Masking off-taste – a balancing act

If you are going to replace sug­ar with some­thing less caloric but just as sweet, a high-inten­si­ty sweet­en­er is a must. But with it come unde­sir­able side effects. This applies regard­less if you choose an arti­fi­cial sweet­en­er (such as aspar­tame, ace­sul­fame K or sucralose) or nat­u­ral­ly occur­ring ste­vi­ol gly­co­sides. The unwant­ed flavours can be masked by oth­er flavours. But watch out! It can cre­ate new prob­lems. It is a bal­anc­ing act to get the right taste.

Side effects of steviol glycosides

It is hard­ly a secret that we pre­fer ste­vi­ol gly­co­sides every day of the week. We think it is a fan­tas­tic sweet­en­er. And it is the only nat­u­ral­ly occur­ring high-inten­si­ty sweet­en­er approved in the EU for gen­er­al use in food.

But like all high-inten­si­ty sweet­en­ers, ste­vi­ol gly­co­sides come with unde­sir­able side effects. They have some bit­ter­ness and a taste that is rem­i­nis­cent of liquorice and is some­times described as metal­lic. The liquorice-like flavour also lingers for a while.

So when ste­vi­ol gly­co­sides are used, the bit­ter­ness and liquorice flavour needs to be masked.

But wait a minute! Not all ste­vi­ol gly­co­sides are the same.

Steviol glycosides without unwanted taste

Initially, foods sweet­ened with ste­via extract had a rather bit­ter taste. It came from ste­vio­side, which is the ste­vi­ol gly­co­side most com­mon­ly found in the leaves of the plant ste­via, from which ste­vi­ol gly­co­sides are extracted.

But nowa­days the most pop­u­lar ste­vi­ol gly­co­side is Rebaudioside A, which in short is called Reb A, con­sist­ing of 50 to 98 per cent of ste­vi­ol gly­co­side. It is not as bit­ter at all, which makes the liquorice-like off-taste more noticeable.

And now more and more com­pa­nies start to use Rebaudioside M (Reb M), which is the most sug­ary ste­vi­ol gly­co­side of them all. It has prac­ti­cal­ly no unwant­ed off-taste and no pun­gent aftertaste.

But despite the good qual­i­ties of Reb M, Reb A is often pre­ferred. And then we still have to deal with the off-taste and after-taste.

Off-taste

There is a lot of talk about off-taste and after­taste. But what is it really?

Usually, off-taste is caused by an unde­sir­able sub­stance that comes with a raw mate­r­i­al, from a chem­i­cal change dur­ing the pro­duc­tion or stor­age of food or from microorganisms.

But when we replace an ingre­di­ent with one or more oth­er ingre­di­ents (which is often the case with sug­ar reduc­tion) it becomes a lit­tle pecu­liar to talk about an ‘unwant­ed sub­stance’. Steviol gly­co­sides are high­ly desired, even if they do not taste exact­ly like sugar.

So a more appro­pri­ate def­i­n­i­tion of off-taste is sim­ply a taste that is not desired. It con­tains both flavours from unwant­ed sub­stances and flavours that are found in a sub­sti­tute for an ingre­di­ent but which are not in the ingre­di­ent it replaces.

Aftertaste

Aftertaste is eas­i­er to define. It is the taste that lingers in the mouth after that which gave the taste has vanished.

Note that both the desired taste and the off-taste can have an aftertaste.

Aftertaste of an off-taste is, of course, as unde­sir­able as the off-taste itself. If the off-taste can not be avoid­ed, it needs to be masked, and then it is impor­tant to remem­ber to also mask the after­taste of the off-taste.

But even with the off-taste under con­trol, the after­taste can cause prob­lems with sug­ar reduc­tion. If sug­ar is replaced with oth­er ingre­di­ents, we get a dif­fer­ent after­taste. On the one hand, the actu­al taste can be dif­fer­ent. On the oth­er hand, it can last for short­er or longer peri­ods than sug­ar. This too should be masked.

Masking off-taste and unwanted aftertaste

It sounds like sug­ar reduc­tion is some­what of a mas­quer­ade. And yes, mask­ing off-taste and unwant­ed after­taste is a big part of the job of replac­ing sug­ar with­out chang­ing the desired taste.

