Understanding Onions


Onions can be pretty confusing. We try to make it sense of 6 types.

Posted by Cuisitive on Sunday, 24 January 2016


How Caramelization works


Caramelisation is defined as the process of heating and cooking sugars until its browns and forms new flavour compounds’. A complex mix of flavour compounds develops when sugar oxidizes. The flavour profile that results is one of rich nuttiness, caramel sweetness and an intense brown colour.

Flavour generation is maximised only when a piece of meat reaches over 140°c and Maillard Reactions occur. As…

Posted by Cuisitive on Monday, 25 January 2016


Essentially the reaction relies on the removal of water through steam and the breakdown of the sugar. Caramelization is a non-enzymatic browning reaction. Caramelization occurs during dry heating and sustained temperatures to ensure the breakdown of sugars and the formation of new flavour compounds.


There are several types of sugar found naturally in ingredients. They include fructose, galatose, glucose, maltose and sucrose. Often when learning to cook, people are led to believe that caramelization depends on the addition of table sugar (sucrose) to an ingredient in order to encourage or instigate the process of caramelization. Luckily this is not the case as a huge range of ingredients contain some form of natural sugar that has the potential to caramelize.

  • Sucrose | 160° C, 320° F – Caramelization temperature

Sucrose is the most important sugar in plants. The most common way to extract it is from sugar cane or sugar beet. The final product goes through a process of purification and then crystallization.

Initially when sucrose starts to heat it will reach a stage of foaming or boiling. It begins to decompose into fructose and glucose resulting in water loss of individual sugar components. This sets off a series of new reactions that produce hundreds of new aromatic compounds that ultimately create the desired complex flavour profile known as caramelization.

  • Fructose | 110° C, 230° F

Found naturally in honey, berries, melons, sugar beet, sweet potato, parsnip and onion normally in combination with sucrose and glucose. Fructose is the sweetest sugar in nature (around twice as much as sucrose).

  • Glucose | 160° C, 320° F

A simple sugar found in plants. Along with fructose and galactose, it is among the 3 dietary monosaccharides absorbed directly into the bloodstream through digestion.

  • Galactose | 160° C, 320° F

Less sweet than fructose and glucose, Galactose is found in dairy products, sugar beet, gums and plant mucilage.

  • Maltose | 180° C, 356° F

It is the least common sugar found in nature. Maltose is usually found in germinating seeds.


Despite other ingredients like carrots and beets containing the highest concentration of natural sugars, the onion is the most common ingredient to be caramelized. The reason for this being the speed at which it can be heated, browned and plated. Within 5-10mins you can produce perfectly caramelized onions.

Ingredients that are high in sugar content but also high in water are usually not the best for caramelization as it is a dry heating process that benefits from a greater ratio of sugar over water content.

  • Carrots (sugar 5% | water 87%) and Beets (sugar 7% | water 55-65%)

Among vegetables these two ingredients contain the highest amount of natural sugar. They are excellent to use for caramelization as well as creating flavour compounds through the Maillard reaction.

  • Potatoes (sugar 1% | water 79%)

The golden brown colouration seen when potatoes are roasted is caused by caramelization.

  • The Alliums (Onion family) – Onions (sugar 5% | water 86%) and shallots (sugar 8% | water 80%)

As they are heated the strong pungent sulphur compounds dissolve allowing new sweeter flavour compounds develop and replace the bitterness.

  • The Brassicas (Cabbage family) – Brussel sprouts (sugar 2% | water 87%) and cauliflower (sugar 2% | water 92%)

Very popular caramelized. The sprouts benefit as they develop a greater sweetness that overwrites the often disliked bitter taste when boiled.

In addition apples (sugar 10% | water 84%), bananas (sugar 12% | water 83%), pears (sugar 10% | water 84%) and Plantain (sugar 15% | water 65%) are all very good when caramelized.



Several compounds have been identified that give the distinctive caramel aroma and flavour.

Diacetyl ( 2,3-butanedione) – Buttery or butterscotch flavour.
Esters and lactones – Alcoholic rum like flavour.
Furans – Nutty flavour.
Maltol – Toasty flavour.

Although these are some of the most important, over 100 flavour compounds have been identified that produce the characteristic caramel profile.


If sugars continue beyond their caramelization point it can lead to an eventual destruction and a burnt and bitter horrible result.


A lot of cooks confuse the two chemical processes. Simply put the Maillard reaction occurs when sugar breakdown and reacts with amino acids (proteins) such as the process of baking bread, cakes etc as well as cooking meat, whereas caramelization involves purely sugar. More often than not both reactions work in tandum and it becomes difficult to really establish the distinction when cooking many ingredients.