# Effect of Ultrasound on Fermentation of Thick Molasses Worts by Distiller's Yeast
## 3 Results and Discussion
### Wort Analysis
#### 3.2.4 The Influence of Ultrasound Treatment on Ethanol Formation in Molasses Wort
[56] obtained about 150 g/L of ethanol from a word containing 300 g/L during cane molasses fermentation. [PERSON] et al. [70] reported a 93% conversion of starch to ethanol using the Thermosacc Dry strain for the fermentation of wheat starch mashes. [PERSON] et al. [55] fermented two types of beet molasses wort using the Thermosacc Dry strain. They obtained from the word containing initially 125 g/L sugars between 25 and 55 g/L ethanol, and from the word 225 g/L sugars between 50 and 90 g/L ethanol with 120 h of fermentation. [PERSON] and colleagues [60] reported that using a wild-type _S. cerevisiae_ strain, fermented wort containing 50 g/L of sugars at the start was converted to around 19 g/L of ethanol. The 5-10% increase in ethanol yield observed in our tests between the control sample and the sonicated sample with an amplitude of 50% is consistent with the trends described by others. When reviewing the literature, however, it must be emphasised that previous authors estimate the effect of ultrasound differently. This is probably also due to the different processing sequences, ultrasound strengths, media, and strains utilised. [PERSON] et al. [47] report that during 50 h of fermentation of wort containing 250 g/L of sugars by the _S. cerevisiae_ 1048 strain, they observed an increase of up to 30.7% in the yield of ethanol produced under the influence of ultrasound at a frequency of 28 kHz. The authors also observed a significant increase in the activity of enzymes crucial for ethanol production, such as hexokinase, pyruvate kinase and phosphortuckinase, and an increase in the intracellular concentration of calcium ions in the cells treated with ultrasound. An increase in cytoplasmic membrane permeability was also observed. [PERSON] et al. [48] observed an increase in biomass concentration of about 7% and an increase in glutathione concentration of more than 15% when ultrasound was applied to the _Saccharomyces cerevisiae_ SCZ40 strain. [PERSON] et al. [71] observed a similar increase in biomass concentration and cytoplasmic membrane permeability. Still, they did not observe any changes in the yeast's tolerance to ethanol present in the medium. [PERSON] et al. [30] reported an increase in ethanol yield of around 350% when treating the lactose medium (50 g/L lactose) fermented by the strain _Kluyveromyces marxianus_ ATCC 46537 with ultrasounds. [PERSON] and [PERSON] [72], describing their research on the fermentation of newspaper hydrolysate by _5. cerevisiae_ SS328 yeast, reported a 180% increase in ethanol yield under ultrasonic treatment. [PERSON] et al. [PERSON] et al. (2018) observed that sonification reduced the time needed for full fermentation from 6 to 4 days during rice wine fermentation. They also observed an increase in biomass of over 31% and in ethanol of 26.5%. [PERSON] et al. [PERSON] et al. (2018) observed an increase of more than 34% in ethanol yield by _S. cerevisiae_ CICC1048 when fermenting a wort containing 25% dextrose under ultrasonic treatment. What may help explain the mechanism of the effect of sonication on yield is that the authors described that they observed changes in the coding of the alcohol synthetase gene [PERSON] et al. (2018). Also, [PERSON] et al. support this finding by mentioning a 31% increase in ethanol consumption [PERSON] et al. (2018). A literature review also provided us with one report that was sceptical of the effectiveness of ultrasound. [PERSON] et al. [PERSON] et al. (2018) claimed that during their research on the effect of fermentation on yeast metabolism, they observed a negative effect of ultrasound on the assimilation of sugars and ethanol. This report, in comparison with all the aforementioned ones, may suggest that it is crucial to choose the right sequence of ultrasonic treatment to improve fermentation parameters, as too strong ultrasonic treatment can cause lethal changes in the yeast cell population.