Search

The aim of this study was to compare parameters of nanocellulose obtained by two different procedures: hydrolysis with ionic liquids (1-allyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium acetate) and hydrolysis with ionic liquids in combination with hydrolysis using a cellulolytic enzyme from Trichoderma reesei. Avicel cellulose was treated with two ionic liquids: 1-allyl-3-methylimidazolium chloride (AmimCl) and 1-ethyl 3-methylimidazolium acetate (EmimOAc). In the two-step hydrolysis cellulose after treatment with ionic liquids was additionally hydrolyzed with a solution of enzymes. In order to characterize the obtained material, the following analyses were used: infrared spectroscopy, X-ray diffraction and dynamic light scattering. The results indicated that cellulose obtained by two-step nanocellulose production methods (first hydrolysis with ionic liquids and then with enzymes) showed similar parameters (particle size, XRD patterns and degree of crystallinity) as the material after the one-step process, i.e. hydrolysis with ionic liquids.

The effect of the time process of enzymatic hydrolysis on nanocellulose properties - the aim of the study was to evaluate the effect of enzymatic hydrolysis time on the properties of obtained nanocellulose. Two cellulose materials were tested as a raw material for nanocellulose production in the experiment: Avicel and Whatman. The cellulolytic enzyme obtained from the fungus Trichoderma reesei was used to carry out the enzymatic hydrolysis reaction. Enzymatic hydrolysis was performed on cellulose using the reaction times of 0.5, 1, 2 and 4 hours. In order to characterize the obtained materials, the following analyses were used: infrared spectroscopy, X-ray diffraction and dynamic light scattering. The recorded results showed that cellulose after enzymatic hydrolysis showed similar parameters (particle size, XRD patterns and degree of crystallinity) after all the applied reaction times.

BACKGROUND The exact mechanism of lipid autoxidation in vegetable oils, taking into account physical aspects of this phenomenon, including the role of association colloids, is still not fully understood. The purpose of this study was to consider changes in moisture content and DOPC phospholipid (1,2-dioleoyl-sn-glycero-3-phosphocholine) critical micelle concentration (CMC) in rapeseed oil during autoxidation as well as to find the relationship between these parameters and the accumulation of primary and secondary lipid oxidation products. RESULTS The experiments were performed at initial oil humidity 220 ppm and 700 ppm, with DOPC below and above CMC. The increase in water concentration was favored by the presence of phospholipids above CMC and, at the same time, high initial water level, which favored oxidation processes and the creation of amphiphilic autoxidation products. At relatively high water level and low amphiphilic DOPC concentration, the growth of water content does not affect the concentration of oxidation products. CONCLUSION Amphiphilic substances play a significant role in increasing the water content of oil. Autoxidation products may reduce CMC of DOPC, but water is able to compensate for the CMC-reducing effect of oxidation products. The presence of association colloids and initial water content play a crucial role in the oxidation process of rapeseed oil. The increase in water concentration does not cause a sufficiently large increase in the number of micelles or sufficiently significant changes in their structure to effect an increase in the level of oxidation products. The formation of micelles requires an appropriate content of both water and amphiphilic substances derived from seeds (phospholipids). © 2021 Society of Chemical Industry.

Starch paste is a very complex dispersion that cannot be clearly classified as a solution, colloid or suspension and many factors affects its properties. As these ambiguities constitute a barrier to technological development, the aim of this study was to investigate the interaction of starch macromolecules with water by analysing the results of rheological properties, low field nuclear magnetic resonance (LF NMR), dynamic light scattering (DLS) and ζ potential analyses. Starch pastes with a concentration of 1%, prepared with distilled water and buffered to pH values of 2.5, 7.0 and 9.5 were analysed. It was proved that the pH buffering substantially decreased the values of consistency index but the pH value itself was not significant. LF NMR studies indicated that the dissolution of starch in water resulted in a reduction in spin-lattice as well as spin-spin relaxation times. Moreover, changes in relaxation times followed the patterns observed in rheological studies. Electrokinetic and DLS analyses showed that potential values are primarily influenced by the properties of the starches themselves and, to a lesser extent, by the environmental conditions. The conducted research also showed complementarity and, to some extent, substitutability of the applied research methods as well as exclusion chromatography (a method not used in this work).

Background One of the requirements for proper nutrition and maintenance of good health is to supply the body, through diet, with an appropriately increased quantity of bioactive compounds. With this in mind, modern milling and baking industries keep introducing new types of products. The use of such additives as wholegrain flours and bran in baked products provided the basis for research in this paper. Methods The aim of the study was to conduct a qualitative and quantitative evaluation of marketable wheat, barley and oat grain, used as raw materials to produce dehulled kernels, ground grain, wholemeal flour and wheat flour type 550 (all-purpose or plain flour), as well as wheat bran. Additionally, analyses were performed to determine the chemical composition and contents of nutrients, selected bioactive compounds and antioxidant activity. Results The studied raw materials in commercial cereal differ in their chemical composition. Dehulling of wheat, barley and oat grains significantly contributed to the reduction of minerals, protein and total dietary fiber (TDF) contents, except for the amount of protein in dehulled wheat and oat grains. Oat bran, in contrast to other oat products, was characterized by the highest contents of minerals, protein, TDF, and the smallest amounts of saccharides and total starch. The lowest content of minerals was recorded in wheat flour type 550. Thermal processes affect the concentration of tocochromanols in the grain, with tocotrienols being more resistant to hydrothermal treatment than tocopherols. Grain dehulling also significantly decreased the total amount of tocochromanols in relation to the original grains. Conclusions Wheat products differ in the contents of their individual components. They are characterized by high contents of tocochromanols, phenolic compounds and water-extractable arabinoxylans, with the exception of white refined wheat flour, which is mainly a source of saccharides. In the case of barley and oat products, the analysis showed no differences between these product groups. It was also shown that dehulling of barley and oat grain causes statistically significant differences in the contents of nutrients and natural antioxidants.

