ASSESSMENT OF HARDNESS AND SPREADABILITY OF BUTTER - A CRITICAL LITERATURE SURVEY

Spreadability is the most important physical property of butter. In ma ny countries it is officially tested at regular intervals and used as a main criterion for awarding a quality mark (e.g. ''Deutsche Markenbu tter''). Because sensory evaluations require much effort and are also often lacking reliability frequently the simplest possible physical me asurements are preferred for rapid objective assessment of spreadabili ty, e.g., distance and force penetrometer methods, extrusion or the cu tting wire method. Based upon the literature published in the last dec ades it is shown that, in particular, quasi-static hardness parameters obtained using the yield stress are closely correlated with the senso rially assessed spreadability. The same is true for the flow parameter s (e.g., the apparent viscosity) although not always to the same high degree. Extrusion techniques seem to reflect, however, spreadability l ess well. One reason may be the apparently lower precision of the meth od. Data relating to precision obtained in collaborative tests under c onditions of repeatability and reproducibility are so far only availab le for the cutting wire method. Considering the individual studies pub lished it can, however, be expected that repeatability of the cutting wire method is better compared with penetrometer measurements (cone (d istance, force) and disc penetrometer). Nevertheless, the latter metho ds are often preferred because sample preparation is simpler and the m easurements can be more rapidly performed.