Characterization of the Biochemical Potential of Moroccan Onions (Allium cepa L.)

Amal Brahimi,Abdelhakim Boudboud,Mohamed El Ouardi,Lhoussain Hajji,Amal Kaouachi,Hassan Hajjaj,Hamid Mazouz,Eduard Hernández

doi:10.1155/2022/2103151

Amal Brahimi, Abdelhakim Boudboud + Show 6 more

Open Access

https://doi.org/10.1155/2022/2103151

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Abstract

Allium cepa L. remains the most cultivated Allium species in Morocco and around the world. With the purpose of making the first biochemical characterization of Moroccan onions, several biochemical components have been measured in eleven onion ecotypes. Onions were collected as seeds from different geographical origins and cultivated in the same environment, to eliminate the influence of the environment on biochemical expression. Moisture, total phenols, flavonoids, antioxidant activity, total and reducing sugars, and sulfur dioxide were the biochemical properties of interest. Except for moisture, the eleven onion ecotypes revealed a highly significant variation in terms of the studied biochemical characters. The total phenol and flavonoid content ranged from 5.94 to 11.22 mg equivalent gallic acid/g dry weight and 0.67 to 1.52 mg equivalent quercetin/g dry weight, respectively. The antioxidant activity of the studied onions showed a strong correlation with the polyphenols (R2 = 0.7189), especially with the flavonoids (R2 = 0.8063). The sulfur dioxide content parted from 85.60 to 30.43 ppm when measured using the Monier-Williams distillation method. The current results show that there is no correlation between total sugars and reducing sugars. In conclusion, these findings present a clear biochemical profile of Moroccan onion ecotypes, as well as confirm, for the first time, the presence of a clear variation between the biochemical profiles of Moroccan onion ecotypes, which could be useful for future valorization programs.

Highlights

IntroductionOnion is one of the oldest and most valuable cultures practiced in the world
The current study found that, based on bulb skin coloration, white onion had the lowest Total phenol content (TPC) level compared to red and yellow bulbs, which matched the findings of Lee et al [8]
The study of the biochemical properties of eleven Moroccan onion ecotypes confirms that the onions studied contain a high level of phenolic components, the flavonoids, which explains the high antioxidant activity detected

Summary

Introduction

Onion is one of the oldest and most valuable cultures practiced in the world. Despite the high-cost investment, fund, price fluctuation, and the absence of sustainable income, onion remains the most cultivated culture on the planet [1]. It has a total cultivated area of 5.15 million hectares and an annual production of 99.5 million tons [2]. In Morocco, onion culture is the second most important crop after potatoes. During the 2019–2020 season, 29177 hectares of onion bulbs were planted, yielding an average of 30.17 tons/ha [2]. The economic income from onion culture was estimated to be 480.22 million USD [3]

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