Lupine seeds are proposed as a source of valuable protein in human and animal nutrition. However, not only protein content but its bioavailability is important. Thus, the protein digestibility of twenty Lupinus angustifolius varieties seeds and the impact of some factors (protein and polyphenols content, trypsin inhibition and amino acids composition) on the protein digestion were discussed. Composition as well as the digestibility of these seeds was influenced by variety, weather conditions (precipitations) and place of cultivation (soil quality). The average digestibility of the seeds was 46%. The positive impact on the digestibility had the extractivity of the protein. Higher than it was expected activity of trypsin inhibitors (even up to ~32%) in some varieties influenced the protein availability, while the lysine and phenolic compounds content did not affect digestibility. The content of compounds influencing protein digestibility depends both on variety as well as on agronomical conditions.

In this research effects of heat treatment duration on the electrical properties (zeta potential and conductivity), texture and color of polymerized whey protein (PWP) were analyzed. Whey protein solutions were heated for 30 min to obtain single-heated polymerized whey protein (SPWP). After cooling to room temperature, the process was repeated to obtain double-heated polymerized whey protein (DPWP). The largest agglomeration was demonstrated after 10 min of single-heating (zeta potential recorded as −13.3 mV). Single-heating decreased conductivity by 68% and the next heating cycle by 54%. As the heating time increased, there was a significant increase in the firmness of the heated solutions. Zeta potential of the polymerized whey protein correlated with firmness, consistency, and index of viscosity, the latter of which was higher when the zeta potential (r = 0.544) and particle size (r = 0.567) increased. However, there was no correlation between zeta potential and color. This research has implications for future use of PWP in the dairy industry to improve the syneretic, textural, and sensory properties of dairy products.

A comparison of methods for obtaining nanocellulose using acid and ionic liquid hydrolysis reactions. In this study, two methods were compared, i.e. acid hydrolysis using sulphuric acid (VI) and ionic liquid hydrolysis using 1-methyl-3-butylimidazolium chloride to obtain nanocellulose from Sigmacell Cellulose Type 20. The efficiency of both processes was tested for weight loss of the material during the reaction. The study showed that much more material can be obtained using ionic liquid hydrolysis than using acid hydrolysis. A dynamic light scattering study was performed to determine material particle size before and after these processes. Particles of nanometric size were recorded only for cellulose after the reaction with an ionic liquid. In addition, Fourier transform infrared spectroscopy was performed to determine the chemical structure of the materials tested.

Background The basic parameter influencing the quality of cold-pressed oil is the quality of seeds usedn for pressing. Adverse moisture content and storage temperature of rape seeds may affect the quality of oil obtained from them. This paper presents the effects of increased rapeseed moisture content on the quality of the oil pressed. Methods The material used for the tests was rapeseed (canola) cv. PR 46 W14. The moisture content of the seeds was adjusted to 10%, 12% and 20%, and the seeds were stored at room temperature for 14 days. The samples were then dried to a seed moisture equal to 7% and oil was pressed from them. Acid and peroxide values, as well as the content of water, tocopherols and phenolic acids, were determined. In addition, a sensory analysis of the oil samples was carried out, and structural changes in the association colloids in the oil were determined using a fluorescent probe. Results With the increase in seed moisture, the increase in peroxide and acid values of the analyzed oils was recorded. A slight decrease in tocopherol content and a significant increase in phenolic acid concentration, depending on the seed moisture content, was observed. Sensory analysis showed odor sensory profile changes that probably indicate microflora development. Conclusions The rapeseed moisture content has a crucial influence on the quality of oil obtained from them. Along with an increase in seed moisture, the possibility of developing undesirable microflora grows, which results in a deterioration in the quality of the obtained oil.

A number of scientific data indicate that γ-conglutin can be internalised by different human cells and undergoes secretion from the seed in response to high temperature. In both of these cases, the protein must interact in some manner with biological membranes, however, the mechanisms underlying this phenomenon remain unknown. Herein, we found that the remarkable change of total surface hydrophobicity after appropriate heat treatment of γ-conglutin monomer led to its interaction with model membranes (liposomes). Before the interaction, the protein undergoes an intriguing thermal unfolding pattern which was studied based on a spectroscopic approach. Insight into the interaction mechanism with liposomes was possible thanks to applying two molecular probes that were differentially localised in the lipid bilayer. The results show that the thermal rearranged γ-coglutin monomer affects hydrocarbon chains in membranes leading to their morphology change and disruption. The main driving force of this phenomenon is based on hydrophobic interaction.

