Screening of rice cultivars for brewing high quality turbid rice wine

LWT - Food Science and Technology 56 (2014) 145e152

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Screening of rice cultivars for brewing high quality turbid rice wine Qi Jun Wang a, Da-Wen Sun a, b, *,1, Seok-Tae Jeong c, Soo-Hwan Yeo c, Ji-Ho Choi c, Han-Seok Choi c, ** a

College of Light Industry and Food Sciences, South China University of Technology, Guangzhou 510641, China Food Refrigeration and Computerized Food Technology, Agriculture and Food Science Centre, University College Dublin, National University of Ireland, Belfield, Dublin 4, Ireland c Department of Agro-food Resources, National Academy of Agricultural Science, RDA, Suwon 441-853, South Korea b

a r t i c l e i n f o

a b s t r a c t

Article history: Received 22 September 2012 Received in revised form 18 October 2013 Accepted 22 October 2013

To screen proper rice cultivars for brewing high quality turbid rice wine, 5 high-yield rice cultivars, 9 high-eating-quality rice cultivars and 5 glutinous rice cultivars were collected. At the end of fermentation, significant differences (p < 0.05) were observed in the fermentation properties, sensory properties and suspension stability of the original fermented mash (OFM) among individual rice cultivars. The assayed fermentation properties of OFM included pH value, total acidity, amino acidity, reducing sugar, alcohol yield, fusel alcohols and ethyl acetate. Seven rice cultivars were screened out for producing high quality wine by the comparative analysis. This research provided the basic scientific data for producing potential high quality turbid rice wine. Ó 2013 Elsevier Ltd. All rights reserved.

Keywords: Turbid rice wine Makgeolli Rice screening Wine properties Fusel alcohols

1. Introduction Unlike European wine (Bautista-Ortín et al., 2013; BelisarioSánchez, Taboada-Rodríguez, Marín-Iniesta, Iguaz-Gainza, & López-Gómez, 2012; Ivanova et al., 2013; Ivanova, Vojnoski, & Stefova, 2011; Morakul et al., 2013; Smit & du Toit, 2013), which is normally made from grapes, the alcohol beverage produced from rice is called rice wine. Turbid wine called as makgeolli in Korean (Kim, Kim, Park, Kang, Ryu and Kim, 2011), zhuojiu in Chinese (Jiang, 2009; Yu, 2009) and nigorizake in Japanese (Gauntner, 2013), is one kind of traditional cereal (generally rice) wine in eastern Asia area. However, turbid wine from Korea, China and Japan differs in wine starter, raw materials, alcohol content, color, flavor and so on. Korean turbid wine is made by fermentation with a traditional fermentation starter (nuruk in Korean), water and starch-containing materials (excluding germinated grains). During or after the fermentation process, extra sugar, fruits, vegetables or

* Corresponding author. Food Refrigeration and Computerized Food Technology, Agriculture and Food Science Centre, University College Dublin, National University of Ireland, Belfield, Dublin 4, Ireland. Tel.: þ353 1 7167342; fax: þ353 1 7167493. ** Corresponding author. Tel.: þ82 31 299 0584; fax: þ82 31 299 0554. E-mail addresses: [email protected] (D.-W. Sun), [email protected] (H.-S. Choi). 1 www.ucd.ie/refrigwww.ucd.ie/refrig; www.ucd.ie/sun. 0023-6438/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.lwt.2013.10.032

other legally permitted food additives may be added. Unlike other wines, no filtration process is performed at the end of the fermentation, which makes the wine having turbid appearance (Sol, 2007). The main nutritional components per 100 mL turbid rice wine (6 mL ethanol/100 mL) were 6 mL ethanol, 91.8 g water, 1.6 g protein, 2.4 g saccharide, 41 mg ashes and 1.34 mg vitamins (Park, Park, Kim, Lee, & Rim, 2010). Turbid wine is firstly characterized by the low alcohol content (2e6 mg/100 mL, and generally 6 mg/100 mL), secondly by the harmony attributes of sweetness, sourness, bitterness, piquancy, and bouquet (Lee & Choi, 1998), thirdly by nourishments (Lee & Joo, 2008), and finally by functional activities (Kim, Kim, & Bae, 2001; Kim & Cho, 2006; Shin, Kang, Kim, & Bae, 2008). Turbid rice wine with its wellbeing characteristics was recognized as a sort of outstanding food in the early of 2000s, since then turbid rice wine consumption increased greatly over the years. The licenses issued for producing turbid rice wine were 768 in 2009 in Korea according to the official Statistics Korea, 2011. The amount of turbid rice wine sold in 2010 has already reached 412,279 tons whereas it was only 170,165 tons in 2006, and export of the wine was 3290 tons in 2006, and reached 19,407 tons in 2010 according to the official report of Korea National Tax Service in 2011. In addition, the number of published papers on turbid rice wine was 88 from 1990 to 2000, while it was 169 from 2001 to 2010. These papers can be sorted into 6 groups, i.e., raw materials, fermentation

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starter, fermentation conditions, nutritional functions, food quality and package design. In terms of raw materials, most studies focused on only 1e2 raw materials such as sweet potato (Kim, Choi, & Oh, 1972), puffed rice (Kim, Sung, Bae, & Lee, 2007), rice plus grape (Koo, Yook, & Kim, 2006), rice plus Yulmoo (Shin, Suh, Cho, Lee, & Hwang, 2003), rice plus cyclodextrin (Song, Park, & Shin, 1997) and etc. However there is no investigation on how rice cultivars affect turbid rice wine brewing. The reason is that rice was officially forbidden for using in making alcoholic drinks during 1965e1990 due to food shortage after the Korean War (Kim, Jeong, & Choi, 2011). However, since the late 1980s, the rice yearly yield in Korea was far more than consumption, and since 1990, the Korea government encouraged people to use rice for alcoholic beverage. Therefore, in the current study, the fermentation characteristics of 20 rice cultivars collected in Korea were comparatively investigated in order to provide some basic scientific data for producing potential high quality turbid rice wine. 2. Materials and methods 2.1. Rice cultivars Eighteen Korean domestic rice cultivars produced in 2009 (including two sub-types: Japonica and Indica) were obtained from the National Institute of Crop Science, Rural Development Administration (RDA), South Korea. Among these, five cultivars were high yield rice (HY-rice), eight were high eating quality rice (HEQ-rice), and the other five were glutinous rice. In addition, rice cultivar Chucheong (produced in 2009, belonging to HEQ-rice) was bought from a local market and used as control. These rice cultivars are listed in Table 1.

