Sucrose esters in fondant, fudge and chewies
Sucrose esters of fatty acids, commonly known as sucrose esters (E473), are a special type of emulsifiers. The most notable aspects of sucrose esters are their water solubility and high HLB value. Sucrose esters are produced from sucrose and edible oil and are therefore an ingredient that naturally fits into sugar confectionery. Sucrose esters have several benefits in food besides emulsification, such as starch interaction, protein protection, sugar crystallisation and aeration. In confectionery products like fudge, chewies and fondant sucrose esters have three distinctive functions: improved crystallisation, excellent emulsification, and anti-stickiness. All three effects will be described in this article.
Confectionery products such as chewies, fudge and fondant, are basically made up of a matrix of very small sugar crystals. This matrix entraps moisture, fat and other added components and thus largely determines the texture and stability of the confection.
In the production process, crystallisation is often initiated by adding fondant combined with pulling, kneading, cooling and drying of the confectionery mass. Completion of this sugar crystallisation is a time and energy consuming process. A fine sugar matrix gives a confection with a smooth, soft texture. A rough sugar matrix will result in a coarse or gritty product. During storage bigger sugar crystals form, as small sugar crystals partly dissolve in the remaining water and re-crystallise into bigger crystals. Over time the confection could become gritty and hard and moisture or fat can separate.
Sucrose esters and crystallisation
Sucrose esters can positively influence the sugar crystallisation from the initial crystal forming up to the stability of the sugar matrix of the confection during storage. They effectively interfere in the initial crystallisation, also known as ‘graining’ of confection. At very low dosages, sucrose esters actively start the formation of the first nuclei, by expansion of the metastable (over-saturated) phase. These nuclei promote further sugar crystallisation, and with more nuclei, crystallisation will be accelerated and the average crystal size will be smaller.
The acceleration of crystallisation has several benefits:
- Toffees or fudges become solid more quickly after cooking. This prevents sticking on transport lines and cutting devices. Production stops to clean equipment are needed less frequently. Also further processing like wrapping or coating can be done with reduced or no further maturing.
- Pulling or kneading time of chewies can be shortened.
After graining sucrose esters prevent the crystals from growing. The sucrose part of the sucrose ester molecule fits in the orderly form of the crystal, at the same time, the long fatty acid tail of the sucrose ester disturbs further growth of the crystal, by forming a ‘film’ around the crystal. This results in a stable matrix of small sugar crystals for a long time.
The improved sugar matrix has several benefits:
- An improved whiteness of fondants.
- A very smooth non-grainy confection.
- Less issues with fat or moisture separation in fudges or fondants.
- Delayed hardening in chewies, fondants and fudges.
- More stablility in extreme conditions (high temperatures).
Fudge, toffee, caramels and chewies contain fat. The fat is kept inside the sugar matrix, which can be a challenge at varying storage temperatures. If the fat seeps out of the matrix, the fat becomes visible on the outside of the candy. The appearance of the candy becomes very unattractive when that happens.
For health reasons this (hardened) fat is sometimes replaced by oil. Traditionally some types of candy are produced with butter. Both oil and butter are more susceptible to oxidation, with an off flavour as the direct result. Rancid components that are formed by oxidation can ruin the flavour very quickly, while the shelf life needs to be long.
Being water soluble, sucrose esters have a very high HLB value (hydrophylic – lipophylic balance), which makes them unique and very effective oil-in-water emulsifiers. More than any other emulsifier they are able to keep the fat emulsified in the candy, preventing the fat or oil from seeping out. Even when the candy is stored at high temperature or varying temperatures, the stability is excellent.
When sucrose esters are used in a candy recipe, the fat and oil will be very well dispersed in the product. In this way hardly any oil is at the surface of the candy. Oxygen and UV light, the promoters of oxidation, cannot easily penetrate in the oil, and rancidity is delayed. The taste will remain fresh much longer, and shelf life can be extended.
In a laboratory study, fudge with sucrose esters (HLB 11) was compared with fudge with lecithin. Sensorial specialists noted a big difference in (rancid) taste, in favour of fudge with sucrose esters. This result was confirmed by GC-MS (gas chromatograph mass spectrometer) analysis on rancid components (hexanal): after two months storage under harsh circumstances (in UV light, unpacked, at ambient temperature), fudge with lecithin contains far more hexanal compared to fudge with sucrose esters. The graph below shows that the hexanal peak is high in fudge with lecithin and low in fudge with sucrose esters.
Sucrose esters and stickiness
Stickiness is a major challenge in confectionery processing. Products made with glucose syrups – such as cereal bars and caramels – are hard to work with because the product adheres to the equipment, leading to product loss. Stickiness increases as product cools. Frequent cleaning is required, in particular the knives that are used to cut confectionery. Cleaning interrupts production, resulting in shorter production runs and increased cost.
Sucrose esters disperse the fat or oil very finely through the candy, optimising the lubrication power of fat. This results in less adhesion to equipment surfaces, wrappers and teeth.
A laboratory study shows the effect of emulsifiers on the adhesion of syrup to a stainless steel surface. Less adhesion means a less sticky solution. The study compares syrup using lecithin and sucrose esters (HLB 15) as an emulsifier. Syrup without emulsifiers is also tested. The test set up is shown in the below picture. Samples with less adhesion are those that flow easily down the wall, with little material remaining on the wall. In the study, glucose syrup, sugar and water are boiled and melted fat (five per cent) is added. Sucrose esters are mixed with the sugar and cooked in the syrup. Lecithin is dissolved in the fat.
To study the flow rate and adherence, the syrup (35°C) is poured onto a stainless steel wall at an angle of 80°, and the weight of the binder syrup that remains on the wall after a certain time is measured.
In comparison with the syrup without emulsifier, the syrup with sucrose esters (0.05 and 0.1 per cent) shows significantly reduced adhesion. Lecithin (0.2 per cent) does not reduce adhesion.
Sisterna publishes guide recipes and technical notes for a wide range of confectionery products, and food engineers are able to provide tailor-made advice.