Early-stage analysis on developing different oat (Avena sativa L) added value fractions by ultrasound-assisted three-phase partition (UATPP): Effect of variables on yield and environmental impacts

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This research explores an oat refinery using an ultrasound-assisted three-phase partition (UATPP) to obtain three value-added fractions (oil, protein, and fiber). Ultrasound-assisted pretreatment (time), salt (weight %), and butanol (volume %) were assessed against the mass extracted (weight %) at the different fractions by response surface methodology (RSM) and environmental impacts critical for the planetary boundaries framework by life cycle assessment (LCA). Experimental results showed an acceptable regression for predicting the different fractions and their environmental effects. The protein-rich phase (wt %) varied from 4.5 to 15.3 %, where the effect of salt (wt %) and butanol (vol %) was significant, while crude protein content (65–78 %) was affected by ultrasound pretreatment (time) and salt (wt %). The oil-rich phase extracted was between 5 and 8.6 % wt, showing a typical oat's fatty acid profile: oleic (38.18–42.81%), linoleic acid (25.51–33.86 %), and palmitic acid (20.25–23.54%). For this phase, the interaction of butanol with salt (wt %) and ultrasound pretreatment (min) was significant. The fiber-rich phase showed significance with salt (wt %) and ultrasound pretreatment ranging from 66.3 to 78.8 wt %. Moreover, their rheological characteristics (G′ and G″) seemed to change by the variation in oil content, like oat flour and starches. The optimization of the process to maximize protein and oil gave the following conditions: 15 min of ultrasound pretreatment, 4.5 salt (wt %), and 50 butanol (vol %). Regarding LCA, butanol manufacture was a hot spot on environmental indicators such as global warming (kg CO2 eq·kg−1), marine eutrophication (kg P·kg−1), freshwater eutrophication (kg N·kg−1), and freshwater consumption (m3·kg−1). Land use (m2·kg−1) impacts were mainly caused by running UATTP at high dilution ratios (typical at the lab scale). Activities such as solvent reduction and recirculation were found critical to minimize environmental impacts. This analysis can aid in foreseeing potential processing and environmental implications at an early stage of development, allowing better holistic decisions.