2 results
Application of pressurized liquid extraction on isolation of fennel seeds' polyphenols fractions
- Maja Repajić, Ana Marija Medved, Josipa Bilobrk, Ivona Elez Garofulić, Sandra Pedisić, Sanja Radman, Verica Dragović-Uzelac
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- Journal:
- Proceedings of the Nutrition Society / Volume 79 / Issue OCE2 / 2020
- Published online by Cambridge University Press:
- 10 June 2020, E548
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Due to nowadays endeavoured green approach, the utilization of environmentally-friendly extraction techniques is encouraged, where pressurized liquid extraction (PLE) provides such possibility. The PLE application allows shorter extraction time and simultaneously less solvent consumption through combined temperature and pressure effect, thus improving energetic and economic efficiency. Accordingly, in order to accomplish satisfactory extraction yield, it is necessary to optimize PLE conditions, depending on sample type and aimed compounds. As fennel (Foeniculum vulgare Mill.) seeds are rich source of structurally different bioactive compounds, this study aimed to examine the influence of PLE temperature (75 and 100 °C), static time (5 and 10 min) and cycle number (1, 2 and 3) on the content of fennel seeds’ polyphenols fractions: total hydroxycinnamic acids (THA), total flavonols (TF) and total flavan-3-ols (TFO). For this purpose, samples of grinded dry fennel seeds were extracted according to the mentioned PLE conditions in serial exhaustive extraction using solvents ordered by its polarity: hexane, aqueous acetone solution (30 %, v/v) and aqueous methanol solution (30 %, v/v). After defatting with hexane, acetone (AE) and methanol (ME) extracts of residues were collected (n = 24) and used for spectrofotometrically determination of THA, TF and TFO. In order to access data about effect of examined PLE conditions on analyzed parameters, results were statistically analyzed using multivariate analysis of variance (MANOVA) and Tukey's HSD test at significance level p ≤ 0.05. Obtained results showed that observed fractions of polyphenols were present in 4–5 folds higher amounts in AE compared to ME, where established grand means in AE were as follows: THA = 312.82 mg/100 g, TF = 113.23 mg/100 g and TFO = 29.01 mg/100 g, while in ME they were THA = 56.90 mg/100 g, TF = 28.78 mg/100 g and TFO were determined in traces. As for influence of extraction temperature and time, content of all tested compounds was significantly affected by examined sources of variation in extracts of both solvent types, except static time on ME’ THA content. Generally, 100 °C/10 min/3 cycles were conditions which yielded the highest THA, TF and TFO in AE, while ME results showed diversity upon examined conditions. Accordingly, the highest THA content was established at lower temperature (75 °C/10 min/2 cycles), while 100 °C/10 min/3 cycles conditions documented the greatest TF content.
Bioactive compounds and antioxidant capacity in fennel seeds influenced by pressurized liquid extraction
- Maja Repajić, Petra Tonković, Valentina Kruk, Zoran Zorić, Ivona Elez Garofulić, Igor Palčić, Verica Dragović-Uzelac
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- Journal:
- Proceedings of the Nutrition Society / Volume 79 / Issue OCE2 / 2020
- Published online by Cambridge University Press:
- 10 June 2020, E547
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- Article
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- You have access Access
- Export citation
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Fennel (Foeniculum vulgare Mill.) is a well-known aromatic plant, widely used as spice and remedy herb. It provides many beneficial effects and is used as diuretic and expectorant, as well as for various dyspeptic disorders. Beside essential oils, fennel seeds are abundant with various phenols, which are known as strong antioxidants and thereby contribute to human health. Among different extraction methods for phenols isolation, pressurized liquid extraction (PLE) represents a novel technique with numerous advantages over conventional extraction approaches. Its efficiency manifests through combination of high temperature and pressure, enabling extraction time shortening, as well as decreased solvent consumption, thus being environment-friendly technique. In order to achieve maximum extraction yield, it is of great importance to select optimal PLE conditions, e.g., extraction temperature and time. Additionally, solvent selection also affects on content of targeted compounds, where phenols amount depends on polarity of solvent. Hence, the aim of this study was to examine the effect of temperature (75 and 100 °C), static time (5 and 10 min) and cycle number (1, 2 and 3) on total phenols (TP) and total flavonoids (TF) content, as well as the antioxidant capacity (AC) in fennel seeds using three-step exhaustive PLE. Firstly, grinded dry fennel seeds were subjected to PLE using non-polar solvent (hexane) under the mentioned conditions in order to remove seeds' lipid fraction. Afterwards, defatted samples were extracted with polar solvents by the increasing polarity: aqueous acetone solution (30 %, v/v) followed by aqueous methanol solution (30 %, v/v). Obtained acetone (AE) and methanol (ME) extracts (n = 24) were analyzed for TP (Folin-Ciocalteu method), TF (aluminium chloride colorimetric assay) and AC [ferric reducing antioxidant power (FRAP) method]. Multivariate analysis of variance (MANOVA) and Tukey's HSD test (p ≤ 0.05) were applied for statistical analysis of collected data. Expectedly, AE were described with higher values of analyzed parameters (grand means: TP = 416.18 mg/100 g, TF = 41.87 mg/100 g, AC = 359.57 mg AAE/100 g) in comparison with ME (grand means: TP = 80.25 mg/100 g, TF = 16.41 mg/100 g, AC = 96.13 mg AAE/100 g. Furthermore, all examined influences significantly affected TP, TF and AC in all samples, except temperature on TP in ME. Thus, conditions of 100 °C/10 min/3 cycles showed the greatest yield of tested parameters in AE, while 100 °C/5 min/1 cycle were sufficient for maximum TP and AC levels in ME. Regarding TF in ME, slightly longer extraction time was required to achieve the highest efficiency (100 °C/10 min/1 cycle).