Hardness of high fat yog-ice creams was observed to be considerably lower than the low fat control (Figure 4), whilst the addition of 5% inulin to the low fat yog-ice base reduced the overall hardness of the low fat product.
The addition of inulin at 7% and 9% increased the overall hardness. of the products (Figure 4). These observations are consistent with those of Guinard et al.,who demonstrated that ice-cream hardness, as measured instrumentally, was inversely related to fat and. sugar contents.
Any differences in hardness may also be related to changes in freezing points as a result of higher solute concentrations.
The addition of 5% inulin slightly reduced the hardness of yog-ice cream in comparison to the low fat product (Figure 4).
However, this was not observed at higher inulin additions after 10 min tempering. As mentioned before, the melting and softening rate is reduced in relation to increasing inulin concentration.
Indirectly, this effect may be due to the gelling properties of inulin improving the consistency of the mix (Figure 1) together with. the increased water binding, resulting in decreased rates of ice crystallization. Similarly, the increased stickiness observed within inulin enriched samples (Figure 3) can be related to the formation of a viscous gel matrix.