Renata Zawirska-Wojtasiak

Application of headspace—solid phase microextraction and multivariate analysis for plant oils differentiation

Application of multivariate analysis (MVA)—principal component analysis (PCA) and cluster analysis—for the analysis of chromatographic and sensory data was investigated for volatiles of plant oils. Five oils—rapeseed, soybean, peanut, sunflower and olive oil—were compared. Volatile compounds of fresh oils and oils subjected to storage at 60 °C were isolated by HS-SPME sampling and analysed by GC/MS, and fast GC with FID detection. Based on developed methods and data treatment it was possible to distinguish between different oils and oils stored for various periods of time. PCA of chromatographic data was related to PCA sensory analysis and similarities in sample clustering were observed. Multivariate analysis facilitates comparison of chromatographic profiles of volatile compounds characteristic for various plant oils and for monitoring oil quality in storage.

Evaluation of Antioxidant Activity of Green Tea Extract and Its Effect on the Biscuits Lipid Fraction Oxidative Stability

This article investigates the effect of green tea extract (GTE) on biscuits lipid fraction oxidative stability. The antioxidant activity of GTE was compared with commonly used synthetic antioxidant butylated hydroxyanisole (BHA). Biscuits were prepared in 3 variations. Control samples were prepared without addition of antioxidants. The other variations were prepared by adding BHA (0.02%) and GTE at 3 different levels: 0.02%, 0.1%, and 1%. Biscuits were subjected to sensory studies and instrumental and chemical analysis. Phenolic compounds of GTE characterized powerful antioxidant activities evaluated using free radical, 2,2-diphenyl-1-picrylhydrazyl method, compared with gallic acid and significantly better than BHA. Antioxidants added to the samples clearly slowed down the process of oxidation of fatty acids, inhibiting the monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) decomposition. Addition of GTE at the level of 1% gave an excellent antioxidant effect on the biscuits lipid stability, inhibiting hydroperoxides formation by about 47% to 73% compared with BHA, which showed about 16% to 60% inhibition. However, GTE did not improve significantly lipid stability, measured by anisidine value (p-AV), and inhibited formation of secondary oxidation products only by 3.5%. After accelerated storage time, insensitivity of oxidized-like flavor was about 2 times higher for control samples compared to samples with addition of antioxidants. Moreover, after storage biscuits treated with natural antioxidant received a higher panel score of overall acceptance compared to samples with BHA. Using volatile compound formation as a marker of lipid oxidation, both GTE and BHA were effective inhibitors of the decomposition of hydroperoxides.

White grape pomace as a source of dietary fibre and polyphenols and its effect on physical and nutraceutical characteristics of wheat biscuits.

BACKGROUND Grapes are one of the worlds staple fruit crops, with about 80% of the yield being utilised for winemaking. Since grape by-products still contain large amounts of secondary metabolites, uses other than as fertilisers might be appropriate. In this study, white grape pomace (WGP) was incorporated in wheat flour at levels of 10, 20 and 30% (w/w) to investigate its influence on rheological, nutraceutical, physical and sensory properties. RESULTS Farinograph characteristics of dough with different levels of WGP showed a decrease in water absorption from 56.4% (0% WGP) to 45.9% (30% WGP). Addition of WGP reduced hardness and caused a deterioration in brightness and yellowness of all enriched samples. The smallest addition of WGP (10%) caused an approximately 88% increase in total dietary fibre content as compared with the control. The content of phenolic compounds increased from 0.11 mg g⁻¹ with 0% WGP to 1.07 mg g⁻¹ with 30% WGP. The most stable phenols were as follows: γ-resorcylic acid < gallic acid < tyrosol < catechin < isovanilic acid. An assay of radical-scavenging activity showed that WGP addition greatly enhanced the antioxidant properties of biscuits. Acceptable biscuits were obtained when incorporating 10% WGP. CONCLUSION WGP might be utilised for the novel formulation of biscuits as an alternative source of dietary fibre and phenols.

Determination of geosmin, 2-methylisoborneol, and a musty-earthy odor in wheat grain by SPME-GC-MS, profiling volatiles, and sensory analysis

Geosmin and 2-methylisoborneol-compounds responsible for the musty-earthy off-odor of wheat grain, were isolated by SPME and analyzed by GC-MS. Carboxen/PDMS/DVB fiber coating was selected because of its highest extraction efficiency. Concentrations of geosmin and 2-methylisoborneol as low as 0.001 microg/kg were detected in SIM mode using ion trap mass spectrometer. Apart from GC-MS determination of geosmin and 2-methylisoborneol, various methods for evaluating the musty-earthy off-odor caused by these compounds in wheat grain are presented. Sensory profile analysis differentiated wheat grain into sound and off-flavored, but the method was tedious. Similar groupings, however, were obtained using more rapid methods such as comparison of volatile profiles using SPME-fast GC with PCA projection of data and metal oxide (MOS) based electronic nose.

Volatile compounds responsible for aroma of Jutrzenka liquer wine.

