Since man created fire we have been observing, analysing and understanding the physical and chemical reactions during the preparation and cooking of food. From the most primitive of milled grain creating the first flour to the array we see on our supermarket shelves in contemporary society, we can track the new developments and understand of reactions throughout the cookery process and how to exploit them.
Throughout cookery of the some of the most seemingly basic foods we consume today we can see the physical and chemical processes live in action, when they work and when they don’t, as discovered during this study. We will be using a brunch classic, eggs benedict with sourdough and butter to demonstrate.
Isaac and Smith (1991, p59) identify some of the reasons why we alter the native state of foods;
- Preservation of foods
- Make food safe to consume
- Increased shelf life
- Make foods more palatable by improving smell, taste and texture
- Creating an increased variety of foods to satisfy ever demanding changes on food patterns, fads and tastes.
Although most of us understand cookery methods (boiling, roasting, frying) we do not often further consider the physical and chemical changes that are occurring during these processes beyond what we see.
The premise of this task seemed quite simple upon first glance, sure I can make poached eggs, hollandaise sauce and butter. I have tried to bake bread before so how hard could sourdough actually be? This mindset was the worst possible approach to this task, Murphies Law certainly paid me a visit. It took more than one attempt of both the sourdough and hollandaise sauce to get the correct combination of physical and chemical reactions resulting in a successful, complete and most importantly tasty dish.
Through this process of making the eggs benedict, we are exposed to several food science manifestations. The growth of food industry over the past few decades has seen and increased interest in food science and molecular gastronomy. The term molecular gastronomy is much more prevalent in todays foodie, blogger, cheffy world but what does is actually refer to in the realm of food science? Gisslen (2010, p79) suggests molecular gastronomy is the “selective use of technology and non standard ingredients to help enhance flavours, aromas, appearance and textures of natural foods”. But is there a difference between food science and molecular gastronomy? Herve This (2005) suggests that there is difference between the two seemingly similar concepts, with food science focussing on the properties of food and molecular gastronomy is the understanding the effects of cooking. Let’s look at the effects of cooking further throughout the process of making eggs benedict.
Who came first the chicken or the egg?
Eggs are involved in so many aspects of cookery and an essential part of many cuisines. Used in all aspects of sweet and savoury cookery, eggs are seen as a complete protein (Rombauer and Becker 1975, p2). The various uses of eggs in cookery make them the perfect medium for studying food science. During the process of making this dish eggs were used in two elements, using different cookery methods leading to different reactions and results.
We can see the process of denaturation occurring through the poaching of eggs. Scope (1993, p95) suggests denaturation is the destruction of the tertiary structure of a protein molecule and the formation of random polypeptide chains, the strains are aggregated physically (via thermal heat) and become tangled. The result is product which cannot denature any further. Mirsky and Pauling (1936, p440) support this concept, identifying that denaturation is defined by the change in solubility, i.e. we have taken the egg in its raw state, applied heat agitation causing the coagulation of the protein strands, creating its own skin, rendering it no longer soluble.
Egg as a protein in its native state.
Poaching is the cooking of food in a liquid below boiling point (Isaac and Smith 1991, p62). McGee (2004, p84) provides a poetic description of the process of protein coagulation, taking the liquid raw egg to its cooked solid state.
“when we heat the egg, all its molecules move faster and faster, collide with each other harder and harder, and eventually break the bonds that hold the long protein chains in their compact, folded shape. The proteins unfold, tangle with each other, and bond to each other into a kind of three-dimensional network.”
Here we have a short clip of the raw eggs becoming submerged in the poaching liquid, in this case simmering water and white vinegar. We can see the immediate coagulation of the whites, taking them from the liquid state to the denatured cooked state, no longer a soluble product.
The final product after the coagulation of protein strands is the perfectly poached egg, with the yolk still in a liquid state, but the whites firmed nicely.
The use of egg yolk only in the making of the hollandaise – butter emulsified into egg yolks (Ruhlman 2009) – will provides another example of the versatility of the egg. We again use the application of heat to physically transform from its native state to the desired taste, texture and consistency, but in a very different method. Further explanation and of the emulsification process is explained later, during the egg yolk stage of the sauce we gently apply indirect heat through the use of a double boiler method (simply a bowl over a pot of simmering water, but never touching the water). The heat thickens the yolk, vinegar and pepper mixture, creating a creamy texture which can be ‘ribboned’ when the whisk in pulled through it. Overheating at this stage will cause cause the eggs to coagulate, or what we know as ‘curdle’, the separation of solids and liquids (see image below as the first attempt of the sauce and the resulting curdle), this is the sauce breaking and often this is the point of no return. As Mirsky and Pauling stated, once denatured the product cannot be returned to it native state, so time to start again!
Flour Power.
