The results provide relevant information on the fermentation properties required of a customised starter for amaranth flour.

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This contribution describes a new and noninvasive method for the determination of density during the primary fermentation of beer. A piezo crystal sensor is fixed at the outer surface of the cylindroconic tank and works as emitter and receiver alternatively. The ultrasonic signal passes the fermenter twice before triggering the time of flight measurement. Principle studies were performed, which point out the applicability of the system. In particular interferences, which occur during beer fermentation, were characterized. A strong sensitivity exists to changing temperature and the concentration of diluted carbon dioxide. In this special application no dependencies on dispersed microorganism or gas bubbles in the media could be observed. A signal filtering system as well as a calibration method were developed. Finally, the measurement system was tested under technical conditions for the on‐line supervision of density during a fermentation process at an industrial plant. The results obtained were in representative agreement with the values of a standard reference method with mean standard deviation of about 0.7° Sacc extract.

To gain further technological knowledge of mashing, pilot scale mashing trials were carried out varying mashing programme (upward /isothermal mashing), milling procedure, grist : liquor ratio, time of mash stands, and grist modification level (well and poorly modified malt). During mashing β-glucan, free amino nitrogen (FAN) and extract contents were analysed as key indicators for cytolysis, proteolysis, and amylolysis, respectively. The malt modification was of major impact for the β-glucan release in contrast to a variation of milling procedure and of grist : liquor ratio. Extended stands lead to increased final values only for poorly modified malt. Similarly, FAN release was predetermined by malt modification while variation of milling and of grist : liquor ratio was not relevant in contrast to stand extension. None of the variations applied influenced extract yield as long as gelatinization temperature was reached. Greatest gains occurred around 57°C. In conclusion, wort quality is critically determined by malt modification. Mashing with well modified malt in combination with short stands should result in a mash of low β-glucan and sufficient FAN level without losing extract yield. However, for poorly modified malt the variation of mashing parameters has an impact on the key indicators in which cytolysis plays the dominating role.

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