Fermentation, alcoholic temperature effects

Fayolle et al.12 described work done on alcoholic fermentation, wherein they studied the effects of temperature and various calibration methods. The samples were removed and submitted for HPLC and other conventional analyses. The samples were used as is for MIR spectra generation. PLS-1 was used for equation constmction. The test RSDs for glucose, fructose, glycerol, and ethanol were, respectively, 12.5,6.1, 0.6, and 2.9 g/1. The wavelengths assigned to various components were also listed. 

The temperature and pH level of alcohol fermentation are reported as having a limited effect on fumonisin content (Bothast et ah, 1992 Hlywka and Bullerman, 1999). 

Suppose we are interested in investigating the effect of fermentation temperature on the percent alcohol response of the wine-making system shown in Figure 1.6. We will assume that ambient pressure has very little effect on the system and that the small variations in response caused by this uncontrolled factor can be included in the residuals. Further, we can use the same type and quantity of yeast in all of our experiments so there will be no (or very little) variation in our results caused by the factor yeast . 

Having determined the effect of temperature and NaCl on koji autolysis, the next step in finding an optimal protocol for the rapid production of soy sauce with high flavor quality was to examine die effect of independent and combined effect of lactic acid fermentation and alcohol on koji autolysis. 

To show correlation between occurrence of malo-lactic fermentation and bacterial inoculation, and to show consistency of results among the control lots and inoculated lots, it is imperative that the division of lots be made before alcoholic fermentation. For red wines, great care must be taken to obtain equitable distribution of the crushed grapes in each of the lots. The inconsistency in the results mentioned above may have been caused by variation in amounts of grape skins during the alcoholic fermentation with the accompanying effect on fermentation temperature, sulfur dioxide concentration,. pH after pressing, and concentration of nutrients (55, 56). 

Let us carry out a so-called screening experiment in which we attempt to discover if the fermentation temperature (factor x ) has a significant effect on the response (% alcohol content). We will choose two levels of temperature, 23°C and 27°C. This is the minimal number of factor levels required to fit the two-parameter model... 

In the fermentations under the cellar conditions, higher ethanol concentrations were reached compared with those under the vinsantaia temperature conditions. This could be due to the combined stress effects on the yeasts of alcohol and high temperatures during the summer period in the vinsantaia aging. In the Vin Santo obtained without inoculation with the commercial starter, satisfactory ethanol levels were however reached (13.7-15.3%, v/v). 

Solvent extraction has long been established as a basic unit operation for chemical separations. Chapter 7 summarizes the effects of temperature, pH, ion pairs, and solvent selection on solvent extraction for biomolecules. Solvent extraction of fermentation products such as alcohols, aliphatic carboxylic acids, amino acids, and antibiotics are discussed. Enhanced solvent extraction using reversed micelles and electrical fields are also discussed. Solvent-extraction equipment and operational considerations are adequately covered in this chapter. 

Nevertheless, the proposed protocols do not simulate flavonoid extraction during the maceration and fermentation process, as they do not reproduce the effect of gradual alcohol accumulation, temperature increase and duration of the maceration phase. 

Nano/microporous cellulose (NMC) prepared after removal of lignin from wood cellulose was found suitable for the development of cold pasteurization" processes acting as a biofilter for cell removal. It was also used successfully as biocatalyst in food fermentations acting as both cell immobilization carrier and as promoter of biochemical reactions, even at extremely low temperatures. The cumulative surface area of the NMC pores was found to be 0.8 to 0.89 m g" as indicated by porosimetry analysis. This surface is relatively small compared with other porous materials such as y-alumina however, using a natural organic material is attractive from the point of view that it is safer for bioprocess applications and is better accepted by consumers. The NMC/immobilized yeast biocatalyst increased the fermentation rate and was more effective at lower temperatures compared with free cells. Furthermore, the activation energy E, of fermentation was found to be 28% lower than that of free cells, indicating that it is an excellent material to promote the catalytic action of cells for alcoholic fermentation. 

Low fermentation temperatures (10-15 0,) reportedly extends the alcohol tolerance range of C. stellata (Gao and Fleet, 1988). However, in aging wine, the interactive effects of alcohol and low (<15°C/60°F) cellar temperature retards growth. This observation is not unique to Candidahul is characteristic of film yeast in general. 

Lethal effects of a high fermentation temperature are often thought to result from the effect of temperature alone. However, inhibition is also the result of intracellular accumulations of ethanol. Temperature tolerance of yeast varies with species and strain and reflects intrinsic and extrinsic properties of the growth medium. Generally, yeast viability in alcoholic media subsides at temperatures near 35°C (95°F). 

Alcoholic fermentation is an exothermic reaction (generating heat), and its kinetics (velocity of the reaction) depends strongly on temperature. Several factors affect the course of fermentation (e.g., pH, alcohol concentration, high salt concentration), but temperamre has the greatest effect. Several research studies have shown that the optimum temperature for S. cerevisiae in alcoholic fermentation is close to 32 °C (Costa et al. 2009). 

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