# Glycaemic Index of Bakery Products and Possibilities of Its Optimization
### Rapidly Digestive, Slowly Digestive and Resistant Starch  
The starch contained in cereals and other starchy raw materials for food production in intermediate products and in the products, themselves can be divided, from the point of view of human nutrition, into rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS). RDS and SDS are, as a result, completely metabolized. RDS represents the highest glycaemic load, and is the main factor responsible for the high  
Figure 1: Diagram of basic operations in the processing of cereals for bread production and the sections where the GI value is significantly affected (bold). glycaemic index of cereal products and the resulting consequences for human nutrition and consumer health [33; 34; 35; 36; 37; 38]. A high GI value caused by a high proportion of RDS is the de facto cause of the increased potential for type 2 diabetes and related health problems and diseases. SDS is more favourable in this respect. Digestibility (rate of resorption) is influenced by a number of factors, including origin (source plant), starch grain size, the ratio of amylose to amylopectin, the extent of molecular associations between starch components, the type and degree of crystallinity, the length of the amylose chain, the molecular structure of amylopectin, and the presence of amylose-lipid complexes. Morphology and ultrastructure should also be taken into account, e.g., specific surface area, channels, and the porosity of starch grains [3; 39; 32; 38]. Starch is hydrolys in the small intestine by \(\alpha\)-amylase from the pancreas (\(\alpha\)-1,4-glucan-4-glucuron-abdrorolase, EC 3.2.1.1), hydrolysing the \(\alpha\)-D-(1\(\rightarrow\)4) linkage. In contrast to the hydrolysis of amylose, which is randomly cleaved into maltooligosaccharides, the action of \(\alpha\)-amylase on amylopectin is systematic: its resulting products are maltose, maltotriose, and branched \(\alpha\)-boundary dextrins containing all the original \(\alpha\)-D-(1\(\rightarrow\)6) linkages and adjacent \(\alpha\)-d-(1\(\rightarrow\)4) linkages. amylose is resorbed more slowly and to a lesser extent than amylopectin. The glycaemic response of amylose has been shown to be less than that of the same amount of amylopectin [40]. The specific surface area of the grains is determined by their size. Native starch grains are divided according to size into fractions A and B, with the smaller starch grains (fraction B) having a larger specific surface area and (according to X-ray diffraction patterns [34]) having most of their branching points clustered in the amorphous region and therefore more being readily subject to enzymatic hydrolysis. The specific surface area is related to the particle size distribution that is characteristic of the crop, i.e., with cereals not only for the cereal species, but also for its variety [41; 42]. Resistant starch (RS, which is subdivided into types 1 to 5) is starch that is not digested in the human small intestine and passes into the large intestine, where it is partially metabolized by the microorganisms present, and is therefore a component of fibre [41; 42]. RS is therefore a heterogeneous group of starch-based compounds that are classified into 5 groups according to their resistance to digestion, i.e., according to the nature and properties of the starch grain. Resistant starches, depending on their origin and the way the food or food preparation is processed, exhibit health-promoting physiological effects on the human body similar to other fibre components with a probiotic function [41; 42]. Resistant starch types RS1, RS2, RS3 and RS5 are naturally present in foods. Resistant starch type 1 (RS1) is a physically inaccessible (unavailable) starch, e.g., starch in intact whole or partially disturbed grains or seeds of legumes and raw cereal grains, where the starch is part of the cell wall or protein matrix and is not amenable to enzymatic hydrolysis by amylolytic enzymes.