Cold pressed oils obtained from chia (Salvia hispanica L.), milk thistle (Silybum marianum L.), nigella (Nigella sativa L.), and white and black varieties of poppy (Papaver somniferum L.) seeds were character­ized. The nutritional quality was determined based on the analysis of fatty acids, tocochromanol and phytos­terol contents, as well as antioxidant activity and general physico-chemical properties. Among the oils analyzed the fatty acid composition most beneficial for health was found in chia seed oil, with 65.62% of α-linolenic acid and the n-6:n-3 fatty acid ratio of 1:3.5. Other oils studied were rich sources of linoleic acid (18.35-74.70%). Chia seed oil was also distinguished by high contents of phytosterols, mainly β-sitosterol (2160.17 mg/kg oil). The highest content of tocochromanols was found in milk thistle oil with dominant α-tocopherol (530.2 mg/kg oil). In contrast, the highest antioxidant activity was recorded for nigella oil (10.23 μM Trolox/g), which indi­cated that, in addition to tocopherols, other antioxidants influenced its antioxidant potential. Se caracterizaron aceites prensados en frío obtenidos de semillas de chía (Salvia hispanica L.), cardo mariano (Silybum marianum L.), nigella (Nigella sativa L.) y de variedades blancas y negras de amapola (Papaver somniferum L.). La calidad nutricional se determinó en base al análisis de ácidos grasos, el contenido de tococromanoles y fitosteroles, así como la actividad antioxidante y las propie­dades fisicoquímicas generales. Entre los aceites analizados, la composición de ácidos grasos más beneficiosa para la salud se encontró en el aceite de semilla de chía, con un 65,62% de ácido α-linolénico y una relación de ácido graso n-6:n-3 de 1:3,5. Los demás aceites estudiados fueron ricos en ácido linoleico (18,35-74,70%). El aceite de semilla de chía también se distinguió por el alto contenido de fitosteroles, principalmente β-sitosterol (2160,17 mg/kg de aceite). El mayor contenido de tococromanoles se encontró en el aceite de cardo mariano con α-tocoferol dominante (530,2 mg/kg de aceite). Por el contrario, se registró la mayor actividad antioxidante para el aceite de nigella (10,23 μM Trolox/g), lo que indica que, además del tocoferol, otros antioxidantes influyeron en su potencial antioxidante.

Cellulose nanocrystals were prepared using ionic liquids (ILs), 1-ethyl-3-methylimidazolium chloride [EMIM][Cl] and 1-propyl-3-methylimidazolium chloride [PMIM][Cl], from microcrystalline cellulose. The resultant samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The XRD results showed that nanocellulose obtained by treatment with both ILs preserved basic cellulose I structure, but crystallinity index of samples (except for Sigmacell treated with [EMIM][Cl]) was lower in comparison to the starting microcrystalline cellulose. The DLS results indicated noticeably smaller particle sizes of prepared cellulose for material treated with [PMIM][Cl] compared to cellulose samples hydrolyzed with [EMIM][Cl], which were prone to agglomeration. The obtained nanocellulose had a rod-like structure that was confirmed by electron microscopy analyses. Moreover, the results described in this paper indicate that cation type of ILs influences particle size and morphology of cellulose after treatment with ionic liquids.

Formation of free radicals’ and antioxidants’ biosynthesis during seeds sprouting strongly depends on plant growth conditions, especially while sprouts are fortified in iron. The influence of watering with FeSO4 solution on soybean and lupine sprouting, yield of iron accumulated in plant tissue, as well as free radical (reactive oxygen and nitrogen species) synthesis and antioxidant activity (capacity) were the objective of this study. Optimal iron accumulation and biomass efficiency were obtained for 3 day watering with water, followed by abiotic stress application (Fe2+ ions). For lupine sprouts, maximal radical formation (up to ~ 5.7 a.u.) took place on the fifth day of culturing in these conditions, while, for soybean sprouts, continuous increase in their activity was observed until the seventh day (up to ~ 5.8 a.u.). Total antioxidant activity in lupine sprouts increased definitely, even more than three times during 7 days of lupine growing, but, for soybean, it was almost steady. The same trend was observed in phenolic compounds and flavonoids contents. For soybean sprouts, these antioxidants were almost steady, while, for lupine sprouts in these conditions, the intensive synthesis of these antioxidants was observed. In response to high iron content applied from the fourth day in the cultivation media, lupine sprouts synthesize low molecular antioxidants effectively. For soybean sprouts, another mechanism of defense against oxidative stress should be expected.

β-Cyclodextrin (βCD)-coated CdSe/ZnS quantum dots (QDs), provide a sensitive method for the determination of phenolic compounds. The current study aimed to explain the mechanisms involved in photoluminescence quenching of CdSe/ZnS QDs, during the determination of quercetin and gallic acid, and select derivatives thereof. Quercetin, quercetin glycosides, gallic acid and gallate esters, were investigated to understand how the glycoside moiety in glycosides and the hydrocarbon chain in esters, affect the interactions of the investigated polyphenols with βCD-coated QDs. The phenomenon of βCD-coated CdSe/ZnS photoluminescence quenching, is caused by the effective formation of host-guest inclusion complexes between polyphenols and βCD. The presence of the glycoside moiety in the quercetin molecule reduced the effectiveness of the complex formation, while, in contrast, the efficiency of complexation increased with increasing hydrocarbon chain length of the gallate ester molecule. QD photoluminescence quenching may be a consequence of the proximity between the interacting phenolic compounds with the QD surface, rather than βCDs peeling off from the QD surface, resulting in structural destabilization. From the thermodynamic parameters, it was concluded that the formation of the complexes is based both on the van der Waals interactions forces and hydrophobic interactions between guest and host molecules. Ionic interactions may also play an important role in the effectiveness of polyphenol-βCD inclusion complex formation. In order to obtain QDs with long-term stability, there is a need to increase the zeta potential value of the QD surface. Recognition of the above-described mechanisms, should enable the optimization of existing methods and the development of new applications of βCD-coated CdSe/ZnS QDs, such as determination of octyl gallate in foodstuffs.

