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WATER HYDRODISTILLATION RESIDUES OF BAY LAUREL, ROSEMARY AND SAGE AS A SOURCE OF POLYPHENOLS

Water hydrodistillation residues produced in parallel with bay laurel, rosemary and sage essential oils contain a remarkable source of bioactive molecules. Despite rich bioactive content, these fractions considered as waste and are often underexploited. To date, there are no studies reporting on the chemical composition of water residues remaining after hydrodistillation of bay laurel and sage leaves, while there are only few reports demonstrating the valuable composition of other hydrodistillation co-products of these plants as a valuable secondary source of polyphenol components. We have used different pretreatments prior to hydrodistillation, i.e. reflux extraction, ultrasound and enzyme assisted extraction. It was described the effect of these pretreatments on the composition of polyphenolic compounds in the water hydrodisillation residues. HPLC analysis showed that the water hydrodistillation residues of bay laurel, rosemary and sage were richest in polyphenols. In bay laurel water hydodistillation residues, procyanidins represented the dominant components, with procyanidin dimer I and II (up to 4.65 mg/g), tetramer II (up to 5.43 mg/g), trimer II, III and IV (up to 4.37, 4.92, 13.15 mg/g, respectively) as major compounds. Among other components, epicatechin-hexoside, epicatechin and epicatechin- 3-O-gallate (up to 3.56, 1.60, 1.07 mg/g, respectively) were also detected in significant quantities. In sage hydrodistillation water residues, rosmarinic acid (up to 5.39 mg/g) was major compounds, followed by caffeic acid methyl ester (up to mg/g) and epicatechin (up to 2.06 mg/g). Finally, in rosemary hydrodistillation water residues rosmarinic acid, galocatehin, p- coumaric acid and syringic acid (up to 7.57, 4.83, 2.19, 3.25 mg/g, respectively) were most represented components. In general, the pretreatments didn’t significantly affect the phenolic composition of water hydrodistillation residues (p<0.05), i.e. the composition was comparable to the no-pretreatment control, as confirmed by Spearman´s test. Our results point out that water residues remaining after hydrodistillation of bay laurel, rosemary and sage are valuable source of polyphenols and can find their application in many fields of food industry.

bay laurel, polyphenols, rosemary, sage, water hydrodistillation residues

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