Mineral composition and bioactive potential of red raspberry fruits, juice, and jam

Raspberries are highly valued by consumers due to their nutraceutical properties, which have been associated with various health benefits. The aim of this study was to evaluate the differences in quality characteristics of fresh raspberry fruits and final products (jam and juice) collected from plantations under different agroecological conditions (three localities). The total phenolic content in raspberry fruits and products was quantified by the FolinCiocalteu method and the total anthocyanin content by the pH-differential method. In the same samples, eight elements (phosphate, iron, manganese, zinc, calcium, potassium, magnesium, and sodium) were determined using atomic absorption spectrophotometry. The productivity of red raspberry (Rubus idaeus L.) cultivar 'Willamette' was studied by examining the variation in the number of floricanes per espalier meter and per unit area as well as the variation in yield per cane and per unit area. The results showed that the highest yield was observed in the L2 locality (660.00 g per cane and 14,840 kg ha-1 of total area), while the lowest yield was recorded in the L3 one (519.67 g per cane and 11,779 kg ha-1 of total area). The amount of macro-and microelements in the soil and raspberry fruits varied between the localities with a higher nutrient content obtained in the L2 locality. The antioxidant capacity and total anthocyanin and phenolic content of the raspberry fruits were influenced by the cultivation area with the highest values of anthocyanins (63.45 mg cyn-3-glu 100 g-1 FW) and phenols (630.00 mg GAE 100 g-1 FW) observed in the L2 locality. The study also revealed that the processing of raspberry fruits into juice and jam had minimal effects on the antioxidant capacity and phenolic content. The findings highlight that 'Willamette' raspberries are a valuable source of bioactive compounds and minerals that contribute to their nutritional value and potential health benefits. Further research and optimisation of processing techniques are necessary to effectively preserve and enhance the bioactive compounds in processed raspberry products.