Nutritional, Phytochemical, and Antioxidant Profiling of Cold-Pressed Oils and Press-Cake Byproducts from White, Yellow, and Blue Poppy ( Papaver somniferum L.) Seeds

Seeds, cold-pressed oils (CPOs), and press-cake flours (PSCFs) derived from three poppy (Papaver somniferum L.) seed color varieties (white, yellow, and blue) were systematically characterized to elucidate compositional changes associated with the cold-pressing process. The effects of seed color, material type, and their interaction on the evaluated parameters were assessed using two-way analysis of variance. Relative to the whole seeds, the PSCFs were markedly richer in protein (33.70–37.45% versus 19.58–24.22%) and ash (12.38–13.46% versus 7.07–8.87%), lower in fat (9.72–10.59%), and were concentrated sources of Ca, Mg, P, K, Mn, Fe, and Zn, the white-seed flour ranking highest for most macroelements. Linoleic acid dominated every matrix (64.41–76.81% of total fatty acids), and the yellow-seed oil showed the highest unsaturated fraction (91.64%). The free amino acid pool was 33–97 times larger in the flours than in the seeds, and the yellow-seed flour was the richest source overall. The flours exhibited higher total phenolic content and stronger DPPH, FRAP, and CUPRAC activities than the seeds and oils, and the color × material interaction was significant for almost all variables (p < 0.05). Cold-pressed poppy press-cake flour is therefore a nutrient-dense, antioxidant-rich byproduct and a promising candidate for functional food applications, pending further safety, technological, and sensory evaluation.