A Pinch of Culinary Science

by Anu Inkeri Hopia

  Why did the farm wives cook their porridge this way? Looking in recipes of today there are few, if any, traces of the 19th century practice of leaving part of the flour to add in the end. So why did they do this? In historical accounts of the porridge feud, the farm wives’ own voices are seldom heard, except via the statements by sociologist Eilert Sundt. Did anyone ask the cook directly why she cooked the porridge this or that way? Sitting at a cafe table in Helsinki with our respective bowls of porridge, we wondered why on earth the Norwegian farm wives cooked their porridge the way they did. We have tried to reason and have three possible hypotheses: the nutrition hypothesis, the texture hypothesis, and the flavor hypothesis.

  The nutrition hypothesis. Doctor Faye presented one possible interpretation of the reasons for this cooking practice: if the porridge was cooked in a way that it was not as easily digestible, but took longer to digest, it could be beneficial for the working man. The food would stay longer in the belly, the food would provide energy over a longer period, and worker or farmer would not become hungry too soon. So, this way of cooking the food would be suitable for body laborers, which constituted the major part of the Norwegian population at the time. Today, surrounded by abundance and constantly being worried about getting too much carbohydrates from our food, we might actually be happy to go back to pre-Asbjørnsen times. While he was worried about people wasting food as part of the energy-containing nutrients staying in an unabsorbed form (not bioavailable), many today would be happy if the abundance of food we ate liberated less energy into our bodies. Indeed, one of the wonder substances of today for those who want to watch their weight is resistant starch. These are types of starch that are non-digestible, or slowly digestible, in the small intestine where nutrient absorption takes place. Rather, they are broken down by bacteria in the large intestine and thereby function as fiber, without providing any energy. Today, we also know that starch is bioavailable only in gelatinized form, as it is generally after cooking. However, if the gelatinization does not take place, or if the starch is recrystallized, it will not be digested. This recrystallization takes place, for example, during refrigeration of cooked potatoes or pasta. The Norwegian farm wives might have been ahead of their time and served porridge where part of the starch from the flour was in its resistant form, functioning as fiber, and thus keeping the hunger at bay for a longer time. Furthermore, this recent knowledge proves Asbjørnsen right.

  The texture hypothesis. Historian Jarle Sanden at Romsdal Cultural Historic Museum in Western Norway hints toward a rather different reason for adding flour after cooking, as he uses the term “really hardly pounded/pestled porridge” in a book about food traditions in the Romsdal region of Norway. Leftovers of such firm porridge could, the day after, serve as a replacement for potato when sliced and fried in bacon fat. Indeed, it was common to cook enough porridge for more than one meal, and a usual evening meal was lumps of porridge reheated in milk or buttermilk. Food writer Catherine Brown describes a similar practice from Scotland, another country where porridge has been an important staple. Porridge leftovers, if they are firm enough, serve well as a packed lunch for the working farmer to bring with him out in the fields. We have ourselves corresponded with two informants of age, asking them if they have ever experienced this way of cooking porridge and if they could explain why it was done. One of the informants used the same texture explanation as Sanden: “Here is a true story about the porridge: in old times, our neighbor cut grass all the way up to the foot of the mountain, and it was important to be meticulous about it so there would be enough feed for the livestock. Of course, they brought porridge in a porridge pail [small wooden bucket with lid]. The pail tipped over and the porridge went rolling down the hill. That porridge was pounded for sure!”

