Texture properties of extrudates, hardness and fracturability, are
shown in Fig. 2. Hardness increased proportionally to spelt ratio,
while fracturability decreased. Decrease of fracturability was not
significant after addition of 5% spelt, however,10% and 20% addition
resulted in significant difference. These results are in accordance
with research of Anton et␣al. (2009), who concluded that texture
properties are highly influenced by expansion degree, i.e. extrudates
with higher expansion ratio had lower hardness and higher
fracturability. Furthermore, Zhu et␣al. (2010) in research about
mechanical and microstructural properties of extrudates obtained
from high amylose corn starch and soy protein concentrate
observed that hardness increased with combination of expansion
decrease and protein agglomeration which occurs due to high
temperature and shear. In other investigations same conclusions
are reported, where presence of fibers also caused the increase of
product hardness due to reduction of cell wall thickness and their
premature rupture (Lazou and Krokida, 2010; Nascimento et␣al.,
2012; Yanniotis et␣al., 2007).