Dextrin – from seed to Eureba

Every time you bake bread, you make dextrin. It happens in the crusts of the bread; the starch is converted by the heat to dextrin. There are different types of dextrin. Some break down into glucose during digestion. Others are dietary fibre. The latter we use in some of our sweetened fibres (Eureba). They are produced from non-GMO maize. Here you can read about the dextrin’s path from corn to sweetened fibres.

5 December 2019 • and

Dextrin is a tricky name, as it is used about a large fam­i­ly of car­bo­hy­drates that con­tain both dietary fibre with 0 calo­ries and 0 in gly­caemic index (GI) and such car­bo­hy­drates that pro­vide calo­ries and affect blood sug­ar lev­els. We use dex­trin as a dietary fibre for some of our sweet­ened fibres (Eureba). But let’s start from the beginning…

Starch

The ori­gin of all forms of dex­trin is starch. The source of the starch is unim­por­tant. Starch from corn, wheat, pota­toes, rice, tapi­o­ca (cas­sa­va) or oth­er starch-rich crops goes equal­ly well.

Whatever the source, starch is just a long chain of glu­cose mol­e­cules. And glu­cose mol­e­cules are noth­ing but ordi­nary grape sug­ar.

To under­stand the rela­tion­ship between starch and dex­trin, we need to have some con­trol over how glu­cose mol­e­cules can link to each oth­er (and oth­er sim­ple sugars).

Glycoside bonds

Each glu­cose mol­e­cule con­sists of six car­bon atoms that each holds an oxy­gen atom in their hand. (Also, twice as many hydro­gen atoms are includ­ed, but we will leave them out this time.)

Two car­bon atoms in each glu­cose mol­e­cule can hold the same oxy­gen atom in hands. This is called a gly­co­side bond or, for short, a bond.

Which car­bon atoms of the glu­cose mol­e­cules that hold the shared oxy­gen atom in hand, and how they do it, is of great impor­tance, for exam­ple, for whether the bond can be bro­ken and glu­cose mol­e­cules released dur­ing diges­tion. Therefore, we must keep track of who is hold­ing who in hand and how. The eas­i­est way is to give gly­co­side bonds names that say it all.

Illustration: Annika Modigh

The name says everything

Glycoside bonds are called either alpha or beta fol­lowed by two dig­its. The num­bers tell which car­bon atoms hold the oxy­gen atom in their hands and the Greek let­ter how they do it.

A glu­cose mol­e­cule has six car­bon atoms. These have been giv­en the imag­i­na­tive names 1, 2, 3, 4, 5 and 6 after where­in the glu­cose mol­e­cule they are. If it is car­bon atom 1 of one and car­bon atom 4 of the oth­er hold­ing the oxy­gen atom in hand, one writes (1→4) or (1,4).

Illustration: Annika Modigh

A car­bon atom can hold the oxy­gen atom in the left or right hand. (Yes, you actu­al­ly talk about left-hand­ed and right-hand­ed car­bon atoms.) If both hold the oxy­gen atom with the same hand (both use the left hand, or both use the right hand), the method is denot­ed by α-(alpha). If both of them hold the oxy­gen atom with dif­fer­ent hands (one with the left hand and the oth­er with the right hand), the method is denot­ed by β-(beta).

Illustration: Annika Modigh

If both car­bon atom num­ber 1 in one glu­cose mol­e­cule and car­bon atom num­ber 4 in anoth­er hold the shared oxy­gen atom with their left hands (or right hands), the gly­co­side bond is named α-(1→4). Had they cho­sen dif­fer­ent hands, the bond would have been called β-(1→4). And had it been num­ber 6 instead of car­bon atom num­ber 4, the bonds would have been called α-(1→6) and β-(1→6), respectively.

What is starch?

Now, back from the chem­istry les­son, it is soon time to address the ques­tion of how starch becomes dex­trin. But first, we need to find out what starch real­ly is, and why it is an essen­tial source of ener­gy for us.

Starch is a long chain of hun­dreds of glu­cose mol­e­cules linked to gly­co­side bonds termed α-(1→4).

Human diges­tive sys­tems have var­i­ous enzymes, for exam­ple, amy­lase, which are super-effi­cient tools for break­ing up α-(1→4) bonds.

They act like scis­sors that cut the starch into small­er chains, which in turn are cut into even small­er ones and so on until only glu­cose remains. And glu­cose, as you know, is the body’s pri­ma­ry source of energy.

(Our diges­tive sys­tem is quick to break up α-(1→4) bonds, but it strug­gles with α-(1→6) bonds. A glu­cose chain with two or more α-(1→6) bonds slips through all the way to the large intes­tine before some­thing hap­pens. By def­i­n­i­tion, that makes them fibres. See the arti­cle about iso­ma­l­tooligosac­cha­rides.)

Illustration: Annika Modigh

The relationship between starch and dextrin

When starch is heat­ed up to 160–200 ° C, for exam­ple, when bak­ing, things start to hap­pen. The starch breaks down into small­er parts when some bonds are broken.

At the end of one of the small­er parts is now an oxy­gen atom that has lost one of its two car­bon atoms, or a car­bon atom that has lost one oxy­gen atom. They would like to find some­one new to hold in their hand.

The oxy­gen atom is not so con­sci­en­tious, so car­bon atoms with num­bers oth­er than 4 have the chance. It is also not so strict about using the same hand. The result is short­er chains of glu­cose mol­e­cules branch­ing in dif­fer­ent directions.