2.2.2. Aspergillus kawachii-starter A. kawachii (CF1005, Chung-mu Fermentation Company, Korea) starter was prepared in laboratory. The preparation process was as follows: rice (10 kg, Odae polished rice, Japonica type) was rinsed and then soaked in water for 2 h, and then the excess water was drained off for 1 h. The rice was then steamed for 40 min to allow the full gelatinization of rice. The steamed rice was cooled down to less than 30  C and was inoculated with 800 mL cultured liquid of A. kawachii for 48 h (The components of the liquid medium per 100 mL consisted of 2.0 g glucose, 5.0 g rice powder, 0.80 g yeast extract and 100 mL water). Incubation was carried on for 44 h in an automatic rice fermenter (Mini 15 PX, Yaegaki Co., Japan), in which the humidity was maintained at 80% and temperature at 38  C. After incubation, the starter was dried at 50  C for around 12 h till the water content was less than 12 g/100 g. The dried starter was stored at 4  Ce10  C for up to 12 months. 2.2.3. Yeast SAF-Instant Gold Label Yeast (consisting of yeast of Saccharomyces cerevisiae, sorbitan monostearate, and ascorbic acid) was purchased from Lesaffre Yeast Corporation, France. This yeast product was a granular free-flowing yeast which could be used in doughs with sugar levels from 10 to 30%, the suggested inoculum amount was 0.5e1% by dry weight. 2.2.4. Activated starter Activated starter was prepared by mixing 1 kg A. kawachii starter, 12.5 g SAF-Instant yeast and 1500 mL sucrose water solution of 15 g/1000 mL in a container, and incubated at 25  C for 30 h under aerobic condition. 2.3. Fermentation process for original fermented mashes

2.2. Fermentation starters 2.2.1. Modified starter The modified starter was purchased from Korea Enzyme Company, Seoul Korea, which was modified from the Korean traditional starter by using wheat flour as raw material instead of wheat grain, and using screened pure microorganisms such as Rhizopus japonicus, Aspergillus oryzae and Hansenula yeast as inoculum instead of the microorganisms from environment. The general culture conditions were the same as those used by So, Lee, and Noh (1999). Table 1 Rice type, producing region and grouping of rice cultivars. Rice group

Rice cultivar

Cultivation region

Rice type

HY-ricea

Dasan2 Deulaechan Namchan Hanaleum Keunseom Gaopum Miguang Hanseol Huaseong Ju-an Cheong-a Jo-un CHHjinmi Baekjinju Baekjinju1 Haepyeongchal Hangangchal Huaseonchal Chucheong

Suwon Iksan Miryang Miryang Miryang Iksan Suwon Suwon Miryang Suwon Iksan Suwon Suwon Suwon Suwon Miryang Miryang Miryang Suwon

Indica type Japonica type Indica type Indica type Indica type Japonica type Japonica type Japonica type Japonica type Japonica type Japonica type Japonica type Japonica type Japonica type Japonica type Japonica type Indica type Japonica type Japonica type

HEQ-riceb

Glutinous rice

Control ricec a b c

HY-rice: high yield rice cultivars. HEQ-rice: high eating quality rice cultivars. The control rice Chucheong, bought from market, belongs to HEQ-rice.

One kilogram rice was rinsed 3 times to remove the impurities, followed by soaking in water (w25  C) for 2 h until saturation of water adsorption. Excessive water was removed, and the soaked rice was then steamed for around 40 min to allow the full gelatinization of rice. The steamed rice was cooled down from more than 95  C to less than 30  C within 10 min in an air blast cooler (YW-30, Yaegaki Co., Japan), then the steamed rice was transferred to a 5 L plastic fermentation container. 2 L water, 20 g modified starter, and 200 g activated starter were added into the container and incubated at 22  C until the completion of the fermentation, which took 7 days. At the end of fermentation, the whole mash was mixed and filtered, the coarse filtrate was used as original fermented mash (OFM). In the whole process of turbid rice wine preparation, no food additives were allowed to be added, so as to investigate the effects of different rice cultivars on the quality of turbid rice wine. Triplicate fermentations for each rice cultivar were carried out. 2.4. Making turbid rice wines by diluting OFM Turbid rice wine was made by diluting OFM to the alcohol concentration of 6 mL/100 mL with cold boiled water. OFM and turbid rice wine were stored at 20  C for further uses. 2.5. Assessment on chemical properties of OFM To compare the fermentation characteristics of different rice cultivars under the same conditions, OFM instead of turbid rice wine was used for the assessment. The methods for assaying the general chemical properties of OFM such as pH, soluble solids, total acidity, amino acidity and reducing sugar were those recommended by Analysis Regulation for Alcoholic Beverages (National Tax

