Dynamics of nitrate and nitrite content during storage of home-made and small-scale industrially produced raw vegetable juices and their dietary intake

Abstract

The influence of storage conditions on nitrate and nitrite contents, pH, and total viable bacterial count of raw vegetable juices was studied. Three different types of juices from an Estonian small-scale producer and five different types of home-made juices were analysed. Analyses were performed immediately after opening the commercial juice packages and immediately after preparation of a home-made juice. Additionally, samples were taken after open storage of a juice at the refrigerator and ambient temperatures during 24 and 48 h. The biggest changes in nitrate and nitrite contents were found during storage of carrot, beetroot and radish juices. During 48 h of storage at ambient temperature, the mean increases of nitrite content in home-made carrot, beetroot and radish juices were from 0.1 to 187, from 2.1 to 578, and from 0.5 to 259 mg l(-1), respectively. In the case of commercial lightly pasteurized products, the biggest increase of nitrite content, from 3.2 to 11 mg l(-1), was found in red beetroot juice. After 48 h of storage at refrigerator temperature, the changes of nitrite and nitrate were smaller. In the case of consumption of 300 ml of home-made carrot juice, with a nitrate and nitrite content of 64 and 110 mg l(-1), respectively, stored for 24 h at ambient temperature, the average intake was 8% and 846% of the acceptable daily intake of nitrates and nitrites, respectively. After consumption of 50 ml of the same carrot juice by children (1-2 years of age) the average intake of nitrates and nitrites was 7% and 733% of the acceptable daily intake, respectively.