produce a reasonable loaf volume through increasing dough viscosity
for better gas trap and by improving water-binding due to
the hydroxyl groups in the hydrocolloid structure, which allow
more water interactions through hydrogen bonding (Nishita et al.,
1976). This improvement in the volume of soy donut could be due
to the similar fuctions of HPMC in other gluten-free breads with
hydrocolloids.
The surface color of deep-fat fried products is one of the most
important quality attributes. There were significant color differences
in all of the formulations (Table 3) (p < 0.05). Generally, the
wheat donut had higher L and lower a* and b* values than the soy
donuts, except for the SH donut. Soy flour seemed to impart the
donut with a darker color. This result might be attributed to the
lysine groups in soybeans that react with sugars in a non-enzymatic
browning reaction or Maillard reaction (Marco & Rosell, 2008). The
L value of SH donutswas 60.64, whichwas significantly lighter than
other samples. On the other hand, SHC exhibited the lowest L
values (48.49). The chroma value of the W donut (26.08) had a