Q.J. Wang et al. / LWT - Food Science and Technology 56 (2014) 145e152

Service press, Korea, 2009). The contents of alcohol, ethyl acetate and fusel alcohols of OFM were analyzed by GC. 2.6. GC conditions GC instrument (GC2010, Shimadzu Co., Japan) used in the study was equipped with an auto injector of Aoc-20i, a capillary column of DB-WAX (30 m  0.320 mm, 0.25 id., J & M Scientific Co., USA) and a flame ionization detector. The following temperature procedure was followed: isothermal at 50  C was first maintained for 5 min, then the temperature was increased to 160  C at 5  C/min, and to 200  C at 10  C/min, and finally the temperature was held at 200  C for 5 min. 1000 mg/L stock standard solution of each standard higher alcohol was made. The standard solution of n-propyl alcohol was prepared with water as solvent, and the iso-butyl alcohol and iso-amyl alcohol standard solutions were prepared with methanol as solvent. Then the mixed working standard solutions of 5 mg/L, 10 mg/L, 100 mg/L were made with methanol as solvent. The mixed standards solutions (1 mL) were filtrated into glass vials through 0.22 mm nylon membrane. OFM samples were diluted by 20 folds with water. Then 1 mL diluted samples was filtered into the glass vial through 0.22 mm nylon membrane, and 1 mL was injected into GC with a split ratio of 25 being used. 2.7. Sensory evaluation of turbid rice wine After dilution from OFM, the turbid rice wine was stored at around 4  C overnight before sensory evaluation. The sensory parameters of color, aroma, taste and overall preference of each turbid rice wine were evaluated by 10 trained and experienced panelists working in Brewing Research Center, RDA, South Korea. Among them 5 panelists were females of 28e39 years old, and 5 were males of 26e41 years old. The sensory scores were represented by 5-point hedonic scale. 2.8. Determination of turbid rice wine suspension stability To determine the suspension stability of turbid rice wine of different rice cultivars, 15 mL of each thoroughly-mixed turbid rice wine was introduced into a glass test tube of 1.8 cm diameter and 13 cm length. The test tubes holding the turbid rice wine made of different rice cultivars were thoroughly mixed before leaving them for the observation of their suspension stability. Photos were taken at 30th min to record the sedimentary distances of turbid rice wine. The suspension stability was represented by the sedimentary distance. 2.9. Statistical analysis The statistical analysis was performed with SPSS 14.0 (SPSS Inc., Chicago, IL). The means, standard deviations and significant difference of results were obtained by variance analysis (ANOVA). For post hoc multiple comparisons, Duncan test was used when equal variances were assumed, and Dunnett’s T3 was used when equal variances were not assumed. Significance level of 0.05 was adopted in this research. 3. Results and discussion 3.1. Chemical properties of OFM At the end of fermentation, the general chemical properties of OFM, i.e., alcohol, pH, total acidity, amino acidity, soluble solid, reducing sugar, ethyl acetate and fusel alcohols were analyzed, and the results are listed in Table 2.

147

3.1.1. Alcohol yield At the end of fermentation, alcohol content of OFM was detected by GC. The alcohol contents varied from 15.29  0.31 mL/100 mL to 16.38  0.35 mL/100 mL. According to the experimental conditions for making turbid rice wine in this study, the alcohol yield of rice cultivar was consistent with the alcohol content of OFM. Significant differences in the alcohol contents of OFM (and thus alcohol yields) were observed among some individual rice cultivars. The alcohol contents with letter “a” are higher than those with letters “b” and “c” (p < 0.05). The average alcohol concentrations of HY-rice, HEQ-rice and glutinous rice were 16.30  0.20 mL/100 mL, 16.15  0.25 mL/ 100 mL and 15.60  0.30 mL/100 mL, respectively. Averagely, HYrice produced 0.9% more alcohol than HEQ-rice and 4.5% more than glutinous rice. Significant difference (p < 0.05) in alcohol contents was also observed between non-glutinous rice and glutinous rice. However, there was no significant difference (p > 0.05) between HY-rice and HEQ-rice. Park, Kim, Hwang, Cho, and Jung (2005) reported that glutinous rice produced less alcohol than non-glutinous rice. Lee, Lee, Choi, and Lee (1996), Lee, Lee, Park, and Noh (1996) reported that the alcohol content in the makgeolli made of non-glutinous rice, glutinous rice, barley and wheat flour 11.6 mL/100 mL, 11.1 mL/100 mL, 10.1 mL/100 mL and 9.8 mL/100 mL, respectively, also showed that glutinous rice produced less alcohol than non-glutinous rice. In the preliminary experiments, the starch contents of rice cultivars were examined, and it was found that there were no significant differences in starch content between glutinous rice group (mean ¼ 89.39 g/100 g, on dry basis) and non-glutinous rice group (mean ¼ 89.97 g/100 g on dry basis). Park et al. (2005) mentioned that the content of free sugars in the fermented mash of glutinous rice included maltose, glucose, fructose and sucrose, and their contents were 2.03 g/100 g, 2.52 g/100 g, 0.18 g/100 g and 0.25 g/100 g, respectively, however, the free sugars in the fermented mashes of non-glutinous rice only included maltose and glucose, and the contents were 0.95 g/100 g and 1.95 g/100 g, respectively. In terms of the reducing sugar contents of turbid rice wine mashes, the glutinous rice cultivars showed higher contents than those of non-glutinous rice. These may potentially explained the slightly lower alcohol yields for glutinous rice than for nonglutinous rice. 3.1.2. pH, total acidity, amino acidity, soluble solid and reducing sugar Experimental results (Table 2) showed that the pH values of OFM varied from pH 4.08  0.02 to pH 4.42  0.05, total acidity varied from 0.40  0.00 g/100 mL to 0.49  0.02 g/100 mL by lactic acid, and the amino acids varied from 0.188  0.00 g/100 mL to 0.238  0.01 g/100 mL by glycine, soluble solids varied from 9.65  0.15 to 10.18  0.06  Brix, and the reducing sugar contents varied from 1.32  0.03 mg/mL to 2.07  0.05 mg/mL. Similar data for pH, total acidity, amino acidity and reducing sugar of the turbid rice wine mashes were reported by Lee, Lee, Choi, et al. (1996), Lee, Lee, Park, et al. (1996) and So et al. (1999). The results also showed that except for the property of reducing sugar, no significant differences were observed among the rice groups of HY-rice, HEQ-rice and glutinous rice in either pH value, total acidity, amino acidity, or soluble solids. However, significant differences in pH value, total acidity, amino acidity and reducing sugar content were observed among some different individual rice cultivars (Table 2). This indicates that for chemical fermentation characteristics of rice, generally, significant differences exist among individual rice cultivars rather than among different rice groups such as glutinous rice group, high eating quality rice group and high yield rice group.

