Masala Lab

Cooking is ultimately the application of heat to physically and chemically transform ingredients into food.

The single most crucial process that turns ingredients into food - Heat. The transfer of heat from an energy source like a gas stove, micro wave, etc to your food.

Heat is energy. In an abstract sense it is the ability to make things happen.

Heat will move from a place where there is more to a place where there is less. This is simple Entropy.

Stoves and ovens are sources of energy that can chemically modify food, while refrigerators remove energy from your food and stall most chemical reactions. To know where all that energy goes, feel the back of your fridge.

If you touch a pan that is at 70°C, you will burn your finger badly. If you touch a pot of water at 70°C, it will mildly scald you, but if you put your hand inside an oven at 70°C, the air will feel only mildly hot. This is because of Density.

Density is a measure of how much substance there is in a given space. Metals are denser than water and water is denser than air. It has more molecules. More molecules moving around means that there is more heat energy, which is why metal at 70°C feels hotter than water at 70°C. This is precisely why cooking something dry on metal pans is the fastest way to cook (or burn) food, while boiling something in water takes more time, and baking in an oven takes even longer.

Specific heat capacity is the amount of energy required to raise the temperature of a substance. Water has high SHC. Steel has low SHC. This is what we mean when we say that metals are good conductors of heat.

Air pressure is the measure of the amount of force experienced by anything as a result of the weight of air above it. This is important to cooking because of how water behaves at low or high air pressures. The boiling point of water fluctuates based on the air pressure. With high air pressure its more than 100°C. In high altitude areas, the boiling point drops below 100°C.

Air becomes thinner the higher you go, which is why planes need stored oxygen and cannot merely open some windows to let air in.

Heat transfer mechanisms

Conduction is the transfer of heat from a solid to any other substance via surface contact. When you heat a pan its molecules starts moving around furiously. They collide with the molecules of the oil you our on the pan to transfer some of those heat to the oil.

Convection is the transfer of heat from a liquid or gas to your food. Because liquids and gases have molecules that are farther apart, the transfer of heat via conduction, where molecules close to one another happily collide and heat things up, is not as practical, so the transfer of heat in water happens via bulk movement of molecules from the hotter parts of the liquid to the cooler parts.

The third mechanism for transferring heat is Radiation. Electromagnetic waves with high-enough energies can transfer heat directly to your food, provided they are close enough to the source. Oven works with this principle. Your Shawarma stick is heated up with the glowing orange thing it rotates in front of.

Technically microwaves also work by the same principle of electromagnetic waves. But they belong to their own category because they themselves don’t have enough energy to heat things up. They have less energy than a toaster. But they are good at getting the water molecules in the food to align with the magnetic field they create. When it rotates inside, the water molecules constantly flip/move to re align themselves to the magnetic field. This movement basically generating energy, energy is heat. It heats up the water molecules in the food. Which is why microwave doesn’t work on food with low moisture.

The 4 major chemical reactions that happen when you cook food:

Starch Gelatanisation

This is what happens when you cook starches like rice, wheat, lentils etc in water. Long starch molecules break up in the presence of water and heat. And some part of their molecules form hydrogen bonds with water. This is why cooked rice or dal increase in size.

Protein Denaturation

When heat or acid is applied to proteins, its complex structure starts to unfold. You can notice this when you put Vinegar in milk and see it crumble into Paneer. Or how meat becomes hard when you cook it.

Hydrolysis

This is the next step after Protein Denaturation when you continue to provide heat, the meat becomes more tender when connective tissues break into Gelatin. This process can also be accelerated by use of enzymes, which are basically proteins that can assist the hydrolysis reaction. Bromelain found in Pineapple juice, and Papain found in Papayas are used to tenderise meat this way.

Hydrolysis which also happens to Sugar and fat is enabled by a strong acidic environment. Which is exactly what happens inside your stomach with the 2 litres of Hydrochloric acid that it produces every day.

Maillard reaction

This causes onions to brown or your chicken to sear in a pan. It causes browning of food and a host of delicious aromatic by-product. It happens between 110°C - 170°C

Molecules are combinations of atoms that have formed bonds with each other until heat, enzymes, acids or bases do them apart. And

The simplest explanation of a Chemical bond is that it is a transaction involving atoms greedy for electrons and atoms that are generous donors of electrons.