  The flavor hypothesis. Historical literature describes porridge as an important source of energy for people whose lives were characterized by hard physical labor. Nowhere in the literature do we find any statements about taste or enjoyment of this food. Is it so that food was seen only as fuel for working bodies except during festivities? Were flavor preferences pushed in the background by necessity in a country inhabited by hard-working peasants? Surely, the cook would try to make the food as enjoyable as possible in this context, and not only in the wealthier contexts of traders and aristocrats? This porridge, literally translated in Norwegian as “water porridge,” does not enjoy a reputation for being among the culinary high points in Norwegian cuisine; although, some would say that this reputation is somewhat unfair. Making the food more palatable is probably always a motivation for anyone making staples, and if we look to Finnish food culture, this is exactly where we find a hint at making the porridge tastier. Looking to Finland is not entirely unlikely since there was a great migration from Finland westwards to Norway during the 16th and 17th century. Maybe a procedure or recipe from Finland might have found its way to Norway? The practice of sweetening starchy foods by taking advantage of naturally occurring enzymes in raw materials is an old practice in Finnish food culture (but virtually unseen in contemporary Norway). Such sweetening can, for example, be achieved by adding non-heated flour to starch-rich food after it is cooked. This still-existing common practice is found in a traditional Finnish dish, the Christmas dish called “imelletty perunalaatikko”—potato casserole. It is made with potatoes, water, and flour in a manner that in principle might resemble that of the Norwegian porridge. Potatoes are cooked, mashed, and left to cool slightly. When lukewarm, some flour is mixed in and the casserole left at room temperature or slightly above for several hours, preferably overnight. During this time, amylase enzymes from the flour will break down the starch abundant in the potatoes into sweet sugars. The result is a looser texture, because some of the long starch molecules that otherwise will be entangled in each other, are broken down into small water-soluble sugar molecules. Starch does not taste much, but sugars are sweet. By using the naturally occurring enzymes in flour, the dish becomes sweeter without adding any sweetening. When the dish is then baked in the oven, the presence of sugars results in browning reactions to give a light brown dish with a dark brown crust, very different from what you’d get if you put the mashed potatoes straight into the oven. This sweetening process is sometimes quite tricky to achieve, so recipes for the potato casserole often include a safeguard: if it hasn’t become sweet by its own, add some syrup before placing it in the oven.

  Finnish Christmas potato casserole (imelletty perunalaatikko)

  The parts of the recipe that concern enzymatic sweetening, and what to do if this fails, have been italicized.

  Ingredients

  1 kg potatoes (starchy/mealy variety)

  1 dl wheat flour

  25 g butter or margarine

  0.25–0.5 l milk

  1 tablespoon syrup, if necessary

  1.5 teaspoons salt

  Procedure

  Peel and cut the potatoes into cubes. Cook in a small amount of water until soft and strain. Mash the potatoes and let cool until approximately hand warm. Mix in half of the butter and a little more than half of the flour into the potatoes. Add the rest of the flour on top. Keep the pan covered overnight, or at least 5–6 hours, in a warm place. You may stir it once or twice, but this is not strictly necessary. Taste every once in a while to monitor the sweetening process. If the texture has not become looser during the first 6 hours, don’t worry, just add a spoonful of syrup. Add cold milk to the mixture and stir thoroughly, the mixture should be loose like porridge, much looser than regular mashed potatoes. Add salt. Pour the mixture into a high-walled ovenproof dish and add the remaining butter on top. Bake for 30 minutes at 200°C to bring the mixture to the boil. Reduce the oven temperature to 150 °C and continue cooking for another 2 hours until you get a slightly sweet and light brown dish with a dark brown crust.

  Such starch-cleaving enzymes are found several places, including in our own saliva. This principle is used to produce traditional alcoholic drinks such as the Japanese sake and chicha found i
n Central and South America. In the latter case, the starchy food is chewed and then put back into the tray. The enzymes from the saliva break down the starch into sugars whereby naturally occurring or added yeast may digest these sugars to give alcohol. You can test this phenomenon yourself by taking a teaspoon of flour in your mouth and leave it there for a few minutes; you should notice that it turns slightly sweet. The knowledge about enzymatic cleavage of starch to sugars by amylase enzymes from saliva was already known during the time of the porridge feud, and indeed described by Dr. Faye. However, none of the literary sources say anything about a process of using uncooked flour as a source for enzymes to sweeten the porridge. Could it still be that the Norwegian housewives had learnt this from the Finnish and applied it into their own cooking practices? After all, a sweeter porridge might be more enjoyable, and maybe they could cut down on the expensive sweet syrup or sugar? They didn’t need to know about the chemical processes going on between enzymes and starch; the only necessary knowledge would be to know how to do it and the fact that the porridge would become sweeter.