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Table 2 Chemical properties of original fermented mashes. Rice cultivar

Alcohol (mL/100 mL)

Dasan2 Deulaechan Namchan Hanaleum Keunseom Sub-average Gaopum Cheong-a Hanseol Huaseong Ju-an Miguang CHHjinmi Jo-un Sub-average Baekjinju Baekjinju1 Haepyeongchal Hangangchal Huaseonchal Sub-average Chucheongc

16.26 16.36 16.36 16.31 16.22 16.30 15.81 16.38 16.32 16.27 16.09 16.38 16.07 16.17 16.15 15.96 15.44 15.29 15.85 15.47 15.60 15.84

                     

pH

0.19aa 0.20a 0.31a 0.24a 0.15a 0.20 0.25b 0.20a 0.20a 0.21a 0.30ab 0.35a 0.25ab 0.25ab 0.25 0.40ab 0.35bc 0.31c 0.25bc 0.20bc 0.30 0.20b

4.14 4.30 4.31 4.30 4.08 4.23 4.28 4.27 4.19 4.42 4.31 4.41 4.37 4.22 4.30 4.35 4.27 4.33 4.26 4.28 4.30 4.26

Acidity (g/100 mL)                      

0.03a 0.04b 0.03bc 0.03bc 0.02a 0.03 0.02b 0.02b 0.02ab 0.05c 0.03bc 0.04c 0.04bc 0.02ab 0.03 0.03bc 0.02b 0.02b 0.03b 0.02b 0.02 0.02b

0.45 0.41 0.43 0.43 0.49 0.44 0.42 0.45 0.41 0.45 0.45 0.40 0.42 0.44 0.43 0.44 0.46 0.45 0.43 0.45 0.45 0.45

                     

AA acidity (g/100 mL)

0.01ab 0.01bc 0.01bc 0.01bc 0.02a 0.03 0.01bc 0.02ab 0.01bc 0.02ab 0.02ab 0.00c 0.01bc 0.02ab 0.01 0.02ab 0.02ab 0.02ab 0.01bc 0.02ab 0.02 0.02ab

0.188 0.219 0.238 0.227 0.203 0.215 0.228 0.215 0.219 0.208 0.218 0.217 0.217 0.215 0.216 0.225 0.213 0.213 0.216 0.207 0.215 0.206

                     

Soluble solid ( Brix)

0.00a 0.00ab 0.01b 0.01b 0.00a 0.03 0.00b 0.00ab 0.00ab 0.00a 0.00ab 0.00ab 0.00ab 0.00ab 0.00 0.01b 0.01ab 0.00ab 0.00ab 0.00a 0.00 0.00a

9.95 9.99 10.17 10.07 10.11 10.06 9.65 10.00 9.99 9.69 10.10 10.03 10.02 9.67 9.89 10.10 10.18 10.15 10.09 10.15 10.13 9.88

                     

0.05a 0.10a 0.06a 0.05a 0.11a 0.03 0.15a 0.12a 0.06a 0.08a 0.05a 0.06a 0.05a 0.15a 0.10 0.05a 0.06a 0.08a 0.08a 0.05a 0.06 0.15a

All data were presented as mean  standard deviation (n ¼ 3). a Values not sharing the same letter within one column are significant different (p < 0.05). b TFA: Total fusel alcohols, and total fusel alcohols in the unit of g/L of p.a. were calculated with the data of ethanol content and total fusel alcohols content of the turbid rice wine mashes. c Control.

The correlation coefficients between sensory overall preferences (Table 3) and the pH, total acidity, amino acidity, soluble solid and reducing sugars of OFM were calculated and were 0.280, 0.180, 0.112, 0.000, 0.000, respectively (Fig. 1). Each of these chemical properties showed weak-correlation (r < 0.3) or no correlation (r ¼ 0) with sensory overall preference. This indicated that the sensory overall preference of turbid rice wine almost received no sensory recognizable influence by these slight differences in each of the above properties. This also indicated that the sensory overall preference of turbid rice wine mashes represented the composite influences of all the physicochemical properties.

3.1.3. Ethyl acetate Esters in alcoholic beverages contribute several fruitlike and floral aromatics (Erten, 2002; Yukihiko, Masato, Makoto, Mitsuo, & Mikio, 2000). Esters are mainly produced during ethanol fermentation by yeast, in the reaction between alcohols and acetyl-CoA catalyzed by acetyl-transferases (Smogrovicova & Domeny, 1999; Zohre & Erten, 2002). Since ethanol is the main alcohol among all the alcohols produced during fermentation, ethyl acetate formed from ethanol and acetyl-CoA is the predominant ester synthesized by yeast, which is approximately one third of all esters produced in alcoholic beverages (Erten, 2002), and is about 10e20 times more than isoamyl acetate in Sake, and has a fruity flavor (Tadao,

Table 2 (continued ) Reducing sugar (mg/mL) 1.48 1.83 1.54 1.48 1.50 1.57 1.55 1.45 1.54 1.71 1.32 1.41 1.38 1.33 1.45 1.93 1.91 1.93 1.87 2.07 1.94 1.39

                     

0.02ab 0.05cd 0.03a 0.03ab 0.02a 0.03 0.03a 0.02ab 0.02a 0.04c 0.03b 0.05ab 0.03ab 0.04b 0.03 0.05cd 0.04cd 0.04cd 0.03cd 0.05cd 0.04 0.02ab

Ethyl acetate (mg/L) 76.40 70.30 57.04 61.19 68.87 66.79 77.73 87.30 76.40 54.94 75.95 81.33 71.76 83.23 76.60 68.61 74.72 73.79 73.21 61.37 73.85 84.49

