Tocopherols content in gluten-free extruded composite flours of rice and different legumes
Artigo de Conferência
Visão geral
Visão geral
resumo
Extrusion cooking is a high temperature short time process, which modifies flour properties through
starch gelatinization, protein denaturation, complex formation between amylose and lipids, degradation of
pigments and improvement of sensory characteristics [1]. Vegetables contain numerous phytochemicals,
such as tocopherols, useful for their nutritional and nutraceutical properties. Tocopherols (constituents of
vitamin E) appear in several active forms, presenting α-tocopherol the highest biological activity, and
being γ-tocopherol the most abundant in vegetable foods, such as sesame seed, soybean, black bean
and peanut. Due to its action as a free radical scavenger, vitamin E also plays a role on body protecting
against degenerative abnormalities, mainly cancer and cardiovascular diseases [2]. The aim of this study
was to evaluate the changes induced by extrusion-cooking on tocopherols content in functional novel
formulations of flours containing different proportions of rice (50-80%), bean (20-40%), and carob (5-10%)
using the raw materials as control. Tocopherols were determined in the different flours mixtures of ricelegumes
by high performance liquid chromatography coupled to a fluorescence detector (HPLC-FL)
programmed for excitation at 290 nm and emission at 330 nm, following a procedure previously
described by Barros et al. [3]. In general, the samples showed low levels of tocopherols and, in some
cases, namely in extrusion samples, the total absence of this vitamin was verified. 𝛼-, γ- and δ-
Tocopherols were the vitamers detected in several flours, highlighting bean with the highest concentration
of total tocopherols (180 ± 1 μg/100 g). In the samples where tocopherols were detected, the raw
materials and in all the evaluated mixtures, γ-tocopherol was the predominant vitamer, being present in
greater concentration in bean with values of 172 ± 1 μg/100 g. In this study it was also observed that,
after extrusion, a significant reduction occurred in the total tocopherols content, being verified the
absence of these molecules in different flour mixtures.
In addition, the sensitivity of vitamin E to extrusion cooking depends on the extrusion processing
variables and conditions used, particularly extrusion temperatures (that promotes the decrease in α-
tocopherol) and moisture during extrusion (decreasing γ-tocopherol content).
