Fermentation has its place in the pantheon of great natural sciences, exploited for the benefit of human health and well-being. Mark J Tallon, PhD, explores the basic principles of fermentation and the resultant functional ingredients, and their applications to health
Evidence of the use of controlled fermentation can be dated to China, South America and ancient Egypt.1,2,3 Since the early proposals put forward by Louis Pasteur in 1858 about the use of microbial metabolism as a means to produce fermented foods, microbiologists have uncovered the interactions of bacteria and yeast as a means of producing many natural products.
Fermentation is the microbial-mediated conversion of sugars into products such as alcohol and lactic acid. The two kinds of microbial life used in most fermentation of functional foods are fungi and bacteria. In general, yeasts are produce ethanol and bacteria produce lactic acid, and it is the balance of spoilage vs fermentation with these microbes that allows positive changes (nontoxic bacterial formation) in microbial growth to occur.
Over the last 150 years (since Pasteur), the application of fermentation has changed significantly as it transitioned from traditional to modern techniques. Traditional methods focused on individual establishments, while modern techniques have turned mainstream manufacturing of fermentation products into a major business with a profile similar to other mass manufacturing. Industrial fermentation is now a huge part of the raw-material market including functional ingredients such as hyaluronic acid (fermentation with streptococcus bacteria), fermented green tea (production of theaflavins), and GABA (lactic fermentation of red perilla leaves), to the widely used carnitine xylitol, vitamins B2, B12 and K, CLA and glucosamine hydrochloride from Aspergillus niger.
Harnessing health benefits
One of the earliest functional attributes of fermented foods was their ability to introduce a change in the microflora of the human digestive tract.4 Because many fermented micro-organisms, such as probiotics, survive digestion, they can reach specific sites of benefit within the intestinal tract where they perform functions that may aid in host health. Fermented foods can provide an innate set of other functions such as increasing the nutritive value of foods by producing or enhancing the absorption of vitamins and minerals during digestion.
During the last 20 years there have been many natural products that owe their success to advancements in fermentation technology. The following table provides only a small sample of the many fermented foods and their action on health. These benefits range from specific functional attributes such as acting as an antihypertensive to the broader wellness category, such as antioxidants.
Market trends and opportunities
The fermentation market has become one of the largest ingredient categories within the supply side of functional ingredients. In 2009, the market was worth an estimated $17.8 billion and a compounded annual growth rate, between 2004 and 2009, of 4.7 per cent.5 It is estimated the global market for fermented products will reach $22.4 billion by 2013, up seven per cent over 2008 figures. In the global market, Asia leads the fermentation category, with price as the key driver of success. China and Japan are Asia's major players, which have become known for their head-to-head battle for control of fermented co-Q10 production. However, of all ingredient categories, amino acids are clearly leading the category with the largest share of the market at $5.4 billion in 2008, and growth expected to take the amino acid segment to $7.8 billion by 2013 (CAGR of 7.6 per cent).6 Enzymes have also been strong players in the category and will represent $4.9 billion by 2013, up 8.9 per cent (CAGR) since 2008.
The fermentation market is relatively unknown to many not directly involved in manufacturing of functional ingredients. However, the research surrounding natural products from fermentation has rapidly evolved. As the search for natural products grows, the potential application of fermentation as a more natural manufacturing method is still to be exploited. In 2009, we saw the emergence of at least three key fermented foods, which should retain strong growth through 2010 and increase the awareness of the category to consumers outside of Asia.
Kimchi is a traditional Korean pickled food often delivered as a spicy fermented cabbage dish. Recent research has shown that one of the actives in kimchi (3-(4-hydroxyl-3,5-dimethoxyphenyl) proprionic acid) has the potential to reduce the risk of atherosclerosis.7 A kimchi research study revealed rabbits on a cholesterol-elevating diet that were given concentrated kimchi extract over a four-week period had lower levels of oxidative stress and triglycerides than those on a pharmaceutical intervention (Simvastatin) or control. Kimchi has also shown signs of providing immune benefits, with recent press by the Korean Food Research Institute highlighting its effects in fighting the H5N1 (bird flu) virus.8
Further research in 2009 has shown that, in an animal model of diabetes, kimchi can significantly reduce blood-glucose levels compared to controls over a two-week period. The data of this study suggest that dietary kimchi has some antidiabetic effects even when coupled with a high-fat diet. Better results were possible if kimchi was consumed with a normal or low-fat diet rather than a high-fat diet.9
Tempeh is a food made from the fermentation of cooked soybeans with a rhizopus mold (Rhizopus oligosporus is the dominant tempeh fungus). Many health benefits are suggested for its soy saponin and isoflavone components. Tempeh's benefits are often linked to that of soy protein or soybeans despite its fermented form, which offers a different food matrix. One key difference is the concentration of Rhizopus oligosporus in the final format of tempeh. This starter culture has been shown to have some unique antimicrobial effects such as the inhibition of Helicobacter pylori and also acts as an inhibitor of E coli.10,11 These unique actions, in combination with soy as a food base, provide tempeh a very desirable nutritional profile.
Shoyu polysaccharides (SP) are an extract of soy sauce and wheat, which are traditionally fermented raw materials. These SP represent about one per cent (weight per volume) of soy sauce and are known for their anti-allergenic activity.12 However, recent evidence has demonstrated a disease risk-reduction ability through the reduction of serum triglycerides in lard-fed mice and humans during short and longer-term interventions.13 Some of the more recent work has focused on the immune system and there seems to be some initial data supporting the use of SP to increase production.14 However, specific human studies with clear biologically relevant endpoints are required to clarify SP's potential promise as a food with host-enhancing defence properties.
The process of fermentation results in a unique product matrix with health benefits beyond that of the starting material, as is the case with tempeh. In order to develop consumer awareness of fermented foods as a separate category, as has been achieved, for example, with 'organic' foods, more consumer and industry education is needed.
Mark J Tallon, PhD, is founder of NutriSciences Ltd, a consultancy firm specialising in health-claim substantiation, product development and technical writing. www.NutriSciences.com
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7. Kim et al. 3-(4-hydroxyl-3,5-dimethoxyphenyl) proprionic acid, an active principle of Kimichi, inhibits development of atherosclerosis in rabbits. J Agric Food Chem 2007 Dec 12;55(25):10486-92.
8. No Author. Kimchi Effective in repressing bird flu. KBS World radio. http://english.kbs.co.kr/News/News/News_view.html?id=Dm&No=63596 (Accessed December 28, 2009.)
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13. Kobayashi M, et al. Hypolipidemic effect of Shoyu polysaccharides from soy sauce in animals and humans. Int J Mol Med 2008; 22(4):565-70.
14. Matsushita H, et al. Stimulatory effect of Shoyu polysaccharides from soy sauce on the intestinal immune system. Int J Mol Med 2008;22(2):243-7.