Investigation of the effects of sample preparation on gluten quantitation in rye and barley flours

Proper gluten quantitation is essential for providing safe gluten-free food for patients living with celiac disease (CD). However, gluten quantitation faces several challenges: the lack of a reference method and certified reference materials, the variability of methods and the effects of genetic and environmental factors on gluten. Among all these challenges our research group focuses on gluten reference material development. Gluten content is determined by enzyme linked immunosorbent assay (ELISA) methods to obtain comparable data for the selection of cultivars used in our reference material development efforts. As ELISA methods are developed for determining low gluten concentrations, application for these special research purposes requires a 10,000-fold dilution. The formerly performed process was a post-extraction liquid dilution that proved to be sufficient for wheat samples. However, gluten contents of rye and barley samples were found to be overestimated by ELISA methods. One of the suggested reasons is the structural and solubility changes of gluten proteins during the dilution process. Therefore, our present study focuses on the comparison of the original dilution method and a revised version using solid-phase dilution in a gluten-free matrix

Investigation of the effects of sample preparation on gluten quantitation in rye and barley flours

AbstractProper gluten quantitation is essential for providing safe gluten-free food for patients living with celiac disease (CD). However, gluten quantitation faces several challenges: the lack of a reference method and certified reference materials, the variability of methods and the effects of genetic and environmental factors on gluten. Among all these challenges our research group focuses on gluten reference material development. Gluten content is determined by enzyme linked immunosorbent assay (ELISA) methods to obtain comparable data for the selection of cultivars used in our reference material development efforts. As ELISA methods are developed for determining low gluten concentrations, application for these special research purposes requires a 10,000-fold dilution. The formerly performed process was a post-extraction liquid dilution that proved to be sufficient for wheat samples. However, gluten contents of rye and barley samples were found to be overestimated by ELISA methods. One of the suggested reasons is the structural and solubility changes of gluten proteins during the dilution process. Therefore, our present study focuses on the comparison of the original dilution method and a revised version using solid-phase dilution in a gluten-free matrix.</jats:p

Relationship of colour and other quality parameters of sweet cherry during development and ripening

Sweet cherry fruits ( Prunus avium cv. Vera, Carmen, Linda and Krupnoplodnaja) were harvested in different ripeness stages after anthesis 39, 42, 49, 56 days (Carmen); 37, 40, 47, 52, 59 days (Krupnoplodnaja); 32, 36, 44, 53, 58 days (Linda); 38, 42, 50, 52, 57 days (Vera). The colour, total soluble solids, dry matter content, β-galactosidase and polygalacturonase activity were determined. The dry matter content and total soluble solids content (Brixo) increased during development. The L* values significantly decreased as a function of ripening while a* values increased up to 3 rd harvest, then they decreased, b* values continuously decreased as a function of development. The a*/b* values linearly increased as a function of development, indicating reddening of fruits. Hue angle (ho) increased rapidly between harvest one and two. The measured (a*, b*, L*) and calculated parameters (ho, a*/b*, chroma) well represented the colour development of sweet cherries. Linear and strong correlation was found between a*/b*, L* values and the Brixo, exponential correlation was found between ho, chroma and Brixo. Activity of β-galactosidase was different among cultivars and as a function of development. The two maximums might β-galactosidase isoenzymes. The role of PG (polygalacturonase) could not be explained clearly enough, further investigations are needed to find the exact role of the enzyme in the cell wall metabolism of sweet cherry