Multi-response Modelling of the Maillard reaction in a model cheese

International audienceProcessed cheese derives from a secondary milk processing step that involves mixing and heating dairy (cheese, butter and milk powders) and non-dairy products (emulsifiers). This processing yields a homogeneous product, usually spreadable, with a shelf-life often longer than 6 months. During cheese processing and storage, lipid oxidation, caramelization and Maillard reactions occur and produce odour-active compounds. In this study, a methodological approach was used in order to (i) identify odorants responsible for flavor attributes or compouds involved in the reaction chain, (ii) monitor the evolution of these markers during the heat treatment applied to the matrix, (iii) establish an observable reaction scheme and (iv) model and predict the evolution of these compounds during thermal operations. In this aim, a model cheese and a cooking cell were elaborated. Various couplings of gas chromatography with olfactometry were used to identify odorous compounds. Two-dimensional comprehensive chromatography allowed a semi-quantitation of trace and ultra-trace compounds, while precursors were quantitated by high performance liquid chromatography. An observable reaction scheme of the Maillard reaction was extracted from these data and makes the multi-response modeling step possible despite a partial quantitation of the volatile compounds. Finally, we obtained a formal model combining 19 components (including four odorants) connected by 14 stoechiometric balanced reactions. This model makes it possible to predict the evolution of these components depending on the initial content of lactose, galactose and according to the heat treatment applied to the cheese matrix. This work was carried out with the financial support of the ANR-Agence Nationale de la Recherche-The French National Research Agency under the Programme National de Recherche en Alimentation et nutrition humaine , project ANR-06-PNRA-023REACTIAL "Prediction and control of the appearance or disappearance of reactional markers during food process and conservation "

Modelling the Maillard reaction during the cooking of a model cheese

During processing and storage of industrial processed cheese, odorous compounds are formed. Some of them are potentially unwanted for the flavour of the product. To reduce the appearance of these compounds, a methodological approach was employed. It consists of: (i) the identification of the key compounds or precursors responsible for the off-flavour observed, (ii) the monitoring of these markers during the heat treatments applied to the cheese medium, (iii) the establishment of an observable reaction scheme adapted from a literature survey to the compounds identified in the heated cheese medium (iv) the multi-responses stoichiokinetic modelling of these reaction markers. Systematic two-dimensional gas chromatography time-of-flight mass spectrometry was used for the semi-quantitation of trace compounds. Precursors were quantitated by high-performance liquid chromatography. The experimental data obtained were fitted to the model with 14 elementary linked reactions forming a multi-response observable reaction scheme

6.5. La traçabilité des aliments : enjeux, définition, rôle

Fig. 1 – Traçabilité dans la chaîne agroalimentaire. Schéma montrant la traçabilité (matérialisée par le flux d’informations) tout au long de la chaîne agroalimentaire. Les informations choisies pour tracer un produit doivent accompagner le flux physique de marchandises tout au long de la filière agroalimentaire, depuis la production (et même depuis les fournitures nécessaires pour produire) jusqu’à la distribution au consommateur. À certaines étapes (transformation-conditionnement par exempl..

Mesure des nuisances olfactives associées à l'élevage porcin

National audienceThis paper summarises the contribution of the "Porcherie verte" programme in the development of methods that measure olfactory nuisance. Indeed, for the public, olfactory nuisance is associated with pig breeding and is a limiting factor to its development. Two approaches, one sensorial and the other instrumental, were used conjointly. The sensorial approach was aimed at developing a method for appreciating piggery. odours that is at a different location (the jury does not have to be on the site), less difficult than the official method using diluted air samples and that considers the quality of the odours. Petri dishes containing lipid phases were exposed to the air in piggeries and were then submitted to olfactory approval by a jury of 10 people from the laboratory. The notes of the jury were is well correlated with the in situ olfactory appreciation of the person having taken the samples. The breeding situations are classified in the following decreasing order of intensity: post-weaning and fattening on wood slats > gestation on wood slats > litter. In order to correct for the inconvenience associated with the subjective character of sensorial analysis, in instrumental approach was used to develop a sampling method (solid phase micro extraction) and analysis of volatile components entrapped in the solid phase (mass spectrometry). The spectra obtained allow the differentiation of the breeding situations as explained above and satisfactorily predict (R(2)=0.92) the results of the olfactory appreciation of a jury from the laboratory. The methodological improvements made within the framework of this study show that it is possible to measure and characterise odours from piggeries in a very simple and rapid way. However, these methods have only been tested on relatively concentrated air inside piggeries. Their validity for outside air remains to be shown.Cet article résume les apports du programme « Porcherie verte » dans le développement de méthodes de mesure des nuisances olfactives qui, dans l’esprit du public, sont fortement associées à l’élevage porcin et constituent un facteur limitant essentiel à son développement. Deux approches, l’une sensorielle, l’autre instrumentale, ont été utilisées conjointement. L’approche sensorielle visait à mettre au point une méthode d’appréciation des odeurs de porcherie qui soit délocalisée (le jury n’a pas besoin de se déplacer sur les lieux), moins lourde que la méthode officielle par dilution d’échantillons d’atmosphères et qui prenne en compte la dimension qualitative des odeurs. Des boîtes de Petri remplies de phase lipidique ont été exposées à l’atmosphère ambiante de porcheries et soumises à une appréciation olfactive par un jury de 10 personnes en laboratoire. Les notations du jury sont bien corrélées à l’appréciation olfactive in situ par la personne ayant réalisé les prélèvements et discriminent bien les situations d’élevage dans l’ordre décroissant d’intensité d’odeurs suivant : post-sevrage et engraissement sur caillebotis > maternité sur caillebotis > litières. Pour pallier les inconvénients liés au caractère subjectif de l’appréciation sensorielle, l’approche instrumentale visait à mettre au point une méthode de prélèvement (Micro Extraction en Phase Solide) et d’analyse des composés volatils piégés sur la phase solide (Spectrométrie de Masse). Les signatures spectrales obtenues permettent de différencier les situations d’élevage comme exposé précédemment et de prédire de façon satisfaisante (R2 = 0,92) les résultats de l’appréciation olfactive par le jury de laboratoire. Les avancées méthodologiques obtenues dans le cadre de ce travail semblent ouvrir la voie à la possibilité de mesurer et caractériser les odeurs de porcherie de façon simple et rapide. Ces méthodes n’ont cependant été testées que pour des atmosphères relativement concentrées à l’intérieur des porcheries. Leur validité pour caractériser des atmosphères extérieures reste à établir

Traceability of animal feeding diet in the meat and milk of small ruminants

International audienc

Traçabilité de l'alimentation à base d'herbe dans la viande et le lait des petits ruminants

International audienc

Mise en place de nouvelles méthodes de caractérisation des atmosphères de porcherie

National audienc

Effect of nitrite on the odourant volatile fraction of cooked ham

International audienceThe aim of this work was to reliably identify the key odour compounds in cooked ham and acquire new knowledge on the role of sodium nitrite on the formation of its aroma. Gas chromatography coupled with mass spectrometry and (or) olfactometry was used. In all, 24 odourants were identified in the volatile fraction of cooked ham. Their main origins are discussed. Orthonasal sniffing of the hams was used to study how these substances contributed to the overall aroma of the product. The aroma of cooked ham is a balance between that of certain sulfur compounds produced during cooking and that of oxidation compounds commonly found in cooked meats. In the absence of nitrite, this balance is disturbed by extensive formation of oxidation compounds that mask the meaty notes induced by the sulfur compounds. (C) 2013 Elsevier Ltd. All rights reserved