Tối ưu hóa các yếu tố ảnh hưởng đến quá trình sản xuất sirô sim (Rhodomyrtus tomentosa) để có hàm lượng anthocyanin cao
Trái “Sim” là loại trái mọng nước phân bố nhiều ở vùng Đông Nam Á. Trái Sim rừng có thể ăn được và chứa nhiều dược chất trị nhiều bệnh. Trái Sim chứa hàm lượng anthocyanin cao. Anthocyanin là hợp chất polyphenol có khả năng chống ôxy hóa rất tốt. Trong nghiên cứu này, Sim từ Mang Đen, Kontum được xử lý với enzyme pectinase để tối ưu hóa hiệu suất thu hồi, độ trong và hàm lượng anthocyanin. Sau khi phối chế với đường và acid, dịch Sim được vô chai và thanh trùng ở nhiệt độ và thời gian khác nhau. Quá trình trích ly dịch Sim bằng enzyme pectinase được tối ưu hóa bằng phương pháp bề mặt đáp ứng (Response surface methodology). Kết quả cho thấy rằng điều kiện trích ly tối ưu là 0,1% pectinase ở nhiệt độ 40oC trong 60 phút để có được hiệu suất thu hồi (62.93%), độ trong (T=38.3%) và hàm lượng anthocyanin (68.52 mg/L) cao nhất. Để đạt được chất lượng cao về an toàn vệ sinh và hàm lượng anthocyanin cao, sirô Sim được thanh trùng với giá trị PU858,3 = 9.18 (phút) ở điều kiện 85oC trong 4 phút
Tóm tắt nội dung tài liệu: Tối ưu hóa các yếu tố ảnh hưởng đến quá trình sản xuất sirô sim (Rhodomyrtus tomentosa) để có hàm lượng anthocyanin cao
J. Sci. & Devel., Vol. 12, No. 1: 98-107 Tạp chí Khoa học và Phát triển 2014, tập 12, số 1: 98-107 www.hua.edu.vn 98 OPTIMIZATION OF FACTORS AFFECTING SYRUP PRODUCTION FROM "SIM" FRUIT (Rhodomyrtus tomentosa) FOR HIGH ANTHOCYANIN CONCENTRATION AND GOOD QUALITY Nhân Minh Trí, Nguyễn Minh Thủy*, Phạm Thị Kim Quyên Food Technology Department, College of Agricultural and Applied Biology, Can Tho University Email*: nhanmtri@ctu.edu.vn; nmthuy@ctu.edu.vn Received date: 11.11.2013 Accepted date: 24.02.2013 ABSTRACT Rhodomyrtus tomentosa or Rose Myrtle is a wild plant native to Southeast Asia. Its berry or fruit is sweet, edible and medicinally used as a folk remedy for various diseases. The fruit contains high concentration of anthocyanin, a natural polyphenol with powerful antioxidant activity. In this study, Sim fruits harvested from Mang-Den, a highland area in Komtum, were pretreated with pectinase to maximize yield, transmittance (clarify) and anthocyanin in the filtrate. After taste adjustment with sugar and citric acid, the juice was pasteurized for preservation. The extraction by pectinase enzymes was optimized using response surface methodology. The results showed that the extraction condition with 0.1% pectinase at 40oC in 60 min was optimal for maximum yield of fruit juice (62.93%), clarity (T=38.3%) and amount of anthocyanin (68.52 mg/L). Pasteurization with PU858,3 = 9.18 minutes at 85oC for 4 minutes yielded syrup with good safety and high anthocyanin concentration. Keywords: Anthocyanin, pasteurization, pectinase, Rhodomyrtus tomentosa fruit, syrup. Tối ưu hóa các yếu tố ảnh hưởng đến quá trình sản xuất sirô sim (Rhodomyrtus tomentosa) để có hàm lượng anthocyanin cao TÓM TẮT Trái “Sim” là loại trái mọng nước phân bố nhiều ở vùng Đông Nam Á. Trái Sim rừng có thể ăn được và chứa nhiều dược chất trị nhiều bệnh. Trái Sim chứa hàm lượng anthocyanin cao. Anthocyanin là hợp chất polyphenol có khả năng chống ôxy hóa rất tốt. Trong nghiên cứu này, Sim từ Mang Đen, Kontum được xử lý với enzyme pectinase để tối ưu hóa hiệu suất thu hồi, độ trong và hàm lượng anthocyanin. Sau khi phối chế với đường và acid, dịch Sim được vô chai và thanh trùng ở nhiệt độ và thời gian khác nhau. Quá trình trích ly dịch Sim bằng enzyme pectinase được tối ưu hóa bằng phương pháp bề mặt đáp ứng (Response surface methodology). Kết quả cho thấy rằng điều kiện trích ly tối ưu là 0,1% pectinase ở nhiệt độ 40oC trong 60 phút để có được hiệu suất thu hồi (62.93%), độ trong (T=38.3%) và hàm lượng anthocyanin (68.52 mg/L) cao nhất. Để đạt được chất lượng cao về an toàn vệ sinh và hàm lượng anthocyanin cao, sirô Sim được thanh trùng với giá trị PU858,3 = 9.18 (phút) ở điều kiện 85oC trong 4 phút. Từ khóa: Anthocyanin, pectinase, sim, sirô, thanh trùng. 