                     

3.99b 4.52b 3.50c 2.58c 3.20b 3.56 5.62b 5.25a 3.58b 3.30c 3.81b 4.52ab 3.54b 4.20a 4.42 3.42b 3.30b 3.20b 4.20b 2.89c 3.40 5.95a

n-propanol (mg/L) 52.35 55.08 51.71 42.22 50.31 50.36 59.23 65.01 45.78 43.08 60.50 75.07 60.92 50.55 57.90 53.30 72.71 65.49 55.73 42.06 57.87 60.88

                     

2.35b 3.12b 1.26b 4.34a 2.56b 2.73 4.12bc 3.12c 3.99ab 4.56ab 3.88bc 3.54c 2.56bc 2.02ab 3.59 2.13b 3.24c 3.02c 2.24b 2.04a 2.53 4.56bc

Iso-butanol (mg/L) 150.64 141.66 144.07 135.18 133.19 141.00 138.08 133.43 131.80 140.93 142.16 124.75 149.84 152.71 138.94 156.02 154.38 151.05 152.38 143.01 151.40 136.71

                     

4.17c 3.20b 3.20bc 2.00ab 2.42ab 3.00 2.51b 2.50ab 2.60a 2.88b 2.99b 3.56a 2.45bc 3.56c 2.73 3.50c 2.86c 2.85c 3.51c 3.30b 3.20 1.56ab

Iso-amyl alcohol (mg/L)

TFAb (mg/L)

                     

411.52 412.53 387.99 356.34 360.54 385.94 391.83 394.28 397.97 378.07 413.44 405.11 439.51 430.81 409.01 413.85 435.74 444.81 436.60 387.16 423.63 429.49

208.53 215.79 192.21 178.93 177.04 194.58 194.52 195.84 220.39 194.06 210.78 205.29 228.75 227.55 212.17 204.53 208.65 228.28 228.49 202.08 214.37 231.90

4.23b 4.18bc 5.60ab 4.40a 5.23a 4.73 6.59ab 5.66ab 8.72c 7.02ab 6.00bc 6.60b 8.70c 6.50c 6.92 4.00b 3.58b 5.00c 7.20c 6.00b 5.16 6.52c

TFA (g/L p.a.)                      

1.96c 2.24c 3.00b 4.08a 2.75a 2.81 3.00b 2.85b 2.46b 3.42ab 3.54bc 2.55b 2.48de 3.49d 3.00 2.65c 3.46de 4.04e 3.56de 3.42b 3.43 3.21d

2.53 2.52 2.37 2.18 2.22 2.37 2.48 2.41 2.44 2.32 2.57 2.47 2.73 2.66 2.53 2.59 2.82 2.91 2.75 2.50 2.72 2.71

Q.J. Wang et al. / LWT - Food Science and Technology 56 (2014) 145e152 Table 3 Scores of four sensory evaluated items of turbid rice wine. Rice cultivar

Color

Dasan2 Deulaechan Namchan Hanaleum Keunseom Sub-average Gaopum Cheong-a Hanseol Huaseong Ju-an Miguang CHHjinmi Jo-un Sub-average Baekjinju Baekjinju1 Haepyeongchal Hangangchal Huaseonchal Sub-average Chucheong

4.3 4.2 4.3 4.4 4.5 4.3 4.1 4.1 4.3 4.5 4.0 4.2 4.1 4.2 4.2 4.3 4.3 4.2 4.3 4.1 4.2 4.2

                     

Aroma 0.05aba 0.06ab 0.06ab 0.08a 0.05a 0.06 0.06b 0.05b 0.03ab 0.07a 0.06b 0.05b 0.12b 0.08b 0.06 0.12ab 0.08ab 0.06b 0.09ab 0.10b 0.09 0.06b

3.1 3.2 3.1 3.5 3.6 3.3 3.1 3.2 3.5 3.5 3.0 3.2 3.2 3.2 3.2 3.3 3.2 3.2 3.4 3.1 3.2 3.0

                     

Taste

0.06b 0.09b 0.10b 0.03a 0.05a 0.07 0.09b 0.09b 0.05a 0.07a 0.09b 0.08b 0.06b 0.07b 0.07 0.06ab 0.08b 0.09b 0.05a 0.10b 0.08 0.08b

3.5 2.5 3.3 4.3 4.3 3.6 3.4 3.2 3.9 3.9 2.5 3.9 3.2 4.2 3.5 3.1 3.2 3.0 3.3 3.1 3.1 3.5

                     

Overall preference 0.08b 0.15d 0.10b 0.05a 0.09a 0.09 0.15b 0.12bc 0.10a 0.06a 0.06d 0.10a 0.12bc 0.15a 0.12 0.12c 0.20bc 0.12c 0.14bc 0.10c 0.14 0.20b

3.6 2.8 3.2 4.1 4.2 3.6 3.4 3.3 3.9 3.9 2.4 3.8 3.3 3.9 3.5 3.5 3.1 3.0 3.3 3.1 3.2 3.6

                     

0.10b 0.05d 0.20c 0.06a 0.08a 0.10 0.15bc 0.12bc 0.07a 0.07a 0.10d 0.06ab 0.14bc 0.02a 0.10 0.10b 0.20c 0.14c 0.15bc 0.16c 0.15 0.13b

a Means  S (n ¼ 10), sensory score is represented 5-point hedonic scale and the scores not sharing the same letter within one column are significant different (p < 0.05).

