Delattosate milk

Milk: general aspects

Milk is essentially a food.

It is produced by the female breast of mammals, which, following the birth of their offspring, feed it for a sufficient period of time for a first and essential physical development.

The milk appears as a white and opaque liquid, sweet and with an almost neutral pH; chemically, milk is an EMULSION of lipid globules dispersed in a similar fluid (by composition) to the blood plasma; this fluid is in turn composed of dissolved proteins and serum (salts, lactose and water).

From a nutritional point of view, the milk additionally provides four types of nutrients:

Lipids (especially triglycerides and cholesterol)
Protids (caseins, albumins and globulins)
Glucides (essentially lactose, a disaccharide composed of glucose + galactose)
Salts (calcium, phosphorus, etc.)

However, other quantitatively inferior components are also noteworthy, such as vitamins, lecithins, enzymes, nucleotides, prebiotics, antibodies, etc.

The milks are not all the same; in addition to the more or less relevant differences present in the different species of mammals, the LACTATION CYCLE also determines significant variations in the chemical composition of the mammary secretion. At the time of birth, for example, milk is defined as COLOSTRO and differs from that produced later on due to the importance of the protein component and of the salt component; subsequently, the breast modifies the composition of the fluid impoverishing it of nutrients as the weeks go by.

Lactose

Lactose is the characteristic carbohydrate of milk; it is present in varying degrees among the secretions of the different species but, compared to the other nutrients, its content is limitedly heterogeneous. Lactose is particularly present in human milk, in which it reaches more than half of the dry weight (65 g / l), but its content is very abundant even in vaccine and goat secretion; in humans, lactose is produced from glucose, while in ruminants the starting substrate is made up of volatile acids present in the rumen. Moreover, since lactose is very abundant and characterized by a remarkable osmotic power, the compromise of its synthesis is a limiting factor in the overall breast milk production.

Lactose, in addition to having an energetic function, represents the primary source of galactose, which in turn is an important structural component of nervous tissues.

Lactose is also a typical substrate of many microorganisms that break it down by producing lactic acid or other aliphatic acids, while in the animal organism the hydrolysis of lactose and desmolysis of galactose depend on the presence / enzymatic availability of:

β-1, 4 galactosylase, also called intestinal lactase
Galactose-1-phosphate uridyltransferase, also called hepatic galactase

"Ordinary" lactose also possesses several similar isomers or disaccharides; these can replace other glucose monosaccharides or may derive from lactose following the application of different chemical or physical processes; among these we remember:

Epilactose: galactose + mannose → Typical of heavily heated milk
Lactulose: galactose + fructose → Resulting from the alkaline treatment
Allolactose: galactose + glucose → It has a β 1, 6 bond and is typical of transglycosylation by β-galactosidase
Lactitol: galactose + sorbitol → Lactose-reducing product

NB . For osmotic regulation, the concentration of lactose is INVERSELY proportional to that of salts

What is milk delattosate?

The milk delattosato, also defined HD (High Digestible), is a food manufactured by man and designed in order to allow lactase-deficient subjects (or populations!) To consume cow's milk without incurring the typical (and unpleasant) symptomatology gastro-intestinal lactose intolerance.

Lactase deficiency, often but not always, derives from some genetic factors; sometimes it is a transient deficiency, while at other times it concerns a permanent but NOT hereditary deficit, attributable to the definitive elimination of milk from the diet; in this case, after long periods of abstinence from milk, the concentration of intestinal lactase progressively decreases to become INSUFFICIENT.

Delactosed milk is nothing but a cow's milk subjected to ENZYMATIC hydrolysis of lactose ; this process reduces lactose concentrations up to 70% of the initial concentration. The production of lactose-free milk is becoming increasingly important thanks to the high number of consents among consumers.

The chemical process of lactic hydrolysis occurs through the use of specific enzymes; among these the most used are:

Yeast lactase: Kluyveromyces fragilis or Saccharomyces lactis
Fungal lactase: Aspergillus niger, Rhizopus oryzae etc.

Although the final result is the same, the technological-food process to be applied, if one or the other enzyme is used, must take into account at least two factors: pH and temperature. Yeast lactases act in fact at neutral pH and at medium temperature, while fungal ones act in an acid medium and at high temperatures.

NB . All heavy metals inhibit this reaction

Why not use thermal hydrolysis?

Obviously, wherever an enzymatic reaction is present it is possible to reproduce it in the absence of the catalyst by means of a chemical or physical process; therefore, the production of milk delattosate is no exception. Lactose can in fact be degraded simply by using a heat treatment between 110 and 130 ° C (remember that at 150 ° the lactose turns yellow and caramelizes at 175 ° C).

It goes without saying that the finished result is absolutely not the same! While the production of milk lactose-free with hydrolytic enzymes keeps the taste, color and aroma of the common milk almost unchanged (resulting only a little sweeter), if degradation by heat were used, qualitative alterations such as: