ang. 2-Methyl-1- butanol, HEMF, and 4-EG were not produced and the

Table 3. Organic acid contents in doenjang made of SB-, 0.8SB-0.2R-, 0.6SB-0.4R-meju.

Table 4. Antioxidative compounds and activity in doenjang made of SB-, 0.8SB-0.2R-, 0.6SB-0.4R-meju.

production of 3-methylbutanol, propionic acid, and furfuryl alcohol commonly decreased by the rice addition to the meju dough as shown in Table 5.

3.6. Bacterial Community Variation in Doenjang

16S-rDNA was normally amplified but 18S-rDNA was not. This may reflect the maintenance or growth of specific bacteria during meju fermentation and doenjang ripening, while fungal hyphae may lose their physiological activity. The number of DNA bands detected in the TGGE gels for SB-doenjang was more than 50% lower than that for SB-R-doenjang, and the TGGE patterns for 0.8SB-0.2Rand 0.6SB-0.4R-doenjang were completely identical with each other as shown in Figure 1. Bacteria belonged to Bacillus genus were commonly identified in all doenjang preparations [26-28]. In addition, bacteria of the genera Staphylococcus and Virgibacillus were commonly identified in 0.8SB-0.2Rand 0.6SB-0.R-doenjang as shown in Table 6.

4. Discussion

The quality of doenjang can be evaluated based on the contents of various nutritional ingredients that include free amino acids, organic acids, volatile compounds, minerals, fatty acids, and antioxidative compounds [29, 30]. Free amino acids, volatile compounds, and organic acids are biochemically produced by microorganisms responsible for meju fermentation. However, antioxidative compounds (polyphenol and total phenolic compounds) and minerals originated from the soybean ingredient. Practically, contents of free amino acids and organic acids measured for 15 doenjang preparations were markedly varied from 1.70% to 5.36% and from 0.5% to 1.65%, respectively. Meanwhile, the contents of polyunsaturated fatty acids and unsaturated fatty acids measured based on area% were slightly varied from 51.52% to 64.91% and from 82.28% to 85.22%, respectively [31]. Variations of the free amino acid contents were greatly higher than those of fatty acids, considering that variation of contents of crude protein and lipid were from 11.8% to 16.8% and from 7.1% to 8.6%, respectively, in 15 doenjang preparations. This indicates that contents of microbial metabolites in doenjang may be an index to evaluate doenjang quality because those are produced depending on metabolic and physiological activity of microorganisms responsible for meju fermentation. Accordingly, the effect of rice on doenjang quality may be evaluated on the basis of the biochemical metabolites contained in doenjang. However, the chemical ingredients originating

Table 5. Volatile organic compounds in doenjang made of SB-, 0.8SB-0.2R-, 0.6SB-0.4R-meju.

Table 6. The homologous bacteria with DNAs extracted from the numbered bands in TGGE gel were arranged in the order of the band numbers in Figure 1.

from soybean and rice must be analyzed for comparison of the nutritional value of rice-supplemented doenjang.

Adding rice to the dough used in the preparation of meju may alter the percentage balance of organic carbon and nitrogen sources for microbial growth. A prior study reported protein contents in SB-, 0.8SB-0.2R-, and 0.6SB-0.4R-meju to be about 40%, 34%, and 27% (w/w), respectively, and carbohydrate contents to be about 35%, 46%, and 57% (w/w), respectively [12]. These contents are 5 - 8 times higher than the total free amino acids (Table 1) and 11 - 15 times higher than the total organic acids (Table 3) in doenjang. The higher and appreciably higher ratios of free amino acids and organic acids to soybean content, respectively, in SB-R-doenjang as compared with SB-doenjang is a clue that that rice addition to meju dough may not be a cause to limit protein content for free amino acid production but may be a factor to activate microbial metabolism for fermentation of organic acids [32]. The present observation of higher bacterial diversity in SB-R-doenjang than in SB-doenjang (Figure 1 and Table 6) is another clue that the rice addition to meju dough be a factor to nutritionally activate bacterial growth and ecologically increase bacterial diversity [33]. Increase of bacterial diversity may cause to

