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

A preliminary study of the genetic diversity of Bolivian oca (Oxalis tuberosa Mol.) varieties maintained in situ and ex situ through the utilization of ISSR molecular markers

ISSR molecular markers have been used to investigate genetic diversity of oca (Oxalis tuberosa Mol.), an Andean neglected tuber crop species. Sampling procedure allowed a preliminary study of the genetic diversity at the intra- and intervarietal levels. Twenty tuber lots conserved in situ in the microcentre of Candelaria and ex situ in the Toralapa Centre (Bolivia) were identified. Four ISSR primers amplified a total of 25 fragments of which 17 (68%) were polymorphic. These experiments show that the structure of oca varieties is mainly based upon vernacular names with a greater differentiation among tuber lots than within them, supporting agromorphological data. ISSR technique enlightened the existence of heterogeneous varieties in oca and divergence between in situ and ex situ conservation, strategies. These observations are potentially linked to the different ways of management of tubers in these two conservation systems

Variabilité génétique de soja pour la résistance à la sclérotiniose (Sclerotinia sclerotiorum Lib de Bary). Liaisons statistiques avec certains caractères de la culture

Pour de nombreux chercheurs, le classement des cultivars de soja pour la résistance à la sclérotiniose ne donne pas des résultats constants. Pour étudier ce problème, nous avons entrepris une expérimentation qui a duré 4 ans. Nous avons notamment mis en évidence que certains cultivars de soja, comme Labrador et Kingsoy, sont constamment et significativement moins attaqués que d'autres, tels que Dom et Messidor. Grâce à une technique d'infection par des sclérotes initiés, nous avons trouvé, sur les 31 cultivars étudiés, une corrélation significative entre la sensibilité à la sclérotiniose et la hauteur de la plante (r = +0,54). Sur 17 cultivars les plus précoces parmi ces 31, il existe une liaison du même ordre avec la date de maturité des gousses (r = +0,57). Par contre, nous n'avons trouvé aucune corrélation significative avec d'autres caractères de la culture (date de fermeture du couvert végétal, date de floraison, nombre d'apothécies par m2, etc). Ces résultats sont discutés afin d'avoir une meilleure approche de la résistance du soja à la sclérotiniose.Genetic variability of soybean for resistance to Sclerotinia sclerotiorum (Lib) de Bary. Statistical relationship with some traits of the crop. The ranking of the cultivars of soybean for stem rot resistance in many cases does not provide consistent results. To study this problem, we undertook a 4-yr experimental study. It was found that some cultivars such as Labrador and Kingsoy were less susceptible than others, eg Dom and Messidor. Using a new infection method of the soil via sclerotia, a significant correlation was found in 31 cultivars between the percentage of diseased plants and height at maturity (r = +0.54). A significant correlation was also found with the susceptibility to stem rot and the date of pod maturity for the 17 earlier maturing cultivars (r = +0.57). There was no significant correlation with the date of full canopy, the date of 50% flowering, or the number of apothecia per m2. These results are discussed and a viable approach regarding resistance of soybean to S sclerotiorum is proposed

Classical and NIR measurements of the quality and nutritional parameters of apples: a methodological study of intra-fruit variability

For the past few years, research has focused on the application of Near Infrared Spectroscopy (NIR) techniques to analyze the quality of apple varieties. As all fruit quality and nutritional parameters are affected by many factors, to standardize the sampling methods prior to analysis is very important. In this study, the intra-fruit variability of apple varieties in terms of quality parameters (sugar, total polyphenol and vitamin C content) was examined. The adequacy of the protocols usually applied to analyze apple quality (reference analyses of a representative sample of the apple and NIR measurements collected at four points 45° from each other in the equatorial region of the apple) was then investigated. The reference values for the quality parameters showed important intra-fruit variability for all quality parameters analyzed. The results also showed that there was little difference between the mean value at the four points and the mean value of the entire apple. This suggested that a mean value obtained from a representative sample of an apple is enough to assess the variability within the fruit and to estimate, with precision, the content of the quality parameters. The results of NIR spectroscopy showed that measurement at the four target points is suitable for predicting quality parameters precisely. The study concluded that standardized reference analyses should be done on a representative fruit sample of an apple and spectral measurements made at four points 45° from each other in the equatorial region of the apple

Use of NIR spectroscopy on fresh apples to determine the phenolic compounds and dry matter content in peel and flesh

Description of the subject. The article deals with the use of near-infrared spectroscopy (NIR) on fresh apples to determine the phenolic compounds and dry matter content in peel and flesh powders. Objectives. The aim is the rapid and non-destructive determination of these nutritional parameters. Method. Two hundred twenty-nine fruits from 20 varieties were analyzed with NIR spectroscopy and reference methods. Results. Great variability of total phenolic compounds (TPC) in peel and flesh powders was observed among varieties. The dry matter (DM) content also differed greatly between peel and flesh. Calibration and validation models showed high coefficients of determination for the TPC content, which were slightly higher for the peel than for the flesh (R² val = 0.91 and 0.84 respectively). For the DM content, high coefficients of determination and ratios of prediction to deviation (RPDs) were also observed (R² val = 0.94, RPD = 4.8 and R² val = 0.94, RPD = 4.9 for the peel and flesh respectively). Conclusions. Calibration and validation models allow quantitative predictions to be made for TPC and DM content. They confirm the potential of NIRS for predicting the polyphenol content and highlight its potential for determining the DM content, a parameter often neglected in research into apple quality

Milk and milk products

Milk is a nutritious food that plays an important role in the diet of particular groups, such as the new-born, children, the elderly and pregnant women. In addition to those groups, milk is consumed worldwide by a large part of the population, either alone or in the form of dairy products.info:eu-repo/semantics/publishedVersio