Quality related aspects of sous-vide processing of borage (Borago officinalis L.) stems

- Effects of boiling, sous-vide cooking and microwaving on borage stem quality.
- Sous-vide cooking enhances total phenolic content and antioxidant activity of borage.
- Sous-vide cooked borage is brighter, greener and richer in antioxidants than boiled.
- The quality of sous-vide borage is maintained for 14 d of storage except for color.

The effect of sous-vide processing of borage stems on the organoleptic and health-related properties of this product was evaluated. Color, hardness, chlorophyll and total phenolic contents and antioxidant activity were analyzed after thermal treatment, during storage (28 days at 2 °C) and after microwave heating (700 W for 1.5 min). Vacuum-packed borage stems were heat-treated at 90 °C for 949 s to achieve the desired softening for their consumption after subsequent microwave heating (5.0 ± 0.5 N). The resultant product had enhanced total phenolic content and antioxidant activity compared to the raw product (1.8 and 2.5 times higher respectively) while the boiled borage suffered losses of 32% in the total phenolic content. The product maintained its brightness and exhibited better preservation of its greenness (82.4% retention) and total chlorophyll content (62.0% retention) than boiled stems. Independently of the storage time, the microwave heating did not significantly modify (P > 0.05) the properties analyzed except for a decrease in the hardness. No significant changes were observed in the analyzed quality parameters for 14 days of storage (P > 0.05), apart from the fact that the product became more yellowish (coordinate b*) during the first week.