Dulce de Leche. Sección "Lactose: chemical and physical properties and significance to dairy products”

HYNES, ERICA; CARLOS ANTONIO ZALAZAR

“Advanced Dairy Chemistry-3. Lactose, Water, Salts and Minor Constituents”

Springer

Lugar: New York; Año: 2009; p. 58 - 68

Dulce de leche (DL) is a typical product of Río de la Plata region, in South America. Main producer countries are Argentina and Uruguay; consumption in Argentina is about 2.70 kg per caput per annum, with a stable production of 109,000 tonnes/year. The role of lactose in DL is related to texture quality, colour and nutritional value.  DL is a concentrated dairy product, similar to sweetened condensed milk, and the crystallization of lactose can occur as the moisture in DL is supersaturated with lactose. If the crystals of a-monohydrate lactose grow to exceed 10 mm, they will be perceived in the mouth, giving the product a defective texture called “sandiness” or “grittiness”. Unlike most food products, milk contains both proteinaceous material and a reducing sugar, which leads to non-enzymatic browning and changes in the nutritional value of the food when it is heated even at mild levels. A typical reddish-brown colour and caramel-like flavour are major sensory attributes of DL that impact on consumer acceptability of the product. Colour, as well as typical texture, correlates positively with the overall acceptance of DL. The impact of lactose on the nutritional properties of DL may be evaluated from two different points of view, the principal of which is the loss in nutritive value by damaging essential amino acids by Maillard reactions. The second aspect is the nutritional concern for lactose-intolerant people, as DL is rich in lactose. The technological approaches intended to reduce costs and to improve texture and the visual aspect of DL by replacing sucrose by glucose syrup, or to retard the appearance of sandiness by hydrolysis of lactose, impact on important properties of the product such as its colour and nutritional value. Consequently, equilibrium should be found between the proportion of non-reducing sugars, lactose and monosaccharides in DL. Besides, the shelf-life of the food should be realistically fixed as lactose crystallisation will eventually occur. The technological approaches intended to reduce costs and to improve texture and the visual aspect of DL by replacing sucrose by glucose syrup, or to retard the appearance of sandiness by hydrolysis of lactose, impact on important properties of the product such as its colour and nutritional value. Consequently, equilibrium should be found between the proportion of non-reducing sugars, lactose and monosaccharides in DL. Besides, the shelf-life of the food should be realistically fixed as lactose crystallisation will eventually occur.