RESUMO
The effect of spontaneous fermentation by lactic acid bacteria on the extraction yield of bioactive compounds and antioxidant activity from rosemary leaf extracts was investigated using high-performance thin-layer chromatography (HPTLC). Brining and spontaneous fermentation with lactic acid bacteria more than doubled extraction of polyphenolics and antioxidants from the rosemary leaves. The results show that lactic acid fermentation enhances antioxidant activity in extracts by increasing the total phenolic content but does not increase extraction of phytosterols. Increased extraction of phenolic oxidants during fermentation assisted extraction, results from the in situ generated natural eutectic solvent from the plant sample. ATR-FTIR spectra from the bioactive bands suggests that this increased antioxidant activity is associated with increased extraction of rosmarinic acid, depolymerised lignin, abietane diterpenoids and 15-hydroxy-7-oxodehydroabietic acid.
Assuntos
Antioxidantes/química , Antioxidantes/metabolismo , Lactobacillales/metabolismo , Extratos Vegetais/química , Extratos Vegetais/metabolismo , Rosmarinus/química , Rosmarinus/metabolismo , Abietanos/química , Abietanos/metabolismo , Cromatografia em Camada Fina , Cinamatos/química , Cinamatos/metabolismo , Depsídeos/química , Depsídeos/metabolismo , Fermentação , Humanos , Lignina/química , Lignina/metabolismo , Fenóis/química , Fenóis/metabolismo , Folhas de Planta/química , Folhas de Planta/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Ácido RosmarínicoRESUMO
When several near-infrared instruments are used in a network and a common chemometric model is applied to spectral processing, comparison of the instruments is indispensable. Direct transferability often claimed by the producers should be treated with caution. It has been found experimentally that when measurements are performed with the help of a fiber optic probe, the main source of spectral discrepancy is related to probe sensitivity in contactless measurements. Here the influence of the probe-to-object distance on the acquired spectra is analyzed in detail. Special experimental setups are proposed to isolate various strongly influencing factors and to maintain stable measurement conditions. The application of an artificial standard instead of real-world objects helps to focus on the instrument/accessory characteristics.