Creating confidence in chemistry among students using ‘unboiling’ versus ‘unfrying’ of an egg: seasoning a food-science workshop with inquisitiveness, experimentation and research-dependent applications

Introduction – why food science?

Food content has always dominated viewership on television channels. According to Broadcast Audience Research Council (India), data with respect to the Lifestyle genre in Week-3, 4 of 2021(Saturday, 16th January – Friday, 29th January), the top five eyeball grosser were TLC, Zee Zest, Food Food, TLC HD World, Fox Life^[1] – all of which allow food shows to rule the roost. This is a rule rather than an exception. As an audience, the age-group of 2–14 years accounts for 20% of total TV impressions here – the highest share across all age cuts.^[2] Food science, particularly the chemistry of cooking is thus an ideal subject matter for introduction of practical chemistry to this group. What makes it so acceptable to a general audience, even those with largely a neutral to negative attitude to science? Along a few other advantages, Arthur E. Grosser (1984) emphasizes, “It presents science applied to matters which are personal, nonthreatening and small-scale, in a word, ‘domestic’… reveals to the audience that they are practicing chemists whenever they prepare a meal” (Grosser, 1984). “Few people”, Grosser goes on to reason, “in such an audience will have personally formulated a face cream, cracked a hydrocarbon, radio-dated a relic or taken a ride in a rocket, but all of them will have cooked something”.

Since food already takes up 16% of our waking time and we go through around 20 tonnes of it in our lifetime, this time on 16th October 2020, the World Food Day, we at the Birla Industrial & Technological Museum, Kolkata, under the aegis of the National Council of Science Museums, India, dedicated an online Science Workshop to food – we called it Incredible Edibles. Aiming to ‘lift the lid’ on its science and ‘bite deeper’, we explored food as a chemical store-house, employing complex physics, imbibed in a fascinating biological specimen.

Our methodology – food fables & facts

Registration to the online workshop was welcome from interested school-students through a questionnaire-cum-enrolment Google Form (Figure 1), aiming to test some prevalent ‘food-myths’ and eventually debunking them during the Workshop. This served the dual purpose of acquainting the audience with the topics to be discussed in the interactive-sessions and helped them come better informed. We emphasized that behind most food and nutrition myths, there may or may not be a kernel of truth. We formulated the questions as below, encouraging the prospective participants to “talk food – because many of the fables you already know may really be fictitious”. Participant responses from 50 students were registered as indicated.

Figure 1:

Preview of the Workshop’s questionnaire-cum-enrolment Google Form.

(Picture courtesy: Birla Industrial & Technological Museum, Kolkata).

These responses (Table 1), from students aged 11–18 years, attempting to enroll for the workshop, clearly indicated that they were well-versed in the basics of food-science. From the objective of cooking, the fundamentals of digestion, idea about nutritional value of food, purpose of various food components and even the implications of food-browning – our audience were mostly informed in the culinary chemistry of common food-stuff. It took some more questions – those detailed below – to reveal the slippery areas (Table 2). The items they dealt with were still regular kitchen staples: sugar, chillies, mustard, fats and eggs. Yet separating the facts from the fables had proved a little more difficult in these cases.

Divulging the responses obtained for each question during the discussion helped to bust some of the common food-myths. We followed it up by using fruits, vegetables, leavening agents, condiments, surfactants, oils, food-colours and seasonings in live-science demonstrations to elucidate redox reactions, catalysis, neutralization reaction, polymer-isolation, electrolysis, diffusion and even the presence of polarized molecules in solutions. We reasoned and showed them how and why scientists had already managed to ‘unboil’ an egg, but will never attempt to ‘unfry’ it – completing the culinary journey with a video-tour of a laboratory that routinely does unboil their eggs.

Live chemistry – fresh from the kitchen pantry

If cooking is an experimental science then the kitchen is the most accessible laboratory globally. The kitchen pantry is the classical cabinet-of-curiosities for any science enthusiast. For our online Workshop sessions, it made sense to raid our pantry and come up with experiments that celebrated the everyday staples and revealed the chemical complexities that make them function.