The aim of this study was to analyse contents of phytosterols, carotenoids, tocochromanols and fatty acid composition in oil from nutlets of linden. Standard determination methods for these compounds were applied using liquid and gas chromatography. In the analysed oils from small and large-leaved lime the dominant acids included linoleic (53.1 and 54.1%), oleic (18.5 and 22.2%), palmitic (15.3 and 11.8%). Linden seed oil was characterised by very high contents of phytosterols (2–2.5 g/100 g). β-Sitosterol was the dominant phytosterol (80–83%). Additionally squalene was detected at 806 and 607 mg/100 g, respectively, for Tilia cordata and T. platyphyllos. It was found that linden seed oil contains tocopherols (93%) and tocotrienols (7%). In terms of tocochromanol contents this oil is surpassed only by wheat germ oil. In terms of the α-T equivalent these oils contain 95 (Tilia cordata) and 50.6 mg/100 g vitamin E (Tilia platyphyllos)

A physicochemical characteristic of the cold-pressed oil obtained from seeds of common beech (Fagus sylvatica L.) has been presented. This plant may be considered as unconventional oilseeds crops because of relatively high content of fat (27.25%). The analyzed beech seeds oil has been classified as oleic-linoleic acids oil with more than 76% percentage share of those species. Beech seeds oil contains 4.2% of gamma-linolenic acid (GLA). Unique characteristic is the high content of γ-tocopherol (75.4mg/100g) and δ-tocopherol (34.05mg/100g). γ-Tocopherol is effective scavengers of reactive nitrogen species and prevents DNA bases nitration, what makes beech seeds oil interesting raw material in the production of cosmetics. Additionally the content of carotenoids, very effective photooxidation inhibitors, is at high level in comparison with other cold-pressed oils. It was demonstrated that PCA analysis may help to determine the authenticity of oil obtained from beech seeds.

Interactions between the different compounds present in foods are common and have influence on the nutritional and functional properties of food products. Among a wide range of these interactions, the formation of complexes between proteins and phenolic compounds seems to be the most important issue. Complexation of the phenolic compounds with proteins can be analysed considering several aspects. These complexes might strongly affect nutritional potential of polyphenols by masking their antioxidant capacity, and on the other hand might have influence on the structure of proteins which may cause their precipitation or decrease susceptibility to digestion. The complexity of protein–phenolic compound interactions is a challenge for food analysts and forced researchers to establish a wide range of analytical methods, allowing determination of complexes formation. The main aim of this review is to give researchers an overview of the currently used methods that can be applied to study the interactions between proteins and phenolic compounds.

The efficient and environmentally friendly method for preparation of novel flocculants using ILs with non-toxic anions are presented. Poly(ionic liquids) (PILs) were prepared by the photopolymerization of polymerizable ILs. All monomers were obtained via anion exchange reaction. Additionally, the polymers were fully characterized by 1H NMR and FTIR spectroscopy, thermal analysis and gel permeation chromatography. Furthermore, these cationic polymers containing harmless anions were used as flocculants. The efficiency was tested using the yeast suspension as a model system of negatively charged particles. The synthesized water-soluble PILs exhibited high molecular weight and significant flocculation efficiency in the wide range of concentrations. Furthermore, the results of experiments show that flocculation of yeast occurs by charge neutralization and bridging mechanism.

The purpose of this study was to verify the influence of different chromatographic column beds (silicic acid, activated charcoal, aluminum oxide, silica gel) on the concentration of individual minor components (sterols, tocopherols, carotenoids and chlorophyll) in rapeseed oil. With the use of a combination of these beds, a three-stage optimized method for removing minor components from rapeseed oil was developed. It was demonstrated that the combination of silicic acid and activated charcoal removed about half of the sterols present from the oil. Aluminum oxide turned out to be the most effective bed in removing tocopherols, purifying the oil to their minimum level (2.6 mg/kg). All adsorbents used had similar capacity to purify oil from pigments (carotenoids and chlorophyll). In the three-stage purification process free sterols were almost completely removed (to the level 90.0 mg/kg). Purification of β-carotene and chlorophyll from the oil was also very effective. Tocopherols were completely removed with this method, except for a small amount of α-tocopherol (0.4 mg/kg), which results from its relatively weak interaction with a hydrophilic bed. The developed method may be used in studies on the effect of association colloids on bulk oil autoxidation processes. El propósito de este estudio fue verificar la influencia de diferentes rellenos de columnas cromatográficas (ácido silícico, carbón activo, óxido de aluminio, gel de sílice) sobre la concentración de componentes menores individuales (esteroles, tocoferoles, carotenoides y clorofila) en aceite de colza. Gracias a esto, se desarrolló un método optimizado de tres etapas para eliminar los componentes secundarios del aceite de colza (utilizando una combinación de todos los rellenos descritos anteriormente). Se ha demostrado que con la combinación de ácido silícico y carbón activo se elimina del aceite alrededor de la mitad de los esteroles presentes. El óxido de aluminio resultó ser el relleno más eficaz para eliminar los tocoferoles, purificando el aceite hasta su nivel mínimo (2,6 mg/kg). Todos los adsorbentes utilizados tenían una capacidad similar para purificar el aceite de pigmentos (carotenoides y clorofila). En el proceso de purificación en tres etapas, los esteroles libres se eliminaron casi por completo (hasta el nivel de 90,0 mg/kg). La purificación de aceite de β-caroteno y clorofila también fue muy efectiva. En este método, los tocoferoles se eliminaron completamente, excepto pequeñas cantidades de α-tocoferol (0,4 mg/kg), lo que resulta de su interacción relativamente débil con un relleno hidrófilo. El método desarrollado se puede usar en los estudios sobre el efecto de los coloides de asociación en los procesos de autooxidación de aceites a granel.

