with different yeasts
The aroma components of PJW and PPW fermented with BCRC 22332 yeast were mainly 3-penten-2-ol, isoamyl alcohol, amyl alcohol, 2,3-butanediol, phenethyl alcohol, 4-hydroxyphenethyl
alcohol, elemol, 2,6-dimethoxy-4-allylphenol, t-muurolol, ß-eudesmol, ferruginol, ethyl acetate, ethyl lactate, isoamyl acetate, ethyl 2-hydroxy-3-phenylpropanoate, acetic acid, palmitic acid, limonene, and 5-cadinene, with no significant differences in the content of most of the aroma components. The aroma components of PJW and PPW fermented with HF-08 yeast were isobutyl alcohol, 3-ethoxy-1-propanol, 3-methyl-1-pentanol, hexanol, dimethyl carbitol, methionol, farnesol, a-cadinol, butyrolactone, 2-methyl-3-thiolannone, ethyl 3-hydroxybutyr-ate, ethyl caproate, ethyl 4-hydroxybutanoate, ethyl caprylate, phenethyl acetate, ethyl caprate, ethyl 3-methylbutyl butane-dioate, diethyl 2-hydroxypentanedioate, hexanoic acid, benzoic acid, caprylic acid, capric acid, lauric acid, and g-elemene. Most of the aroma components in PJW were higher than those in PPW. Table 4 shows that PJW fermented with HF-08 had better preferences.
In terms of aroma property, the ponkan wine fermented with HF-08 contained more volatile components, such as isobutyl alcohol (wine aroma), isoamyl alcohol, diethyl succinate (grape), phenethyl alcohol (sweet, honey), ethyl acetate (fruity), and isoamyl acetate (fruity), than that fermented with BCRC 22332. Table 5 shows that PJW fermented with HF-08 produced more alcohols, esters, acids, and terpenes. The main volatile components of ponkan wine were ethyl acetate, phenethyl alcohol, isoamyl alcohol, lethyl hexanoate, citronellol, terpinene, a-pipene, a-terpineol, limonene, g-elemene, and a-octadecene. Compared with the previous studies [22-25,40,41], the ponkan wine fermented with HF-08 bacterial strain from ponkan juice had more and higher amounts of components in ponkan wine. The study results showed that the amount of aroma components such as isoamyl alcohol, phenethyl alcohol, and a-terpineol of PJW08 was higher than that fermented with BCRC 22332. The wine fermented with HF-08 contained higher amounts of aroma components such as ethyl acetate, phenethyl alcohol [24,25,42], a-pipene, a-terpineol, and limonene [39,40,41], which are the important aromas found in citrus fruit and ponkan wine. The aforementioned results showed that PJW and PPW fermented with HF-08 contained more alcohols, acids, esters, terpenes, and other aroma compounds than that fermented with BCRC 22332. Lin [10] found that alcohols, esters, and acids had a significantly positive effect on wine flavor. Therefore, it was speculated that more types of volatile components fermented with HF-08 yeast produced high-quality taste and aroma of ponkan wines.
4. Conclusions
Our study indicated that the ponkan juice was preferable for ponkan wine fermentation. Ponkan wines fermented with BCRC 22332 and HF-08 yeasts had more aromatic constituents and better acceptability than other tested yeasts. Both BCRC 22332 and HF-08 strains had characteristics of higher alcohol productivity, lower residual sugar, less browning, and better sensory evaluation. However, the ponkan wine fermented with HF-08 strain contained more isobutyl alcohol, isoamyl alcohol, diethyl succinate, phenethyl alcohol, ethyl acetate, and isoamyl acetate, as compared with that fermented with BCRC 22332. Apparently, for ponkan wine fermentation, yeast HF-08 was superior to BCRC 22332.
Acknowledgments
This work was supported by a research grant from the Council of Agriculture, Executive Yuan of the Republic of China, under the project title "The Development of Wine Brewing Techniques for Increasing the Fruit Wine Diversity (93AS-5.1.4-FD-Z1)."
REFERENCES
[1] Anonymous. Citrus: comment ¡éviter une pénurie. Arômes Ingred Addit 1996;7:38-40 [in France].
[2] Boulton RB, Singleton VL, Bisson LF, et al. Principles and practices of wine making. New York: Chapman & Hall; 1996. p. 45-56.
[3] Boulton RB, Singleton VL, Bisson LF, et al. Principles and practices of wine making. New York: Chapman & Hall; 1996. p. 73-9.
[4] Aragon P, Atienza J, Climent MD. Influence of clarification, yeast type, and fermentation temperature on the organic acid and higher alcohols of malvasia and muscatel wine. Am J Enol Vitic 1998;49:211-9.
[5] Lea AGH, Piggott JR. Fermented beverage production. London, UK: Blackie Academic and Professional; 1995. p. 361-85.
[6] Amerine MA, Berg HW, KunKee RE, et al. The technology of wine making. 4th ed. AVI: connecticut; 1980. p. 794.
[7] Wzorek W, Chruszczyk A. Przemysl Fermentacyjny i Rolny, vol. 16; 1972. p. 11 [in France].
[8] Rose AH. Scientific basis of alcoholic beverage production. In: Economic microbiology. London, UK: Academic Press; 1977. p. 10-40.
[9] Girard B, Yuksel D, Cliff MA, et al. Vinification effects on the sensory, colour and GC profiles of pinot noir wines from British Columbia. Food Res Int 2001;34:483-99.
[10] Castellari L, Magrini A, Passarelli P, et al. Effect of must fermentation temperature on minor products formed by cryo and non-cryotolerant Saccharomyces cerevisiae strains. Italian J Food Sci 1995;7:125-32.
