Nutritional and phytochemical comparative analysis of conventional/organic maize grain before and after subjection to accelerated aging test - a preliminary study

Abstract

This study aimed to ascertain the differences in the nutritional composition of maize grains by analysing their lipid, protein, fatty acid, triacylglycerol, and sugar content before and after undergoing an accelerated aging (AA) test. Additionally, phytochemicals (total pigments, phenolics and flavonoids), as well as antioxidant potential of maize grains were evaluated through ABTS•+ scavenging capacity and ferric reducing power (FRP) assays. Maize was cultivated in Serbia during the 2017 season, employing two growing systems (conventional and organic). Although minimal differences were observed in protein and lipid content, the grains proved to be an excellent source of polyunsaturated fatty acids and triacylglycerols with ECN44 fraction being predominant. The total soluble sugar content was low, while starch content was significantly higher. HPLC analysis confirmed a considerably higher prevalence of non-reducing disaccharides compared to reducing disaccharides. Maize grains emerged as a substantial source of chlorophyll a (0.53-4.38 µg/g DW), phenolics (1498.9-1931.3 mg FAE/kg DW), and flavonoids (85.7-381.9 mg QE/kg DW). All tested extracts exhibited satisfactory abilities to neutralize free ABTS•+. The FRP assay revealed a significantly higher ability to reduce Fe3+-ions in conventionally produced grains. According to the Blunt-Altman test, all analysed parameters showed considerable similarity, except for chlorophylls a and b. Principal component analysis (PCA) revealed that grains exposed to the AA test were mainly separated based on chlorophyll a, C20:0, C18:1n-9, MUFA, carotenoids, lipids content. Conversely, conventional untreated grains were primarily distinguished by their pentose, hexose and chlorophyll b content, while in the case of organic samples, disaccharides (both reducing and non-reducing) and soluble sugars were the main differentiating factors. The present preliminary study can serve as foundational research for future investigations aimed at comprehending alterations in nutrients and phytochemicals induced by accelerated aging tests. However, it should be supplemented and expanded upon by subsequent studies in the future.

Keywords

• accelerated aging
• grain
• nutrients
• organic agriculture
• phytochemicals
• Zea mays L.