Figure 1. TGGE pattern of 16S-rDNA variable region amplified with genomic DNA extracted from doenjang made of DFS- (1), DFS-0.2R- (2), DFS-0.4R-meju (3).

increase specific metabolites in fermenting meju and ripening doenjang, resulting in the increased ratios of free amino acids and organic acids to soybean content, while the production of volatile compounds may be limited or inhibited [34]. Certain volatile compounds that cause fragrant flavors and off-flavors may be generated by biochemical conversion of amino acids and metabolic fermentation of sugars during meju fermentation. Increase of the percentage balance of carbohydrate in meju dough may induce the active microbial catabolism of carbohydrates while limiting the catabolism of protein. As a consequence, off-flavors or unwanted flavors (such as peppermint, caramel, bacon, spice, camphor, sweet, and smoky) for doenjang may be produced in limited quantity. Contents of free amino acids and organic acids, especially, citric and lactic acid, are major factors to the improved taste and nutrients of doenjang [35]. Volatile compounds, such as 2-methyl-1-butanol, HEMF, 4-EG, 3-methylbutanol, propionic acid, furfuryl alcohol, and HDMF detected in SBand SB-R-doenjang are improper or unwanted factors for doenjang [36,37]. Accordingly, it can be suggested that the addition of 20% - 40% (w/w) rice to meju dough may induce nutritional conditions that are favorable for bacterial growth and fermentation, with consequent improvement of doenjang quality.

Generally, minerals including Mg, Ca, Mn, Fe, Zn, and Cu, and antioxidative compounds including polyphenol and total phenolic compounds [12] contained in soybean and rice become chemical ingredients of doenjang. Adding rice to meju dough was a cause the minerals and the antioxidative compounds to be maximally 30% and 40% decreased, respectively, in proportion to the percentage balance of soybean and rice. However, nature of doenjang may be not influenced by the reduction of the minerals and the antioxidative compounds because doenjang has not been used as mineral source for nutritional requirement or as antioxidant for functional reinforcement of food but has been used as a sauce for seasoning to taste of various foods. Generally, doenjang quality may be commercially fortified by the supplementation or content of antioxidative compounds [38,39]. From the nutritional standpoint, polyphenol and total phenolic compounds contained in doenjang may be helpful for the long-term preservation of foods, which may be substituted by other antioxidative compounds biochemically generated by microorganisms responsible for meju preparation and ripening of doenjang, considering that the antioxidative activity (DPPH scavenging and ferric ion reduction activity) was not decreased by addition of rice and was not proportional to the contents of the antioxidative compounds in doenjang. It is very possible that various metabolic intermediates, reduced metabolites, and coenzymes originating from chemically or biochemically lysed microbial cells can function as antioxidative agents, which may be proportional to biomass and diversity of microorganisms [40].

5. Conclusion

Rice may be useful as a supplement for meju dough when evaluated on the basis of free amino acid production, organic acid production, volatile compounds, and bacterial community diversity. Especially, DPPH scavenging and ferric ion reduction activity of doenjang may possibly be intimately related to the rice addition because the proper environmental conditions for bacterial growth may induce increased bacterial community diversity and activated bacterial physiology. The environmental condition of doenjang may be converted to the biophile condition. Positive interrelationship between bacteria and doenjang condition may be a factor to improve doenjang quality by activation of fermentation metabolism or enzymatic reaction. The use of rice in meju preparation may be helpful to activate rice consumption and improve doenjang quality, because the fermentation and ripening process may positively influenced by the chemical and nutritional balance between protein and carbohydrate. Especially, a maximum of 40% (w/w) rice may be substituted for soybean in the meju process according to the comparable quality of SB-, 0.8SB-0.2R-, and 0.6SB-0.4Rdoenjang.

6. Acknowledgements

This research was supported by Seokyeong University in 2009.

