5 results
UPLC-MS/MS characterization of phenolic constituents in fennel seed extracts (Foeniculum vulgare Mill.)
- Zoran Zorić, Maja Repajić, Valentina Kruk, Branka Levaj, Danijela Bursać Kovačević, Irena Landeka Jurčević, 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, E395
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Reports in the recent literature indicate that consumption of phytochemicals (e.g. plant polyphenols) has been associated with a wide range of health benefits. Fennel (Foeniculum vulgare Mill.) is common Mediterranean plant that has been widely used as medicinal and aromatic herb. Numerous studies reported the use of fennel extracts (plant or seed) due to its diversity of phenolic compounds to whom inhibitory effects against several diseases are prescribed. Hence, phenolic compounds isolated from fennel are of the great interest for the use in food, chemical and pharmaceutical industries.
In order to obtain the highest quality of the fennel extracts, the selection of an effective extraction procedure is required. Nowadays, innovative extraction techniques have been introduced for isolation of bioactive compounds from plant material, among which pressurized liquid extraction (PLE) was reported as automated extraction procedure that combines effects of elevated temperature and pressure to increase the efficiency of the extraction process. Improved efficiency is also achieved by selecting the right solvent and by optimizing processing conditions (temperature, static time, cycle number).
Thus, PLE was applied for the extraction of phenolic compounds from fennel seeds. The effects of exhaustive extraction (acetone followed by methanol) as well as extraction temperatures (75 and 100 °C), static time (5 and 10 min) and cycle number (1,2,3) on the phenolic compounds concentrations were evaluated. A total of 27 phenolic compounds were identified and characterized by UPLC-ESI-MS/MS whereas 6 different categories are distinguished: (1) simple phenolic acid derivatives, (2) hydroxycinnamoylquinic acid derivatives, (3) flavonoid diglycosides, (4) flavonoid O-rhamnoglucosides, (5) flavonoid glucuronides and (6) flavonoid glycosides. Phenolic compounds were identified by comparing retention time and m/z values obtained by MS and MS/MS with the mass spectra from corresponding standards whereas the quantification was made on the basis of their peak areas and comparison with calibration curve obtained with the corresponding standards. Obtained results indicated that hydroxycinnamoylquinic acid derivatives (10 compounds) and flavonoid glucuronides (3 compounds) were found as the most abundant phenolics in acetone and methanol extracts, respectively. Statistical analysis showed that optimized PLE conditions for the most effective extraction of phenolic compounds were as follows: 100 °C/10 min/3 cycles for acetone and 100 °C/5 min/3 cycles for methanol extracts. In conclusion, PLE might be considered as a rapid and effective extraction procedure that could be useful in production of fennel seeds extracts.
Phenolic compounds in minimally processed potato: Effect of cultivar, tuber storage time and thermal treatment
- Draženka Dite Hunjek, Zdenka Pelaić, Sandra Pedisić, Maja Repajić, Dino Jakupec, Verica Dragović Uzelac, Branka Levaj
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- Journal:
- Proceedings of the Nutrition Society / Volume 79 / Issue OCE2 / 2020
- Published online by Cambridge University Press:
- 10 June 2020, E479
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Potato (Solanum tuberosum spp.) is worldwide consumed mostly as table potato, but due to lifestyle changes, production of minimally processed potato (MPP) became an important sector of the food industry. From the health point of view, phenolic compounds as potatoes constituents are desirable, but also responsible for undesirable browning of peeled and sliced potato. The most abundant are phenolic acids such as chlorogenic acid, which is a substrate for enzymatic oxidation in the presence of phenolase and is responsible for browning processes. Its concentration in tubers depends on cultivar type as well as storage, and thereby can influence on shelf life of MPP. The purpose of the present study was to evaluate the effect of two potato cultivars of different tuber age on the phenolic content of MPP during 8 days of storage followed by thermal treatment. Cultivars Birgit and Lady Claire were selected and stored for 1 and 4 months in warehouse (8 °C/RH 95 %). Potatoes were washed, peeled, sliced and treated with 2 % sodium ascorbate solution for 3 minutes. After draining, MPP samples were vacuum packed in PE/PA bags and stored for 1, 5 and 8 days at 10 °C. After storage, samples of raw, boiled and fried MPP were freeze dried and phenolic content was determined by UPLC MS/MS. In all potato samples chlorogenic acid, catechin and epicatechin were determined, where chlorogenic acid predominated (almost 97 %).
