Variability in Bulb Organosulfur Compounds, Sugars, Phenolics, and Pyruvate among Greek Garlic Genotypes: Association with Antioxidant Properties.

Ioanna Avgeri,Vasileios Papasotiropoulos,Penelope J Bebeli,Konstantina Zeliou,Fotini N Lamari,Spyridon A Petropoulos

doi:10.3390/antiox9100967

Ioanna Avgeri, Vasileios Papasotiropoulos + Show 4 more

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https://doi.org/10.3390/antiox9100967

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Abstract

In order to assess the diversity of Greek garlic (Allium sativum L.) landraces, 34 genotypes including commercial ones were grown in the same field and their content in organosulfur compounds, pyruvate, total sugars, and total phenolics, alongside antioxidant capacity, was determined. The organosulfur compounds were studied by Gas Chromatography–Mass Spectrometry (GC–MS) after ultrasound-assisted extraction in ethyl acetate, identifying 2-vinyl-4H-1,3-dithiin and 3-vinyl-4H-1,2-dithiin as the predominant compounds, albeit in different ratios among genotypes. The bioactivity and the polar metabolites were determined in hydromethanolic extracts. A great variability was revealed, and nearly one-third of landraces had higher concentration of compounds determining bioactivity and organoleptic traits than the imported ones. We recorded strong correlations between pyruvate and total organosulfur compounds, and between antioxidant capacity and phenolics. In conclusion, chemical characterization revealed great genotype-dependent variation in the antioxidant properties and the chemical characters, identifying specific landraces with superior traits and nutritional and pharmaceutical value.

Highlights

Introduction28,494,130 tons and a total harvested area of 1,546,741 hectares [1,2]
Common garlic (Allium sativum L., family Alliaceae) is the second most widely consumed bulb crop and one of the most cultivated bulb vegetables in Greece and worldwide, with an annual production of28,494,130 tons and a total harvested area of 1,546,741 hectares [1,2]
ultrasound-assisted extraction (UAE) was used for the extraction of garlic volatiles based on the methodology earlier described [22]; in that study, the authors demonstrated that UAE diminishes the danger of thermal decomposition of sensitive aroma compounds

Summary

Introduction

28,494,130 tons and a total harvested area of 1,546,741 hectares [1,2] It is consumed raw, cooked, or as an ingredient of herbal medicinal products and food supplements [3,4]. The main bioactive compounds are saponins, flavonoids, organic acids, and various organosulfur compounds [3] The latter are present in intact bulbs as peptides, like γ-glutamyl-S-alk(en)yl-l-cysteine, and sulfoxides of S-alk(en)ylo-l-cysteine, like alliin, which is the predominant cysteine derivative. This compound is metabolized to allicin by the enzyme alliinase, when the bulb is crushed, producing ammonia and pyruvic acid. The chemical composition and organoleptic characteristics of garlic are influenced by the genotype, the cultivation/environmental conditions, and the processing methods (temperature, pH, solvent) [8]

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