  We went ahead to test whether it would be possible to cook a sweet porridge using the old method. In the context of a science teacher conference in Norway, we cooked two parallel portions of porridge. One was cooked according to modern recipes, as recommended by Asbjørnsen: water was brought to the boil and all the flour was added gradually while stirring. The porridge was thereafter boiled for 20 minutes. The other parallel started four hours earlier. With the exact same amounts of flour and water, the porridge was cooked according to the farm wives’ procedure so that the last one-fifth of the flour was added after the porridge had cooled to below 60°C. Above this temperature, amylase enzymes are deactivated (denatured), so we kept the porridge warm, but below 60°C, for four hours. The two porridges were served to ca. 45 science teachers in a blind tasting, and the participants were asked to rank them according to sweetness. The result was very convincing indeed: the “modern” procedure received only one vote for being sweetest. The remaining 44 or so participants experienced the porridge cooked according to the farm wives’ practice as sweetest. We concluded that our informal experiment had quite overwhelmingly strengthened our claim that it is possible to cook a porridge with increased sweet taste using a procedure that resembles that of the 19th century farm wives.

  Can we prove, or falsify, any of the hypotheses? We turn to the science philosopher Karl Popper, who wrote that it is not possible to prove a hypothesis to be true. The best we can achieve is to falsify possible hypotheses, and those that still stand after we, by the very best of our ability, have tried to falsify them, are the ones currently valid. In this case, it is difficult to falsify any of the three hypotheses. Cooking porridge the 19th century way is a human practice that is no longer present in today’s food culture, at least not to our knowledge. All three hypotheses are possible explanations, and it could even be that all three are correct.

  But we would call to attention the fact that the texture hypothesis and the flavor hypothesis, to a certain extent, contradict each other, because sweetening the porridge by enzymes would also give a much looser texture. You wouldn’t get a porridge the next day that was both sweet and could roll down the hill in one piece; sweet and firm at the same time is an unlikely combination. But an important factor is that this sweetness is quite difficult to achieve, the exact reason for the Finnish potato casserole recipes including syrup as safety net. We might speculate that some housewives were able to make the sweet porridge while others failed. But in failing, they got a porridge with a firm texture which gave another benefit. You lose some and win some. This is, of course, speculation, and since rural cooking practices are seldom documented in writing, it is not possible to trace the motivations of the farm wives’ cooking practices. Although many were literate in 19th century rural Norway, the fact that these people apparently didn’t find their everyday activities important enough to document was the very reason that Eilert Sundt made his travels around to talk with them and observe how they lived.

  So, what have we gained by reopening this chapter in history? Have we just added more confusion by introducing yet another hypothesis? Yes, indeed. But that is also how knowledge is built. And we noticed that those previously studying the porridge feud had apparently not considered, or at least described, flavor to be a motivation for how people cooked their porridge. Surely, trying to make something you eat 300 days a year a bit tastier could be a possible reason for doing things a specific way?

  20

  Doing the Dishes

  The meal is finished, and it is time to do the dishes (any volunteers?). After all this cooking with science, we would hope that chemistry could also help us clean up the mess. Science is a field of classification, so let’s start the dullest part of dining by classifying the dirt from dining. Food scraps can be seen as consisting of four main types of substances: fat and grease, proteins, carbohydrates, and burned residues in your pots and pans. And you have four different strategies to get rid of these sticky fellows, namely rinsing, dissolving, scrubbing, and breaking them down chemically.

