PHYSICOCHEMICAL CHARACTERIZATION OF FRUIT AND VEGETABLE FIBER SUSPENSIONS. I: EFFECT OF HOMOGENIZATION

ABSTRACT Different physicochemical properties and the chemical composition of soluble and insoluble fiber were studied. The influence of fiber source (apple, tomato, carrot and potato pulp), concentration and homogenization were investigated. The fiber suspensions respond in different ways to homogenization. This can, for most physicochemical properties investigated, be due to the fundamentally different microstructure. Carrot and potato pulp suspensions were found to consist of large cell clusters and aggregates, respectively, which were degraded to smaller cell clusters when homogenized. Apple and tomato suspensions were found to consist of large, single cells and cell fragments before homogenization. Tomato suspensions were easily degraded by homogenization, affording a high water‐holding capacity. Apple suspensions were only slightly affected by homogenization, but had the highest elasticity. However, no change in the composition of soluble and insoluble fiber was detected in the homogenized fiber suspensions. PRACTICAL APPLICATIONS Processing of dietary fiber before use as an additive in food products can change its physicochemical properties. These changes must be understood in order to predict the changes in the product resulting from the addition of dietary fiber. Processing in the form of pressure homogenization of the fiber suspensions gave rise to smaller particles and an increased elasticity. Furthermore, it was shown that the more aggregated the microstructure of the fiber suspension the lower its water‐holding capacity and elastic modulus. This knowledge represents a great potential for the product development process which can then be less time consuming. Thus more products fortified with dietary fiber can appear on the market, increasing the consumption of dietary fiber.