1. INTRODUCTION Rhodomyrtus tomentosa fruit or "Sim" fruit is a wild berry mainly distributed in highland and mountains in Vietnam, especially in Phu Quoc, Kien Giang and Mang Den, Kontum. Sim fruit has been recognized as an excellent source of anthocyanins, with the anthocyanin content of its skin being approximately 4.358 g/kg dry weight, indicating that the fruit has great potential as an ingredient for functional beverages (Liu et al., 2012). Anthocyanins are the principal water- soluble pigments responsible for the red, blue, and purple colors. Anthocyanins are commonly present in plants and non-toxic (Nabae et al., 2008). Anthocyanins are particularly attractive as natural substitutes for synthetic pigments and antioxidants (He and Giusti, 2010). In addition, Nhân Minh Trí, Nguyễn Minh Thủy, Phạm Thị Kim Quyên 99 an increasing number of studies have demonstrated that anthocyanins have the ability to prevent chronic and degenerative diseases including type 2 diabetes, cardiovascular disease and cancer (Felgines et al., 2006; Ghosh and Konishi 2007; Wu et al., 2006). Efficient extraction of Sim juice is one of the most important steps for syrup production from Sim crudes. However, Sim crudes are usually too pulpy and pectinacious to yield juices. One of the most effective methods is the enzymatic liquefaction technique. Anthocyanins degrade easily and discolor to form undesirable brown pigments in products such as fruit juices and syrups. Discoloration makes consumers perceive loss of the product quality (Torskangerpoll and Andersen, 2005). Anthocyanin stability is affected by several factors including pH, temperature, light, oxygen, enzymes, ascorbic acid, sugars, sulfur dioxide and metal ions (Francis and Markakis, 1989; Mazza and Brouillard, 1987). Thermal treatments (pasteurization and concentration) adverse strongly on the stability of anthocyanins in fruit juices such as blueberry, strawberry and blood orange. There have not been many studies about optimization of effects of enzymatic extraction and pasteurization on change of anthocyanins in sim syrup. The aim of this study was to optimize the temperature/time/enzyme concentration for extraction of anthocyanin from Sim, and to optimize pasteurization for good quality of Sim syrup. High sugar content in the sim syrup is usepful to enhance the shelf-life of the product and inhibit degradation of anthocyanin. The sim syrup can be diluted and served as fruit juice drink with high contents of vitamin and anthocyanin. 2. MATERIALS AND METHODS 2.1. Materials 2.1.1. Fruits Sim fruits were collected from Mang Den- DakLong, Kon Tum from February to April, 2013. They were cleaned and then frozen at - 20oC for a week in Mang Den. The frozen Sim fruits were transported by airplane or trucks to Can Tho, and futher stored at -20oC in the freezers until use for experiments in Food Technology Department, Can Tho University. 2.1.2. Enzyme source Pectinex Ultra SP-L (Denmark) was used in the food industry for fruit juice processing to reduce viscosity and juice extraction. Pectinex Ultra SP-L is a commercial pectinase enzyme from Aspergillus aculeatus. It contains different pectinolytic and cellulolytic enzymes [endo- polygalacturonase (EC 3.2.1.15; C.A.S. No. 9032-75-1), endopectinylase (EC 4.2.2.10; C.A.S. No. 9033-35-6) and pectin esterase (EC 3.1.1.11; C.A.S. No. 9025-98-3)], and other activities. It is recommended that the optimum enzyme reaction conditions are pH 3.5–6.0 and temperature range below 50oC 2.2. Processing line Sim fruit Cleaning & washing Freezing (-20oC) Transporting Storing (- 20oC) Washing Grinding Adding water (2.5kg water with 5kg sim crude) and Pectinex Hydrolyzing Filling into the cotton bag Filter pressing (100-120kg/cm2) Blending (with sugar and citric acid) Filling in glass Sealing Pasteurizing Sim syrup If 5kg sim crude was added with 2.5kg water, the sim filtrate would be 5.6kg after extracting with Pectinex. Sugar (sucrose) and citric acid were blended with the Sim filtrate to have 50 brix and pH=3.7 for good sensory attributes of taste and colour (study was not shown in this paper). 