Takayuki, Naotaka, Nobutsugu, & Sadao, 1999). Therefore the content of ethyl acetate in OFM was detected, and higher ethyl acetate producing rice cultivar was preferable. The contents of ethyl acetate in OFM varied from 57.04  3.30 mg/L to 87.30  5.25 mg/L (Table 2). Significant differences (p < 0.05) were observed between some different individual rice cultivars. However, no significant differences were observed among the rice groups of HY-rice, HEQ-rice and glutinous rice (p > 0.05). The coefficient between sensory overall preferences and ethyl acetate contents was 0.06 (Fig. 1), showing nearly no correlativity. This indicated that the variation of the ethyl acetate within 57.04 mg/L to 87.30 mg/L in OFM has no significant difference in the influence to the taste of turbid rice wine. This again indicated that the sensory overall preference of turbid rice wine represents for all the influences of overall physicochemical properties, rather than determined by a single

0.6

Coefficient

0.3

149

property. However, since esters are a main group of aromatic components, and usually has a low limit in alcoholic beverages, for example, in China the minimum total esters (calculated by ethyl acetate) is 150 mg/L for Shaoxing rice wine with the alcohol content around 16 mg/100 mL and 650 mg/L for rice flavor Chinese spirits with the alcohol content of 41e65 mg/100 mL, by the current Chinese Standards for related beverages, accordingly it is recommended that for turbid rice wine, higher content of ethyl acetate is preferable. 3.1.4. Fusel alcohols The fusel alcohols contents of n-propanol, iso-butanol and isoamyl alcohols of the fermented undiluted turbid rice wine mashes were measured by GC (Table 2). The total fusel alcohols contents ranged from 356.34 mg/L to 444.81 mg/L, equivalently, from 2.18 to 2.91 g/L of pure alcohol. The average total fusel alcohols yield of glutinous rice was 2.72 g/L of pure alcohol, higher than those of HEQ-rice (2.53 g/L of pure alcohol), and HY-rice (2.37 g/L of pure alcohol). However no significant differences in fusel alcohols production were observed among the 3 rice groups. Similar to the most of other properties, the significant differences in fusel alcohols production were also observed between some individual rice cultivars (p < 0.05). There are more than 100 compounds reported in fusel oils (Hsieh, Huang, Lai, Ho, & Ko, 2010), however, generally fusel oils in alcoholic beverages mainly mean fusel alcohols, including npropanol, 1-butanol, 2-butanol, iso-butanol, iso-amyl alcohol and 1-hexanol (Lachenmeier, Haupt, & Schulz, 2008; Michiko, Hiroshi, & Suteaki, 2008), and especially, n-propanol, iso-butanol and isoamyl alcohol, which constitute more than 80% of total fusel oils (Pawel & Tadeusz, 2010). Higher alcohols were considered as aromatic compounds, especially of iso-amyl alcohol, which was reported to have the flavor of banana sweetish smell (Jackson, 2000, pp. 101e106; Lee, Lee, Choi, et al., 1996), however excessive higher alcohols were considered as the main responsive factor for alcoholic liver disease and alcohol hangover (Lee, Lee, Choi, et al., 1996). In some countries such as China and Mexico, the maximum limits for higher alcohols in beverages have been established. For example, in China the maximum higher alcohols (by iso-butanol and iso-amyl alcohol) in distilled spirits and liqueur must be less than 3.33 g/L of pure alcohol by the current related Chinese Standards. In Mexico, the range of higher alcohols is from 0.2 g/L to 4 g/L of pure alcohol in Tequila and some other Mexican spirits (Lachenmeier et al., 2008). The correlation coefficients between the sensory preference and the fusel alcohols contents were calculated together with other chemical properties (Fig. 1). The coefficient was 0.473, showing the highest correlation among all the chemical properties of OFM. Furthermore, higher alcohols are potentially harmful substances (Lachenmeier et al., 2008; Lee, Lee, Choi, et al., 1996), and therefore lower fusel alcohols producing rice cultivars are preferred if similar sensory properties are available.

0

3.2. Sensory evaluation of turbid rice wine

-0.3

-0.6 pH

TA

AA

RS

SS

EA

FA

Chemical Properties Fig. 1. Correlation coefficients between overall sensory preferences and chemical properties of OFM. pH: pH value; TA: total acidity; AA: amino acidity, RS: reducing sugar; SS: soluble solid; EA: ethyl acetate; FA: fusel alcohols.

For turbid rice wine, the sensory properties such as color, flavor and taste were very important. Sensory characteristics of turbid rice wine were the comprehensive response to all the physiochemical properties. The results of sensory evaluation are listed in Table 3. Seven rice cultivars including 3 HY-rice cultivars and 4 HEQ-rice cultivars, were scored higher than average score (3.43  0.12) and equal or higher than the control rice of Chucheong (3.6  0.13). For color, all the turbid rice wine samples possessed a preferable white milky color, and the corresponding scores varied from 4.0  0.06 to 4.5  0.07, with a low coefficient of variation (CV) of

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2.20%. As for aroma, the scores varied from 3.0  0.09 to 3.6  0.05, and the CV was 3.31%. However, the CV of taste was 26.13%, and the CV of overall preference was 20.45%. This indicated that the variations of the overall preference were mainly contributed by the property of taste (Fig. 2). This was due to that the color and aroma properties were quite similar. The correlation analysis found that the correlation coefficients of color/overall preference, aroma/overall preference, and taste/overall preference were 0.68, 0.66 and 0.96, respectively, illustrating that taste of turbid rice wine played a more important role in overall preference than the color and aroma did. Analysis of variance found that similar to the most properties of OFM, the sensory properties showed no significant differences among the 3 rice groups, however, significant differences were observed between some individual rice cultivars. Seldom reports were found in sensory comparison of turbid rice wine from glutinous rice and non-glutinous rice. Park et al. (2005) reported that glutinous rice showed higher preference in color, taste and overall acceptability for a local turbid rice wine (one sort of makgeolli). However in that study (Park et al., 2005) only one kind of glutinous rice and one kind of non-glutinous rice were tested and the cultivars of the rice were not mentioned. In another study (Lee, Lee, Park, et al., 1996), fermentation characteristics of glutinous rice, non-glutinous rice, barley and wheat flour were investigated, but the sensory test was not conducted, meanwhile, the number and the cultivars of rice used were not mentioned either. In the current study it was found that most fermentation properties of turbid rice wine, such as pH, total acidity, amino acidity, soluble solid, fusel alcohols and sensory properties showed no significant differences between glutinous rice group and non-glutinous rice group, but showed significant differences between individual rice cultivars. This indicates that when conducting fermentation research with rice, it is necessary to report the rice cultivar.

