Content
Weeks 1 and 2 were focused on the introduction to the module, setting up the stage for the future topics by recapping and covering chemistry concepts through online videos and readings. This includes chemical bonding of the molecules in food, physical chemistry, relevant thermodynamics such as phase diagrams, and calculations such as pH and water hardness (the amount of metal ions in our water supply/tap water).
In our reading ‘Chapter 15: The Four Basic Molecules’ of Harold McGee’s On Food and Cooking, the four basic molecules of food are 1) water, 2) lipids, 3) carbohydrates, and 4) proteins.
One common misconception are lipids. Lipids are hydrophobic molecules with long carbon-chains, and common names like fats, oils and fatty acids are classified under lipids. Some examples are beta-carotene, the molecule responsible for the orange coloration of carrots; vitamin E and cholesterol, a ‘dangerous’ molecule in high levels will result in heart disease.
As the saying goes ‘Too much of a good thing is a bad thing’, everything should be in moderation, including moderation.
Fats and oils triglycerides, molecules that linked together on a short backbone called glycerol. There can be up to three fatty acids that can be linked to glycerol. These triglycerides can be hydrolyzed, breaking it down to glycerol and fatty acids. Fatty acids can be saturated (sp3 carbons) and unsaturated (sp2 carbons).
Poly-unsaturated omega-3 fatty acids from fish are healthy fats due to their structures. As they are ‘curled’ and kinked up due to their alkene conformation, they are unable to fit and interact nicely together.
This is also why some meats can be kept longer than others. Beef have more saturated fatty acids compared to chicken, pork, or lamb, thus a longer shelf life as they are less susceptible to atmospheric oxygen oxidation.
In another reading ‘Chapter 3: Taste’ of Hérve This’ Note-by-Note Cooking, I learnt about the term ‘sapid’. A compound can be considered sapid if they bind to a receptor. But taste can appear if two small molecules work together to bind to two parts of a receptor.
I also got to learn about the many common chemical compounds and molecules hidden in daily food and beverages added as additives for various purposes. They are common labeled as E (number), and the first number classifies them into a certain category. ‘2’ belongs to the acids, and E260 is acetic acid or vinegar taste; ‘6’ belongs to the ‘Flavour Enhancers’, and E621 is the widely known monosodium glutamate (MSG); and ‘9’ belongs to the sweeteners, with E951 is aspartame commonly found in diet soft drinks as a sugar substitute. It helps to know what these ‘E’ additives are with a simple online search, and I hope that others taking this module would appreciate this information too.
Workshop
As part of our face-to-face tutorials, the module utilizes hands-on experiential learning through workshops. Our first workshop was a coffee appreciation workshop conducted by Swee Heng, the co-founder and director of The Coffee Roaster, a NUS alumni who opened his own café at AS8 in NUS.
He had us taste 2 different coffees, one from Brazil and one from Ethiopia, and have us described the aroma and taste profile of each coffee.
After that, Swee Heng gave us a lecture on coffee knowledge and appreciation, before covering coffee extraction theory in detail.
He covered the difference between Arabica and Robusta coffee species, one used for cafés and the other in local coffeeshops ‘kopitiams’ respectively. Probably Ya Kun uses Robusta, which is commonly known as Nanyang coffee as well. He provided us an introduction of the coffee belt in the Tropics, which has the conditions for growing coffee. Before moving on to extraction theory, he covered some common myths and facts of coffee.
For the extraction theory lecture, he covered the fundamental brew parameters such as water hardness, brew ratio, coffee grind size, brew time, brew temperature, and extraction pressure.
Just to briefly touch on some examples: brew ratio is defined as the mass of coffee to mass of the final drink. Risettro has a 1:1 ratio; Normale is 1:2; Lungo is 1:3; and a pourover is 1:14 or 1:17. This affects the overall concentration of compounds in the cup, affecting the overall taste profile of the extracted coffee.
Coffee grind size also affects the extraction of compounds from the coffee beans. The smaller the grind size, the more able water would be able to permeate the interstitial (between ground particles) and interstitial (into ground particles) sites of the coffee ground, extracting the soluble compounds out into the drink.
These are just two of many brew parameters affecting the profile of the coffee beverage.
I will cover more of these parameters in detail for Chapter 2 – Brewing and Fermentation.
Class photo in Week 1 Thursday, 16 Jan 2020, for our first class together.
Looking forward to the next workshop on the topic of fermentation!