Oral consistency and simple rheological measurement of strawberry jams

Six series of strawberry jam samples at different Brix values, with different types of pectins or different sugars were prepared and analyzed. Rheological tests were carried out and the obtained flow curves were modelized with the Herschel-Bulkley model. Apparent viscosity was calculated at 5 different shear rate values. At the same time, the samples were evaluated by a panel of a 18 selected and trained subjects. They were asked to rate the oral consistency using an unstructured scale. The effect of the characteristics of the pectin on the consistency of the jam was observed. Our results show that, for a same pectin concentration, viscosity and oral consistency decrease with Brix value, with demethylation and with molecular weight. Relationships between sensory and rheological data were studied. It was shown that the logarithm of apparent viscosity for a shear rate of 50 s-1 is significantly correlated with the oral consistency. This result shows that an easy and quick rheological measurement can give a precise information of the oral consistency of the product.Six séries d'échantillons de confitures de fraises préparées à différents degrés Brix, avec différents types de pectine ou différents sucres ont été étudiées. Des tests rhéologiques ont été réalisés. La viscosité apparente (η) a été calculée pour cinq vitesses de cisaillement (τ). Parallèlement, des analyses sensorielles ont été réalisées. L'influence des caractéristiques de la pectine sur la consistance des échantillons a été examinée