Carbohydrates are oft seen as bad for the human body and health, however they play an essential role in providing energy for the body and breaking down of proteins. In the realm of food science carbohydrates can perform a multitude of functionalities including thickening, emulsification, suspension stabilisation, mouth feel and crispiness (Embuscado 2014, p2). Sourdough has its traditions dating back to Ancient Egypt in 1500 BC (kitchenproject.com, n.d), a society which was keen on fermentation with the production of basic beer like beverages also. In the process of making sourdough we utilise flour in two different ways.
Fermentation, the start of something great.
“Fermentation is a process in which microorganisms, in the absences of oxygen, generate energy by oxidising carbohydrates and related compounds” (Josephsen & Jespersen p27)
This was the most arduous part of creating this dish. It takes time, patience and undying attention. The starter is to be fed on a similar scale as a family house pet, and kept at the right temperature (somewhat difficult to do during a Queensland summer) in order to develop the right flavours and developed a natural yeast. There was a failed first attempt at the instant mashed potato method of creating a starter, just resulting a in wet mash, with no signs of any yeast development. Disposing of the potato flake method and reverting to the classic flour, water and (rice)malt extract successfully created a sourdough starter. The method used took about a week to fully develop, but the distinct yeast scent had started only a few days into the process, a good sign that fermentation was transpiring. Daily observation of the starter saw an obvious increase in activity from the forming of bubbles on the top (sugars converting to gas), indicating the culture was alive. With each feeding and refreshment of the starter the sour smell continued to strengthen, and the bubbles more resilient.
The stages of the making the sourdough starter.
Making the Sourdough Loaf.
The second use of flour is the making of the bread dough. This process utilises flour as the stabiliser and providing texture, flavour and crust. The physical process of coalescing occurs during this process, or what we know as kneading of the dough. We are bringing together the flour and starter culture to form our dough. By this stage the starter culture has developed a wild yeast, so the need for commercial dry yeast is not required. Bread is one of the most basic staple foods in the world, and after attempting this sourdough recipe one can appreciate the hard work involved in producing such high quality loaves consistently. The mixing and kneading process is an essential step in making bread. If the dough is not kneaded enough, the gluten in the flour is not activated, leaving the bread dense with a tight crumb.
Below we have a clip of the kneading process of the dough with two different recipes, the first is using the failed attempt at the potato starter, the second with the successful traditional flour based starter. The first dough failed in spectacular fashion with no rise when proved, or dextrinisation – due to starch modification (Tomasik 2003, p123) – occurring during baking time. The second attempt which used the suitably fermented starter resulted in a stunning crisp, brown, crust and the what seemed like the makings of a proper sourdough crumb inside the loaf (maybe a tad under kneaded). There was not quite enough rise, so the crumb was still slightly dense but well and truly on its way to a real sourdough loaf, with flavour and crust a familiar taste. There are certainly more elements involved in making sourdough from the start than anticipated and getting them close to right was certainly a learning curve in the kitchen!
Sourdough fresh from the oven
Butter Makes it all Better.
Gurr, Harwood and Frayne (2008, p1) define lipids as “a chemically heterogeneous group of substances having in common the property of insolubility in water, but solubility in non-aqueous solvents such as chloroform, hydrocarbons or alcohols”, or more commonly known as fat. During this process we liberally used butter. The first step was to make the butter itself, using two ingredients cream and salt. As a first time butter maker, the process of beater butter is quick and effective. Here we have a clip of the process (which in real time took approximately 10 minutes). We can see the point at which the physical separation of the fat occurs into butter and buttermilk, due to aggressive agitation.
The butter created is used in the final stage of completing our eggs benedict, completing the hollandaise sauce. At this stage we are looking at the emulsification process between our thickened eggs yolk and vinegar mixture and our melted (handmade) butter. In keeping with tradition of the rest of the cookery, it two attempts to make the sauce. The first attempt saw the splitting and curdling of liquids from solids when the butter was added to the eggs, resulting in vigorous whisking in attempt to coalesce, this was to no avail. The second attempt was much more successful, resulting in the perfect emulsification of eggs and melted butter to a thick and creamy sauce. The process of emulsification of lipids is a common cookery technique, not limited to the making hollandaise, think along the lines of mayonnaise with the use of oil.
Failed attempt, sauce split
Successful Hollandaise
The End Result.
Over four weeks of kitchen preparation time went into this attempt to make the classic eggs benedict. The end result was a preservative free, homemade delicious meal. The perfect execution of a denatured, coagulated egg combined with timely fermentation and dextrinisation of the sourdough all topped with a delightful emulsification of egg yolk, acid and lipids. The physical changes that occur from these kitchen basics is one of the most favoured brunch (or anytime) dishes due to the overall mouth feel (creaminess and umami from the hollandaise), flavour developed from the sourdough starts and crispiness of the dextrinisation of the crust and the perfectly soft cooked egg whites with the velvety, shiny yellowy yolk inside the poached egg.