Moisture retaining activity

Topical application of compositions comprising sphingolipids, such as ceramides, improves the barrier function and moisture-retaining properties of the skin. Moreover, sphingoid bases exhibit anti-inflammatory and anti-microbial activities, making sphingolipids valuable active ingredients in cosmetic formulations. " ... 

The functional properties are Relative low viscosity of the solutions, high moisture-retaining properties, low moisture activity, which retards microbial growth, mild sweetness, no fermentability by yeast but entire digestibility by intestinal enzymes, physiological energy content 17.2kJ/g. 

The most superficial layer of skin is the stratum comeum (SC), which consists of terminally differentiated keratinocytes (comeocytes) that originate from actively proliferating keratinocytes in lower epidermis (basale, spinosum, and granulosum cells), and contain a lamellar lipid layer secreted from lamellar bodies (Fig. 7a). Flydration of the SC is an important determinant of skin appearance and physical properties, and depends on a number of factors including the external humidity, and its structure, lipid/protein composition, barrier properties, and concentration of water-retaining osmolytes (natural moisturizing factors, NMFs) including free amino acids, ions, and other small solutes. 

Because many aggregates are hydrophilic, difficulty may be experienced in obtaining or retaining a satisfactory asphalt-aggregate bond in the presence of moisture. This difficulty has been overcome in many instances by the use of special surface-active additives (33, 42, 61, 64, 80, 98, 111, 116). Certain of these have attained appreciable commercial significance, notably those of the cationic type. 

SFE manifests its best advantages when extracting analytes from solid and semisolid rather than liquid samples. A primary limitation in extracting analytes from liquid sample matrices is the mechanical difficulty of retaining the liquid matrix in the extraction vessel. To extract a liquid sample by SFE successfully, analysts must first mix it with a solid material, such as diatomaceous earth or alumina, so that the sample is no longer free-flowing. Control of sample matrix effects is critical in SFE to limit coextractives, moderate the influence of moisture, and improve the efficiency of the extraction. Recent studies have shown that the addition of both inert and active sorbents to the sample matrix can improve the efficiency of SFE (153). 

The activity of the silica is an important parameter. When silica is wet by several layers of water, pores are filled and solutes cannot undergo adsorption. As a consequence these are retained only slightly. They can even undergo partition mechanism. Figure 7 demonstrates the dramatic influence of water on retention. Reproducible retention can be achieved by Engelhardt s method (17) One tank is filled with dry solvent and another tank is filled with fully wet solvent. A proportioning valve allows for the exact mixing, and the water content is controlled. A moisture... 

As described earlier, although water (i.e., moisturization) is required to alleviate dry skin, reduced enzymic activity is the cause of the scaling symptoms associated with the condition. These enzymes can be activated for instance with glycerol,31 hydroxyacids,25 or urea,32 but to retain full desquama-tory activity topical application of enzymes is required. As all corneodesmosomal proteins persist in the superficial layers of the SC in dry skin, either the full spectrum of skin desquamatory enzymes are required to maximally induce exfoliation or broad specificities are needed in a single enzyme. 

Of particular interest is recent work by Pitombo et al. [ 181. They studied the effect of moisture content on the invertase activity of freeze-dried S. cerevisiae with respect to monolayer moisture content. Samples with water activity above the monolayer moisture content lost at least 60% of their invertase activity samples with water activity at about the monolayer moisture content retained at least 85% of their original invertase activity. 

In retained heating methods (dry heat), a simple hot air drying reduces the moisture content to 3-4%. The bran must be kept dry in moisture-proof containers, or the rehydrated bran will regain its lipase activity. If the bran is heated in the presence of moisture, the lipase is permanently denatured. 

On the other hand, looking for the origin of the water required for the hydrolysis step, control experiments using dried solvent and different substrate-to-catalyst ratio have shown that both water retained in the zeolite after the usual thermal activation and the solvent and ambient moisture are responsible for the hydrolysis. This undesirable side reaction has a much higher rate constant for the dimethyl than for the ethylene acetal as it is commonly observed for these types of acetals [9]. 

The primary applications for carrageenans in the food industry are in dairy and processed meat products (Ohshima, 1998). Carrageenans can form gels with milk and water and can be used to coat meats to help retain moisture, seasonings, and flavors and to serve as a protective barrier (BeMiller and Whistler, 1996). From a human health perspective, it has been reported that carrageenans have antihuman immunodeficiency virus (HIV)-1 activity and some anticoagulant properties (Vlieghe et al., 2002). 

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