Prospection of the use of encapsulation in food packaging

Food safety and extended shelf life linked to convenience were the major reasons for the development of the packaging field. However, advances in material science and the widespread encapsulation technologies are allowing the establishment of new concepts for packages, such as intelligent and active packages. Particulate systems have been developed in recent years for the most diverse area with several purposes that can be employed to improve packaging performance mainly focusing on the modification of barrier properties. This review analyzes the recent developments using encapsulation in food packaging and the main concepts about mass transfer evolved in the functionality of these packages, as well as discusses the research challenges faced by the food packaging sector.     

Basic Concepts for Alternating Current through Educational Videos

This article highlights the importance of complementing classes through educational videos, especially in disciplines exclusively with lectures. This proposition is exemplified through basic concepts in alternating current for both single-phase and three-phase circuits, which are critical in the formation of electrical engineers, mechanics, chemists, etc. The main objective of conducting educational videos is to make learning more attractive and stimulate interest in acquiring the knowledge of certain topics, given their importance in professional life in different engineering areas. The videos, filmed in laboratory and of short duration, aim to complement and consolidate the content taught in the classroom lectures.     

Robust industrial Saccharomyces cerevisiae strains for very high gravity bio-ethanol fermentations

The application and physiological background of two industrial Saccharomyces cerevisiae strains, isolated from harsh industrial environments, were studied in Very High Gravity (VHG) bio-ethanol fermentations. VHG laboratory fermentations, mimicking industrially relevant conditions, were performed with PE-2 and CA1185 industrial strains and the CEN.PK113-7D laboratory strain. The industrial isolates produced remarkable high ethanol titres (>19%, v/v) and accumulated an increased content of sterols (2 to 5-fold), glycogen (2 to 4-fold) and trehalose (1.1-fold), relatively to laboratory strain. For laboratory and industrial strains, a sharp decrease in the viability and trehalose concentration was observed above 90 g l?1 and 140 g l?1 ethanol, respectively. PE-2 and CA1185 industrial strains presented important physiological differences relatively to CEN.PK113-7D strain and showed to be more prepared to cope with VHG stresses. The identification of a critical ethanol concentration above which viability and trehalose concentration decrease significantly is of great importance to guide VHG process engineering strategies. This study contributes to the improvement of VHG processes by identifying yeast isolates and gathering yeast physiological information during the intensified fermentation process, which, besides elucidating important differences between these industrial and laboratory strains, can drive further process optimization.     

Mercury methylation and bacterial activity associated to tropical phytoplankton

The methylated form of mercury (Hg), methylmercury (MeHg), is one of the most toxic pollutants. Biotic and/or abiotic methylation, often associated to sulfate-reducing bacteria metabolism, occurs in aquatic environments and in many tropical areas, mostly in the periphyton associated to floating macrophyte roots. Data about mercury methylation by phytoplankton are scarce and the aim of this study was to verify the biotic influence in the methylation process in Microcystis aeruginosa and Sineccocystis sp. laboratory strains and in natural populations of phytoplankton from two different aquatic systems, the mesotrophic Ribeir?o das Lajes reservoir and hypereutrophic oligohaline Jacarepaguá lagoon, Rio de Janeiro state, Brazil. Adapted radiochemical techniques were used to measure sulfate-reduction, mercury methylation and bacterial activity in phytoplankton samples. Methyl-(203)Hg formation from added inorganic (203)Hg and (3)H-Leucine uptake were measured by liquid scintillation as well as sulfate-reduction, estimated as H(2)(35)S produced from added Na(2)(35)SO(4). There was no significant difference in low methylation potentials (0.37%) among the two cyanobacterium species studied in laboratory conditions. At Ribeir?o das Lajes reservoir, there was no significant difference in methylation, bacterial activity and sulfate-reduction of surface sediment between the sampling points. Methylation in sediments (3-4%) was higher than in phytoplankton (1.5%), the opposite being true for bacterial activity (sediment mean 6.6 against 150.3 nmol gdw(-1) h(-1) for phytoplankton samples). At Jacarepaguá lagoon, an expressive bacterial activity (477.1 x 10(3) nmol gdw(-1) h(-1) at a concentration of 1000 nM leucine) and sulfate-reduction ( approximately 21% H(2)(35)S trapped) associated to phytoplankton (mostly cyanobacteria M. aeruginosa) was observed, but mercury methylation was not detected.     

Metal-binding proteins and peptides in the aquatic fungi Fontanospora fusiramosa and Flagellospora curta exposed to severe metal stress

The production of thiol-containing proteins/peptides and its role in metal-binding was examined in the aquatic hyphomycetes Fontanospora fusiramosa and Flagellospora curta exposed to Cu, Cd, or Zn at concentrations inhibiting the biomass production in 80%. Heat-treated cell-free extracts were separated by size-exclusion chromatography and the thiol and metal content in the fractions was determined. F. curta, the species tolerant to metals, showed higher absolute levels of thiol compounds, which bound higher amounts of Cu and Cd than F. fusiramosa. Peptides with very low molecular weight (<9 kDa), most likely glutathione and phytochelatins, were the major Cu- and Zn-binding components in both species of aquatic hyphomycetes. In most cases, proteins with high molecular weight (>26 kDa) were induced by metal ions and they were the major Cd-binding component in both species. Proteins with characteristics of metallothioneins were also induced by exposure to metals in both species, but they showed a minor role in metal-binding, suggesting they might have other functions in fungal cells.     

