Production of conjugated linoleic acid by food‐grade bacteria: A review

Conjugated linoleic acid (CLA) is a group of isomers of linoleic acid (LA) with several potential health benefits which justifies the efforts to obtain foods with enhanced CLA contents. A possible way to obtain CLA‐enriched products is via fermentation as several micro‐organisms, many of which are employed in the manufacture of foods, are known to convert free LA into CLA. However, due to several constraints, the use of CLA‐producing bacteria still remains challenging and continuous efforts are required. This review summarises the current knowledge on microbial CLA production by food‐grade micro‐organisms, its technical issues and limitations, potential applications and bioactivities.     

Effect of Egg Yolk and Egg Yolk + Salt on Rheological Properties and Particle Size Distribution of Model Oil-in- Water Salad Dressing Emulsions

The role of egg yolk and egg yolk + salt in stabilizing oil-in-water (o/w) salad dressing emulsions pre-stabilized with xanthan and propylene glycol alginate was studied using creep tests, steady shear, and particle size analysis. Results show that each combination significantly affects rheological stability of model o/w salad dressing emulsions. All emulsions exhibited viscoelasticity and wcrc characterized by three parameters: η₁, E₁ and η_N. Steady shear measurements showed that both egg yolk and salt increased viscosity radically. Particle size data showed significant changes with both addition of egg yolk and salt to the model system.     

Factors Affecting the Gelation Properties of Hydrolyzed Sunflower Proteins

The effects of temperature and several chemicals on gelation time and strength of gels formed by heating (pH 8) 5% solutions of trypsin hydrolyzed sunflower proteins were studied by dynamic rheological methods. The storage modulus reached a maximum at 80°C. Ca₂Cl (and NaCl at > 0.2M) accelerated gelation and weakened the gel. NaCOCH₃Na₂SO₄ and NaSCN decreased the storage modulus. Urea decreased gelstrength and at high concentrations slowed gelation. Time for gelation diminished and gel strength increased with increasing mercaptoethanol concentration up to 0.1M. Propylene glycol at 5–20% concentrations accelerated gelation and at 5% also increased gel strength. Trypsin hydrolyzed sunflower proteins could be useful in products requiring strong gels at high temperatures.     

The viability of three probiotic organisms grown with yoghurt starter cultures during storage for 21 days at 4°C

This study investigated the viability of probiotic ( Lactobacillus acidophilus LA5, Lactobacillus rhamnosus LBA and Bifidobacterium animalis subsp . lactis BL-04) in milk fermented with Lactobacillus delbrueckii subsp . bulgaricus LB340 and Streptococcus thermophilus TAO (yoghurt – Y). Each probiotic strain was grown separately in co-culture with Y and in blends of different combinations. Blends affected fermentation time(s), pH and firmness during storage at 4°C. The product made with Y plus B. animalis subsp . lactis and L. rhamnosus had counts of viable cells at the end of shelf life that met the minimum required to achieve probiotic effect. However, L. acidophilus and L. delbrueckii subsp . bulgaricus were inhibited.     

The peptide fraction of <i>Bothrops jararaca</i> snake venom induces toxicological effects on the male reproductive system after local envenomation in mice

