Protein enrichment of wheat bread with the marine green microalgae Tetraselmis chuii – Impact on dough rheology and bread quality

Marine green microalgae are a sustainable source of high-quality protein. However, due to their green pigmentation and composition of volatiles, their incorporation into food products is a challenge. Incorporation of cell-wall disrupted Tetraselmis chuii (Tc) into bread (0, 4, 8, 12 and 16% wheat flour substitution) affected dough rheology and bread quality negatively. These effects were more pronounced at addition levels necessary for a EFSA nutrition claim on protein enrichment (12 and 16%). Treatment of Tc with ethanol not only removed much of the green pigmentation and volatiles, but also reduced the negative impact on dough rheology and bread quality. Doughs prepared with ethanol treated Tc (TcEt) showed a clear improvement in dough rheology evident as increased dough-stability-time (DST), resistance to extension (Rmax) and elastic-recovery-compliance (Je) particularly at substitution levels >4%. This was accompanied by an increase in bread quality e.g. at 12% substitution level specific volume increased from 2.1 to 2.69 mL/g, crumb firmness decreased from 1358 to 297 g and slice brightness increased from 25.2 to 49.0. Ethanol treatment of algae may be a feasible strategy to address the sensory and structural challenges that hinder incorporation of algae into foods at levels that can potentially confer nutritional benefits.