THE RESEARCH OF LOW-ULTRASONIC ENERGY AFFECTS TO YEAST GROWTH IN FERMENTATION PROCESS

This paper presents a study of low-ultrasonic energy that can be affected to increase yeast growth. Forces of the ultrasonic stimulation in the yeast media broth, a liquid nutrient medium for the culture of yeast, produce change of liquid densities and surrounding pressure, which affect to the yeast growth. A utilized ultrasonic system including transducer of 20 kHz was varied powers and applied into the 200 ml. starter broth including Saccharomyces cerevisiae yeast. Those powers can be adjusted intensities, repetition times and durations to stimulate yeast cell. For monitoring the yeast growth, a cell direct-count with a Hemacytometer and an optical density using a Spectrophotometer were employed every 1 hour. Experiment results were shown enhancements of the yeast growth which were stimulated by the various ultrasonic powers compared with commonly used methods. Consequently, the ultrasonic can be applied to accelerate the yeast growth in fermentation to increase productivity and decrease the fermentation time.