Types of bond

1. Ionic bond - Strongest kind of bond. Found in Sodium chloride (salt)

2. Covalent bond - Slightly weaker. Found in water

3. Hydrogen bond - Again found in water, where hydrogen and oxygen form side relationships with other water molecules’ hydrogen and oxygen atoms

4. Van Der Waals - Weakest of the lot. But crucial in cooking because this is how fats get their viscous texture

Types of cooking

1. Moist: Blanching, Poaching, Simmering, Boiling, Steaming, Braising, Stewing, Pressure-cooking. Maillard reaction doesn’t happen in moist cooking. Vegetables get soft and meat gets hard and dry (unless you maintain the temperature below 70 C)

2. Dry: Sautéing, Roasting, Baking, Broiling, Frying, Smoking

Ways of cooking

1. Slow cooking: Cooking mutton for a Biriyani at low heat for 45 mins

2. Fast cooking: Deep fry, baking in Tandoor

Heat behaves with different ingredients

1. Adds flavour to meat and fish to a point, after which it makes them dry and chewy

2. Mutes the flavour of Onion and garlic. The raw ingredients are very over powering otherwise

3. Significantly improves the favour of Cabbage and Tomato

4. Adds bitterness to green leafy vegetables. Should only heat them sparingly.

Materials

1. Its quicker to get Aluminium heated up compared to stainless steel

2. Aluminium loses heat very quickly once you simmer down. Stainless steal stays hot for longer and takes some time for its temperature to go down. This way Aluminium is great for avoiding scorching.

3. Aluminium and cast iron will react with any acid in your food (tomatoes, tamarind, etc) and produce off-putting metallic flavours. Stainless steel doesn’t react to food at all. So your material will decide what you can and cannot cook in them.

4. The Teflon coating, especially on cheaper non-stick utensils can disintegrate with heat, over time. The toxic fumes released with it can apparently kill a small bird. A ceramic non-stick skillet is a better alternative.

5. Cast iron retains heat insanely well, reacts with acid and weighs a ton

6. Tri-ply brings stainless steel and aluminiums advantages but costs a lot.

7. Copper is a great conductor of heat, reacts with acids and costs much much more.

Bare minimum cooking essentials

1. Kadai

2. Flat-bottomed frying pan

3. Saucepan

4. Pressure cooker or pressure pan

Additionally:

1. Stock pot

2. Steamer or steaming stand

Essentials for the science minded home cook

1. Instant read thermometer

2. Weighing scale

3. Tongs

4. Silicone Spatulas

5. Mandoline slicer

6. Citrus Juicer

7. Spice Grinder or coffee grinder

8. Microplane Grater

2023-10-07

The heat transfer in an induction stove is entirely different from that in a gas stove. In a regular stove, the gas burns, heating up the entire vessel and then the heat is transferred to the food. But in an induction stove, and AC current flows through a copper coil and creates an oscillating magnetic field in its vicinity. When a cooking vessel made of magnetic material (cast iron or steel) is places on the stove, the magnetic loop induces an electric current which flows around in a loop into the pan. A current flowing through any material runs into an electrical resistance that produces heat. In simple terms the pan literally heats itself because of the currents induced into it by the wireless oscillating magnetic field. Its very different from the heat transfer that happens in a traditional stove setup. This is why the induction glass top doesn’t get as hot. Whatever heat it retains is simply the heat transferred back to the glass surface by the utensil. Induction heating is the most efficient and fast form of heating. Water will boil 3-40% faster than through stove.

Most fruits and vegetables are more than 80 percent water by weight. A carrot has roughly the same proportion of water as milk (around 88%). A cucumber contains more water (95%) than the hard, mineral-heavy tap water you find in an Indian city.

The magic of water

1. It is extraordinary that it is liquid at temperatures human being tend to be comfortable in. Most substances similar to water in chemical structure and simplicity, and not made of metals, are gases. (CO2, H2S, etc).

2. In liquid state the oxygen in water (H2O) is rather greedy. It forms a V-shaped bond with 2 hydrogen atoms but also shamelessly tries to bond with other neighbouring hydrogen atoms. Kinda polygamous. They constantly form and break hydrogen bonds like the characters in Archie comics.

3. But as temperature falls they bond with hydrogen in a specific orientation with strict military discipline. This is why ice floats on water. Just a like a wooden board will.

4. Another astonishing property of water is that its solid form is less dense than its liquid form. Normally solids tend to be denser.

5. Water has high specific heat capacity. This feature, rather important in the Kitchen, is also critical to the planet. It’s because we have so much water on the surface that a place like Mumbai has mostly predictable temperatures, while Bhopal can swing wildly not just across seasons but in a single day.

6. Anything with more water cooks slower than anything with less water. This is why garlic, which has less water by proportion, must be added after the onions have cooked, or else it’ll likely burn.