Instant controlled pressure drop processing modulates phenolic composition and fatty acid profile in Amaranthus...

Instant Controlled Pressure Drop (DIC) is a high-pressure/short-time thermo-mechanical pretreatment that can expand grain structure and improve phytochemical accessibility. This study assessed how DIC conditions (0.10-0.40 MPa/10-90 s) modulate phenolic composition and lipid fingerprints in two Amaranthus hypochondriacus grain varieties ("Criollo" and "Laura") using a 13-run central composite design. Ethanolic extracts were profiled by HPLC, while GC-MS characterized the extracted oils. HPLC identified gallic acid, catechin, p-hydroxybenzoic acid, ellagic acid, trans-4-hydroxycinnamic acid, quercetin, and rutin, plus one additional peak quantified as rutin equivalents. DIC strongly affected total phenolics, with Criollo ranging from 346.14 μg/g (0.14 MPa/22 s) to 3035.2 μg/g (0.25 MPa/50 s) and Laura from 281.51 μg/g (0.36 MPa/78 s) to 2074.15 μg/g (0.25 MPa/50 s). Catechin and Rutin were the predominant compounds across treatments. GC-MS showed oils dominated by palmitic, oleic, and linoleic acids and squalene, with balanced saturated and unsaturated fractions. In both varieties, pressure-time interactions indicated that mild-to-moderate treatments were optimal, maximizing phenolic recovery without markedly altering the fatty-acid signature.