Cone penetrometry

The cone penetrometer was first developed for measuring the firmness or yield point of solid fats such as butter or margarine (Bourne, 1982). Assuming that the cone angle, mass of the cone assembly, temperature, and time for penetration are held constant, results from cone penetrometry can be interpreted based on the depth of penetration (Dixon and Parekh, 1979). Dixon and Parekh (1979) applied a cone penetrometer for measuring the firmness of butter. 

Cone penetrometry has the advantages of being simple and economical to use. Also, its results correlate well with testing by sensory panels (Dixon, 1974 Rousseau and Marangoni, 1999). In addition, standardized tests and commercial standards of design are available. The most widely used method is that of the American Oil Chemists Society (AOCS) (Cc 16-60) (AOCS, 1960). According to this method, the depth (d) (in increments of 0.1 mm) to which the cone penetrates the sample is read (AOCS, 1989). This depth is an indicator of consistency and can be related to some structural parameter of the material. Penetrometry results, for example, are often translated into spreadability or hardness values. For example, spreadability (S), as... 

The AOCS has published a standard method (AOCS Cc 16-60) for constant load cone penetrometry of fats and fat emulsions such as butter (Firestone, 1998). 

Cone penetrometry of paste-like materials can be used to measure the apparent extensional yield stress using the equation... 

During penetration of the cone assembly, the cone sinks into the fat sample until the stress exerted by the increasing contact surface of the cone is balanced by the hardness of the fat (deMan, 1983). In the process, the crystal aggregate network is partially and irreversibly destroyed (Lefebvre, 1983). Cone penetrometry is a large-deformation rheological method. 

Table 10 Cone Penetrometry Penetrating Cone Assembly Characteristics Used for Determining the Hardness Index of Lard-Canola Oil Blends and Palm Oil-Soybean Oil Blends... 

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