The oxidative stability of vegetable oils mainly depends on their fatty acid composition, their degree of unsaturation, and the presence of compounds with antioxidant activity. This paper reports on the effects of the process of roasting oil seeds, prior to pressing them, on the basic characteristics of the oils produced and their oxidative stability. The differential scanning calorimetry (DSC) technique was used to study the process of oxidation of the oil samples in an oxygen-flow cell. Chromatographic analysis revealed that roasting the seeds increased the levels of chlorophyll and &beta, carotene in all the cold-pressed oils. Similar results were observed for the oil&rsquo, s antioxidant activity, measured by the scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical method. Our results also indicated that roasting seeds prior to pressing them for oil had a positive effect on the oil&rsquo, s stability, as determined by the DSC method. This manifested in both the extension of oxidation induction time and the final oxidation time.

The aim of this paper was to monitor changes of antioxidant activity and phenolic contents of pasta enriched with black locust flower (BLF) addition (in such percentages as 2.5, 5, 7.5, and 10) after thermal processing. Pasta microstructure, texture, and consumer acceptance were determined as well. The BLF addition increased the content of phenolics and antioxidant activity. Comparing to the control, the total polyphenol compounds content was two times higher (0.27 ± 0.01 and 0.63 ± 0.01 mg FAE/g, respectively), and the flavonoid concentration increased from 0.48 to 204.46 µg/g in case of 10% addition. It was also observed that the thermal processing improved antioxidant properties of pasta measured in vitro. Moreover, changes in the culinary behavior, texture and microstructure of samples were observed as well. However, changes in the texture and proximate composition of the pasta with 2.5% BLF did not change the consumer attractiveness of the obtained pasta. PRACTICAL APPLICATIONS: Adequate supply of both nutrients and non‐nutrients (including antioxidants) is the basic condition for the proper conduct of all human life processes. Cereal products are the basic product category on the food market. Application to the production of a commonly found raw material (BLF) will allow low financial expense to widen the range of pasta produced. Another element important from the nutritional point of view is the innovative, previously unused composition of pasta, which undoubtedly improves the functioning of the body, but also can prevent diseases caused by oxidative stress. In summary, the pasta has an innovative nutritional qualities and health benefits, unprecedented so far in traditional on the market for products of this type.

Interactions of canolol and α-tocopherol (α-T) with reverse micelles made from DOPC phospholipid (1,2-dioleoyl-sn-glycero-3-phosphocholine) in rapeseed oil were investigated in the current study. Furthermore, the antioxidant efficiency of canolol and α-T as well as the phenomenon of synergism between them in the oil containing association colloids has been determined. As demonstrated by fluorescence measurements, canolol may be incorporated into the structure of DOPC reverse micelles. This antioxidant may also accumulate in bulk oil at oil/water interface. In turn, no interactions of α-T with phospholipid association colloids were observed. The presence of DOPC association colloids affects antioxidant efficiency of canolol and α-T. Simultaneously, at the concentration 100 μmol of both substances, decreasing of their antioxidant activity effectiveness over time was observed. Formed during autoxidation amphiphilic compounds probably influence the structure of reverse micelles, modifying effectiveness of antioxidants. Antioxidant synergism of canolol and α-T occurs only in DOPC reverse micelles. Synergism phenomenon allows eliminating adverse effect of autoxidation products on the effectiveness of antioxidants. The presence of canolol may eliminate prooxidative action of α-T.