2.3. Experimental design 2.3.1. Optimization of concentration of pectinase, temperature and time for extraction of Sim juice Three levels of each of three factors, pectinase concentration, temperature and time for extraction of Sim juice were studied: Optimization of factors to affect syrup production from "sim" fruit (Thodomyrtus tomentosa) (Mang Den, Kontum) for high anthocyanin concentration and good quality 100 Pectinase (%) x temperature (oC) x time (min) = [0.05, 0.1, 0.15] x [40, 60, 80] x [35, 40, 45] = 27 experiments Each experiment was done with 3 replicates. 2.3.2. Effects of pasteurization on quality of syrup and loss of anthocyanin Two factors, temperature and time for pasteurization of Sim syrup were studied follow: Temperature (oC) x time (min) = [85, 90, 95] x [2, 4, 6] = 9 experiments. Each experiment was done with 3 replicates. One thermal sensor was put in the middle of the center glasses (220mL of syrup/bottle) in the retort to record the temperature of the product with time. The other was put outside of the glasses to record and monitor the temperature of the retort. The temperature profiles were recorded on line for every minute on the computer to calculate the thermal processing values as shown in section 2.4.4. The retort (= 40cm, h=60cm) was heated with the steam supplied by the generator with the vapor pressure of 4 kg/cm2. 2.4. Methods 2.4.1. Juice yield determination %100* F wJ m mmy [1] where, y (%) is the yield of fruit juice, mJ (g) is the weight of juice, mw (g) is the weight of water added, mF is the weigth of sim fruit. 2.4.2. Transmittance (clarity) determination The transmittance (T) was determined by a UV-Vis spectrophotometer model U-2800 (Simadzu, Japan). (Sin et al., 2006): x I IlogA o [2] Where, A is the absorbance, Io and I are the light intensity before and after transmission through the cuvet, is the wave length of the light (660nm). The transmittance (T) can be calculated as: %100x I IT o [3] 2.4.3. Total anthocyanin measurement The total anthocyanin content was determined according to the spectrophotometric pH-differential method (Lee et al., 2005). Briefly, an aliquot (1 mL) of the extract was mixed with 0.025 M potassium chloride buffer (pH 1.0, 4 mL) and 0.4 M sodium acetate buffer (pH 4.5, 4 mL). The absorbance of the mixture was measured at 510 and 700 nm using a UV- Vis spectrophotometer model U-2800 (Simadzu, Japan). The absorbance was calculated as A = [(A510 − A700) at pH 1.0] − [(A510 − A700) at pH 4.5] with a molar extinction coefficient of 26,900 for anthocyanin. The total anthocyanin content was calculated as cyanidin-3-glucoside equivalents as the following eaquation: L)(mg mLε VDFMA=C /10 3 [4] where A is the absorbance, MW is the molecular weight of cyanidin-3-glucoside (449.2 Da), DF is the dilution factor, V is the final volume (mL), 103 is the factor for conversion from g to mg, ε is the cyanindin-3-glucoside molar absorbance (26,900), L is the cell path length (1 cm), and m is sample weight (g). 2.4.4. Total microbial count determination Colonies grown in petri dishes by spreading 1 mL of the sample on the medium of Plate Count Aga were used to determine the count of viable microorganisms. The samples may be diluted to enable counting visually. The total microbial count could be calculated as the following equation: 11 21 2 310 . 10 . ... 