Biodegradable PLA based nanocomposites for packaging applications: The effects of organo-modified bentonite concentration

The effects of concentration and surface modification of two Brazilian bentonite clays on nanocomposites' properties based on polylactic acid – (PLA) were investigated. The samples were prepared by the extrusion/injection method to obtain biodegradable packaging plastics. The raw materials and their bionanocomposites were characterized by various techniques. Natural clay samples presented a size of around 2 μm while the modified ones' size was 5–6 μm, probably due to the presence of cetyltrimethylammonium bromide in the interlayer space. The particle size and the contact angle increased with the treatment and the clay's density decreased. The organoclays were homogeneously dispersed in PLA, which can be associated with the interactions between PLA chains' carbonyl groups and the organoclays. The bionanocomposites present modified clay particles axis aligned to the flow direction of the extruder/injector. Chocolate organoclay acts as a nucleating agent to PLA crystal growth, increasing the sample's crystallinity, while Bofe organoclay interferes with the amorphous chain's mobility and diminishes the sample's crystallization. The addition of both organoclays to PLA diminished the sample's elongation at break and strength, although the organoclays increased the sample's Young modulus, even though Bofe organoclay is more active in PLA amorphous phase and Chocolate organoclay on the crystalline one.     

Production of Beta-D-Galactosidase from Kluyveromyces fragilis Grown in Cheese Whey

Two strains of Kluyveromyces fragilis (145 and 276) and one of Kluyveromyces lactis were tested for their abilities to produce beta-D-galactosidase in cheese whey. Kluyveromyces fragilis 145 was selected for its higher beta-D-galactosidase activity per cell at the end of the exponential growth phase.Addition of ammonium sulfate (.3%) and yeast extract (.1%) to the deproteinized cheese whey increased cell mass and enzyme yield.Addition of 3% lactose did not affect beta-D-galactosidase activity per cell, which responded positively to a reduction in aeration from 1 to .25 air volume/medium volume/min.The harvested yeast cells were ethanol- and acetone-permeabilized to enhance lactose hydrolysis by beta-D-galactosidase.     

Tyrosine hydroxylase expression in the Cebus monkey retina

Tyrosine hydroxylase (TH) expression was used as a marker to study the dopaminergic cells in the Cebus monkey retina. Two types of dopaminergic cells were identified by cell body size and location, level of arborization in the inner plexiform layer, and amount of immunolabeling. Type 1 cells displayed intense immunoreactivity and larger somata (12-24 microns) located in the inner nuclear layer or ganglion cell layer, whereas type 2 had smaller cell bodies (8-14 microns) found either in the inner plexiform layer or ganglion cell layer and were more faintly labeled. Interplexiform cells were characterized as type 1 dopaminergic cells. Immunoreactive axon-like processes were seen in the nerve fiber layer, and a net of fibers was visible in the foveal pit and in the extreme periphery of the retina. The population of TH+ cells was most numerous in the temporal superior quadrant and its density peaked at 1-2 mm from the fovea. Type 1 TH+ cells were more numerous than type 2 cells at any eccentricity. Along the horizontal meridian, type 1 cell density was slightly higher in temporal (29 cells/mm2) than in nasal (25 cells/mm2) retina, while type 2 cells had a homogeneous distribution (4.5 cells/mm2). Along the vertical meridian, type 1 cells reached lower peak density (average 17.7 cells/mm2) in the inferior retina (central 4 mm), compared to the superior portion (23.7 cells/mm2). Type 2 cell density varied from 4.5 cells/mm2 in the superior region to 9.4 cells/mm2 in the inferior region. The spatial density of the two cell types varied approximately inversely while the total density of TH+ cells was virtually constant across the retina. No correlation between dopaminergic cells and rod distribution was found. However, we suggest that dopaminergic cells could have a role in mesopic and/or photopic vision in this species, since TH+ fibers are present in cone-dominated regions like the foveola and extreme nasal periphery.     

The acute effects of plyometric and sled towing stimuli with and without caffeine ingestion on vertical jump performance in professional soccer players

Background

Post-activation potentiation (PAP) is the phenomenon by which muscular performance is enhanced in response to a conditioning stimulus. PAP has typically been evidenced via improved counter movement jump (CMJ) performance. This study examined the effects of PAP, with and without prior caffeine ingestion, on CMJ performance.

Methods

Twelve male professional soccer players (23?±?5 years) performed two trials of plyometric exercises and sled towing 60 min after placebo or caffeine ingestion (5 mg.kg^??1) in a randomized, counterbalanced and double-blinded design. CMJ performance was assessed at baseline and 1, 3 and 5 min after the conditioning stimulus (T1, T3 and T5, respectively).

Results

Two way ANOVA main effects indicated a significant difference in jump height after the PAP protocol (F[3, 11]?=?14.99, P?<?0.001, partial η2?=?0.577). Analysis also indicated a significant difference in CMJ performance across conditions, with caffeine eliciting a greater response (F[1, 11]?=?10.12, P?=?0.009, partial η2?=?0.479). CMJ height was increased at T1, T3 and T5 in caffeine condition (5.07%, 5.75% and 5.40%, respectively; P?<?0.01) compared to baseline. In the placebo condition, jump performance was increased at T3 (4.94%; P?<?0.01) only. Jump height was higher in caffeine condition on T1, T3 and T5 (P?<?0.05) but not on baseline (P?>?0.05) compared to placebo.

Conclusions

The results of this study suggest that acute plyometric and sled towing stimuli enhances jump performance and that this potentiation is augmented by caffeine ingestion in male soccer players.