There’s a couple of interesting articles about cereal fermentation in the latest Food Microbiology. Both basically say that fermentation is a useful way of getting more nutrition out of your staples. Rob Nout ((Nout, M. (2009). Rich nutrition from the poorest – cereal fermentations in Africa and Asia Food Microbiology DOI: 10.1016/j.fm.2009.07.002)) describes how various traditional fermented dishes are made in Africa and Asia, ranging from kenkey in Ghana to idli in Sri Lanka. The former is made from maize, the latter from rice. Here’s the part of the paper’s Table 1 which lists fermented foods made from maize and sorghum (pearl millet, finger millet and rice are also considered):
It can get complicated. Here’s how they make jnard in India (I’ve removed the references to ease the flow), for example:
Jnard is an opaque beer made from finger millet (Eleusine coracana). Although – judging by its description – it would seem similar to Tchoukoutou, its mode of processing is fundamentally different. Whereas Tchoukoutou is brewed from sorghum malt, Jnard is saccharified by the action of an indigenous amylolytic starter (Murcha) on previously soaked and cooked fingermillet paste. Murcha is a rice-based dried tablet containing a mixed microflora of filamentous fungi, yeasts and lactic acid bacteria, and differs from koji which is a concentrate of fungal conidia of e.g. Aspergillus oryzae, used in the preparation of soya sauce and similar products. The process of preparing Jnard includes an overnight soak of finger millet seeds to soften them, grinding to obtain a crushed mass which is cooked and cooled to about 30ºC. Then, pulverized Murcha is sprinkled in the cooked mass and during a 1-3 day incubation, saccharification, lactic fermentation and alcoholic fermentation take place simultaneously. Functional microorganisms of Murcha and similar Asian amylolytic starters are filamentous fungi (Amylomyces rouxii, Rhizopus oryzae, etc.) which produce a range of enzymes including glucoamylase that degrades starch directly into glucose; yeasts (Endomycopsis fibuligera, Saccharomyces cerevisiae, etc.) which ferment part of the glucose produced; and lactic acid bacteria (Enterococcus faecalis, Pediococcus pentosaceus and others) growing together with the yeasts. LAB are able to co-exist with yeasts in a protocooperative manner.
The fermentation usually happens under wet conditions in the tropics, and there are often multi-purpose intermediate products, leading to a diversity of marketing and thus livelihoods opportunities. Sometimes, a cereal and a legume are fermented together. And a range of different micro-organisms (lactic acid bacteria and various types of yeasts) are involved, often working together in finely modulated mixed cultures. Agrobiodiversity at work on agrobiodiversity.
Nout concludes that fermentation can alleviate three of the main factors which restrict the nutritive value of cereals. It can decrease the swelling that happens when you cook starch, and which can limit nutritional intake due to bulk. It can increase protein content and quality. And it can improve the bioavailability of iron and zinc. “Fermentations play an important role in providing wholesome food with attractive flavour and texture.” Which is not to say that improvements are not possible:
From a nutrition point of view, new insights on increasing nutrient and energy density and on the removal of phytic acid, offer opportunities for future improvement of nutrient intake by consumers.
The second paper, by Kaisa Pouten et al. ((Poutanen, K., Flander, L., & Katina, K. (2009). Sourdough and cereal fermentation in a nutritional perspective Food Microbiology DOI: 10.1016/j.fm.2009.07.011)) looks more specifically at sourdough fermentation. Again, it finds that such processing can improve the sensory quality and texture of foods, and increase the bioavailability of micronutrients. It also suggests that it may degrade gluten and retard starch digestibility, which would be good for coeliac persons and those watching the glycaemic index of their food.
Which all goes to remind us that the nutritional quality of staples can be improved by processing as well as by breeding, and that agricultural biodiversity can help with the processing.
I am glad that you’ve focused our attention on the role of fermentation in foods. Many studies of agrobiodiversity and food use tend to ignore the added nutritional value of fermented foods (and it is not just fermentation for achieving an altered state of consciousness). West African maize and manioc (cassava), gourd and tree seeds are noteworthy for their use as fermented staple foods ‘ablo’, ‘toh’, ‘atcheke’, ‘inu’, ‘ogiri’. I confess that I am salivating as I write the names of these tasty foods. Also noteworthy is the fact that not all varieties ferment equally well and in the same way; some turn to sugars and become alcoholic rather quickly and others ferment slowly enough to release more proteins and nutrients or combine better with other food components. A large body of genetic diversity data tends to confirm that the quality and structure of starch molecules in crop varieties is largely determined by the genetic identity of the variety. Prof. Sado Sakamoto of Kyoto U. was a pioneer in the study of edible starch quality and genetic diversity and laid the groundwork for further genetic and ethnobotanical studies on this topic.
My dear friends and nutritionist colleagues Drs. Ifeyironwa Francisca Smith (Bioversity Int. expert on West African foods) and Barbara Burlingame at FAO (editor of the Journal of Food Composition and Analysis) are making big contributions by linking crop varietal diversity to food preparation and nutrient content. IF Smith is onto something very important in looking at use of small but rich components from biodiversity in sauces and thickeners like egussi, cassia etc.).
Professor Tim Johns of McGill and Bioversity wrote a fascinating review paper “The Chemical Ecology of Human Ingestive Behaviors.” Johns describes the domestication process in light of biochemistry of human consumtion. To make something taste good and provide necessary nutrients, one can select and shape plant genetic diversity through domestication and improvement or through processing. I think this line of enquiry is important for maintaining crop diversity and our ability to continue using it in a myriad of ways.
Endnotes:
1. Timothy Johns, School of Dietetics and Human Nutrition, Macdonald Campus, McGill University (1999) “The Chemical Ecology of Human Ingestive Behaviors.” Annual Review of Anthropology 28:27-50.
2. Journal of Food Composition and Analysis (www.elsevier.com/locate/jfca)
3. I.F. Smith (1998) Foods of West Africa: Their Origin and Use. IDRC
Thanks, Pablo. A lot of (fermented) food for thought there! Coincidentally, I saw this article today on other sorts of fermented products.
Pablo is right when he says that many species in West and Central Africa are noteworthy for their use as fermented staple foods. Genetic diversity plays important role in this as not all varieties give good quality products. Unfortunately some old varieties known for their high value in fermentation are disappearing for their limited yield potential. They are being replaced with high yielding but poor quality modern varieties. Studies also revealed that cropping practices (type and quantity of fertilizer, chemicals used etc.) may impact on the quality of products.
Desh Subba made the following comment on the Facebook version of this post:
‘Jnard’ sounds similar to Nepali ‘Jand’ . All processing steps look similar to me between these two. The only difference I see is the use of crushed or uncrushed millet grain. Whole grain is used in Nepali ‘Jand’ instead crushed ones in Indian ‘Jnard’ . I wonder where in India ‘Jnard’ is made using ground millet. As far as I know, Rai/Limbu and Sherpa communities in Darjeeling, Kalimpong and Sikkim states use finger millet in Nepali way. If the millet is ground and cooked this way but without application of ‘Murcha’ will probably make ‘Dhindo’ another local food type.