turbid rice wine made from different rice cultivars had different suspension stability. The suspension stability began to show difference in test tubes after 10 min being kept untouched, however in order to obtain a clear picture to illustrate the differences, a photo was taken at the 30th minute. Then the sedimentary distances of turbid rice wine lees were measured (Table 4) according to Fig. 3. The suspension state of the mashes made from Hanseol showed no noticeable changes after 10 min, and flocculent precipitation of the suspending lees was observed after about 15 min, and the sedimentary distance at 30th minute was 0.6 cm. Similar flocculent precipitations were observed with other mashes, but the appearing time was all earlier than Hanseol. From Table 4 it can be observed that Hanseol, Dasan2, Huaseong, Hanaleum, Keunseom, Jo-un, Baekjinju, Hangangchal had higher suspension stability, especially, Hanseol and Dasan2. Correlation coefficient between lees contents and sedimentary distances was 0.30, furthermore, the ratios of the sedimentary distance to the lees content varied from 0.7 to 9.3, which meant that the variation of these 2 parameters was not simply proportional. These indicated that the suspension stability was only weakly relative to the lees content, and there should be other factors that account for the lees suspension stability of turbid rice wine. So far no reports were found on the study of the suspension stability with rice cultivars. So, Lee, Han, & Noh (1999) and Han, Lee, Noh, and Lee (1997) reported that modified starter was better than traditional starter and much better than rice-grain starter, and A. oryzae-starter was much better than R. japonicus-starter in turbid rice wine suspension stability. The reasons for the differences in suspension stability of turbid rice wine made from different rice cultivars need to be investigated further.

3.4. Screening the rice cultivars 3.3. Suspension stability of turbid rice wine One distinguished characteristic of turbid rice wine was that it contained lees. The suspension stability of turbid rice wine would impact not only on the color of turbid rice wine but also on the body taste. The suspension stability in the current study referred to the stability of the suspending lees (or solids) of turbid rice wine, and was estimated by measuring the sedimentary distance of turbid rice wine lees after being kept still for 10e30 min. It was found that

Fig. 2. Variation coefficients (CV) of the scores of four sensory properties, indicating that under the experimental conditions, taste of turbid rice wine played a dominate role in overall sensory preference (O.P.), and the variation coefficient of overall sensory preference was mainly resulted from the taste variation of turbid rice wine.

Based on the above results, the parameters of the alcohol content, ethyl acetate and fusel alcohols in OFM, and the sensory overall preference and suspension stability of turbid rice wine were chosen as the criteria for screening the proper rice cultivars for brewing high quality turbid rice wine. The results are showed in

Table 4 Suspension properties of turbid rice wine. Rice cultivars

Sedimentary distance (cm) Lees contentb (g/100 mL) Ratioc

Dasan2 Deulaechan Namchan Hanaleum Keunseom Gaopum Cheong-a Hanseol Huaseong Ju-an Miguang CHHjinmi Jo-un Baekjinju Baekjinju1 Haepyeongchal Hangangchal Huaseonchal Chucheong

1.7 4.1 3.8 2.9 3.0 5.6 5.6 0.6 2.6 5.3 5.3 4.7 2.9 3.4 5.6 5.2 3.3 4.9 4.9

                  

0.11ba 0.18f 0.20e 0.13c 0.12c 0.22i 0.21i 0.09a 0.12b 0.16h 0.08h 0.18g 0.11c 0.14d 0.19i 0.16gh 0.13d 0.12g 0.15g

0.93 0.81 0.69 0.90 0.81 0.76 0.60 0.83 0.75 0.78 0.76 0.74 0.78 0.89 0.86 0.88 0.82 0.85 0.79

                  

0.03f 0.04cd 0.05b 0.03f 0.03cd 0.03c 0.04a 0.04d 0.05c 0.02c 0.02c 0.03c 0.02c 0.01f 0.01e 0.02f 0.02cd 0.02e 0.02cd

1.8 5.1 5.5 3.2 3.7 7.4 9.3 0.7 3.5 6.8 7.0 6.4 3.7 3.8 6.5 5.9 4.0 5.8 6.2

a Means  S (n ¼ 3), and values not sharing the same letter within one column are significant different according to ANOVA (p < 0.05). b Correlation coefficient (r) between sedimentary distance and lees content was 0.30. c Ratio of the sedimentary distances (cm) to lees contents.

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151

Fig. 3. Physical stability of the solids in turbid rice wine. 1: Dasan2; 2: Deulaechan; 3: Namchan; 4: Hanaleum; 5: Keunseom; 6: Hucheong; 7: Gaopum; 8: Cheong-a; 9: Hanseol; 10: Huaseong; 11: Ju-an; 12: Miguang; 13: CHHjinmi; 14: Jo-un; 15: Baekjinju; 16: Baekjinju1; 17: Haepyeongchal; 18: Hangangchal; 19: Huaseonchal; 20: Daelybbyeo. A: State of turbid rice wine at beginning. B: State of turbid rice wine after 30 min.

Table 5 Criteriona for screening rice cultivars for high quality turbid rice wine.

