Study on Production Process of Roselle Rice Wine

Fangjun LIAO Sumei HUANG

Abstract ［Objectives］This study was conducted to more systematically explore the traditional brewing process of roselle rice wine.

［Methods］ With local high-quality white glutinous rice and sun-dried roselle as raw materials for brewing rice wine, on the premise of extensive research on traditional rice wine technology in China, the addition amount of roselle extract, the addition amount of distiller’s yeast, the variation range of after-fermentation temperature and the starting time of after-fermentation were investigated.

［Results］ The best traditional processing and brewing parameters were the ratio of glutinous rice and roselle extract (mass to volume ratio) at about 1∶1.55, the addition amount of distiller’s yeast of 0.55%, and the fermentation temperature at 30 ℃, and the starting time at 72 h. The sensory quality of the high-quality roselle rice wine that was produced under the best brewing conditions was about (87.7±2.45) points.

［Conclusions］ A number of hygiene inspection technical indexes in the product all met the current relevant national safety standards in China, providing another technical research direction for the development of a variety of new green healthy beverage projects.

Key words Roselle; Sticky rice; Rice wine; Fermentation technology

Received: May 10, 2022  Accepted: July 12, 2022

Supported by Huizhou Science and Technology Bureau Project (2020SD0409037).

Fangjun LIAO (1975-), female, P. R. China, senior engineer, devoted to research about landscape ecology.

*Corresponding author.

Roselle (Hibiscus sabdariffa Linn.), also known as Luoshenhua, Shanqie and Luokehong, is an annual herb of Hibiscus in Malvaceae［1］. It is native to the tropics from the Americas to the Northeast Pacific hemisphere. Its fleshy calyxes are often slightly purple-red, rich in amino acids, and have significant anti-oxidation, anti-cancer, antihypertensive, diuretic and sedative effects［2-5］. Rice wine is often called sweet wine. It is characterized by primitive and simple brewing process steps, mellow, sweet and rich taste, relatively low alcohol content, and extremely rich free amino acids, glucose, and vitamins. It has special medicinal effects such as strengthening the stomach, improving the gastrointestinal tract of the elderly, activating qi and soothing the nerves and nourishing the blood, and is deeply loved by the majority of people［6］.

The main purpose of this research was to optimize the brewing process and production process and formula of Chinese traditional brewed roselle rice wine and traditional brewed rice wine, and to develop a roselle rice wine that has the unique characteristic flavor of traditional Chinese rice wine, as well as the same health-care and nourishing functions as modern rice wine.

Materials and Methods

Materials and instrument

Materials: Dried roselle calyxes were planted by the Plant Tissue Culture Engineering Technology Research Center of Huizhou Engineering Vocational College, and dried after picking; glutinous rice was purchased from Jingdong Supermarket; and Saccharomyces cerevisiae was produced by Angel Yeast Co., Ltd.

Instruments: Ohaus PX2202ZH electronic balance, Ohaus Instruments (Changzhou) Co., Ltd.; Ohaus PX124ZH_E analytical balance, Ohaus Instruments (Changzhou) Co., Ltd.; PHS-3C pH meter, Shanghai Youke Instruments Co., Ltd; JYL-C022 food processer, Joyoung Co., Ltd.; Dongnan GXZ-500D biochemical incubator, Ningbo Dongnan Instrument Co., Ltd.; WYT-4 handheld saccharimeter, Shanghai Precision Instrument Co., Ltd.; C21-WK2102 induction cooker, Changzhou Midea, Jiangsu Province; HH-6 constant temperature water bath, Changzhou Guohua, Jiangsu Province; Haier P20-W pure water machine, Changzhou Suizhiyuan; Haier BCD-215KAGA low temperature food rapid preservation and processing equipment series; Haier electric blast drying oven DHG-9145A, Shanghai Yiheng Technology Instrument Co., Ltd.

Experimental methods

Technical process

Operation points

Selection of raw materials

The calyxes of the roselle flowers with fresh and bright color and no trace of corruption and mildew were selected. The raw materials of the finished glutinous rice should have crystal clear, delicate and white color, and round and plump particles; the number of broken rice hearts and the number of broken rice with broken heart should be small; and no other impurities were mixed in, and the grains were free of mildew and rot.

