Comparison of the volatile antioxidant contents in the aqueous and methanolic extracts of a set of commercial spices and condiments
2017
Brito, Rafael Estévez | González-Rodríguez, José | Montoya, Mercedes Ruiz | Rodríguez Mellado, José Miguel
Spices are of great interest because their aromatic properties and to preserve food, with no or low nutritional value, and also as components of a healthy diet. The composition of the methanolic and aqueous extracts of commercial samples of basil, cinnamon powder, cinnamon sticks, clove, cumin, turmeric, ginger, nutmeg, oregano, rosemary and thyme was studied as a first step in relation to their antioxidant activities with the composition. Methods used were Gas Chromatography coupled with Mass Spectrometry (GC–MS) and High-Performance Liquid Chromatography (HPLC). Extracts were prepared with an amount of the sample suspended in ultrapure water preheated at 100 °C or methanol at 60 °C, stirred at room temperature and filtered; for GC–MS, the extracts were dried and re-dissolved in the methanol. To solve the problem in GC–MS with the flash points of some compounds, both techniques have been combined. The contents in antioxidants of the different species are compared finding spices having much higher antioxidant contents in the methanolic extract than in water, other with aqueous extracts much rich in antioxidants than the alcoholic extracts, and spices with low antioxidant content in both extracts. For clove, turmeric, ginger, cinnamon, rosemary and cumin, it is recommended the use of lipid and/or alcoholic fractions for the food preparation. For Basil, Oregano, Thyme and Nutmeg, to extract most of their antioxidant content only water must be used. Knowledge of the composition in antioxidants can aid the food industry in the design of healthy foods and food preparations.
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