The nutritional value and vitamin C content of different raspberry cultivars from organic and conventional production

Abstract

Raspberry fruit is a source of vitamin C. Vitamin C has antioxidant properties and can neutralize the negative effects of oxidative stress. The aim of this study was therefore to compare the content of vitamin C, sugars and organic acids in organic vs. conventional raspberries and to determine the effects of harvest time and cultivar on the contents of these compounds. The experiment was carried out in 2013–2014. Fruits from four raspberry cultivars ('Laszka', 'Glen Ample', 'Glen Fine' and 'Tulameen') were collected in the summer, and fruits of the 'Polka' cv. were collected in the autumn. The experiment was carried out on three organic farms and three conventional farms. The vitamin C, sugars and organic acids contents were determined using the HPLC method. The conventional raspberries grown in 2013 contained a significantly greater vitamin C (40.5 mg/100 g FW) and dehydroascorbic acid (35.8 g/100 g FW) content compared to organic raspberries (33.7 mg/100 g FW and 29.2 mg/100 g FW, respectively). We observed an effect of the cultivar on the total organic acids and citric acid content in raspberry fruit in 2013 and 2014. ‘Laszka’ cv. (1720 mg/100 g FW and 1650 mg/100 g FW) and ‘Glen Fine’ cv. (1740 mg/100 g FW and 1710 mg/100 g FW) fruits contained significantly more total organic acids and citric acid (1680 mg/100 g FW and 1610 mg/100 g FW) as well (1680 mg/100 g FW and 1670 mg/100 g FW) compared to the other experimental cultivars. However, the 2014 ‘Tulameen’ cv. was characterized by the highest levels of total sugars (14.9 g/100 g FW) and sucrose (5.0 g/100 g FW) content. The conventional raspberry fruits (55.4 mg/100 g FW) harvested in the autumn of 2014 contained a significantly greater malic acid content compared to organic fruits (46.2 mg/100 g FW).