Unfortunately, there is no patent solu­tion that can be used every­where. What works depends on what oth­er ingre­di­ents are already present or added and how they are processed. That is why it takes a long time and requires spe­cial­ist knowl­edge (or luck) to find the right ingre­di­ents and the right proportions.

Ask the expert

This is Ola Boström, inno­va­tion man­ag­er at Bayn. We ask him for advice.

How should we handle the liquorice-like off-taste and aftertaste of steviol glycosides?

– There are dif­fer­ent ways to choose from. One way is to mix dif­fer­ent ste­vi­ol gly­co­sides to get a cost-effec­tive final prod­uct that also tastes good.

– Another way is to add one or more ingre­di­ents that have the prop­er­ty of mask­ing flavours. You can use one or more dif­fer­ent ingre­di­ents that can pro­duce syn­er­gy with the help of each oth­er. They mask the taste expe­ri­ence so that the bit­ter liquorice-like taste does not emerge.

What ingredients can mask the taste?

– There are a vari­ety of choic­es that all have pros and cons. You can, for exam­ple, use thau­matin. Sugar alco­hols such as ery­thri­tol can also be used. A bonus with sug­ar alco­hols is that they also give bulk. The same can be said for inulin, which is a dietary fibre with a sweet taste that can also mask. Fructose syrup and hon­ey can also be used; Fructose is good at mask­ing but con­tains a lot of calo­ries. When monk fruit is approved in the EU, mogro­sides can be used.

We thank Ola and take a clos­er look at the ingre­di­ents that Ola mentioned.

Thaumatin

Thaumatin is a pro­tein found in the fruits of the West African plant katemfe (Thaumatococcus daniel­li).

Thaumatin is 2,000 to 3,000 times sweet­er than reg­u­lar sug­ar and is there­fore con­sid­ered a high-inten­si­ty sweet­en­er. But most often it is used to enhance or mask flavours.

Both ste­vi­ol gly­co­side and thau­matin have a super sweet taste with some bit­ter­ness and licorice-like taste and long after­taste. It is easy to come to the con­clu­sion that they togeth­er become even more bit­ter and liquorice-like, but the fact is that they mask each oth­er. The bit­ter­ness and the liquorice taste become damped.

But thau­matin requires sure instinct. Due to its high sweet­ness, it requires know-how on dosage and mix­ing techniques.

Mogrosides

Another high-inten­si­ty sweet sub­stance that also has a bit­ter taste is mogro­sides, found in the fruit Luo Han Guo, called monk fruit in English. These too can be com­bined with ste­vi­ol gly­co­sides to remove each other’s off-tastes.

Mogrosides have long been cul­ti­vat­ed in China and are today an estab­lished ingre­di­ent in many mar­kets. But it is a pre­cious com­mod­i­ty that is not yet approved in the EU. However, there are hopes that it will be approved with­in a year or so.

Fructose

Fructose is also good at mask­ing the off-taste of ste­vi­ol glycosides.

But it is impor­tant not to add too much. Fructose is a type of sug­ar with as many calo­ries as reg­u­lar sug­ar, so adding it coun­ter­acts the pur­pose of reduc­ing sug­ar. But if the goal is not to remove as many calo­ries as pos­si­ble from the sug­ar, it may very well work.

Fructose can also be used when the goal of sug­ar reduc­tion is pri­mar­i­ly to reduce the effect on blood sug­ar lev­els. Fructose has only 25 per cent of the effect of reg­u­lar sug­ar on the blood sug­ar lev­el (GI 23 com­pared to GI 92, with white bread as a reference).

Inulin

Inulin is a dietary fibre first and fore­most used to replace the bulk that is lost when you reduce sug­ar or fat. However, it has a dis­creet, sweet taste that can be used to mask the off-taste of ste­vi­ol glycosides.

Inulin is found in a vari­ety of veg­eta­bles, but it is main­ly chico­ry root that is used in the prepa­ra­tion of inulin.

Inulin works well in many types of foods, but watch out for foods with low pH. Then hydrol­y­sis can split inulin into short­er chains includ­ing fruc­tose which is a type of sug­ar with as many calo­ries as reg­u­lar sugar.

As always with fibres, it is impor­tant not to have too much, as the ben­e­fi­cial bac­te­ria of the colon break them down into short-chain fat­ty acids with gas­es as a bi-product.