10 . .i i NX n n n n d [5] Where, N is the total counts on the dishes, n1 is the number of count on the dish with the 1st dilution, n2 is the number of count on the dish with the 2nd dilution, n3 is the number of the count on the dish with the 3rd dilution, ni is the number of count on the dish with the i dilution, d is the dilution for the first count and X is the total microbial count /1mL. Nhân Minh Trí, Nguyễn Minh Thủy, Phạm Thị Kim Quyên 101 2.4.5. Total acid and sugar contents Total acid was determined by neutralization with NaOH 0.1N using color indicator of phenolphthalein (Pham Van So and Bui Thi Nhu Thuan, 1991). Sugar content was determined according to Bertrand method using Fehling A and B (Pham Van So and Bui Thi Nhu Thuan, 1991). 2.4.6. Pectin content Pectin content was determined by measurement of pectate calcium (Pham Van So and Bui Thi Nhu Thuan, 1991). 20 g of sample was added and mixed with 100 mL NaOH 0.1 N for hydrolyzing at 28oC in 7 hours. Then, 50 mL of acetic acid 0.1 N was added, mixed and incubated at 28oC for 5 min, and precipitated with 50 mL of CaCl2 1.0 N at 28oC for 1 hour. After boiling for 5 min, the precipitant (pectat calcium) was filtered and dried on the filter paper. The precipitant was washed with the boiling water until no remain of Cl- by testing the drain water with AgNO3 1.0%. After washing, the precipitate on the filter paper was dried until the weight remained unchanged. The content of pectin was calculated as the following equation: sm mpectin 92.0*100* [6] Where, m is the weight (g) of pectate calcium (precipitant), 0.92 is conversion factor from pectat calcium to pectin, ms is the weight (g) of sample. 2.4.7. Pasteurization value calculation Product has pH much less than 4.5, so- called acidic products, hence, food poisoning organisms of the type Clostridium botulinum do not germinate. Consequently, it is only necessary to inactivate molds and yeasts. This can be done at much lower temperatures, with the result that the F0-values are very low, since the lethal rate at a temperature of 80◦C is 7.76 × 10−5 min−1. A more practical unit for quantifying the lethal effect of this type of process is the pasteurization unit PU (Holdsworth and Simpson 2007) given by dt10=PU t 0 z )TT( z T ref ref [7] Where t is the time, T is temperature of the product, Tref is the reference temperature, z is the thermal destruction rate analogous. In this study, with the pH = 3, the Sim syrup has to achieve the PU-value higher than 5 min using the Tref = 85oC and z = 8.3oC (Ly Nguyen Binh and Nguyen Nhat Minh Phuong, 2011; Weemaes, 1997). 2.5. Statistical analysis Response surface methodology (RSM) is an effective statistical method based on a multivariate non-linear model, and has been widely used for optimizing complex process variables (Mundra et al., 2007). Using Statgraphics 15, RSM was used to describe and optimize the extraction of anthocyanins from Sim crudes. 3. RESULTS AND DISCUSSION 3.1. Composition of Sim fruit In this study, the sugar content (27.23%), the total acid (0.76%) and pectin (2.76%) of whole sim fruit from Mang Den, Kom Tum was higher those from Phu Quoc, Kien Giang (Nguyen Thi Ngoc Ngan, 2009). The contents were different due to effect of growing conditions. However, the anthocyanin concent (75.46mg/100g) in whole sim fruit from Mang Den, Kom Tum was lower than that (160mg/100g) from Thai Nguyen and Hai Duong (Lai Thi Ngoc Ha et al., 2013). Beside of growing conditions, the method analysis might contribute to the difference of anthocynin concentration. Table 1. Composition (/100g dry weight) of Sim fruit Composition Content Sugar (g) Total acid (g) Pectin (g) Anthocyanin (mg) 27.23 ± 0.25 0.76 ± 0.01 2.76 ± 0.07 75.46 ± 0.73 Optimization of factors to affect syrup production from "sim" fruit (Thodomyrtus tomentosa) (Mang Den, Kontum) for high anthocyanin concentration and good quality 102 3.2. Optimization of concentration of pectinase, temperature and time for extraction of Sim juice. Extraction is an important step to gain hi ... y and improve filterability in the preparation of clarified banana juice. Figure 1. Response surface plots of the yield of the filtrate affected by incubation temperature and time Using the Eq.[8], the values of yield were predicted from pectinase concentration, temperature and time. Figure 2 shows that the predicted yield and actual yield had high correlation coefficient of 0.95. It means that the model (Eq.[8]) could be used to describe the yield as a function of pectinase concentration, temperature and time in the extraction process. Nhân Minh Trí, Nguyễn Minh Thủy, Phạm Thị Kim Quyên 103 Figure 2. Relationship between the actual and predicted yields Optimization of pectinase concentration, temperature and time for transmittance of the filtrate The surface response shows effect of temperature, time and pectinase enzyme on the transmittance of the filtrate (Figure 3). It is known that fruit juice contains a lot of substrates including pectins and protein which cause viscosity and stupidity of juice. The Pectinex can have pectinase and protease which break down the pectin and protein molecules to decrease viscosity and stupidity in fruit juice (Hoang Kim Anh, 2007). The filtration of fruit juice will be efficient, if the juice is pretreated with pectinase (Le Ngoc Tu, 2003) There were significant differences of the transmittance of filtrate between different pectinase concentration, temperature and time. When the incubation temperature increased upto 40oC, the transmittance of the filtrate increased. Fruit juices contain colloids that are mainly polysaccharides (pectin, cellulose, hemicellulose, lignin and starch), protein, tannin and metals (Vaillant et al., 2001). The major problem is that the presence of pectin causes cloudiness during the preparation of fruit juices. The pectinase hydrolyses pectin and separate the complexes of pectin–protein resulting in flocculation of pectin and protein. Many studies reported that pectinase enzyme Figure 3. Response surface plots of the transmittance of the filtrate affected by incubation temperature and time Optimization of factors to affect syrup production from "sim" fruit (Thodomyrtus tomentosa) (Mang Den, Kontum) for high anthocyanin concentration and good quality 104 was used for clarification of fruit juices (Kashyap et al., 2001; Lee et al., 2001). The response surface could be fitted and described by the model with R2=0.78 as shown below: Transmittance = -230.26 + 9.47X + 1.07Y + 612.65Z – 0.12X2 – 0.01Y2 – 1.01YZ – 2382.96Z2 [9] Where, X is temperature (oC), Y is time (min), Z is pectinase concentration (%). The optimal extraction conditions for the transmittance (38.3%) of the filtrate was pectinase enzyme of 0.1% at temperature of 40oC for 60 or 80 minutes. Optimization of pectinase concentration, temperature and time for anthocyanin concentration in the filtrate The surface response shows effect of temperature, time and pectinase enzyme on anthocyanin concentration in the filtrate (Figure 4). There were significant differences of the anthocyanin concentrations of filtrate between different pectinase concentration, temperature and time. When the incubation temperature increased upto 40oC, the anthocyanin concentrations of the filtrate increased. The concentration of anthocyanin increased with concentration of pectinase enzyme. It is known that pectinase can be helpful to extract colorants (e.g., anthocyanin), tannin and other soluble solids (sugar and acid) to enhance the quality of juice (Le Ngoc Tu, 2003; Hoang Kim Anh, 2007; Tadakittisarn et al., 2007; Liu et al., 2012). The response surface could be fitted and described by the model with R2=0.81 as shown below: Anthocyanin = -313.06 + 15.25X + 1.25Y + 503.07Z - 0,19X2 - 0,01Y2 – 1971.41Z2 [10] Where, X is temperature (oC), Y is time (min), Z is pectinase concentration (%). The optimal conditions for anthocyanin concentration (68.52 mg/L ) in the filtrate extracted from the whole sim fruit was pectinase enzyme of 0.1% at temperature of 40oC for 60 minutes. Liu et al. (2012) found that the optimal conditions for extracting anthocyanins from the fruit skin of downy rose- myrtle (sim fruit) were 64.38 °C, 116.88 min, 15.7:1 liquid-solid ratio, with the corresponding