Effects of sugar, citric acid and pectin content on quality of mulberry fruit leather product

Abstract

The objective of this study was to investigate the optimal formulation of mulberry fruit leather product when varying the weight ratio of mulberry fruit: water as 70:30, 60:40,50:50, 40:60 and 30:70. Three factors were then determined by simplex centroid design; sugar (0-100% or 0-50 grams), citric acid (0-100% or 0-5 grams) and pectin (0-100% or 0-3 grams), which the sum of them equivalent to 100% while other ingredients remained constant. Analysis of the data was performed using ANOVA and Mixture Response Surface Models. The results indicated that the highest adhesiveness force and gumminess of mulberry fruit leather product were founded when the weight ratio of mulberry fruit to water was 70:30. The amount of sugar, acid and pectin had effects on water activity (Aw), texture profile and sensory score of overall liking of product. From contour plot, the predictive models were obtained by plottin g the contour line of all sensory attributes with acceptable score greater than 5.5 and thus the optimization area was selected. After overlapping contour plots, an optimal formulation obtained was composed of 40-70% sugar, 0-5% citric acid and 30-55% pectin. The sensory score of overall liking of product using a 9-point hedonic scale was 6.3. The water activity (Aw),adhesiveness force, cohesiveness and gumminess of the prototype mulberry fruit leather product was 4.9, 945.11 g. sec., 0.85 N and 452.12 N., respectively.