SummaryBackground Skin dryness and an accelerated fragmentation of the collagen network in the dermis are hallmarks of skin aging. Nutrition is a key factor influencing skin health and consequently its appearance. A wide range of dietary supplements is offered to improve skin health. Collagen peptides are used as a bioactive ingredient in nutricosmetic products and have been shown in preclinical studies to improve skin barrier function, to induce the synthesis of collagen and hyaluronic acid, and to promote fibroblast growth and migration. Our aim was to investigate the effect of oral supplementation with specific collagen peptides on skin hydration and the dermal collagen network in a clinical setting. Methods Two placebo-controlled clinical trials were run to assess the effect of a daily oral supplementation with collagen peptides on skin hydration by corneometry, on collagen density by high-resolution ultrasound and on collagen fragmentation by reflectance confocal microscopy. Human skin explants were used to study extracellular matrix components in the presence of collagen peptides ex vivo. Results Oral collagen peptide supplementation significantly increased skin hydration after 8 weeks of intake. The collagen density in the dermis significantly increased and the fragmentation of the dermal collagen network significantly decreased already after 4 weeks of supplementation. Both effects persisted after 12 weeks. Ex vivo experiments demonstrated that collagen peptides induce collagen as well as glycosaminoglycan production, offering a mechanistic explanation for the observed clinical effects. Conclusion The oral supplementation with collagen peptides is efficacious to improve hallmarks of skin aging.
Viable hybridoma cells were encapsulated. The capsules were formed in one step by placing a drop of cell suspension mixed with negatively charged carboxymethylcellulose (CMC) into a positively charged chitosan solution through the interpolymeric ionic interaction between two oppositely charged polymers. These capsules were found to have a mean diameter of about 1. 5 mm and wall thickness of 3 microm. The cells grew in the capsules using supplemented DMEM/F12 (four kinds of growth factor). The maximum cell density in encapsulating cell culture reached 1 x 10(7) cells/ml, 10 times higher than that obtained in the free cell culture. The maximum monoclonal antibody concentration in the free cell culture was 15 microg/mL, but that in the capsule was 45 microg/mL The antibody produced by the cell was concentrated about four times higher inside than outside of the capsules.
Heat-induced gelation of milk was studied using both rheological and structural techniques. The sample was a conventional skim milk, concentrated with an ultrafiltration membrane, which formed gels when heated at appropriate pH. We investigated some factors that are considered to affect the gelation, such as concentration, pH and rennet treatment. The gelation process was monitored with a high precision oscillatory shear rheometer and the structure of gels was evaluated with quasi-elastic laser light scattering. From these results the gelation and phase separation behaviour were determined. By combining the results for different concentrations a phase diagram was obtained, which indicated that skim milk had a two-phase region on the higher temperature side. The effects of pH and rennet treatment were also evaluated with the aid of this phase diagram. The results were discussed on the basis of concepts of the phase behaviour of polymers, which were successfully developed in polymer physics.Milk gels such as yogurt and cheese are amongst the most popular food materials. Although there are numerous studies on milk gels and the gelation process, systematic studies are quite few. This is due mainly to the complexity of milk components and their structure, and also because milk gelation is affected by various factors, such as pH, temperature, metal ions and the presence of rennet. However, there have been some attempts to analyse this complex system theoretically since the late 70s as reviewed by Clark & Ross-Murphy (1987). Payens (1976) analysed the rennet-induced gelation of milk by measuring the turbidity. He introduced two models to explain the process; the Michaelis-Menten model for the enzymic reaction step and the von Smoluchowski model for the casein aggregation step. Parker & Dalgleish (1977) adopted another approach to the milk gelation induced by Ca 2+ or heating. They used a classical branching theory, the socalled Flory-Stockmayer theory (Flory, 1953; Gordon & Ross-Murphy, 1975) to estimate the functionality of casein. Tokita et al. (1984) introduced the three dimensional lattice percolation theory to explain the rheological results of enzymeinduced gelation of casein, and a computer simulation based on this theory was performed by Steventon et al. (1991) for whey protein gels. The percolation theory, which also includes the Flory-Stockmayer theory as a particular case, has been
Flow properties of creams containing milk fat (Cream A), vegetable fat (Cream C), and vegetable fat plus milk fat (Cream B) were determined with a coaxial cylinder viscometer for a wide range of shear rates. All creams examined showed time thickening. The viscosity increase with shearing time was expressed by two stage equations as follows: where ηo and ηt are cream viscosity at zero and t shearing time, K1 and K2 are rate constants and C1 and C2 are constants. The first stage (Eq. 1) was assumed to occur in the course of primary clustering of the independent fat globules, and the second stage (Eq. 2) was assumed to occur in the course of coagulation of the fat globule clusters. Both K1 and K2 increased as shear rate increased. At the same time, the whippability of each cream was determined with a household mixer to which was attached a strain gauge transducer unit for measuring consistency of the whipped creams. There was a tendency for a higher ratio of milk fat/vegetable fat in the creams to decrease the whipping time or to increase whippability of the creams. Correlations of stability, whippability, and flow properties were examined. A cream which was high stability showed a low K1 value, and a cream which has high whippability showed a high K2 value. K1 and K2 values at a suitable shear rate will be quite helpful in the determination of the physical properties of cream.
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