Generally, lower phenolic content was determined in cv. Birgit samples. Comparing cultivars upon tubers age, total phenolic content (as sum of all determined polyphenols) was lower after 4 months storage and ranged from 3.33 mg/100 g freeze dried sample (raw cv. Birgit/1st day) to 7.27 mg/100 g (raw cv. Lady Claire/8th day). MPP's phenolic content in raw potatoes increased over the storage time, except in cv. Lady Claire potatoes stored for 1 month. Influence of thermal treatments on the MPP phenolic content showed decrease in boiled and fried MPP prepared from 1 month stored potato, while in MPP samples prepared from 4 months stored potato did not follow a clear trend. Phenolic content was lower in boiled potatoes compared to fried potatoes, regardless cultivar type, probably because phenolics are lost by cooking in water. The current study demonstrates that cv. Birgit is more suitable in minimal processing than cv. Lady Claire according to lower phenolic content.
Glucose, fructose and sucrose in minimally processed potato: Effect of cultivar, tuber storage time and heat treatment
- Zdenka Pelaić, Draženka Dite Hunjek, Sandra Pedisić, Maja Repajić, Dino Jakupec, Branka Levaj
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- Journal:
- Proceedings of the Nutrition Society / Volume 79 / Issue OCE2 / 2020
- Published online by Cambridge University Press:
- 10 June 2020, E523
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Recently, popularity of minimally processed potatoes (MPP) is growing as well as other minimally processed fruits and vegetables, due to its convenience and easy preparation, what consumers nowadays prefer. However, these types of products are very perishable, influenced by a number of factors, particularly cultivar and tuber condition. Potato is suitable for a long storage, but certain changes occur in its chemical composition during storage. These changes, among other factors, greatly depend upon cultivar, as well as storage conditions, and consequently affect on MPP durability and quality. Besides, MPP is subjected to heat treatment before consumption, where raw potatoes chemical composition and the way of heat treatment affect the chemical composition of the prepared potato dish. Potato sweetening is known phenomenon that occurs during storage, what negatively affect on health safety of fried potato.
Therefore, the aim of this study was to investigate the influence of cultivar and tubers storage time, as well as MPP storage time and heat treatment on the sugar content in raw, boiled and fried potatoes.
Potato cultivars Birgit and Lady Claire used in this study were stored for 1 and 4 months in warehouse (8 °C /RH 95 %). MPP was produced by washing, peeling, slicing followed by anti-browning treatment (dipping in 2 % sodium ascorbate solution/3 min), draining and vacuum packing in PE/PA bags. After 1st, 5th and 8th day of storage at 10 °C, MPP were boiled and fried. All samples, including raw MPP, were freeze dried and sugar content was determined by UPLC MS/MS.
Most abundant sugar was sucrose, followed by glucose and fructose, where cv. Birgit contained slightly higher values of all sugars compared to cv. Lady Claire. Initial sugar content of both cultivars was very low. However, during tuber aging, as well as during MPP storage time, content of individual sugars increased in most of samples, with slightly higher increase in cv. Birgit raw samples. Furthermore, heat treatment affects on sugar composition, since glucose and fructose are generally reduced in boiled and fried potatoes with certain differences depending on the cultivar. Total sugar content of cv. Birgit MPP mostly increased during storage, regardless tuber age and the way of heat treatment, while in cv. Lady Claire samples opposite trend with few exceptions was observed. Generally, cv. Lady Claire has lower and slightly more stable sugar content upon tuber aging, MPP storage time and heat treatment.
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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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).