The Maillard reaction: how sugars create flavour and colour in foods and beverages 

The Maillard reaction is one of the main processes through which food develops a browned colour, a roasted aroma and complex flavours during heating. It is a reaction between reducing sugars and amino acids, peptides or proteins, and is influenced by temperature, time, pH, moisture and the type of sugar used.  

In food and beverage manufacturing, the Maillard reaction helps create the flavour and colour associated with bread crusts, biscuits, cookies, roasted malt, coffee, chocolate, sauces, glazes, meat coatings, confectionery and baked goods. Rather than a byproduct of the heating process, it is a controllable part of product development, processing and quality. 

The Maillard reaction is a non-enzymatic browning reaction between a reducing sugar and an amino compound. It begins with the formation of unstable intermediates, progresses through several reaction pathways and can eventually form brown compounds known as melanoidins. 

Maillard browning is caused by reducing sugars reacting with amino acids under heat. The reaction forms many intermediate compounds before producing brown nitrogen-containing polymers known as melanoidins, which contribute to the colour of browned foods.  

The detailed chemistry is complex, but the practical point is straightforward: the sugar source, amino acid or protein source and processing conditions work together. Changing one variable can alter colour, aroma and flavour, even when the rest of the recipe remains unchanged. 

Maillard browning can be encouraged or limited by adjusting: 

Sugar selection can influence the Maillard reaction because different sugars behave differently under heat and in solution. 

Reducing sugars are the most directly involved in Maillard browning. Glucose and fructose are reducing sugars, which means they can react with amino compounds in the first stage of the Maillard reaction.  

This is why ingredients containing glucose and fructose, including invert sugar syrup, can influence browning and flavour development in heated products. Depending on the formulation, Ragus invert sugar syrup can support sweetness, moisture retention, crystallisation control, texture, fermentation, colour and flavour development.  

Sucrose is made from glucose and fructose, but it is not a reducing sugar while those components remain bonded together. Inversion breaks that bond, creating glucose and fructose. Full and partial invert sugar syrups therefore differ functionally from liquid sucrose syrup. 

Depending on its composition and application, invert sugar syrup can support sweetness, moisture retention, crystallisation control, texture and fermentation as well as colour and flavour development. This combination can be useful where a manufacturer needs to adjust browning without considering sugar in isolation from the wider product specification. 

Glucose syrup contains reducing carbohydrates and can contribute to Maillard reactions, depending on its composition and the product matrix. It can also provide body, viscosity, humectancy and texture, particularly in bakery and confectionery applications. 

Golden syrup, black treacle, cane molasses and molasses-containing sugars such as muscovado and soft brown sugars can bring existing colour and characteristic flavour alongside their processing functions. A dark finished colour may therefore result from Maillard browning, caramelisation, the ingredient’s natural colour or a combination of these effects. 

Raising temperature generally accelerates browning, but the heating profile matters as much as the peak temperature. Short, intense heating can produce a different result from a longer, slower process. Product thickness, equipment and surface heat transfer also influence the reaction. 

High moisture can slow browning by diluting the reactants and absorbing heat during evaporation. Very low moisture can restrict molecular mobility. This helps explain why a bread crust or biscuit surface browns differently from a moist filling, even when related ingredients are present. 

More alkaline conditions can accelerate some Maillard pathways, while acidic conditions can slow them. Proteins, amino acids, minerals and other ingredients also affect the result. A sugar substitution should therefore be assessed in the complete product and production process. 

The target is controlled sensory development and batch consistency. Excessive browning can create unwanted bitterness or an over-dark appearance. In certain heat-processed starchy foods, browning targets also need to sit within the manufacturer’s acrylamide mitigation controls. 

These reactions can occur in the same product, but they are chemically different. Distinguishing them helps a formulation team understand whether colour and flavour are coming from reducing sugars and proteins, heated sugars, starch breakdown or the colour already present in an ingredient. 

In bread, biscuits, cookies, crackers and baked cereals, Maillard chemistry contributes crust and surface colour, baked aroma and toasted flavour. Sugar selection can also affect softness, moisture retention, crystallisation and shelf life, so the correct ingredient depends on the full product brief. 

Heated sauces and glazes may combine Maillard flavour with caramelisation and the natural colour of treacle or molasses. Sugar ingredients can also influence viscosity, gloss and adhesion. The formulation must balance the required sweetness, savoury depth, colour and processing behaviour. 

Toffees, fudges, fillings and coated products use controlled heating to build flavour and colour. Invert sugar syrup, glucose syrup and golden syrup may also be selected for texture and crystallisation control, making the browning response one part of a wider technical decision. 

Maillard reactions during malt kilning and roasting help shape beer colour and flavour. Added sugar ingredients can contribute fermentability, body, colour or flavour according to the required beer style and production process. 

A research and development team should start with the required finished-product performance, then consider how the sugar will behave alongside the proteins, moisture, pH and heating conditions in the formulation. 

Bench and pilot trials remain essential. The same sugar ingredient can behave differently when protein source, water activity, pH, equipment or process time changes. 

Our technical and customer service teams can help you assess the sugar functions required by your product and process, from browning and flavour development to moisture retention, viscosity, crystallisation control and fermentation. To discuss an existing formulation or a new product brief Contact our Customer Services Team to learn more, continue browsing SUGARTALK and follow Ragus on LinkedIn.