REFERENCES

  1. K. Y. Park and K. O. Jung, “Fermented Soybean Products as Functional Foods: Functional Properties of Doenjang (Fermented Soybean),” In: J. Shi, C. T. Ho and F. Shahidi, Eds., Asian Functional Foods, CRC Press, Boca Raton, 2005, pp. 555-596. doi:10.1201/9781420028119.ch20
  2. S. S. Kim, “Effect of Meju Shapes and Strains on the Quality of Commercial Soy Sauce,” Korean Journal of Food Science and Technology, Vol. 10, 1978, pp. 63-72.
  3. J. W. Kim, Y. S. Kim, P. H. Jeong, H. E. Kim and D. H. Shin, “Physicochemical Characteristics of Traditional Fermented Soybean Products Manufactured in Folk Villages of Sunchang Region,” Journal of Food Hygiene and Safety, Vol. 21, No. 2, 2006, pp. 223-230.
  4. I. J. Kim, J. K. Lee, M. H. Park, D. H. Shon, C. H. Rye and Y. L. Ha, “Preparation Method of Meju by Three Step Fermentation,” Korean Journal of Food Science Technology, Vol. 34, 2002, pp. 536-539.
  5. M. Miyazawa, K. Sakano, S. Nakamura and H. Kosaka, “Antimutagenic Activity of Isoflavones from Soybean Seeds (Glycine max Merrill),” Journal of Agricultural and Food Chemistry, Vol. 47, No. 4, 1999, pp. 1346- 1349. doi:10.1021/jf9803583
  6. A. Cardador-Martinez, E. Castano-Tostado and G. LoarcaPina, “Antimutagenic Activity of Natural Phenolic Compounds Present in the Common Bean (Phaseolus vulgaris) against Aflatoxin B1,” Food Additives and Contamitant, Vol. 19, No. 1, 2002, pp. 62-69. doi:10.1080/02652030110062110
  7. Y. Jing and S. Waxman, “Structural Requirements for Differentiation-Induction and Growth Inhibition of Mouse Erythroleukemia Cells by Isoflavones,” Anticancer Research, Vol. 15, No. 4, 1995, pp. 1147-1152.
  8. C .D. Allred, K. F. Allred, Y. H. Ju, T. S. Goeppinger, D. R. Doerge and W. G. Helferich, “Soy Processing Influences Growth of Estrogen Dependent Breast Cancer Tumors,” Carcinogenesis, Vol. 25, 2005, pp. 1649-1657. doi:10.1093/carcin/bgh178
  9. K. M. Hwang, J. Lee and K. Y. Park, “Deoenjang Extract Has Anticancer Activity and Induces Apoptosis in AGS Human Gastric Adenocarcinoma,” Journal of Food Science and Nutrition, Vol. 10, 2005, pp. 167-171. doi:10.3746/jfn.2005.10.2.167
  10. B. Y. Jeon, H. N. Seo, A. Yun, I. H. Lee and D. H. Park, “Effect of Glasswort (Salicornia herbacea L.) on Nuruk-Making Process and Makgeolli Quality,” Food Science and Biotechnology, Vol. 19, 2010, pp. 999-1004. doi:10.1007/s10068-010-0140-9
  11. H. N. Seo, B. Y. Jeon, A. Yun and D. H. Park, “Effect of Glasswort (Salicornia herbacea L.) on Microbial Community Variation in the Vinegar-Making Process and Vinegar Characteristics,” Journal of Microbiology and Biotechnology, Vol. 20, No. 9, 2010, pp. 1322-1330. doi:10.4014/jmb.1003.03041
  12. US Department of Agriculture, “USDA National Nutrient Database for Standard Reference, Release 24,” 2012. http://www.ars.usda.gov/Services/docs.htm?docid=8964
  13. L. E. Erickson, I. G. Minkevich and V. K. Eroshin, “Application of Mass and Energy Regularities in Fermentation,” Biotechnology and Bioengineering, Vol. 20, No. 10, 2004, pp. 1595-1621. doi:10.1002/bit.260201008
  14. H. C. Chen, “Optimizing the Concentration of Carbon, Nitrogen and Phosphorus in a Citric Acid Fermentation with Response Surface Method,” Food Biotechnology, Vol. 10, 1996, pp. 13-27. doi:10.1080/08905439609549898
