Content of nitrate and nitrite in commercial and self‐made beetroot juices and the effect of storage temperature

Abstract

Abstract Popularity of beetroot juice (BJ) is growing due to its high inorganic nitrate content NO3− and its potential physiological benefits. However, the content of NO3− is not indicated in most commercial BJs and it can be affected by seasonal changes and storage conditions. This study analyzed the content of NO3− and nitrite NO2− in five and two commercial and self‐made BJs, respectively, that were purchased in the summer and winter periods. The effect of storage temperature (20°C, 4°C, and −20°C) and pH was also analyzed. In nonconcentrated BJs, the NO3− content was 34 ± 20% (p = .075) in the winter than in the summer. NO3− was fully degraded in self‐made BJ after 3 days at 20°C. This effect was attenuated by 78% and 82% when it was kept at 4°C and −20°C, respectively. The addition of lemon juice (5%) to self‐made BJ was another useful approach to avoid NO3− degradation for 3 days when it was kept at 20°C. Regarding NO2−, self‐made BJ had higher concentration (0.097 ± 0.01 mg/mL) compared to commercial BJs (<0.1 mg/mL; p = .001). The pH of self‐made BJ was higher (6.3 ± 0.1) compared to commercial BJs (4.5 ± 0.3; p = .001). These results suggest that the content of NO3− in nonconcentrated BJs can substantially differ across the year and this is an important factor to take into account when recommending BJs to promote some of its potential physiological benefits.

Keywords

• beet
• nitrate
• nitric oxide
• nitrite
• nitrogen