Physicochemical and nutritional properties of Chinese steamed bread and fresh noodles fortified with linseed (Linum usitatissimum)

Abstract

Originated from China, Chinese steamed bread (CSB) and noodles are staple foods made from wheat. They are recognized as high glycaemic index (GI) food and medium glycaemic index food, respectively. Foods of high GI can increase postprandial blood sugar level rapidly, and raise the risks of diseases, such as obesity, Type 2 diabetes, and cardiovascular diseases. Linseed, as a source of abundant dietary fibre and phenolic compounds, was used to fortify CSB and noodles to produce novel functional foods in this project. Different proportions of ground linseed were added into CSB and noodles, including 2.5%, 5%, 10%, 15%, and 20% of substitutions. The properties of the flour mixtures and the final products were analysed. The results showed that the linseed content in flour mixtures was negatively correlated with the pasting properties (pasting temperature, peak viscosity, final viscosity, and other relative parameters), gel texture after pasting and dynamic oscillatory properties (storage modulus and loss modulus). Assigning the CSB and noodles made from pure wheat flour as control, the addition of ground linseed adversely affected their colour properties. The volumetric properties of CSB and the cooking quality of noodles were also slightly impaired. And with the increase of the ground linseed content, the hardness and other textural properties of linseed CSBs were raised, while the linseed noodles obtained a decreasing hardness, chewiness, and tensile strength. Furthermore, the linseeds fortified into CSB and noodles enhanced their antioxidant capacities and reduced the expected postprandial glycaemic responses. Lastly, sensory profiles including objective facts and subjective preferences were evaluated. CSB and noodles fortified with 2.5% proportion of ground linseed were most popular in their own acceptability profiles. Meanwhile, 5% fortification of linseed granted relatively high scores to the CSB and noodles, and this recipe would be recommended considering the nutritional functions brought by linseeds.