High moisture microwave treatment modulates functional and pasting characteristics of teff flour

Teff (Eragrostis tef) is an annual grass native to Ethiopia. Teff has an attractive nutrition profile, high in dietary fibre, iron, protein and calcium. Being minor cereal, it is considered gluten-free what creates wide range of possibilities for its usage. Recently its cultivation has started also in Europe, especially Spain. There are several different varieties of teff, but the differentiation based on cultivar name/number is more pronounced in country of origin (Ethiopia), while in Europe is the colour – white or brown, which distinguishes the cultivars. Physical treatments are being considered as alternatives to improve the technological properties of various gluten-free flours. Heat-moisture treatment (HMT) is used for improving of poor functional properties of native starch and is particularly favourable for food applications. Compared to conventional HMT processes, the use of microwave radiation (MW) has been proven to be one of the most attractive treatments due to its low cost and high efficiency in heat transmission. MW treatment has also demonstrated a capability to modify the functionality of the flours. The following study assessed the impact of microwave radiation in the conditions of pre-set initial moisture content of 20% and 30% and heating for 4 or 8 min in cycles of MW exposure/rest of 20/40 s for white and brown Spanish teff varieties. The colour changes and techno-functional properties of hydration characteristics correlated with viscometric profile were evaluated. The important factors impacting the differences were initial moisture content and the variety of teff. The viscometric curves were smoothen revealing higher stability of the paste.