Do you recall using a starch solution to test for iodine in your high school chemistry lab? A stock viva voce question about this experiment would be, why must you use freshly-prepared starch solution? The answer to this question is that, if the solution is not freshly-prepared, bacteria will decompose the starch. Old starch solution will be chemically very different – you will not see the iodine ions turning it purple-blue.
But why is the effect of bacteria on the chemical structure of starch (a carbohydrate) important here? To illustrate what microbes can do to carbohydrates: fermentation of carbohydrates can vastly alter their nutritional profile. This is a vital point Ravi Mantha seems to have overlooked in his article on the idli, wherein he argues that the popularly held notion of the idli being a healthy food is profoundly wrong.
Mantha bases his arguments solely on two quantities, the glycemic index (GI) and glycemic load (GL). For idlis, the GI and GL are typically in the range of fruit juices and desserts, he points out. For good measure, he equates the idlis with Coke. Ergo, they must be avoided like the plague. The GI of a food provides a measure of how much it would cause one’s blood glucose levels to spike, relative to pure glucose (which is taken to have a GI of 100). The GL goes one step further, and accounts for the size of the serving (or, more accurately, the amount of carbohydrate in it). Thus, a watermelon has a GI of 72, but two cups of watermelon chunks have a GL of only 4, compared to 22 for a Snickers bar (GI 55). However, neither quantity captures how fast (or slowly) the blood sugar level shall rise, the effect of other nutrients present in the food, or any other downstream effects. In other words, they totally miss the context, which, ironically again, Mantha himself emphasised was so important.
Before I try to counter Mantha’s arguments, a disclaimer: I am not a health expert or dietician; I am, in fact, a materials scientist who works with carbon nanotubes and graphene, and I haven’t been eating idlis or any traditional Indian non-square meal foods as frequently as I did in my childhood, as my lifestyle just doesn’t give me much of a chance to. I have also never particularly liked idlis. I know no biology or biochemistry either – I only presume to know enough chemistry to believe Mantha may have gone off at a tangent in his reasoning.
What Fermentation Does
As readers know, fermentation of idli and dosa batter, typically overnight, is an essential step in their preparation. Fermentation of food for a few hours leads to the breakdown of carbohydrates, resulting in more soluble sugars. (In beers and alcoholic beverages, the fermentation is done all the way up to converting carbohydrates to alcohols, but we needn’t bother with that.) This is what is responsible for the slightly high GI of idlis and dosas.
However, concluding that they must be avoided purely on the basis of their GIs is missing the big, true picture altogether. Firstly, fermentation improves the nutrient profile and increases bioavailability of nutrients and minerals in rice (or any cereal, for that matter). This is similar to what sprouting does for legumes. (Indeed, cooking with heat itself is merely a type of processing to improve the bioavailability of nutrients in food!). What is more, their high GIs notwithstanding, idlis and dosas, counter-intuitively, as a result of the fermentation used in their preparation, are probably particularly useful for blood sugar management for the prevention and amelioration of diabetes, and a host of other health problems.
The outermost, nutrient-rich layer, the bran that is present in brown rice, gets removed in the polishing used to produce the white rice that we mostly eat today. Brown rice is almost never used for making idli batter. However, parboiled rice is much better than polished (white) rice on this count, as the components in the bran are absorbed into the rice grain during the steaming employed in its production. It is mostly parboiled rice that is used for making idli or dosa batter, as it ferments better than white rice; idli rava is ground parboiled rice. It logically follows that idlis and dosas made with parboiled rice possess most of the advantages of brown rice.
Unlike yogurt, though, idlis and dosas are not probiotics, i.e., they are not a source of live cultures. This is because the steaming step sterilises them. But then, everyone knows that freshly-made idlis are healthy for precisely this reason. The benefits of fermentation are not limited to the food becoming a source of these “healthy” bacteria and yeasts – we have yogurt and dishes like pakhala for that. Indeed, we have always been aware of the need to avoid too much fermentation: this is why your grandmother will convert yogurt that has gone sour into morkuzhambu, and will probably make deep-roasted pancakes out of idlis or dosas batter gone sour instead, to neutralise the live cultures by heating. The partial breakdown of carbohydrates by fermentation described above is not compromised by steaming or cooking in any way, implying that its benefits continue to be available after cooking.
