# Physicochemical and Molecular Properties of Spelt and Wheat Starches Illuminated with UV Light
## 3 Results and Discussion
### Susceptibility to \(\alpha\)-Amylolysis  
The size, shape, and surface porosity of the starch grains are of importance in the enzymatic hydrolysis process. Some of the authors [30] proposed that the pores may be a site of initial attack by amylases and affect the pattern of attack. The main products of the enzymatic hydrolysis of starch using \(\alpha\)-amylase are maltose, maltotriose, and maltotetraose [31]. The dependence of the resulting concentration on the hydrolysis time of spelt and wheat starch is illustrated in Figures 16 and 17, respectively.  
Regardless of the irradiation time, the \(\alpha\)-amylolysis for all starches (spelt and wheat) was carried out in two stages and the observations were similar to the values reported by others [31]. The rate of stages were different and the first (up to 40 min)--described with rate constant k\({}_{1}\)--was fast. The second step was considerably slower. Based on Figures 18 and 17, the initial rate constants of the hydrolysis reaction (k\({}_{1}\)) were determined for the native and modified starches, and these values are summarized in Table 4.  
Comparing the rate constants of the first stage of enzymatic hydrolysis and the final result, we may conclude that wheat starch is more responsive to the \(\alpha\)-amylase attack. In [31,32], the authors confirmed that starch containing a high percentage of short chains  
\begin{table}
\begin{tabular}{l c} \hline \hline
**Starch \({}^{**}\)** & \(\mathbf{k_{1}\cdot 10^{-3}\;[mg\times mL^{-1}/min^{-1}]}\) \\ \hline
**Spelt** & 3.52 \(\pm\) 0.1 \\
**Spelt-5** & 4.39 \(\pm\) 0.2 \\
**Spelt-15** & 7.09 \(\pm\) 0.2 \\
**Spelt-25** & 8.55 \(\pm\) 0.1 \\
**Spelt-50** & 7.79 \(\pm\) 0.4 \\ \hline
**Wheat** & 4.32 \(\pm\) 0.2 \\
**Wheat-5** & 5.48 \(\pm\) 0.2 \\
**Wheat-15** & 6.01 \(\pm\) 0.1 \\
**Wheat-25** & 6.70 \(\pm\) 0.1 \\
**Wheat-50** & 8.41 \(\pm\) 0.3 \\ \hline \hline \end{tabular} \({}^{*}\)Calculated from three repetitions of measurement \(\pm\) standard deviation; ** Values indicate the time of exposure [hours].  
\end{table}
Table 4: Rate constants (k\({}_{1}\)) of the hydrolysis of the natural and irradiated cereal starches \({}^{*}\).  
together with a major branch density was less susceptible to amylases. The lower susceptibility of spelt to amylolysis was influenced by the high proportion of short chains in spelt amylopectin. Furthermore, spelt starch is built with higher number of small grains, resulting in a rich content of lipids. Lipids, however, make it difficult for the enzyme to expand inside the granule.  
The UV irradiation of cereal starches (wheat and spelt) significantly increases the first step of enzymatic reaction. This fact is confirmed by the increase in the k\({}_{1}\) values with respect to the unmodified starches. Irradiation of wheat starch granules induces a gradual growth in the k\({}_{1}\) reaction rate along with the increase in the UV illumination time. A significant rise up susceptibility to the action of the enzyme was recorded for a sample of wheat starch exposed to UV for 50 h. This may result from the partial degradation of the starch shell during prolonged irradiation and thus the facilitation of the expansion of the enzyme inside the starch granule. Meanwhile, for spelt starch irradiated for 50 h, a reduction in the rate of enzymatic reaction was noted in relation to the samples irradiated for 25 h. The spelt starch irradiated for 50 h was characterized by the highest values of M\({}_{\rm w}\) polysaccharide chains, which may affect the enzymatic hydrolysis levels. Additionally, the research [31] on the hydrolysis of starch amylopectins indicates that the average chain length distribution affects the enzymatic hydrolysis rate of amylopectin after the first stage. The susceptibility to \(\alpha\)-amylolysis is insignificant at the initial stage for different average chain length amylopectins.