Pretreatment of raw materials

The roselle materials were cleaned, sterilized, sliced, dehydrated, and crushed, and the powder was put into a 60-mesh sieve. The obtained powder was mixed and prepared according to the material-to-liquid ratio (mass to volume ratio) of 1∶50, and the mixture was filtered under the temperature environment of about 50 ℃, and then the filtrate was concentrated to about 1 h. After filtering, dehydrating and concentrating, the concentrate was directly stored into a refrigerator under low temperature or freezer and other fresh-keeping equipment for later use. The glutinous rice was repeatedly soaked in water, and mixed with ordinary japonica rice water at a ratio of 1∶2. The rice was soaked in water at room temperature for about 24 h, so that the surface of the rice grains had absorbed enough water, and rice could be rubbed and kneaded with the palms of hands vigorously into a flocculent powder, without showing the hard core of rice grains.

Steaming of rice, mixing with distiller’s yeast and fermentation

The brewing glutinous rice that had been subjected to activation soaking treatment and activation fermentation primary screening treatment was dried and cooked for 35-40 min under normal pressure and high temperature environment conditions. After steaming, the rice was taken out for drying, followed by heating. The dried brewing glutinous rice was taken out to continue drying at low temperature, and then cooled down to a temperature of about 30 ℃. The cooled rice was added with a little cornstarch and evenly mixed with dried glutinous distiller’s yeast after activation and fermentation treatment. The material was stirred thoroughly until it was evenly mixed. In order to ensure that the fermentation can be more evenly accelerated, we generally perform artificial nesting to facilitate fermentation, and then seal the material and put it in a constant temperature incubator at 30 ℃ for fermentation in the environment for at least 48 h.

Addition to a tank for after-fermentation

After the mixed glutinous rice was fermented in a distiller’s yeast box for 48 h, the mixed glutinous rice solution and roselle extract were slowly added to a fermentation tank solution according to the dilution ratio of a certain concentration, stirred until uniform, and placed in an incubator at 30 ℃ for a total of 64 h of airtight fermentation.

Sterilization and filling

The fermented roselle rice wine was subjected to secondary filtration with three layers of fine gauze, and the filtrate was sterilized and then packed in bottles. The bottles were sealed with fine corks and placed in a high-temperature autoclave for sterilization at 95 ℃ for about 5 min to obtain the finished roselle wine, which was then stored in low-temperature preservation equipment.

Single-factor experiments

Experimental methods

In the process of fermentation production of roselle rice wine and its industrial test research, the fermentation test was based on the content for 200 g of fresh glutinous rice, and with the evaluation value of sensory analysis as the key index, the four key factors, the amount of roselle added, the amount of distiller’s yeast added, the starting time of after-fermentation and the temperature control of fermentation, and their potential effects on the fermentation quality of roselle rice wine, were studied. The setting gradients of the four control factors were as follows: the ratio of roselle extract added (50%, 100%, 150%, 200%, 250%), the ratio of distiller’s yeast added (0.3%, 0.4%, 0.5%, 0.6%, 0.7%), the starting temperature of fermentation (20, 25, 30, 35, 40 ℃) and the starting time of after-fermentation (24, 36, 48, 60, 72 h). The control variable method was adopted to carry out three single-parameter fermentation experiments, and the fixed parameters were calculated as: 150% of roselle juice extract added, 0.55% of distiller’s yeast added, fermentation test temperature of 30 ℃, and the starting time of after-fermentation at 48 h.

Sensory evaluation method

A random group of 20 people with the same ratio of male and female were selected to conduct on-site inspections, and experts and working group members were carefully divided into groups on site to carry out operation skill training in accordance with the national product classification recommendation and registration standards for imported wine and the appendix of GB/T No. 16291.1-2012 Sensory Analysis―General Guidance for the Selection, Training and Monitoring of Assessors. Each expert evaluation and working group members carefully divided into groups to carry out operation skills and training. The samples were randomly sampled and numbered, and the sensory 100-point system was adopted. The assessors should independently, objectively and accurately evaluate the newly prepared rice wine from product smell, taste, color characteristics and sensory organization state according to the needs and conditions. These four major aspects were analyzed and evaluated one by one, and the sensory quality characteristics of rice wine were given the evaluation scores one by one, and the arithmetic mean was taken for each result after calculation. The specific evaluation criteria for sensory characteristics of rice wine are shown in Table 1.

