This research aimed to assess how the partial removal of carbon dioxide affects fermentations to provide a better understanding of how the manipulation of carbon dioxide concentration can be used to optimize industrial fermentations. To achieve this, fermentation kinetics, fermentation metabolic products, and yeast stress indicators were analyzed throughout ongoing brewing fermentations conducted under partial vacuum with atmospheric pressure controls. The partial vacuum reduced the solubility of carbon dioxide in the media and decreased the time necessary to reach carbon dioxide saturation. The effect was an increased rate of fermentation, and significantly more viable cells produced under vacuum pressure compared to controls. Ethanol, glycerol, and volatile organic compound concentrations were all significantly increased under partial vacuum while indicators of yeast stress (trehalose) were reduced Additionally, as the number of yeast cells were higher under partial vacuum, less sugar was consumed per volume of yeast cell. This study measured fermentation kinetics, metabolic products, and yeast health to holistically assess the effect of partial vacuum during a batch fermentation and found significant differences in each that can be individually exploited by researchers and industry. Summary An exploration of batch yeast fermentation in a low-pressure environment, with a focus on the health and productivity of the yeast cells.

Sour beers have been traditionally brewed with spontaneous fermentation. This has been occurring in Belgium for hundreds of years, and more recently in the United States as the American craft beer industry has boomed. Belgian sour styles include lambics, which are mirrored in a burgeoning style called the American coolship ale (ACA). American beers have much more creative leeway than their Belgian counterparts, as American craft brewing tends to incorporate more contemporary techniques and ingredients than their traditional European forebears. This review paper will summarize the history, production methods, fermentation, microbiological profiles, and sensory profiles of Belgian lambics and American coolship ales.

Alternatives to oils with high saturated fatty acid content are often liquid oils (high in unsaturated fatty acids) that have a modified structure created either through additives or processing. Emulsifiers are additives that can be used as structuring agents of liquid fats; this process results in products such as oleogels, which can broaden the applications of these oils. This study assessed and compared the effects of mono- and diglycerides at 3%, 5%, 7% and 10% w/w on the mechanical and thermal properties of high-oleic palm oil (HOPO) oleogels. HOPO was heated to 75 °C and mixed with mono- or diglycerides at those four concentrations. The thermomechanical properties of the melted oleogels were assessed using differential scanning calorimetry (DSC). The melted oleogels were cooled to final temperatures of 5 °C, 10 °C and 15 °C under identical cooling rates, after which a puncture test (via a texture analyzer) was used to assess their textures. Finally, polarized light microscopy was used to assess the mechanical changes induced through emulsifier addition. The results showed that the use of mono- and diglycerides significantly modified the thermal and mechanical properties of the oleogels. The addition of saturated monoglycerides promoted a higher-temperature nucleation stage that did not previously occur in HOPO. The onset crystallization temperature increased with the addition of diglycerides, promoting crystallization at higher temperatures of the high-melting fraction of HOPO. The hardness of the oleogel generally increased with emulsifier addition and a reduction of the temperature. The effect of the temperature on the hardness was significantly greater in the diglyceride oleogel than in the monoglyceride oleogel. This study shows that the addition of mono- and diglycerides allows companies to customize their formulations to achieve desired results that may not previously have been possible, thereby facilitating novel uses for these oils within the industry.

Oils naturally high in saturated fatty acids (mono- and polyunsaturated), are often liquid at room temperature. Emulsifiers have been used to create solid oil matrices, or oleogels, at room temperature to broaden the applications for these oils. This study assessed and compared the effects of mono- and diglycerides on the mechanical and thermal properties of high-oleic palm oil (HOPO) oleogels. HOPO was mixed with emulsifier in eight concentrations (3%, 5%, 7% and 10% w/w), four each for mono- and diglycerides respectively. Thermomechanical properties were assessed by differential scanning calorimetry (DSC), using a temperature regime with a cooling rate of 10˚C/min to -60˚C and a heating rate of 10˚C/min to 80˚C. The oils and emulsifiers were melted at 80°C and then placed in a series of cooling water baths designed to create identical cooling rates for multiple crystallization temperatures. A puncture test using a texture analyzer was used to assess texture of the resulting oleogels. The results showed that the use of mono- and diglycerides significantly changed the thermal and mechanical properties of HOPO. The addition of saturated monoglycerides promoted an early (high temperature) nucleation stage that did not previously occur in HOPO. The onset crystallization temperature increased with the addition of diglycerides, promoting early crystallization of the high melting fraction of HOPO. The hardness of the oleogel increased with the addition of emulsifier. The effect of temperature on hardness was significantly greater in the diglyceride oleogel than in the monoglyceride oleogel. This study shows that the addition of emulsifiers to create stable oleogels increases the industrial usefulness of HOPO. This work also creates the possibility of further study and characterization of HOPO oleogels, especially concerning crystalline structures.