The antioxidant capacity (AC) of boiled-type coffee brews (CB) and phenolic acids (PA) isolated from them, obtained from the caffeinated and decaffeinated beans of different geographical origins and species and with different roasting degrees, was examined. The AC of PA and CB samples was tested in five antioxidant assays: a total antioxidants reducing capacity assay using a Folin–Ciocalteu reagent (FCR), a ferric ion reducing antioxidant power (FRAP) assay, a DPPH· radical-scavenging activity (DPPH) assay, a metal chelating activity (MCA) assay and a total radical trapping antioxidant parameter (TRAP) assay. In most samples, the total amount of phenolic acids, determined by HPLC, decreased with the increasing degree of roasting the coffee beans, leading to reduced AC. All used methods showed that CB exhibits higher AC compared with the PA samples. Phenolic acids isolated from CB samples have the main contribution (on average over 95 and 84 % in green and roasted coffee extracts, respectively) in AC of the CB samples in FCR, FRAP and TRAP assays, whereas in DPPH and MCA tests, the phenolic acid contribution in AC of CB samples was below 50 % (on average over 36 and 45 % in green and roasted coffee extracts, respectively). Significant differences between the AC values determined for CB and PA samples were noticed only for the MCA and DPPH methods which reflect the different molecular mechanisms underlying each of the assays. Additionally, the statistical methods, including principal component analysis, applied to results of antioxidant capacity obtained with different analytical techniques confirmed their feasibility to distinguish between coffee brews with different degrees of roasting, regardless of coffee origin.

This study describes the formation of 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine (DOPC) association colloids (reverse micelles) in rapeseed oil and interactions of sinapic and ferulic acids with these structures. Furthermore, the process of oil autoxidation in the presence of DOPC is characterized and the antioxidant efficiency of phenolic acids in the oil containing reverse micelles is determined. Formation of DOPC reverse micelles above the phospholipid critical micelle concentration (51.13 µmol kg–¹) is observed. The fluorescence probe emission parameters confirm the interactions of sinapic and ferulic acids with reverse micelles and changes of their structure (reduced rigidity) as a result of phenolic acid incorporation. In the analyzed rapeseed oil, an evident prooxidative effect of DOPC reverse micelles is found, as their presence accelerates decomposition of hydroperoxides to hexanal. The antioxidant effect of sinapic acid is strongly influenced by the presence of DOPC reverse micelles. Ferulic acid shows a concentration‐dependent antioxidant effect in relation to the formation of hexanal. Practical Applications: Understanding the influence of sinapic and ferulic acids on the structure of association colloids and rapeseed oil autoxidation in the presence of reverse micelles should facilitate extension of shelf life and reduce oil quality deterioration during storage. This knowledge may also be used to optimize industrial oil refining to provide the desired amount of amphiphilic minor components and native antioxidants. Thus, developed refining using mild conditions or even minimizing the degree of refining is attractive in view of greater retention of health‐promoting compounds in vegetable oil, reduction of processing costs, and increased sustainability of the oil‐refining process.

The physicochemical interactions between alpha-tocopherol and three phenolic acids, which constitute main phenolics in coffee brew: caffeic, chlorogenic and ferulic acid, in l-α-phosphatidylcholine liposome system were studied. Steady-state and fluorescence lifetime measurements were applied to elucidate location of investigated phenolic acids in liposomes, and the results have shown that ferulic acid is most embedded into membrane structure. Lipophilic studies have shown that at pH 7.4 the partition coefficients for all phenolic acids are similar. Antioxidant capacity measurements of studied antioxidants were taken using fluorescent probe BODIPY. The synergistic effect was observed in all tested antioxidant systems with the exception of sample consisting of chlorogenic acid (2.5 μM) and alpha-tocopherol (2.5 μM), where antagonistic effect was noted. Concentration of antioxidants was a significant factor in the observed phenomenon. The most effective antioxidant system against oxidation in liposomes was combination of alpha-tocopherol and ferulic acid. This phenomenon could be explained by interaction of ferulic acid with the interior of the phospholipids membrane.

Summary The aim of this work was to develop a CdSe/ZnS quantum dot -based fluorescence method for the determination of quercetin aglycone in onion. The synthesized nanostructures have been characterized by the use of spectroscopic techniques. The method developed is based on the formation of host–guest complexes between quercetin aglycone and β-cyclodextrin and the consequent fluorescence quenching of the quantum dots. This allowed us to obtain a fast and selective spectroscopic method for the determination of this flavonoid. The developed technique enables determination of quercetin aglycone in real samples (methanolic extracts obtained from onion) in the presence of all components of the matrix, including quercetin glucosides and other phenolic compounds. The limit of detection was 14 μm and sensitivity was 13.2 nm. The accuracy of the method has been confirmed by HPLC measurements and the average recovery was in the 108–113% range, depending on the kind of sample tested.

Eight tocochromanols (a, b, g ,a ndd homologues of tocopherol and tocotrienol) naturally occurring in foods were successfully separated within a 13‐min run in the RP‐HPLC mode. Analytes were separated on the Phenomenex Luna PFP column filled with the pentafluorophenyl stationary phase (3mm, 150mm � 4.6mm)usingthemobile phase containingmethanol:water(93:7v/v)withan elution flow rate of 1ml/min and column oven temperature of 40°C. The method was rapid, linear, accurate, and precise with detection limits in the range of 0.000184–0.000605mg, preventing analyte losses due direct dissolution in 2‐propanol. The developed RP‐HPLC method in comparison with the NP‐HPLC mode had a significantly higher sensitivity, speed, and repeatability, but primarily it protected against the loss of analytes andthusreducedtheriskofpossibleerrormeasurements.Itwasfoundthattocopherolcontentsinthetested butter samples amounted to2.00–16.92mg/100g for samples coming from Poland and 2.61–2.98mg/100g for samples from Latvia, respectively. The method is characterized by simplicity of implementation and it was successfully applied in the determination of tocochromanols in butter to verify product authenticity. Practical applications: To ensure consumers’ protection, food products should be subject to continuous quality and authenticity control. One way to determine butter authenticity is to analyze native tocochromanol contents. This paper describes a simple and fast method determine plant oils added to milk fat with the use of RP‐HPLC techniques.

