. Raw material
Waste wheat–rye bread, the most common bread type in
Poland, was obtained from a large local producer. The material
constituted returns of unsold bread from shops, it did not shown
signs of surface mold spoilage. The whole loafs were manually
cut into ca. 2–4 cm dices and dried in a forced air oven (WTC Binder,
Germany) at 40 C for 12 h. Afterward the material was ground
in a knife mill (Rotary Mill, Brabender, Germany) with 1.5 mm
internal mesh sieve and stored at room temperature in airtight
jar until used. The moisture content in raw material was measured
using WPS 50P weighing dryer (Radwag, Poland) and it ranged
41.43 ± 1.38 g kg1 (mean value ± standard deviation at n = 3).
Starch content in the substrate was measured using Ewers polarimetric
method [25] and it ranged 689.13 ± 4.52 g kg1 of dry matter.
The content of total sugars in waste bread sample was
measured using the DNS method [26] after mild acid hydrolysis
(70 C, 10 min) with 80 g L1 HCl solution (1:7.5 m/v raw material
to acid solution ratio). Total sugars content in the raw material ranged
866.87 ± 2.85 g kg1 dry matter.
2.2.