2.1. Materials
The materials employed in this study were powders of two
kappa type semi-refined carrageenans K12 and K73, and one iota
type K92S, all obtained from Regis Ltd (Krakow, Poland). These
materials, being the mixture of three production batches, were
delivered in aluminum foil laminated polyethylene packages and
stored not longer than two weeks before preparation of carrageenan
gels. Temperature during transportation and storage did
not exceed 20 C.
2.2. Preparation of carrageenan cubes
Semi-refined carrageenan powders or their blends were mixed
with distilled water and homogenized, and then heated in a water
bath up to 70 C. As soon as this temperature was achieved, the
mixture was thermostated for 30 min while stirring using a CAT
R50 mechanical stirrer (Ballrechten-Dottingen, Germany). The
resulting gel was poured onto a stainless steel tray, heated to
70e80 C in a convection oven, and allowed to cool at ambient
temperature (20e22 C). Cubes of 5 mm size were cut out from the
solidified gel using a using a tool comprising two parallel knife
blades with a distance of 5 mm. The drying process was carried out
for cubes of carrageenan gel containing the ingredients presented
in Table 1.