Evaluation of fruit mineral contents of two apple cultivars grown in organic and integrated production systems

Apples are an important source of bioactive compounds, especially mineral nutrients. Minerals (both macro- and micro-elements) are responsible for the functioning of the human body, and involved in the metabolism and production of carbohydrates, lipids, proteins, vitamins and enzymes. The objective of this study was to determine and compare the content of some minerals (K, P, Ca, Mg and Fe) of two different apple cultivars (LSQUORed Aroma OrelindRSQUO and LSQUODiscoveryRSQUO), both in peel and pulp, grown in organic and integrated production systems in western Norway in 2015. Samples of fruits were prepared by microwave digestion using an Ethos 1 microwave system. All analyses were performed in triplicate on a Thermo Scientific iCAP 6500 Duo ICP. The results showed that potassium was found in the largest quantity in both apple cultivars and in both management systems and average concentration was 944.3 µg g^‑1 of fresh weight (FW). Calcium was in second place with average of 180.6 µg g^‑1 FW. Both apple cultivars had largest amounts of both K and P (in peel and flesh) from organic production compared to fruits coming from the integrated production system. The cultivar LSQUORed Aroma OrelindRSQUO had a significantly higher level of Fe in organic fruits compared to integrated. The present study showed that the highest values of K/Ca, (K+Mg)/Ca and Mg/Ca were obtained from the cultivar LSQUODiscoveryRSQUO under organic production (both in peel and flesh). Regarding significantly higher concentrations of P, K, Mg, Fe and balanced mineral ratios in organic apples, it can be concluded that those fruits have higher quality, and are at lower risk of bitter pit when stored.