Juiciness of fresh fruit: a time–intensity study

Abstract

The pattern of release of juice into the mouth during consumption of watermelon, ‘Honey Dew’ melon, strawberry, pineapple, and apple was determined by a trained sensory panel using time–intensity (T–I) methodology. Juice was released into the mouth in a symmetrical linear pattern of increasing then decreasing intensity. Plots of intensity against time were most simply characterized by the parameters: maximum intensity (IMAX), duration (DUR), and the area under T–I curve (AUC). Two T–I patterns were associated with fruit that are typically thought to be extremely juicy. Watermelon had the highest IMAX but a short DUR. By comparison apple had a moderate IMAX, but DUR was much longer and eventually resulted in a higher AUC than watermelon. The study highlights that juiciness is a texture attribute that defines many fruit, and that the sensation of juiciness changes in intensity during mastication.

Introduction

For the majority of fruits ‘juiciness’ is a principal texture attribute. Few, if any, foods can match most fruit for the intensity of this attribute. Consumers expect fruit to provide the sensation of juiciness immaterial of whether the product has crisp/hard texture as in an apple, or a soft/melting texture as in a peach. Evidence for consumer's preferences for juicy textures can be found in preference maps constructed for apples (Daillant-Spinnler et al., 1996), kiwifruit (Jaeger et al., in press), and pears (Harker et al., in press). A marked reduction in juiciness is often associated with texture disorders that develop in pipfruit, stonefruit, and citrus (Harker et al., 1997a). Despite the importance of juiciness, the majority of studies have tended to focus on texture attributes that relate to mechanical and mouthfeel characteristics of fruit tissue (note that sensory texture is usually separated into mechanical, geometrical, and other—mainly moisture and fat content—characteristics by Szczesniak (1963)). Mechanical aspects of fruit texture, both sensory and instrumental, have become an important focus through the fruit industries' need to understand consumer responses to a biological product that rapidly softens during ripening (Harker et al., 1997a). While many studies have measured juiciness of fruit using trained panels (e.g. Paoletti et al., 1993, Harker et al., 1997b, Barreiro et al., 1998), there has been no previous attempt to quantify the temporal release of juice from fruit tissue during chewing using T–I methodologies.