SENSORY TEXTURE OF COMMERCIAL BISCUITS AS A FUNCTION OF WATER ACTIVITY

Abstract

The variation in sensory texture of four types of commercial biscuits as a function of water activity, using both a trained sensory panel and a consumer panel, was studied. The biscuits were: (a) like toasted bread, aerated and sweet; (b) cracker from whole‐wheat flour; (c) cracker from normal flour; (d) sweet biscuit, vanilla flavored. Texture changes were discriminated better when tested in the mouth than manually. The transition from crisp to noncrisp was gradual and continuous, and could be adequately modeled using Fermi's equation. The sensory perception of crispiness loss depended on how it was measured: for ‘crisp with molars’ the loss occurred at a lower water activity than for ‘noise'. The water activities at which consumers found the crispiness ideal were different for each type of biscuit, showing that the moisture content of a biscuit should be adjusted at particular values for each product to satisfy consumer preferences. The correlation of sensory acceptability versus ‘crispiness with molars’ showed one of the biscuit types to be an outlier, while the rest were well correlated. Differences between biscuits in relation to their textural changes with aw can be explained by differences in their microstructure, degree of starch gelatinization and gluten development.