Some of the small­er parts find no one to asso­ciate with. A free oxy­gen atom can then set­tle down with a hydro­gen atom it picks up from water that found when, for exam­ple, bak­ing. A free car­bon atom can take care of the remain­ing oxy­gen-hydro­gen pair (as you know, water con­sists of two hydro­gen atoms and one oxy­gen atom – H2O).

The result is that the starch’s long chain of glu­cose mol­e­cules, neat­ly arranged in a row with α-(1→4) bound, has been trans­formed into short­er chains of glu­cose mol­e­cules linked by α-(1→4) bound, some of which are joined to oth­ers by oth­er gly­co­side bonds of both alpha and beta type, and oth­ers remain their own.

Some of the short chains are so short that they are not even a chain. Of course, they are the mono­sac­cha­ride glu­cose. Others con­sist only of a sin­gle bond. They are dis­ac­cha­rides. If it is an α-(1→4), the dis­ac­cha­ride is called mal­tose.

The rest, both the straight chains and the branched, are col­lec­tive­ly called dex­trin.

Illustration: Annika Modigh

What is the difference between dextrin and maltodextrin?

Dextrin con­sists of both branched struc­tures of chains of glu­cose mol­e­cules and short­er chains of glu­cose mol­e­cules (typ­i­cal­ly 3–17 pieces). The lat­ter are called mal­todex­trin.

Therefore, when you say only dex­trin, it is usu­al­ly only the branched struc­tures that are referred to.

Methods for preparing dextrin

Starch is con­vert­ed to dex­trin upon heat­ing to 160–200 °C. It’s called roasting.

Another way is to add enzymes that break down the starch. But they only cut the starch, so the result is main­ly mal­todex­trin. (You can read more about how it works in the arti­cle on the prepa­ra­tion of malti­tol.)

A third way is to add a lit­tle water and acid (for exam­ple, nitric acid) and heat to mod­er­ate 160 °C. The result is a dough that is allowed to boil dry before it is pul­ver­ized. That’s what French chemist and phar­ma­cist Edme-Jean-Baptiste Bouillon-Lagrange did when he dis­cov­ered dex­trin in 1811.

A sweet and sticky discovery

Bouillon-Lagrange sought an alter­na­tive to gum ara­bic, which can be used as adhe­sives for paper, and binders in colour and ink, among oth­er things, but is expen­sive to import and hard to replace with a domes­tic alternative.

He tried to grind starch and gen­tly roast it with con­stant stir­ring on an iron stove. After a while, he got an ashen, slight­ly sweet and sticky substance.

He inves­ti­gat­ed the sub­stance and found that unlike starch, it dis­solves com­plete­ly in both cold and hot water and that the solu­tion caus­es polar­ized light clear­ly to rotate right. The sub­ject was there­fore named dex­trin after the Latin word from the right: Dexter.

Resistant dextrin

To reca­pit­u­late, dex­trin is a col­lec­tive name for var­i­ous car­bo­hy­drates that are formed when a long chain of glu­cose mol­e­cules with α-(1→4) bound (starch) is bro­ken up into short chains that are recon­sti­tut­ed with dif­fer­ent gly­co­side bonds.

With a care­ful­ly con­trolled process, it is pos­si­ble to pro­duce dex­trin which has a high pro­por­tion of α- and β-(1→2), (1→3) and (1→6) gly­co­side bonds, which the human diges­tion doesn’t han­dle effi­cient­ly. It is called resis­tant dex­trin and is count­ed as dietary fibre.

Resistant dextrin in sweetened fibre

At Bayn, we use resis­tant dex­trin as a dietary fibre in some of our sweet­ened fibres – which replaces sug­ar one-to-one in recipes with­out need to change production.

Sweetened fibres are a homo­ge­neous com­po­si­tion of dietary fibres, sweet­en­ers from ste­via and pos­si­bly oth­er ingre­di­ents, which togeth­er give the same taste and mouth­feel as sugar.

In some of our sweet­ened fibres, called Eureba, we use resis­tant dex­trin as dietary fibre. We use dex­trin pro­duced from starch from Non-GMO maize.

Non-GMO corn

Corn has long been the most grown crop in the world, and pro­duc­tion is steadi­ly increas­ing. You may think that most of it ends up in tacos on Friday, but it doesn’t. Most become ani­mal feed. But a large por­tion of pro­duced corn becomes starch. This is the starch from which our dex­trin is made.

Maize is not only the most grown crop. It is also the sec­ond-largest genet­i­cal­ly mod­i­fied crop – sec­ond only to soybeans.

Today, corn farm­ing is com­plete­ly dom­i­nat­ed by two genet­i­cal­ly mod­i­fied maize vari­eties intro­duced dur­ing the 1990s. In one, genes from the bac­te­ria Bacillus Thuringiensis are giv­ing corn a built-in pes­ti­cide. The oth­er is corn resis­tant to pes­ti­cides like the glyphosate-based Roundup which kills every­thing – except the genet­i­cal­ly mod­i­fied corn.

Many con­sumers hes­i­tate for health and envi­ron­men­tal rea­sons, to con­sume prod­ucts pro­duced from a genet­i­cal­ly mod­i­fied organ­ism (GMO). Therefore, we only use GMO-free raw mate­ri­als for our sweet­ened fibre. That includes dex­trin as well.

Finally

If you want to know more about sweet­ened fibres, how we use dex­trin and oth­er ingre­di­ents in them, or want to get a prod­uct sam­ple to test your­self, please do not hes­i­tate to con­tact us. Call us on tele­phone num­ber +46 8 613 28 88 or send an e‑mail to info@​bayn.​se.

Please, share this article if you liked it.