# Glycaemic Index of Bakery Products and Possibilities of Its Optimization
### Hydrothermal Treatment of Raw Materials  
The hydrothermal treatment of grain or its products (meal, flour or flakes, for example) has traditionally been used in bakery technology, and is nowadays used in many sophisticated processes. The hydrothermal treatment of cereals (including pseudocreals and legumes, or other grains and seeds) represents a very wide range of different processes involving all the anatomical components of the grain and based on interactions between biopolymers (polysaccharides and proteins) of a hydrocolloidal nature and water, often in combination with tempering or various intensive heating processes, i.e., with various modes and technical designs of interactions with heat [72; 73]. Hydrothermal treatment, in its simpler forms (slicing and dehulling of the grain, slicing and tempering of the grain during dehulling--so-called conditioning), is part of the preparation of the grain for primary processing, particularly milling [72]. With processes that are mainly intended to prepare grain for flaking or milling, these are usually less vigorous, i.e., often involving less intensive wetting or heating. The simplest is sprinkling (moistening by a few per cent) and dehulling, which is used in preparation for the standard milling of wheat or rye. More intensive tempering combined with wetting (conditioning) or steaming of the grains is mainly used before flaking oats and other cereals [72]. However, the possibilities of hydrothermal treatment are incomparably broader, and it is applied to whole grains as well as to the products of their disintegration--hulled and otherwise surface-treated grains (hail), broken grains, cracked grains, shreds, flakes and flours. The grains and other raw materials are soaked in excess water (yield 200-300%), and then the resulting suspension is heated intensively for several hours to temperatures ranging from 40 to 80 \({}^{\circ}\)C, with temperatures of around 60 \({}^{\circ}\)C being the most common. The grains are 'cooked' in this way, whole or disintegrated, to form scrap or flour, often very rich mixtures of grains and parts thereof. Enzyme-active malt preparations (malt flours or extracts) are often added to the mixtures [74; 75; 76; 77]. During the preparation of mash or similar products, many parallel physico-chemical and biochemical processes occur in the tempered suspension (the lubrication and partial enzymatic hydrolysis of starch, partial hydrolysis of proteins, a non-enzymatic browning reaction--the Maillard reaction). The result is the formation of a very wide range of sensory active substances, both aromatic and gustatory. An important nutritional benefit and therefore a reason for the increase in the frequency of use of these technological processes in the production of bread and bakery products is the demonstrable effect on increasing the bioavailability of nutritionally important fibre components and accompanying substances (phenolic compounds, etc.) [75; 77]. However, the effect of these procedures on the structure and properties of starch, and thus on the GI, is problematic. In contrast to the hydrothermal treatment processes used for the preparation of RS3 starch, the processes used in the baking industry for the above purposes differ, firstly, by a significantly (and even several times) higher addition of water, usually working in excess in suspension, by a lower temperature (often below 80 \({}^{\circ}\)C) and in some cases, as mentioned, by the presence of amyloid enzymes. It is therefore reasonable to assume, and in some cases has been demonstrated, that these procedures not only do not have a similar effect to the hydrothermal procedures for modifying starch in terms of resistance, but may on the contrary increase the digestibility of the starch present.