anthocyanin content = 4.345 mg/g. The reasons can be that they studied the skin of sim fruit which contains higher content of anthocyanin. Figure 4. Response surface plots of the anthocyanin concentration of the filtrate affected by incubation temperature and time Nhân Minh Trí, Nguyễn Minh Thủy, Phạm Thị Kim Quyên 105 3.3. Effects of pasteurization on quality of syrup and loss of anthocyanin 3.3.1. Effects of pasteurization on safety Food in the cans or bottles has to be sterilized or pasteurized to inactivate enzymes and microorganisms for safety and preservation (Nguyen Trong Can and Nguyen Thi Le Ha, 2009). The sim syrup with the pH of 3.6 was treated thermally with the Tref = 85oC and z = 8.3oC (Ly Nguyen Binh and Nguyen Nhat Minh Phuong, 2011; Weemaes, 1997). The temperature profiles of Sim syrup heated at 85oC shown on Figure 5 are representative for pasteurization of all samples in this study. These temperature profiles of Sim syrup of the same heating temperature (85oC) were heated at different holding times. The temperature profiles at 80, 85 and 90oC were used to calculate PU-values of pasteurization process (PU = PUcoming up + PUholding + PUcooling) using [Eq.7]. The PU-values and total microbial counts of the pasteurized Sim syrup are shown in Table 2. The longer holding times were, the higher PU-values and the lower total counts were. If the Sim syrups were pasteurized at 85 ÷ 90oC for 2 ÷ 6, the PU-values would be 7.8 ÷ 40 higher PU-value = 5 (Ly Nguyen Binh and Nguyen Nhat Minh Phuong, 2011; Weemaes, 1997) and the sim syrups would be safe with the total microbial count = 0. However, the higher PU-values were the more loss of anthocyanin and the lower sensory values. Figure 5. Temperature profiles of Sim syrup pasteurized at heating temperature of 85oC with holding times for 2, 4 and 6 minutes Table 2. Effects of pasteurization on PU-values with z = 8.3 & Tref = 85oC and total microbial counts Product temperatures (oC) Holding times (min) 2 4 6 PU-value CFU/g PU-value CFU/g PU-value CFU/g 80 1.86 8.2x10 1 2.21 9.4x102 3.15 5.0x101 85 7.82 5.7x101 9.18 - 11.07 - 90 20.98 - 33.06 - 40.33 - Note: ‘-‘, no microbial counts. Optimization of factors to affect syrup production from "sim" fruit (Thodomyrtus tomentosa) (Mang Den, Kontum) for high anthocyanin concentration and good quality 106 3.3.2. Effects of pasteurization on loss of anthocyanin Pasteurization improves the safety and the shelf life of Sim syrup product. However, anthocyanin is degradable due to heat treatment during pasteurization. Anthocyanins degrade easily to form unacceptable browning compounds during thermal process (Torskangerpoll and Andersen, 2005; Liu et al., 2013). The thermal process for Sim syrup was applied at 85oC for 4 min to obtain PU858.3 = 9 min, no total microbial counts and high sensory values. The PU858.3 = 9.18 min for sim syrup with pH = 3.5 meets requirement for the juice product (Holdsworth and Simpson, 2007; Weemaes, 1997). If the product is heated with lower PU858.3 = 9.18 min, the product will not be safe. If the product is heated with higher PU858.3 = 9.18 min, the overcooking will cause high loss of anthocyanin and high waste of electricity and time. Figure 6. Change of anthocyanin concentration with temperature and time during pasteurization 4. CONCLUSION Pretreatment of Sim crudes by pectinase could be described by models for yield, transmittance and anthocyanin concentration in the filtrate as a function of pectinase concentration, temperature and time. They could be optimized by using pectinase enzyme 0.1 % at temperature 40oC for 60 minutes to have the highest yield (62.93%), clarity (38.3%, T) and anthocyanin concentration (68.52 mg/L) in the Sim extract. Sim syrup was pasteurized at temperature 85oC with holding time of 4 min to have PU-value = 9.18 min, high safety and high anthocyanin concentration retained in the Sim fruit syrup. 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