Front-face fluorescence spectroscopy and chemometrics for quality control of cold-pressed rapeseed oil during storage

The aim of this study was to test the usability of fluorescence spectroscopy to evaluate the stability of cold-pressed rapeseed oil during storage. Freshly-pressed rapeseed oil was stored in colorless and green glass bottles exposed to light, and in darkness for a period of 6 months. The quality deterioration of oils was evaluated on the basis of several chemical parameters (peroxide value, acid value, K232 and K270, polar compounds, tocopherols, carotenoids, pheophytins, oxygen concentration) and fluorescence. Parallel factor analysis (PARAFAC) of oil excitation-emission matrices revealed the presence of four fluorophores that showed different evolution throughout the storage period. The fluorescence study provided direct information about tocopherol and pheophytin degradation and revealed formation of a new fluorescent product. Principal component analysis (PCA) performed on analytical and fluorescence data showed that oxidation was more advanced in samples exposed to light due to the photo-induced processes; only a very minor effect of the bottle color was observed. Multiple linear regression (MLR) and partial least squares regression (PLSR) on the PARAFAC scores revealed a quantitative relationship between fluorescence and some of the chemical parameters.Funding Agency Ministry of Science and Higher Education, Poland NN312428239 Poznan University of Economics and Businessinfo:eu-repo/semantics/publishedVersio

Screening of antioxidant properties of the apple juice using the front-face synchronous fluorescence and chemometrics

Fluorescence spectroscopy is gaining increasing attention in food analysis due to its higher sensitivity and selectivity as compared to other spectroscopic techniques. Synchronous scanning fluorescence technique is particularly useful in studies of multi-fluorophoric food samples, providing a further improvement of selectivity by reduction in the spectral overlapping and suppressing light-scattering interferences. Presently, we study the feasibility of the prediction of the total phenolics, flavonoids, and antioxidant capacity using front-face synchronous fluorescence spectra of apple juices. Commercial apple juices from different product ranges were studied. Principal component analysis (PCA) applied to the unfolded synchronous fluorescence spectra was used to compare the fluorescence of the entire sample set. The regression analysis was performed using partial least squares (PLS1 and PLS2) methods on the unfolded total synchronous and on the single-offset synchronous fluorescence spectra. The best calibration models for all of the studied parameters were obtained using the PLS1 method for the single-offset synchronous spectra. The models for the prediction of the total flavonoid content had the best performance; the optimal model was obtained for the analysis of the synchronous fluorescence spectra at Delta lambda = 110 nm (R (2) = 0.870, residual predictive deviation (RPD) = 2.7). The optimal calibration models for the prediction of the total phenolic content (Delta lambda = 80 nm, R (2) = 0.766, RPD = 2.0) and the total antioxidant capacity (Delta lambda = 70 nm, R (2) = 0.787, RPD = 2.1) had only an approximate predictive ability. These results demonstrate that synchronous fluorescence could be a useful tool in fast semi-quantitative screening for the antioxidant properties of the apple juices.info:eu-repo/semantics/publishedVersio

Directions of Colour Changes of Nectar Honeys Depending on Honey Type and Storage Conditions

The colour of honey is one of the most important quality criteria for consumers. The colour depends mainly on the content of plant pigments but the honey consistency, shape, and size of the crystals may also influence the honey colour parameters. It is related to the crystallisation and decrystallisation processes of honey during storage. In the present study, directions of colour changes of honey during storage were evaluated using a tristimulus colorimeter and the CIE 1976 L*a*b* and CIE L*C*ho systems. The effect of time (3 and 9 months) and storage conditions (cold storage, room temperature storage with access to light, and room temperature storage without access to light) on the colour of nectar honeys was investigated. The results obtained showed that both the type of honey and the storage conditions influenced the honey colour parameters. Significant differences in direction and intensity of the colour changes of honey during storage were observed. These differences make it difficult to indicate which storage conditions are optimal to preserve the colour of the honey. It was found that acacia and heather honeys were the most susceptible to colour changes during long-term storage in all of the study’s applied conditions, whereas rape and buckwheat honeys were the most stable in colour parameters

Raspberry seed extract improves the ferroxidase activity of ceruloplasmin in patients with lower artery chronic total occlusion

Ceruloplasmin (Cp) is the major antioxidant in plasma, a protein that carries about 95% of the total copper. Multiple biochemical activities of ceruloplasmin have been described, including copper transport or oxidation of Fe(II) to Fe(III) for subsequent uptake by transferrin and ferritin. Reduction of the pool of free Fe(II) ions by Cp prevents the generation of free radicals and reactive oxygen species by oxidation of Fe(II), thus inhibiting the Haber-Weiss reaction. The removal of both free Fe(II) and Fe(III) ions from blood plasma by polyphenols enhances the antioxidant system of the living organism. However, the mechanism of interactions between exo- and endogenous antioxidants is still under consideration. The effect of raspberry seed extract (RSE) on the ferroxidase activity of ceruloplasmin isolated from plasma of patients with chronic arterial occlusion of the lower limbs due to atherosclerosis (CpAO) was investigated. Moreover, the effect of RSE on the ferroxidase activity of Cp isolated from healthy volunteers (CpC) was also estimated. The ferroxidase activity of Cp, expressed as ΔFe(II), was determined by spectrophotometry with the use of the Fe(II) – histidine complex and ferrozine as a chromogenic reagent. The addition of RSE to samples with the same amount of both CpAO or CpC in each caused an increase in ΔFe(II). The polyphenol-rich RSE may assist Cp in the fight against free radicals and reactive oxygen species when the disease occurs due to an excessive use or reduced production of endogenous antioxidants