We started with a discussion about ‘Science in your Cupcake’ (Figure 2). The common ingredients required for baking – flour, eggs, butter, sugar, milk and yeast – the participants were familiar with them all. It was here that we began linking them to science and equations. We highlighted that by controlling the elastic modulus (E) of aerated versus runny flour batters we may end with spongy or moist cakes. The transformation of the egg phase from liquid to solid is a function of temperature (T), as is the melting of butter in response to the addition of thermal energy (Q) and the distance travelled (L) by sugar solution while diffusion in the baking batter. Bubbles and droplets both play their part in increasing the volume fraction of emulsions like milk, helping us turn them into whipped cream by controlling their elasticity (E). Number of microbes (N), like yeast, grows exponentially and aid in aerating and/or spoiling food-stuff on prolonged exposure – all determined by physical-chemistry.

Figure 2:

Linking science-equations with baking ingredients.

(Customizable template courtesy: Slidesgo and Freepik)

E = elasticity, k _B  = Boltzmann constant, l = crosslink spacing, η = viscosity, τ _flow  = time scale for material to flow, U _int  = molecular interaction energy, C = empirical constant, T = temperature, Q = thermal energy transferred, m = mass, c _p  = specific heat capacity, ΔT = change in temperature, L = distance of diffusion, D = diffusion constant, t = time elapsed, σ = surface tension, R = radius of droplets or bubbles, ϕ = volume fraction, ϕ _c  = critical volume fraction, N = number of microbes in the population, N ₀  = initial count of microbes, k = microbial growth constant and τ ₂  = microbial doubling time.

Yet, food is more than just physical-chemistry. It may be a polymer, protein, polyelectrolyte or carbohydrate along with a myriad of varieties in between. Food structure is defined in part by natural self-organization and molecule-driven non-equilibrium processes, active during food-processing (Vilgis & Limbach, 2016). We explored the functional-chemistry of some food items (Figure 3, Table 3) in the following live-science demonstrations:

Figure 3:

Demonstration of the ‘vitamin-C imprinting’, ‘baking powder-vinegar balloon’ and ‘electrolysis of salt-water with turmeric indicator’ experiments, while the foam arising from ‘elephant toothpaste with yeast’ is seen in the background.

(Picture courtesy: Birla Industrial & Technological Museum, Kolkata).

Unboiling versus unfrying eggs – a chemical conundrum

Although boiling eggs might not sound otherworldly, it is actually an extraordinary cooking process. Turning up the heat on egg whites, mostly a sea of water (88%) and proteins (11%), frees up the weekly bonded proteins to unfold, uncoil, unwind and wiggle freely. This denaturing – changing at the molecular level – is mirrored at the visible level and we observe the semi-fluid egg-white turning firm and resilient. Or, as Arthur E. Grosser (1983) put it, “… hordes of water molecules carom off each other and the proteins in frenzied and chaotic collisions. As the temperature increases, the action becomes more energetic until a molecular demolition derby is under way. The weak internal bonds of the egg protein can no longer hold the ball together, and it opens out into a floppy streamer” (Grosser, 1983). Grosser further acknowledged that the difference between the semi-fluid raw egg and the semi-rigid cooked one is just the difference between the natural sea state of the protein balls and the network that heating has driven them into. This follows first-order kinetics, as proposed by Lumry and Eyring (1954):

where N, U, D, and A are native, unfolded, denatured, and aggregated protein forms, respectively, and k₁, k − 1, and k₂ are the rate constants for the corresponding reactions. The chemical identities of the proteins remain unchanged until denaturation (D) and aggregration (A) stages – no new compounds are generated until this point. The rate at which these proteins denature is strongly temperature dependent. As reported in Protein Science (2003) (Weijers, Barneveld, Cohen Stuart, & Visschers, 2003), at 80 °C, half of the protein is denatured and aggregated in less than 2 min, while at 68.5 °C this takes approximately 6 h. Thus, as per the principle of microscopic reversibility, any seized egg-white protein in unfolded (U) stage can theoretically be made to ‘unhappen’ by retracing the steps. Beyond this point, the protein-structure changes are irreversible.

But simply heating or cooling the cooked egg-white will never be enough to ‘unboil’ it. As Gregory Weiss, a chemistry professor at the University of California-Irvine, inspired by a collaborator’s use of a vortex-fluid device (Figure 4) to pull apart other kinds of complex structures discovered in 2015 – it takes rotational energy to undo what thermal energy had done to the proteins.

Figure 4:

Extracted from the original 2015 paper by Weiss and his team, schematics for protein refolding in vitro with the vortex fluid device, generating shear flow inside thin fluid films (shaded).