Orthogonal test

After comprehensive analysis of the results of the four-level single factor analysis on the amount of roselle added, the amount of distiller’s yeast added, the starting time for fermentation time and the starting temperature for fermentation, the above four comprehensive indexes were selected and determined at a relatively good level, and an L9(34) orthogonal comparative research test was carried out. According to the evaluation criteria in line with the evaluation criteria for the best sensory performance of roselle rice wine proposed in Table 1, the four optimal brewing process parameters that are more suitable for making roselle rice wine were screened out.

Determination of physical and chemical indexes and data analysis

The alcohol distillation turbidity method was adopted for the determination of ethanol content, referring to GB/method T10345-2007 of the State Bureau of Quality and Technical Supervision; a handheld soluble sugar meter was used to determine total sugar; the determination of total acids adopted an acidimeter; and non-sugar solids were

Results and Analysis

Single factor experiments

Amount of roselle extract added and possible effects on the quality of rice wine

The research results of the amount of roselle extract added and its direct effects on the quality of rice wine are shown in Table 3. It could be seen that with the gradual increase of the amount of roselle extract added, the sensory score showed an obvious change trend of first increasing and then decreasing. When the amount of roselle extract added was small, the appearance of the rice wine itself was lighter, and the aroma characteristics and unique taste were relatively insignificant, while the taste characteristics of rice wine were more prominent and obvious. And with the gradual increase in the amount of roselle extract added, the surface color of the roselle rice wine itself was gradually deepened, and the unique flavor characteristics of the roselle wine were also be more obvious. With the proportion of the extract of roselle further increasing, the original taste of rice wine was obviously too sour, and the taste of roselle itself completely covered the original taste of traditional rice wine, so the quality of rice wine dropped sharply. Therefore, when the addition ratio of roselle extract was about 150%, the flavor of the roselle itself could be coordinated with the traditional flavor of the traditional rice wine itself, and the sensory quality score of the rice wine was the highest at this time.

Effect of the addition of distiller’s yeast on the quality of rice wine

The difference in the proportion of distiller’s yeast added can more directly and effectively affect the entire time of the fermentation process of the entire wine, the speed of the cycle rhythm and the length of the cycle, which in turn affects the overall taste, flavor, and fermentation quality of the wine. When the amount of added distiller’s yeast is relatively large, the time period of the entire fermentation cycle will be slightly shorter, but if the fermentation process is too vigorous, the amount of phosphate produced by the acid production will be larger, which will affect the overall mouthfeel quality and flavor of the fermented wine. When the amount of added distiller’s yeast is relatively smaller, it is very unfavorable to continue the fermentation after complete saccharification, which will obviously prolong the time of sugar fermentation, and the flavor substances will gradually produce. And insufficient sugar fermentation time will result in the overall taste of the food becoming obviously weaker. It can be observed from Table 4 that when the addition amount was between 0.3% and 0.5%, the sensory flavor score of roselle rice wine product itself gradually increased with the amount of added distiller’s yeast increasing, but when the added amount exceeded 0.5%, the acidity and astringency of the roselle rice wine gradually increased, and the product quality gradually declined.

After-fermentation storage time and other effects on the quality of roselle rice wine

The starting time of after-fermentation had a direct effect on the sensory quality of roselle rice wine, as shown in Table 5. From the analysis on the results, it could be seen that when the after-fermentation time was between 24 and 48 h, the sensory quality of roselle rice wine had formed a relatively obvious rising change and trend. At first, when the after-fermentation time started, the wine taste obviously became too rough and too light, and the wine taste was obviously not strong and mellow enough. With the further extension of the fermentation time, the sensory taste of the finished rice wine product gradually became better. In addition, with the relatively continuous extension of the fermentation or storage time period of rice wine products, due to the relatively high relative concentration of raw material alcohol content in the brewing of rice wine products, the relative consumption of sugar substances and energy also changed greatly, resulting in the sour taste of such products, and the palatability of the wine became poorer, which was more likely to lead to a decrease in the sensory score of the wine.

