Food Texture Measurements With the Penetration Method

Following the work of Bourne, penetration measurements were performed with two sets of punches. The first set had a constant area and various perimeters. The second set had a constant perimeter and various areas. At constant perimeter, the relationship between punch area and force was a straight line with process cheese, butter and margarine, the latter two going through the origin. At constant area, the relationship between punch perimeter and force was a straight line for process cheese, but no definite relation between punch perimeter and force was obtained with butter and margarine. The relationship between the nature of the curves and the physical structure of the food is discussed. It was concluded that penetration tests of cellular products such as fruits studied by Bourne may involve shear and compression factors. In products with strongly bound network structures, e.g. process cheese, the main factors are shear and flow. In products with weakly bound network structures, such as plastic fats, flow is the only major factor involved.