So what about sugar alcohols?

Sugar alco­hols are anoth­er group of maskers that can cause stom­ach upset. Therefore, it must be stat­ed that exces­sive con­sump­tion may have a lax­a­tive effect if the prod­uct con­sists of more than ten per cent sug­ar alcohol.

Erythritol is an exam­ple of a sug­ar alco­hol that works well with ste­vi­ol gly­co­sides. It is good at mask­ing the off-taste, but it also adds vol­ume and con­tributes to a mouth-water­ing resem­blance to sugar.

There is how­ev­er one problem.

Erythritol is endother­mic, which caus­es it to absorb heat in con­tact with sali­va, which is expe­ri­enced as a cold in the mouth. Therefore, an unwant­ed off-taste can be replaced by an unwant­ed cold if you are not careful.

But the cool­ing effect is not always unde­sir­able. It may be ben­e­fi­cial in some appli­ca­tions, such as chew­ing gum, cough drops and the like.

And in bev­er­ages, ery­thri­tol has no cool­ing effect, since the endother­mic reac­tion – when ery­thri­tol comes into con­tact with water – has already occurred dur­ing manufacture.

Mixing steviol glycosides

Finally, we have the odd pos­si­bil­i­ty of mask­ing the off-taste of ste­vi­ol gly­co­sides with more ste­vi­ol glycosides.

There are eleven ste­vi­ol gly­co­sides approved in the EU. But not all are avail­able indi­vid­u­al­ly as most are very expen­sive to puri­fy. The most abun­dant and eas­i­est to puri­fy ste­vi­ol gly­co­sides can be pur­chased. For exam­ple, puri­fied extracts of the ste­vi­ol gly­co­side Reb A can be pur­chased at 50, 60, 80 up to 99 per cent puri­ty. The remain­der of the extract is ste­vio­side and oth­er ste­vi­ol glycosides.

There is also great vari­a­tion between ste­via extracts from dif­fer­ent refiner­ies, although they have the same degree of puri­ty. As with wine, the sweet­ness and taste of ste­vi­ol gly­co­sides vary with the con­di­tions under which they are grown; dif­fer­ent soils give dif­fer­ent results.

In the same way, vari­a­tions in weath­er can give great vari­a­tion in batch­es from the same supplier.

As a food pro­duc­er, you nor­mal­ly want to be cer­tain that taste is con­sis­tent dur­ing the prod­uct life cycle. Therefore, it is impor­tant to choose a sup­pli­er that ensures con­sis­tent qual­i­ty.

But you can also use the vari­a­tions to your advan­tage. By com­bin­ing ste­via extracts with dif­fer­ent con­cen­tra­tions of dif­fer­ent ste­vi­ol gly­co­sides from dif­fer­ent refiner­ies, you can make them dis­guise each other’s side flavours.

But to pre­pare a mix­ture of suit­able ste­vi­ol gly­co­sides on your own to get rid of unwant­ed flavours is, to say the least, dif­fi­cult. Especially when it comes to dos­ing. For that, it is best to hire experts.

Trade-offs and pitfalls

As you prob­a­bly under­stand, there are many trade-offs that must be made and pit­falls to avoid when it comes to sug­ar reduc­tion and mask­ing of unwant­ed flavours from high-inten­si­ty sweeteners.

Ultimately, it is a bal­anc­ing act where you have to weigh the pros and cons of the var­i­ous solu­tions. To reduce sug­ar and calo­ries but still retain the sweet­ness and good taste, you may have to pre­pare for a slight­ly low­er calo­rie reduc­tion, a high­er price or a risk of a lit­tle flat­u­lence. The goal of the bal­anc­ing act is to come up with a final prod­uct with­out major deficiencies.

But to do so requires the­o­ret­i­cal knowl­edge and prac­ti­cal devel­op­ment work. Resources that cost time and money.

A helping hand

We are hap­py to pro­vide a help­ing hand. We can also sup­ply ste­vi­ol gly­co­sides with high qual­i­ty at an advan­ta­geous price. And we can short­en your time to mar­ket with key solu­tions for a vari­ety of appli­ca­tion areas. Do not hes­i­tate to con­tact us if you want to know more.