EVALUATION OF TEST CONDITIONS DURING THE MEASUREMENT OF COFFEE STABILITY OF INSTANT WHOLE MILK POWDER

Coffee provides a harsh environment for the reconstitution of milk pow der with undissolved powder being manifested as undesirable 'floaters' or 'sinkers'. A coffee test method was adapted to explore the behavio ur of a range of industrial samples of coffee stable and coffee unstab le instant whole milk powders, under varying pH, temperature and water hardness. The development and application of a simulation test sugges ts evidence of some stabilizing contribution by the coffee itself. Hig h surface fat coverage, as determined by electron spectroscopy for che mical analysis, and high ionic calcium levels were associated with ins tances of poor coffee stability. The effects of the physicochemical ch aracteristics of the powders on coffee stability appear to predominate when various measures were implemented, such as prior reconstitution of the powder before addition to coffee, increased agitation and use o f surface active agents, which succeeded in reducing coffee sediment.