Possible effects of changes in fermentation time and temperature after fermentation on the flavor and quality of roselle rice wine

It can be seen from Table 6 that the sensory evaluation value of rice wine with after-fermentation temperature of 30 ℃ was the highest. When adopting low-temperature fermentation, the taste of the wine was too light and the wine body was not mellow enough. As the temperature increased, the taste of rice wine gradually became better. However, as the fermentation temperature increased, the alcohol in the rice wine was too high, and the consumption of sugar was large, resulting in poor palatability of the wine, which thereby reduced the sensory score.

Orthogonal test

After a comprehensive test of the above four factors, various main practical effects of A (addition amount of roselle extract), B (addition amount of distiller’s yeast), C (after-fermentation time) and D (fermentation temperature) on the quality of roselle rice wine during fermentation were considered and determined. However, because the study had not yet completely and further determined other actual effects of the main factors of the above-mentioned factors on the quality of rice wine, in order to further discuss and optimize the production process of rice wine, an identification test method was mainly designed by the orthogonal test method of L9(34), and the orthogonal test was also carried out on the four important parameters affecting the process. The identification and evaluation results of the test are shown in Table 7.

Optimal levelA2B2C3D2

Optimal combinationA2B2C3D2

It can be seen from Table 7 that the relationship between the range R values of the four factors was D>A>C>B, that is, the degrees of effects on the production process of roselle rice wine ranked as D>A>C>B, that is, fermentation temperature> addition amount of roselle extract > fermentation time > addition amount of distiller’s yeast. Among them, the fermentation temperature had the greatest influence on the quality of roselle rice wine, followed by the addition amount of roselle extract and fermentation time, and the fermentation temperature had less effect, which is slightly different from the research conclusion of Guo et al.［14］, which might be related to properties of roselle. It is worth noting that in this study, although the effect of the addition amount of distiller’s yeast ranked last, the previous single-factor experiments showed that adding an appropriate amount of distiller’s yeast could promote fermentation, so that the aroma and taste of rice wine would not be weak, so the amount of distiller’s yeast added was still an important part in the production process of roselle wine, and RB=4.512 also confirmed this. Based on the results of the optimization of the orthogonal test, it could be determined that the optimal production process combination of roselle rice wine was A2B2C3D2, that is, the optimal process was the fermentation temperature at 30 ℃, the addition amount of roselle extract of 150%, the after-fermentation time of 48 h, and the addition amount of distiller’s yeast of 0.5%.

Verification test

According to the optimal fermentation and brewing technical process parameters optimized in the above-mentioned orthogonal fermentation test, the fermentation temperature at 30 ℃, the addition amount of roselle extract of 150%, the after-fermentation time of 48 h, and the addition amount of distiller’s yeast of 0.5%, a total of 3 groups of orthogonal and parallel cross-fermentation tests were carried out respectively, and the total quality scores of the sensory indexes of the qualified roselle rice wine products were all (88.2+2.15) points. Compared with the samples of various groups of the single-factor orthogonal test and the samples of various groups of the two-factor orthogonal test, the test results of the quality scores of the comprehensive sensory performance were significantly improved by many points (P<0.05), indicating that the traditional production and manufacturing process of roselle rice wine had been optimized, and the quality of the experimental analysis data was more accurate, stable and reliable, and the repeatability was also better. For the best finished wine that was identified through the verification test and finally produced test results, a series of key physical and chemical composition analysis and physical and chemical index analysis should be regularly performed. The main identification results and analysis report after the results are obtained and shown in Table 8.

Product quality standards

Sensory quality

The wine should be light rose red, clear and transparent, without white precipitation. It should further have strong wine aroma, moderate sweet and sour taste.

Physical and chemical indexes

Alcohol content: 4.4%; sugar content: 16.4%; edible acidity: pH = 3.1; soluble solids content: 0.183 g/m.

