Microbial stability

The most important methods commonly used in produce preservation are low temperature, aw reduction, low acidity, and preservatives (e.g. organic acids and sulfite). The microbial stability and the sensory quality of most foods are based on passing over a combination of hurdles. 

The relationship between Tg and microbial stability is the least studied of all the stability areas. Based mainly on mold germination data, Slade and Levine (1991) postulated that glass transition parameters, specifically Tm/Ts ratio, T g and W g (related to C defined previously in Figure 32), could be useful for predicting the microbial stability of concentrated and... 

Chirife, J. and Buera, M.P. 1994. Water activity, glass transition and microbial stability in concentrated and semimoist food systems. J. Food Sci. 59, 921-927. 

Microbial resistance problem, 78 265-266 Microbial stability, of liquid enzyme formulations, 70 269-270 Microbial transformations, 76 395-419. 

Drying is a widely used method of fruit and vegetable preservation. Water is removed to a final concentration, which assures microbial stability of the product and minimizes chemical and physical changes (Lewicki and Jakubezyk, 2004). Nowadays, drying is regarded not only as a preservation process, but also as a method for increasing added value of foods (Ramos... 

Microbial stability is one of the factors affecting drug product reliability. Under design and interpretation of stability studies, the Center for Drugs and Biologies... 

Foods high in sucrose, protein, or starch tend to bind water less firmly and must be dried to a low moisture content to obtain microbial stability. 

More impi manl than moisture content, per se. is the objective of creating a preserved food substance lhai is stable and can he eaten directly. An idealized IMF system will have ilia microbial stability at reduced water activity. 17) storage siabiliiy without special conditions. l3i reduction of weight and more compactness of product, and (41 can be consumed from the package without rehvtlrulion Some authorities believe that IMF systems represent excellent potential in the development of the snack market... 

Organic acids may exhibit other sensory properties. For example, citric acid possesses sweet-and-sour sensory notes, and succinic acid has a salty-bitter taste. On the other hand, the typical taste and flavor of Emmental cheese can be ascribed to the propionic acid and a few other compounds, such as proline. In fact, taste and flavor result from the combination of different food constituents in definite proportions. Raw meat smells much like lactic acid, which arises from postmortem anaerobic glucolysis and determines the pH of meat, its final properties, and microbial stability. This same organic acid has been related to the inhibition of certain pathogenic bacteria in yogurt (3). Table 1 lists the reported threshold concentrations for various organic acids in different media (4-6). 

Microbial Stability. Microbial growth is hindered by reducing water activity and adding preservatives. An overview is available (30). Reduction in water activity is typically obtained by including approximately 50% of a polyalcohol such as sorbitol or glycerol. Furthermore, 20% of a salt like NaCl has a pronounced growth inhibiting effect. 

The phenomena associated with maturation are extremely important in directing the positive evolution of the wine s quality as well as physicochemical and microbial stability. It was ascertained that wine oxidation enhanced aldehydes formation and the increase of typicality sensory descriptors of Amarone wine. As a consequence, oxidative aging seems to provide the wine with the peculiar typicality which makes Amarone one of the most renowned wines in the world (Fedrizzi et al., 2011 Tosi et al, 2009a). 

While the above description adequately describes the bottling of V. vinifera table wines, the majority of the fruit and berry wines are bottled without membrane filtration. Virtually all of these fruit and berry wines have potassium sorbate added to them to ensure microbial stability. 

Erickson, M. 1997. Chemical and microbial stability of fluid milk in response to packaging and dispensing, hit. J. Dairy Technol. 50, 107-111. 

Selection of an appropriate base for an ointment or cream formulation depends on the type of activity desired (e.g., topical or percutaneous absorption), compatibility with other components, physicochemical and microbial stability of the product, ease of manufacture, pourability and spreadability of the formulation, duration of contact, chances of hypersensitivity reactions, and ease of washing from the site of application. In addition, bases that are used in ophthalmic preparations should be nonirritating and should soften at body temperatures. White petrolatum and liquid petrolatum are generally used in ophthalmic preparations. Table 1 summarizes... 

The chemical structure of stabilizers, above all the presence of proper functional groups or elements, determines primarily the activity in chemical, physical and microbial stabilizing processes [6]. During the last three decades, the chemistry of stabilizers, involving both syntheses and activity mechanisms, have been studied very intensively and most mechanistic phenomena have been explained. 

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