Dissolving boiled egg-whites in urea allowed the proteins to glide past each other like a lubricant. They were then spun at break-neck speeds of around 5000 rotations per minute in the vortex-fluid device. This modified centrifuge caused solutions near the tube-walls to spin faster than those in the middle of the tube. This gave rise to sheer-stresses that repeatedly stretched and contracted the proteins, causing them to snap back into their native configurations and stay. This finely controlled level of shear stress to refold proteins promises to transform industrial and research production of proteins, prompting Weiss and his team to report as follows (Yuan et al., 2015):

Recombinant protein overexpression of large proteins in bacteria often results in insoluble and misfolded proteins directed to inclusion bodies. We report the application of shear stress in micrometer-wide, thin fluid films to refold boiled hen egg white lysozyme, recombinant hen egg white lysozyme, and recombinant caveolin-1. Furthermore, the approach allowed refolding of a much larger protein, cAMP-dependent protein kinase A (PKA). The reported methods require only minutes, which is more than 100 times faster than conventional overnight dialysis. This rapid refolding technique could significantly shorten times, lower costs, and reduce waste streams associated with protein expression for a wide range of industrial and research applications.

True enough, the implications of protein folding go beyond the whimsical un-cooking of our breakfast. Like a lock-and-key mechanism, proteins work best when folded in the right shape. Alzheimer’s disease, Huntington’s disease, Mad Cow disease and amyotrophic lateral sclerosis are all associated with misfolded proteins that build up in or around neurons and interfere with their function. On the other hand, correctly folded proteins like those of insulin prove to be life-savers. Protein therapeutics help treat multiple sclerosis, autoimmune diseases, osteoporosis, cystic fibrosis, and a host of other conditions.^[3] Hence the stress on understanding protein folding and ‘unboiling’ eggs.

Coming to ‘unfrying’ of eggs – that’s a different ball game altogether. Fried eggs owe their tan to the non-enzymatic browning process called Maillard reaction. The reaction owes its nomenclature to the French scientist Louis Camille Maillard, who, as part of his PhD thesis, studied the reactions of amino acids and carbohydrates in 1912. Typically described as a series of reactions between amino acids (proteins) and reducing sugars, the Maillard reaction sets-off a flavour-frenzy because of the production of many new compounds during the process.

The concerned molecules breakdown (Figure 5) and rearrange (Figure 6), forming ring-like structures, which reflect light in a way that gives away their tell-tale brown colour. This is in sharp contrast to the denaturing of egg-whites – boiling eggs only change the network of protein molecules without affecting their chemical composition – there are no new compounds formed during reversible unfolding of the proteins. The moral of this culinary-story, chemistry allows us to ‘unboil’ eggs, but never to ‘unfry’ it. We presented this up close by taking our participants on a video-tour of unboiling an egg-white using the vortex-fluidic device in lab-settings, courtesy of the Australian Academy of Science.^[4]

Figure 5:

During the Maillard reaction, the carbonyl group on a sugar reacts with a protein or amino acid’s amino group, producing an N-substituted glycosylamine and water.

(Graphics courtesy Wikimedia Commons, author: Matthewslf, 2015).

https://en.wikipedia.org/wiki/File:Maillard.svg.

Figure 6:

The glycosylamine compound generated in the previous step isomerizes, by undergoing Amadori rearrangement, to give ketosamine, which yield an array of new products under various conditions.

(Graphics courtesy Wikimedia Commons, author: Rajatkrpal, 2021).

https://en.wikipedia.org/wiki/File:Dicarbonyls-correction.png.

Analysis of feedback – how we fared

We had analyzed the pre-Workshop responses to understand our audience and tune the sessions as per their understanding and still remain true to our basic objective of introducing chemistry concealed in food-science. Live demonstrations employing fresh food-items were expected hits – we have seen children and adults react favourably to our regular chemical demonstrations too. What we were more skeptical about were the contrasting chemical reactions introduced with respect to the two techniques of cooking eggs. We had highlighted the chemical alliances taking place during the reactions and had given them an online-tour inside a lab equipped with the vortex-fluidic device, to experience the processes associated with egg-unboiling virtually. Had we done enough? Did we go overboard in our zeal of introducing the subtle impacts of chemistry in modern-applications? We decided to test it out by requesting the participants to register their post-Workshop experience in another questionnaire, with a caveat – “… no sugar-coating it please”. We really wanted to know how we had fared and which areas should we focus on in the coming days. Twenty two participants told us and this is what we had scored:

