Characterization of Quinoa Defatted by Supercritical Carbon Dioxide. Starch Enzymatic Susceptibility and Structural, Pasting and Thermal Properties

Abstract

Quinoa has recently been considered as an alternative oilseed crop due to the quality and quantity of its lipid fraction. Supercritical fluid extraction (SFE) was used in this work as a green process to extract quinoa oil without solvent residues. Defatted quinoa flour is a potentially valuable raw material whose performance as food ingredient needs to be established. Structural, physicochemical, pasting and thermal properties of quinoa (cv. Titicaca) defatted by supercritical CO2 extraction (DQ-SCCO2) were characterized. In vitro starch enzymatic susceptibility by Englyst method was also evaluated. Full fatted quinoa (NDQ) and quinoa defatted by hexane extraction (DQ-HX) were also evaluated in parallel. Quinoa cv. Titicaca showed a very high enzymatic susceptibility regardless its lipid content; 90% of the starch was hydrolyzed by digestive enzymes in 20 minutes in the three samples. Defatted quinoa showed lower pasting temperature (4-5ºC) than NDQ and higher gelatinization (14%) enthalpy. DQ-SCCO2 showed a disrupted and microporous structure due to the pressure of CO2 used in SFE. However, its viscometric profile was very similar to that of NDQ, opposite to that observed for DQ-HX, which was significantly lower. This denotes a physical/thermal modification of the flour as a result of the higher temperature applied during hexane extraction, 68ºC, versus 40ºC in SFE. The work confirms the feasibility of using DQ-SCCO2 as a raw material in food applications, free of solvent residues, and with a technological quality superior to that obtained by extraction with organic solvents.

Protein and lipid enrichment of quinoa (cv.Titicaca) by dry fractionation. Techno-functional, thermal and rheological properties of milling fractions

“…Gelatinization data obtained from DSC are shown in Table 3. Thermograms of quinoa samples showed two wide endothermic transitions in the first run; one between 65 and 80°C, due to starch gelatinization, and the other between 85 and 100°C, related to amylose-lipid complex and/or protein denaturation (Solaesa et al, 2019). The reversibility of this second endotherm (Tp~95ºC) confirms the presence of amorphous amylose-lipid complex within these samples (Eliasson, 1994).…”

“…These findings demonstrate that the combination of dry milling (with a ball mill) and sieving allows to obtain a grit fraction (~500 µm) markedly enriched in protein, ash and lipids, with respect to the original grain, with a concentration 50% (for protein and ash) and 80% (for lipids) higher than the whole flour. This indicates that, beyond kinetic and flow considerations, the medium fraction (~500 µm) should be the best choice to use as raw material in supercritical carbon dioxide extraction of quinoa oil (Benito-Román et al, 2018;Solaesa et al, 2019;Wejnerowska & Ciaciuch, 2018). The medium fraction also represents a very suitable ingredient for both gluten free and vegetarian products due to its high protein and mineral content.…”

“…Although quinoa of Andean cultivars is relatively well characterized (Contreras-Jiménez, Torres-Vargas, & Rodríguez-García, 2019;García-Salcedo et al, 2017;Zhu & Li, 2019), so far very little information is available about European quinoa cv. Titicaca (Benito-Román, Rodriguez-Perrino, Sanz, Melgosa, & Beltrán, 2018;Solaesa, Villanueva, Beltrán, & Ronda, 2019). Quinoa is mostly consumed as a whole grain or milled as a whole flour, after removal of the saponins, either by washing or polishing.…”

“…The largest particle size (500-1000 μm) presented a higher resistance to the internal mass transfer, and therefore the extraction was very slow; and very small particle sizes, by contrast, induced the channeling of the CO2, which would leave zones of the packed bed without contact with the solvent. Solaesa et al (Solaesa et al, 2019) reported the good techno-functional properties of defatted quinoa in the form of grits (500 μm) obtained as a coproduct from quinoa oil supercritical extraction. In view of the technological interest that quinoa grits of intermedium size (~500 μm) have for different industrial applications, a simple, efficient and fast dry milling process to obtain quinoa grits of this particle size enriched in lipids (supercritical oil extraction) and proteins (pasta making) has been studied and implemented.…”

The Influence of Supercritical Carbon Dioxide on Graham Flour Enzyme Polyphenol Oxidase Activity

“…Our study was focused on lower pressure conditions compared to those in earlier works due to possible changes in flour quality [ 36 ] (in granulation, lipid content, flour moisture, etc.). Therefore, only pressure up to 300 bar was used for flour treatment, in order to preserve all the valuable characteristics of the flour, because scCO 2 , under these conditions had no deteriorating effects on its nutritional value [ 37 ], while at the same time seeking the greatest decrease in PPO activity possible, as this activity causes unwanted processes in the context of long-term flour storage.…”