微生物学技术

The final product of spontaneous grape must fermentation (natural fermentation) is the result of the combined action of different yeast species and vine varieties. Both of them contribute, in different ways, to the organoleptic properties of wine (1). At the first fermentation stages, lem ...

The coliform group of indicator organisms includes some members of this family that are capable of fermenting lactose with the production of acid and gas within 48 h at 35�C. The family Enterobacteriaceae are Gram-negative oxigenic and facultatively anoxigenic rods, nonspore forming, t ...

The Formol titration is a simple and rapid method for determination of the quantity of assimilable nitrogen in juice (1). It provides an approximate, but useful, index of must nutritional status. The procedure consists of neutralizing a juice sample with base to a given pH, adding an excess of neutra ...

The conversion of grape juice into wine is a complex fermentation process in which yeasts play a central role. The composition of the yeast flora in the fermenting must vary according to geographic location, climatic conditions, and grape variety (e.g., ref. 1). During the early phase of fermentat ...

Yeast and molds (nonfilament and filament molds) may be found as part of the normal flora of a food product on inadequately sanitized equipment or as airborne contaminants. They can produce toxic metabolites, resistance to freezing environments, and cause off odors and off flavors of foods. Me ...

Carotenoid production or occurrence—including derivatives biosynthesized from precursors—is widespread in nature in both the Prokaryota and Eucaryota superkingdoms and more than 600 different chemical structures are reported (1), most of them as tetraterpenoids (C40). Ma ...

The mesophilic microorganism is ones of the more general and extensively microbiological indicators of food quality, (1) indicating the adequacy of temperature and sanitation control during processing, transport, and storage, and revealing sources of contamination during ma ...

Yeasts are the most significant microorganisms in all conversion steps of the grape/must/wine system. Because of their metabolic activity, yeasts play a central role in the must fermentation process and also in contamination and spoilage of the final products—wines. Consequently, on ...

The growth of microbial cells is often inhibited in environments where the water activity is much reduced. However, some microorganisms have developed various strategies in order to resist the stresses to which they are exposed. The ability to adapt to fluctuations in external osmolarity ...

Microbial proteases play an important role in industrial processes. The proteases of Bacillus spp., Mucor spp., and Aspergillus oryzae account for the bulk of enzyme production and represent aproximately 40% of the total worldwide enzyme sales (1).

Lactic acid fermentation is commonly used for food conservation. The main products of this bacterial process are lactic and acetic acids, which are toxic to many microorganisms, most yeasts included. The low pH achieved by the lactic acid fermentation, together with anaerobiosis, provid ...

Lactic acid bacteria (LAB), mainly Lactobacillus and Lactococcus species, are useful microorganisms in many biotechnological processes in the food and feed industries. Bacteriophage contaminations of this important group of Gram-positive bacteria have been reported since ...

Lactic acid bacteria (LAB) are considered weakly proleolytic when compared with many other groups of bacteria (e.g., Bacillus, Proteus, Pseudomonas). However, most strains of LAB rely on a complex proteolytic system that allow them to liberate essential and growth-stimulatory amino ac ...

Lactic acid bacteria (LAB) comprise a diverse group of Gram-positive, non-spore-forming microorganisms (1). Fermentable carbohydrates are used as energy sources and are degraded to lactate (homofermentatives) or to lactate and additional products such as acetate, ethanol, carb ...

Exopolysaccharides (EPS) are exocellular polysaccharides that can be found either attached to the cell wall in the form of capsules or secreted into the extracellular environment in the form of slime.

Among the probiotic effects attributed to lactic acid bacteria (LAB), the assimilation of cholesterol (1) would be of particular interest for reducing the absorption of dietary cholesterol from the digestive system into the blood. Several studies have indicated that the cholesterol r ...

Freeze-drying is commonly used for the long-term preservation and storage of microorganisms in stock collections as well as for the production of starter cultures for the food industry. The choice of an appropriate suspending medium is of primary importance to increase the survival rate of ...

During the fermentation and ripening of dry fermented sausage, a large number of biological reactions occur in the sausage mince. Proteolysis is considered to be one of the major processes involved in texture and flavor development. Moreover, small peptides and free amino acids, thus origi ...

Lactic acid bacteria (LAB), used for centuries by man to preserve food, produce a wide variety of antagonistic compounds, including lactic acid, hydrogen peroxide, and bacteriocins. Bacteriocins are antimicrobial peptides that are bactericidal toward bacteria taxonomically c ...

Lactobacillus represents a major genus of the lactic acid bacteria that have widespread use in fermented food production. They are also found in the mouth, intestinal tract, and vagina of many animals. They produce bioantagonists compounds such as lactic acid and bacteriocins and hence are u ...