Figure 8 shows a clear majority of the participants had admitted to having their food-fables being proved fictitious during the workshop. Figure 7 indicates that the tone and tenor of the sessions were successfully modulated to highlight the ‘science of food-items’ instead of either food or general-science alone. This must have struck a chord with the participants – Figure 9 confirms that 73% of them wanted to return for a ‘longer, deeper and premium session dedicated to food-science in future’. Figure 10 proves, with around three-quarters of votes going to ‘Chemistry’ and ‘Cooking-Techniques’ as future Workshop focus-areas, a winning combination is possible in the form of creative and sustained efforts in such food-based science-workshops.

Figure 7:

Participant responses showing ‘highlights of the workshop’.

Figure 8:

Participant responses validating the inclusion of myth-busting activities.

Figure 9:

Participant responses justifying repeat food-science workshops.

Figure 10:

Participant responses aspiring for ‘chemistry’ and ‘cooking techniques’ as future areas of focus.

Conclusion – the Incredible Edibles experience

Our experience in Incredible Edibles showed that addressing common food-myths and spectacular expositions – in food shows and popular demonstrations alike – play a huge role in disseminating the love of food-science in the audience. Yet, a creative, inquiry-driven approach – starting off with something as mundane as the cooking of an egg – can also be used to impart science-education in general, while fostering the public understanding of science, as well as an in-depth appreciation of the challenges, advances and applications of modern-day chemistry.

Miles away from the traditional approach of using burettes, pipettes, test-tubes and flasks for practicals, our online science-workshop initiated a dialogue on regular food-stuff and highlighted their not-so-regular chemistry. To illustrate their far-reaching implications, the tactile medium of food proved to be an engaging tool for effectively communicating the molecular basis of related science concepts. The advantage associated with food-based science workshops was that the familiarity and tangibility associated with the substrate encouraged students to ask questions and scientifically reason out the efficacy of cooking protocols. As one of the participants gushed after the session, “(Incredible Edibles) opened a whole new world of food. We cannot think of relating science to food, but this workshop taught me to do so. With an innovative experience in this interactive session, I will always look forward for such interactions …”^[5]

We had to conduct the session online, around seven months into the COVID-19-induced museum lockdown. Utilizing the empty laboratory benches for conducting live-experiments, we had borrowed fresh produce, condiments, vegetable-oil and glassware from the canteen facility and utilized whatever residual chemicals were in stock. We improvised and strategized along the way – replacing food-colourings with leftover transparent photo-colours or swapping glass-rods with borrowed Popsicle sticks (Figure 11). Implementing such a workshop would thus also be possible in any large kitchen facility – perhaps the school cafeteria, or be assigned as do-along activities for students to be replicated in their home kitchens. Going forward, we hope to extend this experience to participants physically, whenever we are ready to welcome them back to the museum premises for hands-on science-workshops. The greatest advantage of such a chemical adventure, as Arthur E. Grosser (1984) validated, “… it is amenable to unsupervised experimentation in the home when presented in a precise manner” (Grosser, 1984).

Figure 11:

Improvised food-science workshop lab set-up, featuring leftover transparent photo-colours illustrating the properties of emulsions and borrowed Popsicle sticks holding-up the banana DNA.

(Picture courtesy: Birla Industrial & Technological Museum, Kolkata).

The molecules we eat determine far more than food texture and flavour. They perform a host of essential physiological functions – first as part of the live plant or animal source and then, as minerals in our body. Capable of captivating the attention of a wide variety of audience, food even proves to be an ideal, inexpensive tool for experimentation. As Rowat (2012) put it:

“Understanding the physical and molecular origins of the texture of cells, tissues, and biological materials is a major focus of research in our laboratory. Naturally, the major themes of our research share many commonalities with food; our findings may thus also provide unique perspective into the foods that we eat.”

Our online food-flavoured science-workshop had managed to do just that. By contrasting and exploring the denaturing of egg-proteins as part of an ideal initial exposure to culinary alchemy, it had aggregated the knowledge of chemistry in the workshop participants, piqued their inquisitiveness and fostered its applications in erstwhile unfamiliar and uncharted territories. Ideal for general audiences (“popular science”) or academically inclined ones (“research oriented”), by drawing chemistry principles from cooking experiences, workshops like Incredible Edibles are ideal for illustrating the intricacies that are the hallmarks of pure and applied science.