Effect of vacuum cooking treatment on physicochemical and structural characteristics of purple‐flesh potato

Cook‐vide (CV, vacuum boiling) and sous‐vide (SV, cooking in a vacuum‐sealed pouch) have been applied to cook purple‐flesh potatoes. Response surface methodology (RSM) sets up the work conditions of temperatures (78–92 °C) and times (16–44 min). Textural parameters, colour and anthocyanins have been measured in cooked samples, and microstructure of cooked tissues was observed with cryo‐SEM technique. CV and SV provided similar hardness (P > 0.05), while SV treatments provided samples more adhesive and cohesive than CV ones (P ≤ 0.05). Micrographs of cooked samples showed rounder cells in cook‐vide samples and higher swelling than in sous‐vide ones. SV treatment avoided the leaching into the water of anthocyanins (chromophore) retaining more of them in potatoes (P ≤ 0.05), as a consequence of which total colour difference was lower in SV samples compared with CV ones (P ≤ 0.05). Particularly, CV samples were lighter (higher values of L*) and less reddish (lower values of +a*) than SV ones (P ≤ 0.05).