[11] Amerine MA, Berg HW, Kunkee RE, et al. The technology of wine making. 4th ed. CT: AVI: Westport; 1980. p. 794.
[12] Romano P, Fiore C, Paraggio M, et al. Function of yeast species and strains in wine flavour. Int J Food Microbiol 2003;86:169-80.
[13] Pascal D, Margaret C, Marjorie K, et al. Effect of two commercial malolactic cultures on the chemical and sensory properties of chancellor wines vinified with different yeasts and fermentation temperatures. Am J Enol Vitic 2000;51:42-8.
[14] Karagiannis S, Lanaridis P. The effect of various vinification parameters on the development of several volatile sulfur compounds in Greek white wine of the cultivars batiki and muscat of Hamburg. Am J Enol Vitic 1999;50:334-42.
[15] Simone G, Norscia P, Suzzi G, et al. Relationship between selected strains of Saccharomyces cerevisiae and must composition variability. Industrie-delle-Bevande 1994;23:561-4.
[16] Schreier P. Flavour composition of wine: a review. CRC Critical Reviews. CRC Crit Rev Food Sci Nutr 1979 Nov;12(1):59-111.
[17] Rapp A, Mandery H. Wine aroma. Experientia 1986;42:873-84.
[18] Mateo JJ, Jimenez M, Pastor A, et al. Yeast starter cultures affecting wine fermentation and volatiles. Food Res Int 2001;34:307-14.
[19] Jan YW, Chiueh SY, Miau MJ. Research of the sweet orange making wine (the first newspaper). Bulletin of The Wine Research Institute Taiwan Tobacco & Wine Monopoly Bureau 1976:1-14.
[20] Jan YW, Chiueh SY, Shiu HM. Research of the sweet orange making wine (the second newspaper). Bulletin of The Wine Research Institute Taiwan Tobacco & Wine Monopoly Bureau 1977:1-7.
[21] Liou GD. Make an experiment of fermentation MikanBouya wine. Special Topics on Science & Technology of Alcoholic Beverages 1986;8:228-31.
[22] Zhang WG, Chen ZQ. Comparative research on two fermentation methods of orange wine. China Brewing 2006;7:55-8.
[23] Li R, Feng K, Wu J, et al. Effects of Saccharomyces cerevisiae strains from different sources on the aromatic composition of orange wine. Food Sci 2010;31:206-13.
[24] Selli S, Canbas A, Varlet V, et al. Characterization of the most odor-active volatiles of orange wine made from a Turkish cv. Kozan (Citrus sinensis L. Osbeck). J Agric Food Chem 2008;56:227-34.
[25] Selli S, Cabaroglu T, Canbas A. Flavour components of orange wine made from a Turkish cv. Kozan. Int J Food Sci Technol 2003;38:587-93.
[26] Ortega C, Lopez R, Cacho J, et al. Fast analysis of important wine volatile compounds development and validation of a new method based on gas chromatographic-flame ionization detection analysis of dichloromethane microextracts. J Chromatogr A 2001;923:205-14.
[27] AOAC. Official methods of analysis. In: Helrich K, editor. 15th ed. Association of official analytical chemists: Washington, DC, USA; 1990.
[28] Zoecklein BW, Fugelsang KC, Gump BH, et al. Production wine analysis. New York: Van Nostrand Reinhold; 1990.
[29] Tien CJ, Chiang BH. Clarification of soy sauce by microfiltration using polymeric membrane. Food Sci 1992;19:466-75.
[30] Romer G, Renner EZ. Simple methods for isolation and concentration of flavor compounds from foods. Z Lebensm Unters Forsch 1974;156:329-32.
[31] Majlat P, Erdos Z, Takacs J. Calculation and application of retention indices in programmed temperature gas chromatography. J Chromatogr A 1974;91:89-103.
[32] Heller SR, Miline GWA. EPA/NIH mass spectral data base, vol. 1. Washington, DC: US Government Printing Office; 1978.
[33] Heller SR, Miline GWA. EPA/NIH mass spectral data base, Suppl. 1. Washington, DC: US Government Printing Office; 1978.
[34] TNO. Compilation of mass spectra of volatile compounds in food. The Netherlands: TNO Institute CIVO Analysis; 1981.
[35] Lai ST, Lee JS, Yu TH, Chang CY. Effects of the Addition of Fermented Sorghum or Distilled Fermented Sorghum on the Flavor and Quality of Sorghum Spirit. J Food and Drug Analysis 2012;20(2):539-46.
[36] Fan G, Qi AY, Cha IQ et al. Study on free and glycosidically bound volatile aroma compounds in pulp and peel of glorious oranges. J Food Sci 2007;28:436-9.
[37] Santos JP, Arroyo T, Aleixandre M, et al. A comparative study of sensor array and GC-MS: application to Madrid wines characterization. Sensors and Actuators. B, Chemical 2004;102(2):299-307.
[38] Lee JS, Lai ST, Yu TH. Influence of fermented conditions on the quality and flavor of longan honey wines. Taiwan J Agric Chem Food Sci 2008;46:164-74.
[39] Hognadottir A, Rouseff RL. Identification of aroma active compounds in orange essence oil using gas chromatography-olfactometry and gas chromatography-mass spectrometry.
J Chromatogr A 2003;998:201-11.
[40] Selli S. Volatile constituents of orange wine obtained from moro oranges (Citrus sinensis L. Osbeck). J Food Qual 2007;30:330-41.
[41] Fan G, Xu XY, Qiao Y, et al. Volatiles of orange juice and orange wines using spontaneous and inoculated fermentations. Eur Food Res Technol 2009;228:849-56.
[42] Zhou HY, Qiao Y, Pan SY. Study on aroma components in fruit from three different satsuma mandarin varieties. Food Sci 2007;28:290-5.
