RHEOLOGICAL INDICES OF FRUIT CONTENT IN JAMS: INFLUENCE OF FORMULATION ON TIME‐DEPENDENT FLOW OF SHEARED STRAWBERRY AND PEACH JAMS

ABSTRACT The influence of formulation factors [fruit content (25–55%), soluble solids content (60–70° Brix) and added pectin (0.3–0.7% in strawberry jams and 0.1–0.5% in peach jams)] on time dependent parameters has been analyzed in previously sheared jams. Twenty three samples of each fruit jam were prepared according to a second order composite rotatable design. Weltmann A values depended mainly on fruit content and on its interaction with the other two composition factors for both fruit jams. Weltmann B values, depended on the three variables and on fruit‐pectin interaction for strawberry jams, while for peach jams B values depended also on fruit‐soluble solids interaction. Predictive power of time dependent parameters for estimation of fruit content was low, but considering them in conjunction with soluble solids content and total pectin values explained 91.7% of the variability of fruit content in strawberry jams and 83.7% of same in peach jams.