  Fat and grease can be removed with traditional soap, those split-personality molecules with both a hydrophilic (water-loving) and lipophilic (fat-loving) part. The soap molecules are not truly dissolved in the water but rather form nanoscale particles, micelles, which are easy to rinse away. The lipophilic part aligns toward the fat, surrounding the microscopic (or nanoscopic) fat droplets while the hydrophilic part faces out toward the surrounding water. Thus, the soap molecules facilitate the marriage between the fat from the food and the dishwashing water that runs past, dragging some fat along with it down the drain.

  In dishwashers, a very different strategy must be applied for at least two reasons: firstly, the machine would face serious problems pumping and spraying soapy foam, and secondly it isn’t able to physically scrub the dishes. Instead, the detergent contains a basic (alkaline) substance that reacts chemically with the fat, basically converting it into soap, which is then rinsed away with the hot water. So, dishwashing detergents don’t contain soap, but some soap is produced along the way in a chemical reaction type called saponification. So, while hand-washing involves quite a lot of physical force combined with forming of dispersions, mainly foams and emulsions, machine-washing relies to a greater degree on chemical reactions between detergents and dirt.

  ^Soap molecules (black) have a lipophilic (fat-loving) and a hydrophilic (water-loving) part. The lipophilic part aligns in toward the fat, the hydrophilic toward the surrounding water. This way, the fat droplets follow along with the water.

  Proteins are large molecules, at least in the world of molecules, that are easily stuck to surfaces. When uncooked, they are dissolved in the water of the food, such as in a raw egg, and will therefore easily find their way into cracks and scratches. When the proteins are heated during cooking they coagulate and solidify—basically functioning as a glue that fixes the food to the surface. Scratches on the surface of kitchenware might be smaller than visible to the naked eye, even microscopic, but still large enough for proteins to have ample space to get a firm foothold.

  When you use fat for pan frying, the fat fills these scratches and, to a certain extent, obstructs proteins and other molecules from finding their way in. Coagulated proteins are not water soluble, and soaps or bases will not dissolve or break them down. Earlier, scrubbing was the most effective way to get rid of proteins, but the downside of scrubbing is that you scratch the surface and the kitchenware will be even more prone to sticking the next time you cook.

  Today, dishwasher detergents contain protease enzymes, a class of enzymes that break down proteins chemically, turning them into water-soluble and rinseable substances, or simply break them down enough for the dirt to come loose from the kitchenware. Indeed, this is the same class of enzymes also found in fruits such as kiwi and pineapple, making your mouth sore when you eat too much of it or eat it slowly because they start reacting with the proteins in
your skin to break them down. They are also found in carnivorous plants, allowing the plant to dissolve and make digestible the unfortunate insect that might fall in the “enzyme bath” usually found in the flower. And proteases function to tenderize meat as they break down muscle proteins, be it as naturally present enzymes doing their work during curing of meat or as deliberately added tenderizers in fresh meats.

  For a frying pan with stuck remains of an omelet, soaking it for extended time in warm water with some dishwashing powder might do the trick, if you have the time to let the proteases do their job. If you are a busy restaurant chef, scrubbing might be the only alternative. If so, using a scrub that is softer than the surface of the kitchenware is a good bet, as it would reduce the risk of further scratching.

  Carbohydrates are often not that difficult to get rid of. Many of them, such as sugars, are naturally water soluble. Larger carbohydrates such as pectin and cellulose do not burn and stick to surfaces as easily as proteins. The most challenging carbohydrates are perhaps sticky, gelatinized starch from starchy foods such as potatoes, cornstarch, rice, and flour. The long polysaccharide molecules dissolve in hot water and turn into hardened glue-like substances when drying. As for proteins in machine dishwashing, this challenge is solved using enzymes. Indeed, this is the same class of enzymes as those that turn starch into sweet sugars described in the porridge chapter describing enzymatic sweetening and the Finnish Christmas casserole: amylase enzymes. For the home cook who faces dishes with stubborn starchy residue, the strategy to clean is the same as for proteins: chemically by soaking in water with some dishwasher detergent, or, if you are in a hurry, using your muscles.