2.3.2. Enzymatic pretreatment (Variant II)
Raw material samples (30 g dry matter basis) were slurred in ca.
150 mL of distilled water in a 300 mL conical flasks and pH of the
slurry was adjusted to 4.5 using 1 mol L1 H2SO4 solution. Then
Ceremix 6X MG preparation (1.25 g of enzyme per kilogram of
raw material dry matter) was added and the total weight of the
flask content was adjusted to 200 g with distilled water. The flasks
were sealed with rubber stoppers to avoid water evaporation and
were placed in a water bath heated to 45 C for 20 min with constant
agitation [12]. Afterwards the slurries were cooled to 35 C,
inoculated with yeast, GSHE and protease (Neutrase 0.8 L) were
added and further procedure was the same as described in the Section
2.3.1.
2.3.3. Microwave pretreatment (Variant III)
Raw material samples (30 g dry matter basis) were spread in a
thin layer on a Petri dish and irradiated in a microwave oven KOR-
63X5 (Daewoo, China) for 2 min with 400W microwave power
output and 2450 MHz frequency. After the pretreatment samples
were cooled to room temperature in a desiccator. Further procedure
was the same as in Section 2.3.1.
2.3.4. Ultrasonic pretreatment (Variant IV)
Ground waste bread samples (30 g dry matter basis) were
slurred in ca. 150 mL of distilled water preheated to 35 C in a
300 mL conical flasks. The flasks were placed in an ultrasonic bath
SONIC-0.5 (Polsonic, Poland) for 5 min, as described by the
manufacturer the power of the bath was 250W and ultrasonic