Benefits Of Fermentation
In addition to soluble sugars, fermentation of undigested carbohydrate in food within the digestive system also produces soluble fatty acids that are believed to improve glucose tolerance and reduce the overnight production of glucose in the liver (the liver produces glucose at night so the body gets the energy it needs during the long gap between meals) in humans. This sort of explains the logic behind the assumption that fermentation can be purposely employed in the processing of food as a beneficial strategy for pre-digesting carbohydrates. But is there any evidence that prior fermentation shall actually have such benefits? A study found that feeding fermented brown rice to Type-2 diabetic mice led to significantly better glucose tolerance (i.e., the ability to remove excess blood glucose) than diabetic mice that were fed ordinary brown rice. A study has shown that fermented rice bran prevented increase in cholesterol and glucose levels in blood serum of mice, and enabled them to cope with physical stress and fatigue better, over several days. Crucially, fermented rice bran may be able to counter the oxidative stress caused by Type-2 diabetes. The oxidative stress is the real problem with diabetes, which can in the long term, lead to problems like stroke and kidney failure. Fermented brown rice may have potential for preventing prostrate cancer. In other words, if you lead a high-stress or sedentary lifestyle, then idlis and dosas are just the foods for you! (But don’t soft-pedal the exercise.) I must point out that I have merely cited five papers for illustration. There is now a wealth of scientific evidence for the health benefits of fermented cereals, and rice in particular as it is the staple of half the world.
Little wonder, then, that fermented foods have such an important place in Indian cuisine. The east has its fermented rice, Kerala has the vellayappam, Gujarat the dhokla, and there is the ubiquitous jalebi, to name but four dishes made by fermentation. Mantha’s objections to the idli and the dosa apply to pretty much all these dishes. But I don’t believe a passing increase in blood glucose levels need bother one at all – barring outrightly syrupy indulgences like the jalebi, the enormous benefits of these fermented foods should make them positively essential in healthy diets.
Even so, idlis, dosas, vadas and many other foods like dibba rotti (immortalised in Gurazada Apparao Pantulu’s Kanyasulkam*), which combine rice with urad dal, are in a class of their own. They are not “superfoods” purely because of the fermentation step, either.
Urad, The Great Anti-Diabetic
Both rice and urad are native to south India. Urad dal (Vigna mungo) was probably first cultivated in this region, which was probably also an independent centre for starting the cultivation of rice in Neolithic times. From here, urad cultivation spread all over the subcontinent, and urad is today an essential component of much-loved dishes like the dal makhani. Urad is believed to be an excellent source of inhibitors for enzymes linked with diabetes and obesity, as well as antioxidants that may have potency in countering the oxidative stress caused by diabetes. Researchers are beginning to study this with increasing interest, for obvious reasons (quick aside: moong, also of the vigna family, is an even better source of these inhibitors and antioxidants). I will be looking forward to the day when I can get these from a can of Coke. The coupling of urad with rice and the beneficial effects of fermentation to give rise to a whole category of foods that are at once outstandingly healthy and irresistibly delicious is a remarkable invention indeed! I could not come across any studies on the effect of fermenting urad and rice together – the cocktail of nutrients this unique combination may give rise to, may well turn out to be far more beneficial than either component on its own. The possible synergy between rice and urad is something that Indian scientists may want to look into.
Grandma Was Right
Most Indians are genetically closely related to each other, and probably constitute a distinct race unto themselves (never mind the rubbish you were taught about India being a “melting pot” in your high-school history). What is the need to bring this up here? Because of our similar genetic make-up, we may all be susceptible to similar diseases. In fact, unfortunately, we are genetically much more prone to Type-2 diabetes and heart disease than other populations. And our sedentary lifestyles are not making the situation better.
What we must allow for, though, is the fact that we’ve had an extremely advanced system of medicine – Ayurveda – in place for millennia, that must not have failed to note our propensity for some diseases. It may be in response to this that Ayurveda has made many protective measures an unconscious part of our daily lives. For a taste (pardon the pun), how else can we explain why adding a pinch of turmeric to nearly every dish is as de rigueur as adding salt, in every single household from Kashmir to Kanyakumari, from Bhuj to Bomdila, and apparently has been as far as one can remember? Ayurveda has a long history of regarding diet as the primarily vehicle for health, a concept acquired by the West only recently. The things your unlettered grandmother made you do, from drinking water kept overnight in a copper pot (unfailingly cleaned daily) first thing in the morning, to making you eat steaming hot idlis or dosas, insisting that they were the best things you could possibly eat, are all the result of the pervasive influence of Ayurveda. It was ensured that this vital knowledge percolated down to everyone, regardless of background, as that was the only way it would be meaningful.
Your grandmother was right about the idlis. Grandmothers are always right.
* A line in the poem, “The Widow” in Apparao Pantulu’s satirical novel goes, “Of wondrous size she makes the cake...”
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