- Definition of natto and possible mass production methods
Weng, Tien Man, and Ming Tsao Chen. “Effect Of Drying Methods On Γ-Pga, Isoflavone Contents And Ace Inhibitory Activity Of Natto (A Fermented Soybean Food).” Journal of Food Processing and Preservation 36.6 (2012): 483-88. Wiley Online Library. Web. 27 Jan. 2016.
This journal is a report on how different drying methods of fermented natto affect the nutritional contents; however, the paper focuses more on natto’s nutritional background than on the experiment and its practical applications. Natto is a Japanese traditional soybean product fermented by Bacillus subtilis (natto), contains isoflavones, fiber, vitamins, and minerals, and has a very unpleasant smell. Because fresh natto has a short shelf-life as it secretes ammonia after time, food companies have attempted to dry the product into powder form in order to sell it as a more acceptable food. The experimentation of different drying methods depict that vacuum-drying, freeze-drying, and oven-drying does not affect most of the nutritional content, but angiotensin-converting enzyme (ACE) inhibition. This article pinpoints that the correct drying process could maintain the functional nutrients and could lead to mass production.
- Process of natto-making and how some nutrients are beneficial to the body (ex. oxidation and antioxidants)
Hu, Yongjin, Changrong Ge, Wei Yuan, Renjun Zhu, Wujiu Zhang, Lijuan Du, and Jie Xue. “Characterization of Fermented Black Soybean Natto Inoculated with Bacillus Natto during Fermentation.” Journal of the Science of Food and Agriculture J. Sci. Food Agric. 90.7 (2010): 1194-202. Wiley Online Library. Web. 27 Jan. 2016.
Fermentation, a widely used method of preparing food in Asian countries, effects the improvement of sensory characteristics, elimination of undesirable content, and enhancement of some nutritional properties. Natto, made by cooking pre-soaked soybeans and fermenting them to grow Bacillus natto, is low in cost and high in nutrition; natto of good quality should be covered in white mucous sap and should have a soft texture. Natto has a high supply of protein, calories, isoflavone, vitamin E, anthocyanin, and other nutrients, of which soy proteins, biological inhibitors, and bacterial enzymes break into easily digestible peptides when fermented. During the fermentation of soybeans, the total protein content increases due to the increase of microorganisms, the synthesis of enzymes, and the rearrangements of pre-existing compositions. Nutrients of natto, such as isoflavone, help inhibit low-density lipoproteins oxidation, quench free radicals, and reduce DNA damage. Oxidation, the chemical reaction of transferring electrons from a substance to another, produces free radicals, which may cause damage or death to cells through chain reactions; antioxidants, removing free radicals and inhibiting oxidative reactions, are of high content in natto. Such nutritional abundance allows natto to be a functional food and dietary supplement.
- Experimentation of the effect of natto on osteoporosis
Iki, M., A. Morita, Y. Ikeda, Y. Sato, T. Akiba, T. Matsumoto, H. Nishino, S. Kagamimori, Y. Kagawa, and H. Yoneshima ·. “Biochemical Markers of Bone Turnover Predict Bone Loss in Perimenopausal Women but Not in Postmenopausal Women-the Japanese Population-based Osteoporosis (JPOS) Cohort Study.” Osteoporosis International Osteoporos Int 17.7 (2006): 1086-095. ProQuest Biology Journals [ProQuest]. Web.
This article is an assessment of the association of eating natto habitually and bone mineral density (BMD), a means of measuring osteoporosis; the experiment was done with 944 healthy Japanese women of ages 20 to 79, whom were categorized into pre- or post-menopausal. Osteoporosis is a disease that affect elderly people around the globe, and nutrition may prevent osteoporosis. After years of repeated measurements, a positive relationship was shown between natto and the women’s BMD – the more natto intake, the higher the BMD, meaning possessing stronger bones. This research also adds that habitual natto intake is associated with reduced bone loss at the femoral-neck. Furthermore, researchers commented on natto as a preventative food for osteoporosis, since it contains a very rich content of vitamin K and isoflavone, even more than 100 times the amount of vitamin K in some cheese. This report, in the end, asks whether natto intake would reduce the risk of hip fracture, and also comments on its limitations.
- Natto’s further impacts on health
Ibe, Sachie, Kaoru Kumada, Keiko Yoshida, and Kazunori Otobe. “Natto (Fermented Soybean) Extract Extends the Adult Lifespan of Caenorhabditis Elegans.” Bioscience, Biotechnology, and Biochemistry Biosci. Biotechnol. Biochem. 77.2 (2013): 392-94. Taylor & Francis Online. Web. 27 Jan. 2016.
Excessive oxidation, whether wanted or not, is a major factor that reduces human lifespan; however, this article comments on the antioxidative effects of natto and not other soybean products. Results from an experimentation of injecting water extract from natto into C. Elagans, a well-used species of worm, illustrate that the average lifespan can be lengthened by approximately 30% as bacterial growth is inhibited by natto. Natto extract also raised the survival rate under excessive oxidation; this is most likely due to the rise of antioxidative peptides and phenolic compounds from the fermentation of soybeans with B. subtilis/natto. Moreover, the high polyamine content of soybeans are further boosted during fermentation, known to have extended the lifespan of yeast, flies, worms, and human immune cells. Even though this article strongly argues that natto exerts high levels of anti-aging material, it concedes that additional studies are yet necessary.