The study describes isolation and semi-preparative HPLC scale purification of plastochromanol-8 (PC-8). The PC-8 standard was obtained from flaxseed oil. The purity of the obtained PC-8 standard was 93.06% determined by UV–Vis detection. The HPLC/MSn fragmentation pattern of PC-8 side chain resulted in the successive release of eight isoprene fragments which confirmed the correct structure identification. The established PC-8 molar absorption coefficient (3616.5 M−1cm−1) will allow the precise quantitative analysis of this compound in real samples without the use of a standard. Usefulness of the obtained PC-8 standard was verified by HPLC determination of PC-8, tocopherols, and tocotrienols at the same time. The PC-8 recovery was 107.08%, and limit of detection (LOD) and limit of quantitation (LOQ) were 0.75 and 2.27 µg/mL, respectively. Practical applications: There are no commercially available standards of plastochromanol-8 (PC-8), and therefore effective ways of isolation of this compound are needed. A semi-preparative HPLC is one of the available options allowing obtaining pure PC-8.

Sinapic acid and its derivatives are main phenolic compounds present in rapeseed. Identification and quantitative determination of those compounds were carried out in crude extracts as well as extracts after basic and acidic hydrolysis. The total phenolic content in the crude extracts, expressed as sinapic acid equivalent, ranged from 1577 to 1705 mg/100 g for cv. Visby and Bellevue, respectively. An increase in total phenolics contents was observed in extracts after hydrolysis in comparison to crude extracts. The predominant phenolic acids in rapeseed samples were trans-sinapic and cis-sinapic acids. The highest concentration of sinapic acid methyl ester (2533–2702 mg/100 g) was detected in the extract after basic hydrolysis. In turn, two sinapic acid derivatives, i.e., kaempferol 3-dihexoside-7-sinapoyl-hexoside and 3-hexoside-7-sinapoyl-hexoside, were detected in the hydrolysed extracts. Total peroxyl radical-trapping potential (TRAP) of the investigated crude extracts amounted to 20.21 and 27.05 μM Trolox Eq/g in the case of cv. Visby and Bellevue, respectively. The increase in antioxidant activity of the analyzed extracts after basic and acidic hydrolysis was probably a result of the release of free phenolic compounds from their conjugates (esters, glycosides). Practical applications: The content and qualitative composition of the phenolic compounds in rapeseed have much influence on the stability, sensory, and nutritional characteristics of the products. During oil production process phenolic compounds may be transferred into final products and inhibit lipid oxidation. Rapeseed oil, among all commercially available oils, has the highest content of phenolic compounds, especially sinapic acid and their derivatives. That is why the antioxidant activity of phenolic compounds was investigated in the presented study. Determination of polar phenolics before and after hydrolysis indicates which compounds are responsible for antioxidant effect in oils and which are available for the human organism after digestion in the digestive tract.

The aim of the study was to reveal antioxidant synergism or antagonism between quercetin, rutin and selected tocotrienols in linoleic acid emulsion. The oxidative stress was generated by 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) or CuSO4; the increase of the concentration of peroxidation products was monitored using fluorescence probe 2,7-dichlorofluorescein (DCF). The antioxidant activity of tested substances depends on the form of the antioxidant (aglycone, glycoside), its concentration, localization in the emulsion, and the factors generating oxidative stress. The synergistic effect occurred when the effectiveness of individual antioxidant was relatively weak and mainly when the concentration of antioxidants was in the physiologically significant range of 1 μM. We suggest that tocotrienols were regenerated by flavonoids. The synergism benefitted from the proximity of the localization of interacting antioxidants (e.g. the presence of one of the antioxidants at the oil-water interface).

Total phenolic compounds, phenolic acids and flavonoid contents and antioxidant activities were measured in extracts from seeds of Lupinus albus, Lupinus luteus and Lupinus angustifolius cultivars. The total phenolic compound contents varied from 491.51 to 731.14 mg/100 g d.m. for cvs. Butan (L. albus) and Parys (L. luteus), respectively. Protocatechuic acid was the most abundant in seeds of yellow lupin (up to 73.60 mg/kg d.m.), whereas p-hydroxybenzoic acid in narrow-leaf lupin (about 43 mg/kg d.m.). The HPLC (high performance liquid chromatography) analysis revealed two dominant flavonoid compounds, which were identified by HPLC/MSn to be apigenin-6,8-di-C-β-glucopyranoside and apigenin 7-O-β-apiofuranosyl-6,8-di-C-β-glucopyranoside. The highest content of the apigenin glycosides was recorded in yellow lupin while the lowest in white lupin. A positive correlation between the content of the analyzed compounds and the antioxidant activity measured by 2,2′-diphenyl-1-picrylhydrazyl (DPPH) method was established, but no such relation was found using the radical-trapping antioxidant parameter (TRAP) method. Modification of the peroxyl radical-trapping potential of lupin extracts by formation of phenoxyl radicals is suggested.