Product quality

The quality standard of roselle rice wine referred to the technical regulations in the national standard GB 2758-2012 National Food Safety Standard: Fermented Wine and Its Preparation Wine［15］. The products were sampled for hygiene indexes, and the results are shown in Table 9.

From the comparison of the results in the above table, it could be seen that the main hygienic indexes of roselle rice wine products produced and sold fully met the relevant national standards, and it can be considered to appropriately put it into domestic industrial production and gradually promote it to domestic and foreign markets.

Conclusions

In this study, the single-factor orthogonal test method was used to determine the optimal level ranges of the four important influencing factors in the production process of roselle rice wine, and on this basis, the orthogonal test method was used to optimize the main production process of roselle rice wine. The identification results not only provide some new scientific theoretical basis for studying how to develop beverage product resources reasonably and effectively in China and how to scientifically and effectively develop and utilize roselle fruit resources, but also provide another technical exploration direction with a new theoretical perspective for further research, development and promotion of product technological innovation in China’s beverage market.

In this study, through the determination results of the various single-factor experiments and the orthogonal distillation extraction and separation test, the optimal brewing process ratios that can be used in the roselle rice wine system were determined and summarized. Specifically, the average weight of glutinous rice was about 400 000 g per ton; the average amount of glucose and additives used in the production of roselle extract system was about 600 000 g per hectoliter; the amount of distiller’s yeast was about 0.22 million g per time on average; and the total number of fermentation time cycles was about 40 000 h or more per year (the saccharification fermentation time was 2 d, and the after-fermentation time was 2 d). The roselle rice wine produced during development was uniform and dark rose red in color, clear and transparent, free of impurities, mellow and rich in aftertaste, moderately sweet and sour and delicate in taste, and had no protein precipitation. Meanwhile, it also had a very good dietary nutritional effect and unique health-care effects.

References

［1］ ZHANG JH, CHEN S, LIU HB, et al. Study on the stability of edible roselie red pigment［J］. Food Science and Technology, 2001(1): 49-50. (in Chinese).

［2］ LIU XH, WANG Z, WU Q, et al. Isolation of anthocyanin from Hibicus sabdariffa by high speed counter-current chromatography［J］. Modern Food Science & Technology, 2014, 30(1): 190-195. (in Chinese).

［3］ LI SF, LIU XM, ZHU ZW, et al. Development and utilization of the roselle resource［J］. Food Science and Technology, 2003(6): 86-88. (in Chinese).

［4］ WANG LY, JING ZH, WANG JJ, et al. Ultrasonic-aided extraction and antioxidant activity of flavonoids from Hibiscus sabdariffa［J］. Journal of Jilin Agricultural University, 2016, 38(1): 117-121. (in Chinese).

［5］ ZHANG HB, ZHANG Y, CHEN SF. Analysis of organic acid in rice win［J］. Food Science and Technology, 2007(7): 203-205. (in Chinese).

［6］ DU YM, SONG XY. Preparation of roselle Jamaica sorrel compound mulberry-capsule［J］. Food and Nutrition in China, 2009(4): 39-41. (in Chinese).

［7］ YE Y, WANG Y, LIU HM. Development of a new jujube rice wine beverage［J］. China Brewing, 2013, 32(1): 157-160. (in Chinese).

［8］ LIU DF, ZHANG ZX, ZHU XW, et al. Study on fermentation techniques of tomato rice wine［J］. CHINA BREWING, 2009(2): 154-156. (in Chinese).

［9］ SUN JT, XIAO FG, ZHU XR. The development of roselle & apple fruit wine ［J］. Liquor-Making Science & Technology, 2015(2): 78-80. (in Chinese).

［10］ HUANG Q, XIONG SY, WU BW. The production of roselle & mulberry fruit wine［J］. Liquor-Making Science & Technology, 2016(4): 81-84. (in Chinese).

［11］ MEI X, WANG SH, CAI F, et al. Development of konjak rice wine［J］. Science and Technology of Cereals, Oils and Foods, 2016, 24(5): 10-13. (in Chinese).