Optimization of the Extraction Conditions of Polyphenols from Red Clover (Trifolium pratense L.) Flowers and Evaluation of the Antiradical Activity of the Resulting Extracts.

The purpose of this study was to analyze the effect of the type of extraction solution (water, different concentrations of ethanol), temperature and time on the polyphenol content and antioxidant properties of red clover extracts and the effect of the addition of selected extracts on the antioxidant properties of enriched blackcurrant beverages. In both the extractions carried out under different conditions and in the enriched beverages, the content of selected polyphenols was determined by HPLC. This study confirmed the significant effect of the alcohol content of the extract, extraction time and temperature on the antioxidant properties of clover extracts. Ethanolic extracts had better antioxidant properties than aqueous extracts. The addition of ethanol extracts had a significant effect on the antioxidant properties of the fortified beverages. Increasing the temperature, time or ethanol content in the extracts mostly resulted in an increase in the total polyphenol content in the obtained extracts. Based on the analysis of the response surface, it was found that for the DPPH radical, the best activity was obtained by extraction for 20 min with a solution of approximately 65% at low temperatures. In the case of the ABTS radical, the best antiradical activity was obtained after extraction for 60 min at 80 °C with a solution of approximately 50% ethanol. It was also found that the use of a solution of approximately 60% ethanol after extraction for 60 min at 80 °C would provide an extract with high antiradical activity against both radicals.

Comparison of the Content of Selected Bioactive Components and Antiradical Properties in Yoghurts Enriched with Chia Seeds (Salvia hispanica L.) and Chia Seeds Soaked in Apple Juice.

Due to the fact that consumers are looking for new, health-promoting products, there is a growing interest in various ingredients with a high biological activity that could enrich conventional foods. As is known, chia seeds are a rich source of various health-promoting compounds. The objective of this study was to determine the content of selected biologically active compounds and their antioxidant properties by means of DPPH●, ABTS+●, and the ability to chelate Fe (II) ions in chia seeds and yoghurts with the addition of these seeds and seeds soaked in apple juice. It was found that chia seeds are a rich source of bioactive ingredients with beneficial effects on human health-especially polyphenols. All the extracts showed antioxidant properties against the radicals used. The addition of seeds to yoghurt contributed to the presence of polyphenols, while soaking in apple juice resulted in a higher content of polyphenols in yoghurts. The enriched yoghurt extracts showed antioxidant properties against DPPH radicals and the ability to chelate Fe (II) ions. The addition of seeds soaked in apple juice significantly influenced the antioxidant activity against ABTS radicals. The addition of seeds (plain and soaked) did not cause significant changes in the pH of the yoghurts.

Verification of the Conditions for Determination of Antioxidant Activity by ABTS and DPPH Assays-A Practical Approach.

The ABTS and DPPH methods are among the most popular assays of antioxidant activity determination. Attempts to adapt them to different analytes and the search for the highest values of antioxidant activity has resulted in a large variety of assay conditions to be presented in the literature, including the way the measurement is made. This makes it difficult to relate the results to real oxidation systems, and often makes it impossible to compare them. Such a comparison is limited in advance by the use of stable radicals that do not exist in nature and that react differently from those generated in food or in vivo. Therefore, it is important to introduce measures aimed at standardizing the conditions of the activity assay, including reaction time and several reaction environments suitable for testing different groups of compounds. In this study, we used natural antioxidants of various structures: phenolic acids, flavonoids, peptides and corresponding amino acids, ascorbic acid and α-tocopherol, and also synthetic analogues of selected compounds. The curves of dependence of the measured absorbance on the concentration of antioxidants were described, the ranges of linearity were determined, and the value of the error made when reading in various ranges of dependencies was estimated. We also determined and compared the activity values using two popular methods (IC50 and TEAC), taking into account different environments and reaction times. Based on the collected data, recommendations were formulated regarding the reaction conditions adapted to the studies of individual groups of antioxidants, and unified reaction times were proposed. Taking into account the state before reaching the equilibrium of antioxidants reacting in a complex manner, this approach may introduce a simplified reference to the competing reaction that occurs in reality.

Determination of the botanical origin of honeybee honeys based on the analysis of their selected physicochemical parameters coupled with chemometric assays.

The aim of this paper was to study the select physicochemical parameters of 58 honey samples of 4 different botanical origins (buckwheat, linden, rape and acacia) using multivariate methods in order to classify honeys according to the botanical origin. Five standard physicochemical parameters were determined according to the international legislation: water content, electrical conductivity, total ash content, free acidity and pH. The results obtained were mostly in agreement with international regulations. Then, the results obtained were analysed by principal components analysis and cluster analysis. The chemometric analysis of results of determinations of the physicochemical parameters demonstrated such markers as electrical conductivity and ash content (i.e. parameters linked with minerals content) to be the most reliable markers in determining the botanical origin of linden and buckwheat honeys. Unfortunately, they appear insufficient for reliable identification of acacia and rapeseed honeys.

Effect of mild roasting on Arabica and Robusta coffee beans contamination with polycyclic aromatic hydrocarbons.

