-Relationships between functional properties and variables obtained with a temperaturesweep dynamic shear test of twenty different varieties of cheese were evaluated. Flowability was assessed using a modified Schreiber test and stretchability by a method involving vertical traction. The dynamic shear test provides a typical profile for each cheese variety, a profile that might be related to the different cheese-making processes, and especially to the heating and mechanical treatments influencing further the response of the cheese matrix by itself in conditions of cooking use. Principal component analysis (PCA) gave evidence of complex and non-linear relationships between the characteristics of the dynamic shear profile and the stretchability or meltability indices. A significant, but weak, link between pH and stretchability was observed. PCA separated cheeses by their cheese-making technology. The effects of the technological factors for the different types of cheese varieties on their functional properties suggest the possibility either of predicting these properties or of changing the processes in order to create new products with new functionalities.
Functional property / dynamic shear test / Schreiber test / stretchability test / cheeseRésumé -Relation entre un test de cisaillement dynamique effectué en balayage température et les propriétés fonctionnelles des fromages. Les relations entre les propriétés fonctionnelles et les variables obtenues par un test de cisaillement dynamique effectué en balayage température ont été évaluées. L'étalement à chaud a été évalué à l'aide d'un test de Schreiber modifié et l'aptitude au filant par une méthode utilisant une traction verticale. Le test de cisaillement dynamique donne un profil caractéristique de chaque variété de fromage, profil qui peut être mis en relation avec les différents procédés de fabrication, notamment avec les traitements thermiques et mécaniques imposés lors de la fabrication dont les effets laisseraient une empreinte dans la matrice fromagère elle-même. Une analyse en composantes principales a mis en évidence des relations complexes et non linéaires entre les variables du test de cisaillement dynamique et les indices d'étalement à chaud et de filant. Une corrélation faible mais significative entre le pH et l'aptitude au filant a été observée. L'analyse en composantes principales a séparé les fromages selon leur technologie de fabrication. Les effets des facteurs technologiques des différentes variétés de fromage sur leurs propriétés fonctionnelles laissent entrevoir la possibilité d'envisager soit de prévoir ces propriétés soit d'orienter les procédés pour créer de nouveaux produits avec de nouvelles fonctionnalités.
The effect of three different aroma compounds on the texture of starch dispersions during gelation and retrogradation was studied. Oscillatory measurements were used to follow gelation and to check the structure of the starch dispersions after retrogradation up to 28 days.
Rheological tests did not indicate any effect of the presence of any of the aroma compounds on the mechanism of gelation. During long‐time retrogradation, some added aroma compound did. We assume that this is a consequence of the ability of aroma compounds to form a complex or to show another type of interaction with starch molecules like entrapment in the amorphous regions of starch. Linalool is known to form complexes with amylase, but did not induce texture modifications, probably because, in our experiments, the added amount of this compound was too low. Isoamyl acetate, which according to literature interacts with amylopectin, exhibited a weak effect after 3 or 4 weeks, depending on the amount added. Octanal also increased gel stiffness after 3 weeks. This phenomenon is consistent with the observation that this aroma compound can form complexes with starch as demonstrated by X‐ray diffraction in this study.
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