Emulsion gels: The structuring of soft solids with protein-stabilized oil droplets

Oral Biofilms: Pathogens, Matrix, and Polymicrobial Interactions in Microenvironments.

As a major etiological agent of human dental caries, Streptococcus mutans resides primarily in biofilms that form on the tooth surfaces, also known as dental plaque. In addition to caries, S. mutans is responsible for cases of infective endocarditis with a subset of strains being indirectly implicated with the onset of additional extraoral pathologies. During the past 4 decades, functional studies of S. mutans have focused on understanding the molecular mechanisms the organism employs to form robust biofilms on tooth surfaces, to rapidly metabolize a wide variety of carbohydrates obtained from the host diet, and to survive numerous (and frequent) environmental challenges encountered in oral biofilms. In these areas of research, S. mutans has served as a model organism for ground-breaking new discoveries that have, at times, challenged long-standing dogmas based on bacterial paradigms such as Escherichia coli and Bacillus subtilis. In addition to sections dedicated to carbohydrate metabolism, biofilm formation, and stress responses, this article discusses newer developments in S. mutans biology research, namely, how S. mutans interspecies and cross-kingdom interactions dictate the development and pathogenic potential of oral biofilms and how next-generation sequencing technologies have led to a much better understanding of the physiology and diversity of S. mutans as a species.

The Biology of Streptococcus mutans

Application of xanthan gum as polysaccharide in tissue engineering: A review.

Effects of drying and grinding in production of fruit and vegetable powders: A review

This article presents a review of drying processes of fruits and vegetables in which vitamin C degradation was considered. Vitamin C is an important and essential nutrient for humans and it can be taken as an index of nutrient quality of processes. Many researchers have reported the effect of different drying methods and the influence of drying conditions on the vitamin C content. In addition, the effect of other parameters related to the sample structure or to pretreatments on the final quality of the dried product is discussed. Vitamin C degradation mechanisms proposed in the literature, models applied to describe its kinetics, and recent advances in drying processes aiming high retention of this nutrient are also provided.

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Retention of Vitamin C in Drying Processes of Fruits and Vegetables—A Review

Biofilms are highly structured microbial communities that are enmeshed in a self-produced extracellular matrix. Within the complex oral microbiome, Streptococcus mutans is a major producer of extracellular polymeric substances including exopolysaccharides (EPS), eDNA and lipoteichoic acid (LTA). EPS produced by S. mutans-derived exoenzymes promote local accumulation of microbes on the teeth, while forming a spatially heterogeneous and diffusion-limiting matrix that protects embedded bacteria. The EPS-rich matrix provides mechanical stability/cohesiveness and facilitates the creation of highly acidic microenvironments, which are critical for the pathogenesis of dental caries. In parallel, S. mutans also releases eDNA and LTA, which can contribute with matrix development. eDNA enhances EPS (glucan) synthesis locally, increasing the adhesion of S. mutans to saliva-coated apatitic surfaces and the assembly of highly cohesive biofilms. eDNA and other extracellular substances, acting in concert with EPS, may impact the functional properties of the matrix and the virulence of cariogenic biofilms. Enhanced understanding about the assembly principles of the matrix may lead to efficacious approaches to control biofilm-related diseases.

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Streptococcus mutans-derived extracellular matrix in cariogenic oral biofilms.

The kinetics of L-ascorbic acid degradation during drying of pineapple in normal and modified atmosphere was studied. Drying experiments were carried out in a tunnel dryer at two drying temperatures and air velocities. The drying atmosphere was modified by the addition of ethanol (0.5% v/v). The presence of ethanol in the drying atmosphere promoted a more intense water evaporation compared to the conventional process. Although the L-ascorbic acid degradation rate during the pineapple drying (final moisture content of 27% wet basis) under ethanolic atmosphere was higher, these samples retained higher amounts of L-ascorbic acid. Moreover, the Weibull model was applied to fit the kinetics data.

Kinetics of L-Ascorbic Acid Degradation in Pineapple Drying under Ethanolic Atmosphere

Mechanically modified xanthan gum: Rheology and polydispersity aspects.

Brownian dynamics simulations are used to study the formation process of colloidal gels and the effect of particle concentration on their rheological properties. To model the interaction between particles, we adopted an R-shifted 12-6 Lennard-Jones (LJ) potential, which allows independent control of the particle size and attractive range. For a short-ranged potential, the percolated network characteristic of a gel exhibited a viscoelastic behavior of weak gels. The storage modulus (G') increased with the particle concentration increase. Moreover, the dependency of storage modulus (G') on the particle concentration followed a power law function, which is commonly reported in the literature for experimental data. Simulating frequency sweep tests showed that the system behaved as a liquid-like or solid-like material, depending on the frequency applied. The crossover frequency, i.e., the frequency at which G' and G'' are equal, appears to shift slightly to lower values when the particle concentration increases, suggesting a more solid-like behavior for systems with higher particle concentration. During gelation, the storage modulus increases as a stretched exponential and reaches a constant value at long times.

P. H. S. Santos

Papers

Retention of Vitamin C in Drying Processes of Fruits and Vegetables—A Review

Streptococcus mutans-derived extracellular matrix in cariogenic oral biofilms.

Kinetics of L-Ascorbic Acid Degradation in Pineapple Drying under Ethanolic Atmosphere

Mechanically modified xanthan gum: Rheology and polydispersity aspects.

Brownian dynamics study of gel-forming colloidal particles.