Analysis of selected primary metabolites and phenolic profile of ‘Golden Delicious’ apples from four production systems

Introduction. Apple fruit contains many compounds with positive effects on human health but even small pesticide residues from integrated production cause many food safety issues for consumers. Materials and methods. The apple fruits from different types of production: organic, integrated and two combined systems were analyzed. Their contents of sugars and organic acids were quantified with the use of HPLC with RI and UV detectors, and phenolic contents from apple skin and pulp were detected with HPLC-MS. Apple quality was also determined in terms of weight, firmness and color. Results. Organically produced fruits had 14% lower weight than integrated fruits, as well as 15% higher firmness and less green skin color than apples from the other three treatments. Among primary metabolites, the sum of sugars (fructose, glucose, sucrose and sorbitol) as well as organic acids (malic and citric) was highest in the integrated production treatment. Among secondary metabolites, eighteen individual phenolic compounds were determined separately in apple peel and pulp. They were classified into four groups: hydroxycinnamic acids, flavan-3-ols, dihydrochalcones and flavonols. The majority of the identified compounds were dependent on the applied management system. Their concentrations were mainly highest in the organic treatment due to higher stress levels. The multivariate analysis of all monitored parameters placed organic production into one group and presented a similarity among the other three management systems