Jutrzenka is a sweet liquer wine produced in Poland from the grape variety of the same name, developed in Poland to withstand the harsh climate of winery regions. Jutrzenka wine has a characteristic aroma with strong fruity and flowery notes, which make it unique among other liquer wines as demonstrated in sensory profile analysis. The work was aimed at characterization of volatile compounds in this wine, with the emphasis on characterization of compounds responsible for its unique aroma. Gas chromatography-olfactometry (GC-O) was applied to identify the key odorants using aroma extract dilution analysis (AEDA) approach. To facilitate free and bound terpenes and C(13)-norisoprenoids identification solid phase extraction (SPE) was used followed by GC/MS. Among identified key odorants β-damascenone was the compound having the highest FD (4096), followed by isoamyl alcohol, 4-mercapto-4-methyl-2-pentanone (FD=2048), methional, linalool, ethyl decanoate (FD=1024) and ethyl hexanoate, furaneol (FD=512). Other significant compounds were ethyl 2-methyl propanoate, ethyl 2-methylbutanoate and phenyl ethyl alcohol. Determination of odor activity values (OAV) showed the highest values for β-damascenone (566), 4-mercapto-4-methyl-2-pentanone (288) ethyl hexanoate (32) and linalool (7). Jutrzenka exhibited also a rich profile of free, and to lesser extent bound terpenes.

GC Analysis of Rosemary Aroma Isolated Traditionally by Distillation and by SPME

Abstract The rosemary aroma composition and the enanatiomeric ratio of chiral compounds were examined by GC (FID), GC/MS and chiral GC. Solid-phase microextraction (SPME) was examined for its suitability for isolation of volatiles from the leaves of five samples of rosemary in comparison with the traditional steam distillation procedure. Mostly five rosemary aroma components were taken into consideration: 1,8-cineole, camphor, borneol, α-terpineol and verbenone. Eight pairs of enantiomers were separated in all of the analyzed samples: α-pinene, camphene, β-pinene, limonene, linalool, camphor, borneol and α-terpineol. But only one compound—borneol was detected in all the samples, with the same enantiomeric ratio and high optical purity of the minus form, over 85% of total. SPME may be used as a fast and precise tool for measuring the enantiomeric ratio of this compound when authenticity of rosemary aroma is controlled.

Odor Active Compounds Content in Spices and Their Microencapsulated Powders Measured by SPME

Within this study, main odorants of marjoram and thyme (linalool and thymol) were determined in spices and microencapsulated powders using solid-phase microextraction (SPME). Analyses were conducted on selected batches of spices before and after decontamination and on microencapsulated powders prepared for technological purposes (improvement of aroma in decontaminated spices). Conditions of SPME analyses were determined for individual compounds and matrices. Determination of total and surface contents of compounds and the percentage dependencies between encapsulated and surface aroma made it possible to identify the best powders in terms of their quality.

Phenolic compounds reduce formation of Nε-(carboxymethyl)lysine and pyrazines formed by Maillard reactions in a model bread system

This study had the objective of determining the antiglycation activity of phenolic compounds (PCs) ((+)-catechin, quercetin, gallic, ferulic, and caffeic acids) added to a model bread with regards to the inhibition of Nε-(carboxymethyl)lysine (CML) formation. PCs were found to significantly reduce CML (31.77%-87.56%), even at the lowest concentration, with the exception of ferulic acid (FA). The strongest inhibitory effect of FA (∼62%) appeared when concentration was increased to 1.0g/100g of flour. The available lysine losses (0.00%-90.51%) showed a significant correlation (0.853-0.990) with effectiveness of CML inhibition, except in the case of samples with FA. (+)-Catechin reduced CML levels the most, probably due to its structure-antioxidant activity relationship, its thermal stability (∼51% loss), and its reactivity with ε-lysine side chains (∼40.77% loss). Although the bread supplemented with PCs contained low levels of CML, this process may adversely affect bread flavor, reducing the formation of pyrazines (1.10%-80.77%).

Bioactive β-carbolines norharman and harman in traditional and novel raw materials for chicory coffee

The β-carboline compounds norharman and harman exhibit neuroactive activity in the human body. Chicory coffee has proved to be a source of β-carboline compounds. This study assessed the norharman and harman contents of traditional and novel raw materials for the production of chicory coffee, as well as in samples of chicory coffee with novel additives. The highest content of the β-carbolines among the traditional raw materials was recorded in roasted sugar beet (2.26 μg/g), while roasting the chicory caused a 25-fold increase in the content of norharman in this raw material (from 0.05 to 1.25 μg/g). In novel raw materials not subjected to the action of high temperature, β-carboline was not detected. Among the roasted novel raw materials, the highest contents of harman and norharman were found in artichokes. High harman levels were also recorded in roasted chokeberry.

Chlorogenic acid in raw materials for the production of chicory coffee.

BACKGROUND Chicory coffee is produced from traditional raw materials. Other materials are added to improve its aroma. The aim of this study was to test new raw materials with a high content of chlorogenic acid (CGA) as the criterion for their selection. This acid is degraded in the course of roasting and is a source of phenolic compounds affecting coffee aroma. For this reason, contents of CGAs were analyzed in traditional and new materials before and after roasting and compared with the chemicals formed in the roasted pure standard of chlorogenic acid (5-CQA). RESULTS It was shown that the novel raw materials contained considerable amounts of 5-CQA, frequently higher than in traditional chicory. The roasting process caused significant losses of 5-CQA in the tested raw materials, amounting to 55-91%. In turn, the analysis of volatile compounds in roasted materials showed the presence of certain phenolic and heterocyclic compounds that were also formed as degradation products of the pure 5-CQA chemical standard. CONCLUSION Novel raw materials, mainly chokeberry, artichoke and lovage, are rich sources of CGAs, particularly 5-CQA. Their application in the production of chicory coffee may result in an increased content of primarily phenolic compounds in its aroma.