Maltodextrin is found in nearly every food from infant formula to coffee whiteners. It is usually prepared from corn starch but other starches from potatoes, oats, tapioca, wheat, and rice etc. may also be used. The conversion from starch to maltodextrin occurs due to hydrolysis of starch to smaller fractions. Starch is huge polymer of glucose and when hydrolysed the molecular weight reduces depending on the extent of hydrolysis.
The hydrolysis was earlier done mostly using acid in a starch slurry in water with heat expediting the process. Now it is mostly done using amylase enzyme which is a milder process with very few by-products. As hydrolysis proceeds, starch molecule becomes smaller and smaller and the final stage would be glucose when complete hydrolysis takes place and no more bonds remain to be hydrolysed. The different molecules with varying degree of hydrolysis are called maltodextrins and the size of molecule or the extent of hydrolysis is indicated by Dextrose Equivalent (DE). Large molecules after very little hydrolysis of starch have low DE while smaller molecules with greater extent of hydrolysis have greater DE. When all the starch is totally converted to glucose the DE would be 100 while unhydrolysed starch would have DE0.
For different applications different DE maltodextrins or glucose syrups are needed. High molecular weight maltodextrins are less soluble in water. They have less reducing sugars so there is little browning upon heating. They also can bind a lot of water and provide viscosity and body to liquids. They prevent ice crystal formation at very low temperature.
As more and more hydrolysis is carried out, the molecular weight reduces and the maltodextrin becomes more soluble. Higher DE will produce glucose syrup. It also starts losing the ability to provide viscosity. As more sugars are formed due to higher level of reducing group, browning can take place upon heating. As more sugars are formed it also becomes sweeter. Thus various applications will depend on what attributes are needed and sometimes a combination may be needed.
Fig: Influence of DE on Physicochemical Properties of Maltodextrins
Maltodextrin is often used as a filler with high intensity sweeteners especially in sachet packets available in restaurants and coffee shops. As sweetener is to be used in mg quantities, dispensing becomes very difficult of such small quantities. Bulking agent gives sufficient volume so may be a spoonful of the maltodextrin containing the sweetener may be easily added to a cup of coffee or tea.
Bulking agents are also used when low or reduced sugar foods are prepared. As many sweets and foods with high level of sugar may contain substantial amount of sugar. When this is to be reduced the amounts of remaining substances increase substantially creating unbalance and loss of bulk. So when sugar is reduced from say peda, the left over protein and fat becomes very high in proportion and also the total amount gets reduced in quantity substantially so you need something to fill that gap. Bulking agents fill that gap with minimal changes otherwise in the product.
Maltodextrin also works as anti-caking agent in powders. It may also work as diluent for some spice powders or extracts. Some spice products may be resinous and difficult to dispense so adding bulking agent makes them powders which is more convenient.
Maltodextrins can also be used replace fat in order to make the food reduced or low fat. Maltodextrins may interact with water to form gel. This gel may mimic the texture and creamy mouthfeel of fats. They could be used in baked goods, salad dressings and dips as well as frozen desserts and sausages. They also can control melting in ice creams.
Maltodextrins can also be used in making tablets. These could be tablets of coated sweets or nutraceuticals or health supplements. Fruit and vegetable juice concentrates can be spray dried onto maltodextrin to create powdered forms. These powdered forms could be used in manufacture or in creating new food formats. Such powders could also be used as base for flavours and many other ingredients.
Maltodextrins can also form shiny surface on many different types of snacks. Low fat extruded snacks like pretzels or cereals could be coated with syrups and maltodextrins give shiny and crisp surface. Maltodextrins also help expedite the drying of confectionery coatings.
As maltodextrins are less sweet than sugar they could be used to reduce sweetness in products if the sweetness is too much and is affecting the flavour of the product. The maltodextrin rounds off the flavour.
Maltodextrins could also be used in infant and child nutrition to replace lactose to prepare lactose free food when they have lactose intolerance. Maltodextrins also can reduce the osmotic load and related gastrointestinal stress.
As maltodextrins are easily digested and converted to energy they are important in sports nutrition products. Maltodextrin spares glycogen breakdown during long- duration exercise. Also when given along with protein, they enhance glycogen recovery and can help muscle protein recovery and build up after physical activity.
Thus maltodextrins can be used in many different food products in many different ways. Each application needs a specific maltodextrin or glucose syrup or a combination for better results.