Fisherbrand isotemp stirring hotplate

One wt% aqueous suspension of each flour sample was heated to pre-determined temperatures (30 °C, 50 °C, 70 °C, and 90 °C) for 1 h with constant stirring using a magnetic stir bar and a stirring hotplate (Fisherbrand Isotemp stirring hotplate; Thermo Fisher Scientific, Mississauga, ON, Canada). Samples were poured into a weighed centrifuge tube and centrifuged at 3000× g for 10 min. The supernatants were carefully poured into weighed aluminum dishes and evaporated at 100°C using a drying oven (Fisherbrand Isotemp 180 L drying oven; Thermo Fisher Scientific, Mississauga, ON, Canada) for 24 h. The weight of dry solids was determined for the calculation of solubility. The weight of wet sediments in the centrifuge tube was determined for the calculation of swelling power:

Solubility and swelling power were measured using a similar methodology that was previously reported by Huang et al. [4 (link)]. One wt% aqueous suspension of each flour sample (ratio of 0.1 g flour for every 10 mL of water) was prepared in a 500 mL glass flask and was heated at desired temperatures (30, 50, 70, and 90 °C) for 1 h with constant stirring using a magnetic stir bar and a stirring hotplate (Fisherbrand Isotemp stirring hotplate; Thermo Fisher Scientific, Mississauga, ON, Canada). Samples were poured into a weighed centrifuge tube and centrifuged (Model 21000, IEC International Equipment Company, Needham Heights, MA, USA) at 3000× g for 10 min. The supernatant was poured into a weighed aluminum dish and evaporated at 100 °C in a drying oven (Fisherbrand Isotemp 180 L drying oven; Thermo Fisher Scientific, Mississauga, ON, Canada) for 24 h. The weight of dry solids and the weight of wet sediments in the centrifuge tube were determined for the calculation of solubility and swelling power, respectively.

Hydrogels were prepared according to the manufacturer’s instructions in accordance with the principles of Good Manufacturing Practice (GMP) [21 ]. The water was heated to 70 °C before mixing. Sepineo™ P 600 and Sepineo™ PHD 100 were mixed with water by mechanical stirring (10 min at 500 rpm; Fisherbrand Isotemp stirring hotplate; Thermo Fisher Scientific, Mississauga, ON, Canada) until a hydrogel was obtained. The polymer matrix preparation process occurred in three steps: diffusion of water molecules into the polymer network (1), relaxation (loosening) of the polymer chains by hydration (2), and swelling of the polymer network (3) [22 (link)]. After 24 h, insulin at a dose of 1 mg/g (28.57 IU/g) was introduced into the resulting substrates using a mechanical mixing method. The composition of the formulation is shown in Table 1.