Food Browning is just not the same: Apple, Caramel pudding VS Roasted Coffee
Seeing food brown or develop brown texture is not something new to all of us, but did you know that browning that happens in Apple is different from what happens in Caramel pudding and what happens in Roasted coffee.
In Apple it is enzymic browning, in Caramel pudding it is Caramelization and in Roasted coffee, it is Maillard reaction.
Why Apple turns brown and how to prevent it ?
Enzymic browning happens when oxygen present in air and enzyme phenolase present inside cells of the apple comes together. When we slice an apple it exposes phenols and the enzyme phenolase in the cells of the apple. This reacts with the oxygen in the air converting the phenols into melanin, which has a brown color. Many fresh fruits like bananas and vegetables like potatoes also become brown when exposed to air as part of food processing or aging.
Since the coming together of the enzyme, plant cells, and oxygen is needed for this reaction to happen, preventing any one of them would help in minimizing or preventing the browning reaction. Since enzymes get deactivated by heat (blanching), exposing the fruit or vegetable to heat will prevent browning. Similarly by keeping them underwater or in the vacuum-sealed container will prevent contact with oxygen and thus can prevent browning. Also, storage at low temperature and the addition of sulfur dioxide, ascorbic acid, citric acid, sodium chloride, or combinations of these compounds will inhibit browning.
Why apple and knife both turn bluish black when cut with an iron knife ?
Cutting apples with an iron knife results in darkening of the blade and apple slice as polyphenols present in apple chelates iron and forms a bluish black iron complex.
How to set up a home experiment to explain Browning reaction to kids
1. Get some apple, or potato
2. Make four slices of them
3. Place them in four containers – a. open plate b. immersed in water c. immersed in sugar syrup d. immersed in lemon juice.
4. Leave it like that for 2 hours and note which slice of apple or potato gives strong brown color and which gives the least
5. Ask children to note down the color change and make a report of the same
How caramel pudding gets its color?
Caramelization happens when sugar is heated dry or in little solution. The caramelization process includes dehydration, fragmentation, and polymerization. Heating sugar dry at high temperatures is the quickest way to make perfect caramelization and a crispy exterior. The large quantities of industrial caramel color that are added to beverages (cola drinks), baked goods, and confections are made by heating high-conversion corn syrups in the presence of catalysts (acids, alkalis, salts).
How roasted coffee gets its color ?
[bctt tweet=”French physician and chemist Louis-Camille Maillard originally described how sugars react with amino acids.”]
Roasted coffee gets its color from Mailard Reaction. This reaction happens when reducing sugars and proteins comes together in presence of heat. The Maillard reaction starts with a reducing sugar reacting with an amine, creating glycosyl amine. The final brown product formed are often called melanoidins, indicating their visual similarity to the melanins of enzymatic browning. The Maillard reaction also creates, besides color, countless complex flavors. Colouration of foods undergoing roasting (coffee, cocoa, beans and cereals), baking (cakes and bread), or grilling (meats and cheese), are often caused by Maillard reactions.
Why food does not turn brown when cooked in a microwave oven ?
In the microwave, food gets cooked by heating water molecules in food, and therefore it has a 100°C temperature limit. Maillard reaction is typically only noticeable at temperatures above 120°C.