The aim of this research was to establish the effect of mild roasting on coffee beans contamination level by polycyclic aromatic hydrocarbons (PAHs). The materials investigated were green Arabica and Robusta coffee beans imported from different countries, as well as those already roasted. The experiment was carried out in a coffee-roasting plant, with the use of an electric coffee roaster, at the temperature of 125-135 °C for 25-26 min. PAHs analysis was conducted by means of high-performance liquid chromatography with fluorescence and diode array detectors (HPLC-FLD/DAD). Results had been verified by means of gas chromatography with mass spectrometry. Contamination level for 19 PAHs, 15 of which were heavy PAHs included on the list of European Union Scientific Committee in Food, varied from 4.29 to 16.17 µg/kg in roasted coffee beans, whereas in green coffee beans varied from 8.66 to 76.63 µg/kg. The results of statistical analysis showed that the contamination level in roasted coffee beans was significantly lower than that in green beans. The applied parameters of roasting did not lead to the occurrence of conditions in which PAHs, especially heavy ones, would possibly be formed. On the contrary, the roasting process itself had significantly reduced the PAHs content in the final product. The reason for this phenomenon was relatively high volatility of light PAHs.

Effect of hydrothermal modifications on properties and digestibility of grass pea starch.

This study aimed to investigate functional and thermal properties and digestibility of grass pea starch, and provide information on the effect of hydrothermal modifications - annealing (ANN) and heat-moisture treatment (HMT) on the physico-chemical characteristics of the starch and digestibility, especially after processing (cooking, storage after cooking and freezing). After heat treatment, especially after cooking and storage at a temperature of -18 °C, the total content of slowly digestible starch and resistant starch in grass pea starch was high, which may indicate its great tendency for retrogradation. The HMT and ANN modifications of grass pea starch caused changes in its crystalline structure and increased integrity of its granules, which in turn resulted in a lower swelling power and amylose leaching, however this effect was more pronounced upon HMT which contributed to starch polymorphic type transformation from C to A. Despite greater resistance of granules of modified starches to swelling during cooking their suspensions, after cooking these starches were characterized by a higher predicted glycemic index than the non-modified ones. A similar content of resistant starch determined in modified and non-modified gelatinized starches stored at lowered temperatures indicates that starch modifications, HMT in particular, cause no changes in its susceptibility to retrogradation.

Effect of Sterilization Process and Storage on the Antioxidative Properties of Runner Bean.

In this study, we investigated the effect of standard preservation of bean seeds on changes in contents and activity of their selected components: dry matter, ash, different forms of nitrogen, composition of protein fractions; total phenolics and condensed tannins; ability to chelate iron(II) ions; antiradical activity against ABTS•+ and DPPH•; and capability for inhibiting autoxidation and enzymatic oxidation of linoleic acid. The conducted technological process caused various changes in contents of nitrogen forms and partial loss of phenolic compounds. The antiradical and antioxidative activity of the extracts decreased significantly, while an increase was observed in their ability to chelate Fe(II). These changes were due to the migration of active compounds to the brine, and to their structural transformations and degradation. Longer storage of the sterilized product caused restoration of part of the antiradical activity of the seeds.

Optimization of extraction conditions of some polyphenolic compounds from parsley leaves (Petroselinum crispum).

BACKGROUND: Parsley leaf is a rich source of natural antioxidants, which serve a lot of functions in human body and prevent food from oxidation processes. The aim of the study was to investigate the influence of different extraction solvents and times of extraction on natural antioxidants content. Owing to the knowledge of the properties of extracted components and solvents, as well as their interactions, it is possible to achieve a high effectiveness of active compounds recovery. MATERIAL AND METHODS: Three different extraction solvents (acetone 70% in water, methanol 80% in water and distilled water) and different times of extraction (30 and 60 minutes) were used to determine the efficiency of extraction of polyphenols and catechins, antioxidant activity against free radicals DPPH and ABTS and the ability to chelate ion Fe(2+) in dried parsley leaves. Other natural antioxidants contents in parsley leaves were also determined. RESULTS AND DISCUSSION: In this study the best extraction solvent for polyphenols was acetone 70% and for catechins was distilled water. All extracts examined displayed the antioxidative activity, but water was the best solvent in the method of assaying the activity against ABTS(•+) and Fe(2+) ions chelating capability, whereas methanol turned out to be the least effective in this respect. Opposite results were observed in the case of determining the activity against DPPH(•). The prolongation of the extraction time enhanced or decreased antiradical activity in some cases. Additionally, important biologically active compounds in parsley leaves, such as vitamin C (248.31 mg/100 g dry matter), carotenoids (31.28 mg/100 g dry matter), chlorophyll (0.185 mg/g dry matter) were also analysed.

Chemical composition and starch digestibility in flours from Polish processed legume seeds.

The study was undertaken to determine the effect of various treatments, i.e. cooking after soaking, freezing after cooking and storage at a low temperature (-18°C, 21days), and autoclaving, of Polish cultivars of bean, pea and lentil seeds on the chemical composition and starch digestibility of the resultant flours. The cooking of seeds caused a significant decrease in contents of ash (by 11-48%), polyphenols (by 10-70%) and protein (to 19%) in flours made of bean. In addition, analyses demonstrated significantly decreased contents of resistant starch, RS (by 61-71%) and slowly digestible starch, SDS (by 56-84%). Storage of frozen seeds resulted in insignificant changes in the chemical composition, and in increased contents of both RS and SDS. The flours produced upon the autoclaving process were characterized by similar changes in the contents of ash and protein as in cooked seeds, yet losses of polyphenols were lower and, simultaneously, contents of RS and SDS were higher. All the analyzed flours were shown to be characterized by a reduced content of amylose in starch, which might have affected its digestibility. This was indicated by a strict negative correlation reported between the value of the starch digestion index (SDRI) and amylose content of starch (r=0.84, p>0.05).