  15. A. Derrien, L. J. M. Coiffard, C. Coiffard and Y. RoeckHoltzhauer, “Free Amino Acid Analysis of Five Microalgae,” Journal of Applied Phycology, Vol. 10, No. 2, 1998, pp. 131-134. doi:10.1023/A:1008003016458
  16. O. S. Ijarotimi and A. J. Olopade, “Determination of Amino Acid Content and Protein Quality of Complementary Food Produced from Locally Available Food Materials in Ondo State, Nigeria,” Malaysian Journal of Nutrition, Vol. 15, 2009, pp. 87-95.
  17. X. Wang, A. Lásztity, M. Viczián, Y. Israel and R. M. Barne, “Inductively Coupled Plasma Spectrometry in the Study of Childhood Soil Ingestion,” Journal of Analytical Atomic Spectrometry, Vol. 4, 1989, pp. 727-735. doi:10.1039/ja9890400727
  18. M. L. Price and L. G. Butler, “Rapid Visual Estimation and Spectrophotometric Determination of Tannic Content of Sorghum Grain,” Journal of Agricultural Food Chemistry, Vol. 25, 1977, pp. 1268-1273. doi:10.1021/jf60214a034
  19. G. K. Jayaprakasha, R. P. Singh and K. K. Sakariah, “Antioxidant Activity of Grape Seed (Vitis vinifera) Extracts on Peroxidation Models in Vitro,” Food Chemistry, Vol. 73, No. 3, 2001, pp. 285-290. doi:10.1016/S0308-8146(00)00298-3
  20. D. O. Kim, K. W. Lee, H. J. Lee and C. Y. Lee, “Vitamin C Equivalent Antioxidant Capacity (VCEAS) of Phenolic Phytochemicals,” Journal of Agricultural Food Chemistry, Vol. 50, No. 13, 2002, pp. 3713-3717. doi:10.1021/jf020071c
  21. S. J. Lee, Y. W Lee, J. Chung, J. K. Lee, J. Y. Lee, D. Jahng, Y. Cha and Y. Yu, “Reuse of Low Concentrated Electronic Wastewater Using Selected Microbe Immobilized Cell System,” Water Science and Technology, Vol. 57, No. 8, 2008, pp. 1191-1197. doi:10.2166/wst.2008.246
  22. B. Y. Jeon and D. H. Park, “Effect of Glasswort (Salicornia herbacea L.) and Rice (Oryzae sativa L.) on Quality of Ganjang (Korean Soy Sauce), ” Food Science and Biotechnology, Vol. 20, No. 4, 2011, pp. 979-986. doi:10.1007/s10068-011-0135-1
  23. N, Batasundram, K. Sundram and S. Samman, “Phenolic Compounds in Plants and Agri-Industrial By-Products: Antioxidant Activity, Occurance, and Potential Uses,” Food Chemistry, Vol. 99, No. 1, 2006, pp. 191-203. doi:10.1016/j.foodchem.2005.07.042
  24. D. Malenčić, Z. Maksimović, M. Popović and J. Miladinović, “Polyphenol Contents and Antioxidant Activity of Soybean Seed Extracts,” Bioresearch and Technology, Vol. 99, 2008, pp. 6688-6691. doi:10.1016/j.biortech.2007.11.040
  25. M. Walter and E. Marchesan, “Phenolic Compounds and Antioxidant Activity of Rice,” Brazilian Archives of Biology and Technology, Vol. 54, No. 2, 2011, pp. 371-377. doi:10.1590/S1516-89132011000200020
  26. S. S. Ham, K. K. Choi, C. B. Cui, B. G. Lee, D. S. Joo and D. S. Lee, “Quality Characteristics of Commercial Soy Sauce Fermented by Bacillus licheniformis NH20 Isolated from Traditional Meju and Aspergillsu oryzae,” Food Science Biotechnology, Vol. 13, 2004, pp. 537-543.
  27. Y. S. Kim, B. H. Oh and D. H. Shin, “Quality Characteristics of Kochujang Prepared with Different Meju Fermented with Aspergillus sp. and Bacillus subtilis,” Food Science Biotechnology, Vol. 17, No. 3, 2008, pp. 527- 533.
