# Chemical Fingerprint of Floral Nectar in Apple (Malus sp.) Cultivars Grown in Norway

## TL;DR

This study analyzed the chemical composition of nectar from different apple cultivars in Norway, finding significant variation in sugars and phenolic compounds.

## Contribution

The study provides a detailed chemical fingerprint of nectar from various apple cultivars, highlighting their potential as a source of bioactive compounds.

## Key findings

- Crab apple cultivars and ‘Rubinstep’ had the highest levels of main sugars in nectar.
- ‘Katja’ nectar had the highest total phenolic content and ‘Dolgo’ showed the best antioxidant activity.
- ‘Eden’ and ‘Fryd’ nectars had very high isorhamnetin levels, while ‘Katja’ had the highest gentisic acid.

## Abstract

This study included the nectar of nine standard apple (Malus × domestica) cultivars (‘Red Aroma’, ‘Discovery’, ‘Summerred’, ‘Rubinstep’, ‘Elstar’, ‘Asfari’, ‘Eden’, ‘Fryd’, and ‘Katja’) and two crab apple (Malus sylvestris) cultivars (‘Dolgo’ and ‘Professor Sprenger’). The aim was to determine the diversity of chemical compounds in the floral nectar of the two different apple species and their cultivars. Chemical analysis identified five sugars, two sugar alcohols, two organic acids, forty phenolic compounds, and five phenylamides. The crab apples ‘Dolgo’ and ‘Professor Sprenger’, along with the commercial cultivar ‘Rubinstep’, had the highest levels of all three main sugars (glucose, sucrose, and fructose). The cultivar’s ‘Katja’ nectar had the highest level of total phenolic content (60.7 mg/100 g GAE), the nectar sample from ‘Dolgo’ exhibited the greatest ability to neutralise DPPH radicals (83.4 mg/100 g TE), and the ‘Dolgo’ (100.6 mg/100 g TE FW) and ‘Katja’ (72.1 mg/100 g TE FW) nectars proved to be the best reducing agents. Floral nectar from ‘Eden’ and ‘Fryd’ showed very high levels of isorhamnetin, 49.04 mg/kg and 50.83 mg/kg, respectively, while nectar from ‘Katja’ had the highest level of gentisic acid at 39.06 mg/kg. Besides being vital for insects, apple floral nectar is a significant reservoir of phenolic compounds and can be considered a “superfood” for the human diet.