Optimization of the sous-vide cooking process in pumpkin and carrot puree using response surface methodology

The current food market trend demands safe, ready-to-eat products with acceptable sensory and nutritional attributes. To meet these demands, sous-vide technology (vacuum cooking under controlled temperatures) emerges as an effective alternative to preserve food properties. This study aimed to optimize the time and temperature parameters of the sous-vide cooking process for a mixed vegetable puree using response surface methodology. The formulation consisted of a mixed puree (75% pumpkin and 25% carrot) incorporated with acidity regulators (citric acid, ascorbic acid, and glucono-delta-lactone at 0.15% each) to achieve a target pH of 4.3. The experimental design comprised 12 runs, including factorial and axial points, alongside five replicates of the central point (75°C- 37.5 min). The independent variables investigated were temperature (53.8°C–96.2°C) and processing time (5.7–60 min). The monitored response variables included pH, soluble solids (SS, °Brix), instrumental color (Minolta CR-350, illuminant C) evaluating L* (lightness), a* (redness), and b* (yellowness) parameters, ascorbic acid (AA) content (mg AA/100 g puree), total phenolic compounds (TPC, Folin-Ciocalteu), and antioxidant capacity (AC, DPPH). Additionally, a sensory evaluation was performed by a trained panel of 10 judges who assessed overall appearance, color uniformity, aroma, sour/sweet balance, overall flavor, and mouthfeel using a 9-point hedonic scale. Results indicated no significant differences (p > 0.05) in SS (9) and pH (4.1–4.2) among treatments. Higher L* values occurred at 60°C, whereas maximum a* values (9.3) were recorded at the central point. Treatments at 60°C exhibited greater AA retention (150 mg AA/100 g) than intense thermal treatments (90°C- 60 min and 96.2 °C- 37.5 min: ~120 mg AA/100 g). A similar trend was observed for TPC and AC. Sensory attributes showed no significant differences across treatments. Response surface methodology proved to be a robust tool for process modeling, demonstrating that moderate cooking temperatures (60°C) maximize bioactive compound retention.