The focus of the present research was to study inhibition of lipoxygenase activity by rapeseed native polyphenols and the interactions between those compounds and the enzyme. The enzyme and polyphenolic compounds (polyphenols, phenolic acids) were extracted from rapeseed (Brassica napus) varieties Aviso and PR45DO3. The total phenolic compounds concentration in tested rapeseed was 1,485–1,691 mg/100 g d.m. (dry matter) and the free phenolic acids content in both rapeseed varieties was about 76 μg/100 g d.m. The isolated proteins showed lipoxygenase activity. Prooxidant properties of phenolic compounds in the presence of lipoxygenase and linoleic acid were observed rather in the case of extracts containing a relatively high concentration of miscellaneous polyphenols. Antioxidant properties were recorded in the case of phenolic acid extracts which contain only 1.4–1.9% of phenolics present in raw phenolic extracts. We propose that the prooxidant effect of phenolic compounds comes from quinone and oxidized polyphenols formation. The observed antioxidant activity of phenolic acid extracts is probably due to their ability to scavenge free radicals formed from linoleic acid. However, reduction of lipoxygenase ferric to ferrous ions, which prevent the activation of the enzyme and inhibited its activity, was also observed.

identified, constituting 64, 19 and 17% of the total amount, respectively. For linolenic acid, the components 13-hydroperoxy-octadecatrienoic acid trans-trans (13-HPOTE t-t), 9-HPOTE c-t and 9-HPOTE t-t contributed 7, 33 and 60% to the total, respectively. The different dominant hydroperoxide isomers detected in linoleic and linolenic acids during oxidation are related to their chemical structure and the microenvironment of emulsion droplets. The ratios between specific isomers for both fatty acid hydroperoxides did not change during oxidation with or without antioxidants. Alpha-T effectively inhibited the oxidation of fatty acids and reduced the formation of hydroperoxides. The total amount of the hydroperoxides decreased along with the increase in the concentration of alpha-T, 1–40 mM. Quercetin inhibited the oxidation of both fatty acids at similar efficiency only at 40 mM concentration. A synergistic antioxidant effect of quercetin with alpha-T in a binary system on both fatty acids was observed.

The effect of D-alpha-tocopherol (alpha-T) on phospholipid dipalmitoylphosphatidylcholine (DPPC) membrane solubilization in their gel phase by anionic detergent sodium dodecyl sulfate has been studied using fluorescence spectroscopy, turbidometric and optical microscopy methods. The solubilization process of DPPC occurs in the range of seconds, whereas the equilibration of the resulting mixed micelles occurs over a much longer timescale. The turbidity changes reflecting the membrane solubilization depended on the D-alpha-T/DPPC ratios and detergent concentration. Increasing alpha-T concentration embedded into DPPC membrane, up to 10 mol%, decreases the solubility of the membrane by 45%. Endogenous alpha-T fluorescence indicated that during solubilization, the formation of detergent/alpha-T/phosphatidylcholine aggregates occurred, which led to the mixed micelle formation. Images of the vesicles obtained by optical micros copy visualized that DPPC membrane solubilization and showed that the presence of alpha-T in the membrane increases its resistance to detergent solubilization. The observed processes were discussed on the basis of the hydrophobic–hydrophilic balance in the bilayer.

Changes of the photoluminescent properties of QD in the presence of oxidized catechin (CQ) were investigated by absorption, steady-state fluorescence, fluorescence lifetime and dynamic light scattering measurements. Photoluminescence intensity and fluorescence lifetime was decreasing with increasing CQ concentration. Dynamic light scattering technique found the hydrodynamic diameter of QD suspension in water is in range of 45 nm, whereas in presence of CQ increased to mean values of 67 nm. Calculated from absorption peak position of excition band indicated on average QD size of 3.2 nm. Emission spectroscopy and time-resolved emission studies confirmed preservation of electronic band structure in QD–CQ aggregates. On basis of the presented results, the elucidated mechanism of QD fluorescence quenching is a result of the interaction between QD and CQ due to electron transfer and electrostatic attraction. The results of fluorescence quenching of water-soluble CdTe quantum dot (QD) capped with thiocarboxylic acid were used to implement a simple and fast method to determine the presence of native antioxidant quinones in aqueous solutions. Feasibility studies on this method carried out with oxidized catechin showed a linear relation between the QD emission and quencher concentration, in range from 1 up to 200 μM. The wide linear range of concentration dependence makes it possible to apply this method for the fast and sensitive detection of quinones in solutions.

This study describes in vitro digestion of lupin seed globulins by pancreatin, trypsin and chymotrypsin. Lupin seed globulins turned out to be almost totally susceptible to chymotrypsin digestion. When panceratin or trypsin were used for digestion of lupin seed globulins, γ-conglutin appeared to be resistant to proteolysis. Different fluorescence spectroscopic methods such as fluorescence anisotropy, fluorescence lifetimes and fluorescence quenching measurements were used for detailed characterisation of this phenomenon. A potential reason for γ-conglutin insensitivity to digestion may be related to the fact that lysine, as well as arginine, are positively charged at cell physiological pH. Simultaneously, flavonoids at this pH are partially ionised, which may lead to the occurrence of ionic interactions between these molecules at pH 7.5. The confirmation of this explanation may be the fact that γ-conglutin and vitexin form a static complex, which was observed using fluorescence quenching measurements.