  28. S. S. Ham, K. K. Choi, C. B. Cui, B. G. Lee, D. S. Joo and D. S. Lee, “Quality Characteristics of Commercial Soy Sauce Fermented by Bacillus licheniformis NH20 Isolated from Traditional Meju and Aspergillsu oryzae, ” Food Science Biotechnology, Vol. 13, 2004, pp. 537-543.
  29. E. L. Kim and S. C. Kang, “Quality Evaluation by the Addition of Pine Needle and Artemisia princeps Extracts in Vinegared Kochjang,” Journal of the Korean Society for Applied Biological Chemistry, Vol. 50, 2007, pp. 167- 177.
  30. B. M. Jung and S. B. Roh, “Physiological Quality Comparison of Commercial Doenjang and Traditional Green Tea Doenjang,” Journal of the Korean Society of Food Science and Nutrition, Vol. 33, 2004, pp. 132-139. doi:10.3746/jkfn.2004.33.1.132
  31. S. K. Park and K. I. Seo, “Quality Assessment of Commercial Doenjang Prepared by Traditional Method,” Journal of the Korean Society of Food Science and Nutrition, Vol. 29, 2000, pp. 211-217.
  32. H. Rughoonundun, R. Mohee and M. T. Holzapple, “Influence of Carbon-to-Nitrogen Ratio on the Mixed-Acid Fermentation of Wastewater Sludge and Pretreated Bagasse,” Bioresource Technology, Vol. 112, 2012, pp. 91- 97. doi:10.1016/j.biortech.2012.02.081
  33. T. F. Thingstad and R. Lignell, “Theoretical Models for the Control of Bacterial Growth Rate, Abundance, Diversity and Carbon Demand,” Aquatic Microbial Ecology, Vol. 13, No. 1, 1997, pp. 19-27. doi:10.3354/ame013019
  34. P. Christen, A. Bramorski, S. Revah and C. R. Soccol, “Characterization of Volatile Compounds Produced by Rhizopus Strains Grown on Agro-Industrial Solid Wastes,” Bioresource Technology, Vol. 71, No. 3, 2000, pp. 211- 215. doi:10.1016/S0960-8524(99)00084-X
  35. Z. Yanfang and T. Wenyi, “Flavor and Taste Compounds Analysis in Chinese Solid Fermented Soy Sauce,” African Journal of Biotechnology, Vol. 8, No. 4, 2009, pp. 673- 681.
  36. P. J. Spillman, A. P. Pollnitz, D. Liacopoulos, K. H. Pardon and M. A. Setton, “Sefton, Formation and Degradation of Furfuryl Alcohol, 5-Methylfurfuryl Alcohol, Vanillyl Alcohol, and Their Ethyl Ethers in Barrel-Aged Wines,” Journal of Agricultural Food Chemistry, Vol. 46, 1998, pp. 657-663. doi:10.1021/jf970559r
  37. I. Blank and L. B Fay, “Formation of 4-Hydroxy-2,5- Dimethyl-3(2H)-Furanone and 4-Hydroxy-2(or 5)-Ethyl- 5(or 2)-Methyl-3(2H)-Furanoned Reaction Based on Pentose Sugars,” Journal of Agricultural Food Chemistry, Vol. 44, 1996, pp. 531-536. doi:10.1021/jf950439o
  38. H. J. Wang and P. A. Murphy, “Isoflavone Contents in Composition in Commercial Soybean Foods,” Journal of Agricultural Food Chemistry, Vol. 42, No. 8, 1994, pp. 1666-1673. doi:10.1021/jf00044a016
  39. J. H. Jeong and J. S. Ki, “Studies on the Contents of Free Amino Acids, Organic Acids, and Isoflavones in Commercial Soybean Paste,” Journal of the Korean Society of Food Science and Nutrition, Vol. 27, 1998, pp. 10-15.
  40. M. Mikelsaar and M. Zilmer, “Lactobacillus fermentum ME-3 an Antimicrobial and Antioxidantive Probiotic,” Microbial Ecology in Health and Disease, Vol. 21, No. 1, 2009, pp. 1-27. doi:10.1080/08910600902815561

NOTES

*Corresponding author.

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