Dasan2 Deulaechan Namchan Hanaleum Keunseom Sub-average Chucheong Gaopum Cheong-a Hanseol Huaseong Ju-an Miguang CHHjinmi Jo-un Sub-average Baekjinju Baekjinju1 Haepyeongchal Hangangchal Huaseonchal Sub-average Total-average a

Alcohol content

Overall sensory preference

Suspension stability

Ethyl acetate

þþ þþ þþ þþ þþ / þ þ þþ þþ þþ þ þþ þ þþ / þ

þ

þþ

þ þ

þþ þþ / þ

þ þ /

þþ þþ

þþ þ

þ þþ / þ

þ /

/ /

/ /

þ / /

þ / þþ þ þþ þ þ þþ þ þþ / þ þ þ þ / /

Fusel alcohols

þ þþ þþ / þ þ þ þ þ

/

þ / /

Number of quality symbol “þ” 6 3 3 7 8 5.4 5 3 5 8 6 3 6 2 7 5.6 3 1 1 1 1 2 4.6

Criterion: for sedimentary distance, þþ:<2.0 cm; þ: 2.0e3.0 cm; for others properties, þþ: values with letter “a”; þ: values with letter “b”.

Table 5. The average numbers of the quality symbol “þ” were 5.4, 5.6 and 2.0 for HY-rice group, HEQ-rice group and glutinous rice group, respectively. Seven rice cultivars were screened out for producing high quality turbid rice wine as they had the number equal to or more than 6 quality symbol “þ”, higher than that of the control rice (Chucheong, 5 quality symbols) and higher than the average numbers of HY-rice group and HEQ rice group. None of the glutinous rice was screened out for turbid rice wine brewing. Each of these 7 rice cultivars has some advantages, i.e., Hanaleum, Keunseom, Hanseol, Huaseong and Jo-un were with the highest overall sensory preference; Hanseol and Dasan2 were with the

highest suspension stability; Jo-un produced highest ethyl acetate; while Hanaleum and Keunseom produced least fusel alcohols. 4. Conclusions By comparing the fermentation characteristics under same experimental conditions, significant differences (p < 0.05) were observed between some individual rice cultivars on the chemical properties such as pH value, total acidity, amino acidity and reducing sugar, alcohol yield, fusel alcohols and ethyl acetate, sensory properties and suspension stability. Out of 18 rice cultivars,

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seven rice cultivars including three HY-rice and four HEQ-rice were selected as suitable rice for brewing high quality turbid rice wine with the advantages of having lower fusel alcohols content, higher ethyl acetate content, higher suspension stability or high scores in overall sensory preference. These results are useful for the wine industry to produce turbid rice wine with high quality. Acknowledgments This study was supported by “ Cooperative Research Program for Agriculture Science & Technology Development (Project No PJ008600) and 2011 Postdoctoral Fellowship Program of National Academy of Agricultural Science (Project No. PJ007396)”, Rural Development Administration, Republic of Korea. The authors are also grateful to the Guangdong Province Government (China) for support through the program of “Leading Talent of Guangdong Province (Da-Wen Sun)”. References Bautista-Ortín, A. B., Jiménez-Pascual, E., Busse-Valverde, N., López-Roca, J. M., RosGarcía, J. M., & Gómez-Plaza, E. (Aug 2013). Effect of wine maceration enzymes on the extraction of grape seed proanthocyanidins. Food and Bioprocess Technology, 6(8), 2207e2212. http://dx.doi.org/10.1007/s11947-011-0768-3. Belisario-Sánchez, Y. Y., Taboada-Rodríguez, A., Marín-Iniesta, F., Iguaz-Gainza, A., & López-Gómez, A. (Aug 2012). Aroma recovery in wine dealcoholization by SCC distillation. Food and Bioprocess Technology, 5(6), 2529e2539. http://dx.doi.org/ 10.1007/s11947-011-0574-y. Erten, H. (2002). Relations between elevated temperatures and fermentation behaviours of Kloeckera apiculata and Saccharomyces cerevisiae associated with wine making in mixed cultures. World Journal of Microbiology & Biotechnology, 18, 373e378. Gauntner, J. (2013). Types of sake, more types 3. http://sake-world.com/html/moretypes-3.html. Han, E. H., Lee, T. S., Noh, B. S., & Lee, D. S. (1997). Volatile flavor components in mash of makgeolli prepared by using different nuruks. Korean Journal of Food Science and Technology, 29, 563e570. Hsieh, C. W., Huang, Y. H., Lai, C. H., Ho, W. J., & Ko, W. C. (2010). Develop a novel method for removing fusel alcohols from rice spirits using nanofiltration. Journal of Food Science, 75, 25e29. Ivanova, V., Stefova, M., Vojnoski, B., Stafilov, T., Bíró, I., Bufa, A., et al. (Jun 2013). Volatile composition of Macedonian and Hungarian wines assessed by GC/MS. Food and Bioprocess Technology, 6(6), 1609e1617. http://dx.doi.org/10.1007/ s11947-011-0760-y. Ivanova, V., Vojnoski, B., & Stefova, M. (Nov 2011). Effect of the winemaking practices and aging on phenolic content of Smederevka and Chardonnay wines. Food and Bioprocess Technology, 4(8), 1512e1518. http://dx.doi.org/10.1007/ s11947-011-0566-y. Jackson, R. S. (2000). Wine science, practice, perception (2nd ed.). San Diego: Academic Press. Jiang, Y. L. (2009). Discussion on the origin of the word “Zhuojiu”. Read and Write Periodical, 6, 64e65. Kim, S. M., & Cho, W. K. (2006). Effect of makgeolli lees on the serum glucose levels in strptozotocin induced diabetic rats. Korean Journal of Food Culture, 21, 638e 643. Kim, C. J., Choi, W. Y., & Oh, M. J. (1972). Studies on the utilization of sweet potatoes for makgeolli brewing. Journal of Korean Agricultural & Chemical Society, 15, 213e219. Kim, T. Y., Jeong, S. T., & Choi, H. S. (2011). Review of Korean traditional wine. Interrobang, 3. Suwon (Korea): Rural Development Administration Press. Kim, M. H., Kim, W. H., & Bae, S. J. (2001). The effect of turbid rice wine on serum lipid concentration in male rats. Journal of Natural Science of Silla University, 9, 73e84.

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