Fortify clarified banana juice with inulin and oligofructose.

Inulin and oligofructose are increasingly being used as functional food ingredients in various product formulations because of their lower caloric value. In addition, they are a dietary fiber and offer a variety of other functional properties.

Inulin has excellent nutritional and functional characteristics. Its taste ranges from completely bland to subtly sweet.

Inulin can be used to replace sugar, fat and flour. This is particularly advantageous because inulin contains one-third to one-fourth the food energy of sugar or other carbohydrates, and one-sixth to one-ninth the food energy of fat. Oligofructose is a subgroup of inulin. It is not digested in the small intestine, and thus has a lower calorific value, while contributing to dietary fiber content.

Malaysian scientists conducted a study to determine the optimum amounts of inulin and oligofructose needed to fortify clarified banana juice. Their work indicates that it is possible to incorporate inulin and oligofructose into the juice. However, consumer and market studies are needed to understand the market potential of this product.

In their experiments, the researchers used regression analysis and response surface methodology (RSM) to obtain acceptable juice formulations based on sensory and physical characteristics. Inulin at up to 2% and oligofructose at up to 10% were used as independent variables. The dependent variables included taste, off-flavor, odor, mouthfeel, viscosity, preference and total soluble solids (TSS). Predictive models with R2 values greater than 0.75 were used for contour plots.

The scientists observed low R2 values for off-flavor (0.58) and odor (0.33), which were not good. However, the R2 values for taste, mouthfeel, preference, viscosity and TSS were greater than 0.75. There were significant F values. The models predicted optimum inulin and oligofructose levels.

Coefficient estimates from seven regression models and other tests revealed that oligofructose was more important than inulin in this application, as it had more influence on the sensory and physical characteristics of the juice. Furthermore, taste, mouthfeel and viscosity were more affected by the inulin and oligofructose levels than by other dependent variables.

The contours of constant response values for taste, mouthfeel, preference and viscosity showed the same optimal region at levels of 2% inulin and 10% oligofructose. Fortifying the product using this amount of inulin and oligofructose would yield a clarified banana juice with acceptable sensory and physical characteristics.

Further information. S. Yousaf, Department of Food Technology, University of Putra Malaysia, Faculty of Food Science and Biotechnology, Serdang, Selangor, 43400, Malaysia; phone: [phone]; URL: www.food.upm.edu.my/fstm2005.htm.