Rubus idaeus L. fruit nutrients are affected by different growing technologies

Abstract

The biochemical compounds of red raspberry (Rubus idaeus L.) fruits cultivated with conventional growing technology and on a nutrient substrate were studied during 2019–2020 at the Federal Horticultural Research Center for Breeding, Agrotechnology and Nursery, Moscow, Russia. The antioxidant activity, phenolic compounds, and ash constituents of the fruits and the metabolites of the alcoholic extract of the raspberries were determined. The effect of growing technologies, i.e., conventional vs. nutrient substrate, on the accumulation of macro- and microelements in raspberry fruits was established. In red raspberries grown on nutrient substrate, the antioxidant activity decreased by 25 times (aqueous extract) and 1.5 times (alcoholic extract). The K and Na contents and Se contents of red raspberries grown on nutrient substrate were 1.5 and 3 times higher than those of raspberries of grown with conventional technology. Raspberries grown with conventional technology contained 2 times more Ca, Ni, and Mn and 7.4 times more Fe than raspberries grown on nutrient substrate. The total amount of elements in raspberries grown through soilless cultivation was 5.5% higher than that in berries grown conventionally. A total of 48 compounds were identified in the alcoholic extracts, and only 29 substances were found in berries grown on a nutrient substrate. Sugar and citric acid constituted the largest share of red raspberry components. Fructose and turanose disaccharide synthesis in raspberries grown on nutrient substrate was 20% higher than that in conventionally grown raspberries. A total of 48 organic compounds with different biological activities were identified. They included five substances with antimicrobial activity, three phenolic substances, eight organic acids, four sugar acids, nine amino acids, and 19 sugars and their derivatives. At the same time, 42 compounds were found in raspberries grown with traditional technology, and 21 compounds were identified in raspberry fruits grown on nutrient substrate. Three fatty acids, namely, ɑ-linoleic acid (polyunsaturated omega-6 fatty acid), palmitic acid, and stearic acid (saturated fatty acid), along with cinnamic acid, shikimic acid, and chrysin were found in berries grown conventionally.