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

Waqas Muhammad Qazi,Simon Ballance,Anne Kjersti Uhlen,Katerina Kousoulaki,John-Erik Haugen,Anne Rieder

doi:10.1016/j.lwt.2021.111115

Waqas Muhammad Qazi, Simon Ballance + Show 4 more

Open Access

https://doi.org/10.1016/j.lwt.2021.111115

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Abstract

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.

Highlights

Certain green microalgae (Chlorophyta) are potential sustainable sources of high-quality protein (40–65 g/100g in dry matter) for human nutrition (Becker, 2007)
The amino acid composition of Tetraselmis chuii (Tc) did not change upon ethanol treatment (Fig. 1) and a high protein quality with contents of all essential amino acids (AA) above the reference scoring pattern for adults (FAO, 2007) was retained
The favourable AA composition of Tc was not affected by ethanol treatment and Tc and TcEt contained all essential AA above the recommended reference values (FAO, 2007)

Summary

Introduction

Certain green microalgae (Chlorophyta) are potential sustainable sources of high-quality protein (40–65 g/100g in dry matter) for human nutrition (Becker, 2007). At low doses of addition (≤3%) the functional properties of bread (specific volume and crumb density) are only slightly impacted (García-Segovia et al, 2017; Graça et al, 2018; Hafsa et al, 2014; Lafarga, 2019), while at higher microalgae doses (5–10%) such effects can be quite substantial (Finney et al, 1984; Graça et al, 2018). A further obstacle is the sulphurous algal smell (Becker, 2007; Graça et al, 2018; Lafarga, 2019) that can be imparted to the bread that probably impacts taste

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