Analysis of tocopherols and phenolic compounds in extruded lentil flour formulations for development of snack-type functional foods

Pulses are currently considered as functional gluten-free foods, which could be included in extrusion formulations in order to develop functional products with high nutritional value [1]. In the present study individual phenolic compounds and tocopherols were evaluated in different lentil flours (raw and extruded at 140 and 160ºC) formulated with nutritional yeasts.Phenolic compounds were analysed by using a HPLC equipped with a diode-array detector and coupled to a mass detector [2].For the analysis of tocopherols, it was used HPLC coupled to a fluorescence detector [1]. Extrusion cooking may affect bioavailability of phenolic compounds due to high temperature that causes decomposition of heat-labile phenolic compounds and may also lead to polymerization of some phenolic compounds under high pressure [3]. Catechin hexoside was the most abundant phenolic compound, with values around 30.7 to 66.1 mg/100g dw in raw samples. After the extrusion process, it was observed the highest decrease in the lentil flours formulated with the highest amount of nutritional yeast (16%). The other phenolic compounds, also experiment a decrease but in a less extend, probably due to partial hydrolysis of conjugated phenolics[4].Particularly in the case of kaempferol-O-desoxyhexide-O-hexoside- O-rutinoside, quercetin-3-O-glucoside, quercetin-O-hexoside and quercetin-O-pentoside. Regarding tocopherols content, there was a significant decrease in all tocopherol vitamer safter the extrusion process.In the studied raw samples, total tocopherols content ranged from 2.05 to 3.02 mg/ 100g (dw). The results showed a reduction of 81.5-92% in total tocopherols, which is in accordance with other authors [3]. The authors are grateful to ALIMNOVA research group (UCM-951505/2012), FCT, Portugal and FEDER under Programme PT2020 (financial support to CIMO (UID/AGR/00690/2013, A. Fernandes grant (SFRH/BPD/114753/2016) and L. Barros contract). info:eu-repo/semantics/publishedVersion