Influence of fat globule membrane composition on water holding capacity and water mobility in casein rennet gel: A nuclear magnetic resonance self-diffusion and relaxation study

International audienceThe effects of the composition of the fat globule surface on water holding capacity and water diffusion were studied in different rennet-derived retentates. Water holding capacity was determined from nuclear magnetic resonance (NMR) relaxation measurements; the water diffusion coefficient was estimated using Pulse Field Gradient NMR. Reconstituted fatty retentates were prepared from fat-free retentate mixed with different fat-in-water emulsions stabilized with native phosphocaseinates (NPCs) or sodium caseinates. Coagulation of retentate reconstituted with native fat globules (fresh cream) and of industrial fatty retentate was also investigated. The study showed that the fat droplet/water interface influenced the water diffusion coefficient in the cream-reconstituted retentate gel only. No effect was observed in the NPC- and Na-caseinate-reconstituted retentate and in the fatty industrial retentate after coagulation. The results of the relaxation measurements in the gelled f! atty reconstituted retentates showed that the nature and the composition of the fat interface influence the syneresis behaviour

Évaluation de l’efficacité de biostimulants chez le colza et la tomate - Laboratoire RMN mobile

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Multiblock analysis applied to TD-NMR of butters and related products

International audienceThis work presents a novel and rapid approach to predict fat content in butter products based on nuclear magnetic resonance longitudinal (T-1) relaxation measurements and multi-block chemometric methods. The potential of using simultaneously liquid (T-1L) and solid phase (T-1S) signals of fifty samples of margarine, butter and concentrated fat by Sequential and Orthogonalized Partial Least Squares (SO-PLS) and Sequential and Orthogonalized Selective Covariance Selection (SO-CovSel) methods was investigated. The two signals (T-1L and T-1S) were also used separately with PLS and CovSel regressions. The models were compared in term of prediction errors (RMSEP) and repeatability error (sigma(rep)). The results obtained from liquid phase (RMSEP approximate to 1.33% and sigma(rep)approximate to 0.73%) are better than those obtained with solid phase (RMSEP approximate to 5.27% and sigma(rep) approximate to 0.69%). Multiblock methodologies present better performance (RMSEP approximate to 1.00% and sigma(rep) approximate to 0.47%) and illustrate their power in the quantitative analysis of butter products. Moreover, SO-Covsel results allow for proposing a measurement protocol based on a limited number of NMR acquisitions, which opens a new way to quantify fat content in butter products with reduced analysis times

Untargeted analysis of TD-NMR signals using a multivariate curve resolution approach: application to the water-imbibition kinetics of Arabidopsis seeds

International audienceThe aim of this study is to investigate the ability of Time-Domain Nuclear Magnetic Resonance (TD-NMR) combined with Multivariate Curve Resolution Alternating Least Squares (MCR-ALS) analysis to detect changes in hydration properties of nineteen genotypes of Arabidopsis seeds during the imbibition process.The Hybrid hard and Soft modelling version of MCR-ALS (HS-MCR) applied to raw TD-NMR data allowed the introduction of kinetic models to elucidate underlying biological mechanisms. The imbibition process of all investigated hydrated Arabidopsis seeds could be described with a kinetic model based on two consecutive first-order reactions related to an initial water absorption around the seed and a posteriori hydration of the internal seed tissues, respectively. Good data fit was achieved (LOF %= 0.98 and r2 %=99.9), indicating that the hypothesis of the selected kinetic model was correct. An interpretation of the mucilage characteristics of the studied Arabidopsis seeds was also provided.The presented methodology offers a novel and general strategy to describe in a comprehensive way the kinetic process of plant tissue hydration in a screening objective. This work also proves the potential of the MCR methods to analyse raw TD-NMR signals as alternative to the controversial and time-consuming pre-processing techniques of this kind of data, known to be an ill-conditioned and ill-posed problem