Fermentation processes classification

A Vasilache, B Dahhou, G Roux, and G Goma. Classification of fermentation process models using recurrent neural networks. Int. J. Systems Science, 32(9) 1139-1154, 2001. 

Currently, advanced molecular methods represent an invaluable tool in the study of food ecosystems and the strains responsible of fermentation processes. At the same time, especially in industrial or applied microbiology, phenotypic tests, which were used widely in the past for microbial identification, are still being considered for the characterization of strain metabolic properties, growth performance, resistance to industrial processes, and shelf life. However, due to their poor reproducibility and low discriminatory power, phenotypic methods have been almost abandoned for identification purposes. Their low taxonomic resolution often leads to differentiation only at the genus level, and they require a labor-intensive approach. On the contrary, genotypic techniques provide a more robust classification and identification, and their costs, over the years, have been decreasing. 

Figure 3.31. Systematic, engineering classification of fermentation processes based on the behavior in time of the input stream, Fj, and the exist stream,...

Unit-process classification provides a ready catalogue of the chemical activities and abilities of microorganisms for the biochemist. More important, it offers a logical approach to an examination of fermentation reaction mechanisms. 

A metabolomic approach was also shown as a very useful one in the field of beer characterization, allowing a classification on the basis of different raw materials (malt), beer types, brewing sites, or even production times of the same brewery [47 9]. Beer is obtained from malted grains, hops, and yeast through a fermentation process other components (fruits, herbs, and spices) can then be added to produce a particular blend. Different fermentation processes distinguish the two principal t3 pes, namely ales and lagers, and alcohol-free beers are produced too. 

Conventionally, woody trees were broadly classified as softwood or gymnosperm and hardwood or angiosperm. Hardwood comes from angiosperms, such as oak, eucalyptus, and alder, which are dicots (Octave and Thomas, 2009). Softwood usually comes from evergreen conifer trees like pine or spruce. Other classifications of forest-based plants are broad-leaved trees and pine-leaved trees. Almost 46% of biorefinery prefers raw materials from conifer species, mainly spruce, pine, etc., and 31% of broad-leaves such as eucalyptus. Mostly stem wood is preferred as a suitable feedstock for the biorefinery process. Approximately 8% of the known biorefinery processes utilize all parts of the tree (Fitzpatrick et al., 2010). Thus the consensus in the biorefinery industry is that the feedstock selection should be based on the main constituents of the wood (cellulose, hemicellulose, and lignin) and not on specific chemicals (glucose, xylose, etc.) generally considered in conventional fermentation processes. 

Most systems have more than one response. The wine-making process introduced in Section 1.1 is an example. Percent alcohol and bouquet are two responses, but there are many additional responses associated with this system. Examples are the amount of carbon dioxide evolved, the extent of foaming, the heat produced during fermentation, the turbidity of the new wine, and the concentration of ketones in the final product. Just as factors can be classified into many dichotomous sets, so too can responses. One natural division is into important responses and unimportant responses, although the classification is not always straightforward. 

A bioreactor is a vessel in which biochemical transformation of reactants occurs by the action of biological agents such as organisms or in vitro cellular components such as enzymes. This type of reactor is widely used in food and fermentation industries, in waste treatment, and in many biomedical facilities. There are two broad categories of bioreactors fermentation and enzyme (cell-free) reactors. Depending on the process requirements (aerobic, anaerobic, solid state, immobilized), numerous subdivisions of this classification are possible (Moo-Young, 1986). 

Fermentation and Biochemical Engineering Handbook Table 1. Classification of Mixing Processes... 

The success of an ISPR process does not depend only on the chosen separation technique but also on the configuration of the bioreactor/separation units and mode of operation. Previous reviews have shown the various possible modes of operation (continuous, batch) and the use of a separation unit outside of the reactor or separation techniques that act right inside the fermenter [19,22,31]. Freeman and coworkers introduced a classification scheme for ISPR process based on batch/continuous operation and internal (within the reactor)/external (outside the reactor) removal of the product [3]. 

As mentioned previously (Sect. 3.3) in connection with the rate of heat transport, the reaction enthalpy AH or AH is given in units of [kcal/gX] or [kcal/gS] for practical reasons. Table 5.3 summarizes AH for fermentations (Bronn, 1971). A systematic treatment is possible using classifications of aerobic and anaerobic processing versus substrate the numerical values are independent of the strain of microorganism. 

A biorefinery is the integral upstream, midstream, and downstream processing of biomass into a range of produas. In the classification system lEA Bioenergy Task 42 (described in the next chapter) has differentiated between mechanical pretreatments (extraction, fractionation, separation), thermochemical conversions, chemical conversions, enzymatic conversions, and microbial (fermentation both aerobic, anaerobic) conversions. 

Viticulture and enology have been part of human culture for nearly 8,000 years, when the first wines were made in the ancient Near East (modem Middle East region). The Romans laid down the foundations for grape classification and the aging process of wine. They also pioneered the use of oak fermentation chambers (wooden wine barrels) and cork for bottling. (The earliest extant prose written in Latin is, in feet, a survey on Roman viticulture.) Winemaking... 

Natural thickeners can be defined as products obtained from natural sources such as plants, seeds, seaweeds and microorganisms. These products are high molecular weight polymers composed of polysaccharides and are often referred to as hydrocolloids. Production processes vary from simple collection of tree exudates and milling in the case of gum arabic to more complex production by fermentation as in the case of xanthan gum. A number of these natural thickeners are also derivatised in order to modify their properties. Table 2.1 provides a simple classification of these products by source. Tables 2.2-2.4 provide an overview of the main natural thickening agents and their applications. A brief description of each class of hydro colloids is given below but for more detailed information on each of the hydrocolloids there are a number of publications available [ 1—3]. 

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