Dextrose is a reducing sugar. The reducing power of a sugar is measured by its ability to reduce solutions of alkaline copper sulphate (Fehling’s solution) to cuprous oxide. The dextrose equivalent (DE) of pure dextrose is defined as 100. Expressed as a percentage of the reducing value of pure dextrose and calculated on a dry weight basis, the total reducing value of a starch hydrolysate is referred to as its DE.
The classic browning in food systems is due to the interaction of reducing sugars and acidified protein compounds. Due to its active aldehyde groups, dextrose is a powerful reducing sugar and promotes rapid buildup of browning.
At temperatures below 55 °C (131°F) dextrose crystallizes from aqueous concentrated solutions in the monohydrate form, in which each dextrose crystal contains 1 molecule crystal water per molecule dextrose (Dx-Monohydrate). Above 55 °C (131°F) the anhydrous form is crystallizing where the dextrose crystal contains no crystal water.
With its pleasant, clean and sweet, cooling taste, dextrose has been used for years as a sweetener in a wide range of food applications. Dextrose is one of the sweetest of the starch derived sugars. On a scale on which sucrose is assigned a sweetness value of 100, dextrose is rated at 75.
Its sweetness is influenced by a variety of factors such as temperature, acidity, salts, flavoring materials, sweetener concentration and the nature of other sugars present. Contrary to sucrose, dextrose is not subject to the process known as inversion, and therefore its degree of sweetness does not change.
Dextrose and sucrose are often used together to control and balance sweetness and total solids. When dextrose and sucrose are combined, they exhibit a synergy. At a 40 percent replacement level, for example, the apparent relative sweetness of dextrose could be as high as 90.
Heat of solution
The heats of solution of dextrose monohydrate (-105.5 J/g) and of anhydrous dextrose (-59.3 J/g) differ greatly from that of sucrose (-16.1 J/g). Hence, the heat required to dissolve dextrose is approximately 10 times greater than for sucrose. Consequently, when eating food containing dextrose in crystalline state, there is a distinct cooling sensation in the mouth. The perception of sweetness is shortened and flavor enhancement is improved.
Crystalline dextrose is readily soluble in water but only slightly in ethanol and hardly soluble in other organic solvents. At temperatures higher than 55°C (131°F), dextrose is more soluble than sucrose.
In addition, at any given specific temperature, there is an optimum sucrose-dextrose saturation ratio that raises total solubility above that of the individual components.
Dextrose, because of its low molecular weight, has the capacity to decrease the freezing point. At a 30% concentration, the freezing point of a dextrose solution is 2°C lower than that of a comparable sucrose solution - crucial in the production and consumption of ice-cream.
The freezing point depression factor (FPDF) is typically used for calculations in the ice-cream industry. The FPDF factor for sucrose is 1.00 compared to 1.90 for dextrose.
[IMAGE Freezing point depression]
Because it is a monosaccharide, dextrose is the ideal carbohydrate source for yeast fermentation in baking and brewing. The fermentation begins immediately and proceeds rapidly. Dextrose provides energy to the cell to produce many by-products in addition to carbodioxide and ethanol. Also, dextrose is used in lactic acid fermentation processes in the pickling and the meat industry.
Dextrose is often used in combination with sugar or other sweeteners. It acts to shorten the sweetness perception and enhance the original food flavor.
Dextrose is a reducing sugar and improves, in comparison with sucrose, the inhibition of oxidative degradation, thus increasing color stabilization. This can help to extend the shelf life of food products.
Dextrose monohydrate and anhydrous dextrose are available in a variety of particle size distributions and granulometry to provide ease and stability of blending. Coarse dextrose products are perfect in relation to flowability and dust minimalisation.