Bothrops envenomation is complex and provokes prominent local tissue damage and systemic disturbances, but little is known about their effects on the male reproductive system. After intratesticular injection, the bioactive peptide fraction (Bj-PF) obtained from Bothrops jararaca snake venom changes the structure of different stages of the seminiferous epithelium cycle in adult mice. For the first time, we investigated whether local envenomation of Bj-PF induces toxicological effects on the male reproductive system, particularly on the seminiferous epithelium and Sertoli cells. Male adult mice were treated with 0.24 mg.kg⁻¹ by intramuscular (i.m.) injection for 24 h. The testes samples were collected for morphological and morphometric evaluation. The toxicological effects of Bj-PF were also analyzed on mitochondrial metabolism and nitrite (NO₂) production in 15P-1 Sertoli cell culture. Bj-PF changed the structure and function of the seminiferous epithelium, particularly the disruption of the epithelium and the presence of degenerated germ cells in the adluminal compartment, but there were no alterations in the basal compartment. Bj-PF increased the thickness of the seminiferous epithelium and decreased the lumen diameter of the tubule. Semiquantitative histological assessment of the degree of tubule degeneration revealed that Bj-PF also increased the number of hypospermatogenic tubules compared to control. Bj-PF reduced NO₂ levels in 15P-1 Sertoli cells without changing the mitochondrial metabolism. Overall, the fact that Bj-PF alters the structure and function of the seminiferous epithelium suggests that bioactive peptides found in B. jararaca snake venom can have toxicological effects on the reproductive systems of affected male mice, providing new insight into the biological characteristics of snake venom and therapeutic strategies for envenomation inflammation.     

Calcitriol induces post-thawed bovine sperm capacitation

Background: Capacitation is a set of physiological changes sperms undergo to acquire fertilizing capacity. In vivo, this process is directly associated with high calcium levels in sperm cytoplasm. Calcitriol, the vitamin D hypercalcemic metabolite, is related to human sperm motility, capacitation, and acrosome reaction. This work aimed to study the effect of calcitriol on bull sperm quality parameters and capacitation. Methods: One million freeze-thawed spermatozoa were obtained from different bulls and treated with 20 nM of calcitriol for 30 min. Untreated cells (negative control) and treated ones with calcitriol or heparin (100 µg/mL, positive capacitation control) were evaluated for motility, viability, and functional parameters. Menadione (70 µM, 30 min) treatment was included as a reactive oxygen species (ROS) positive sperm agent. Results: The results elucidated that sperm exposed to 20 nM calcitriol showed higher viability, vigor, and capacitation than their positive and negative controls. The percentage of sperm with intact plasma and acrosome membranes, mitochondrial membrane potential (ΔΨm), and phosphatidylserine externalization was similar in all the conditions evaluated, while ROS production was higher with heparin and menadione-treated groups than the calcitriol group or negative control. Conclusion: Our results indicate that calcitriol induces the capacitation of thawed bull spermatozoa and maintains acceptable values of progressive motility, viability, and vigor without altering key biological parameters such as redox status, ΔΨm, and cell death.     

Impact of chitosan-based nanocarriers on cytoskeleton dynamics: Current status and challenges

Chitosan-based nanocarriers (CS-NCs) show a promising role in improving drugs and bioactive compounds delivery for therapy. However, the effects exerted by CS-NCs at the cellular level, including their recognition and uptake, have not been fully investigated yet. Many factors, including size, shape, concentration, and surface chemistry of CS-NCs, play an important role in determining the types of intracellular signals triggered. The mechanism of uptake and the involvement of the cytoskeleton during the CS-NCs endocytosis variates among the different cell types as well as further effects observed inside cells. In the present work, we discuss the effects induced by CS-NCs per se on the cytoskeleton, a key component in cell architecture and physiology. The focus of this report is made on tumoral and normal biological models in which CS-NCs could differentially affect the cell cytoskeleton. The recent years reports regarding the impact of CS-NCs on cytoskeleton dynamics and the current techniques for its evaluation are summarized and discussed. Understanding mechanisms underlying cytoskeletal impact after cell exposure to CS-NCs is critical for the design of safest value-added formulations in the biomedical field. Furthermore, this revision points out some interesting aspects of cytoskeletal changes and cell death encompassing anti-tumoral effects.     

THE COMPOSITION OF TWO SPANISH PEPPER VARIETIES (FRESNO DE LA VEGA AND BENAVENTE‐LOS VALLES) IN DIFFERENT RIPENING STAGES

ABSTRACT

The chemical composition of two traditional varieties of Spanish peppers, “Fresno de la Vega” and “Benavente‐Los Valles” harvested in the provinces of León and Zamora, respectively, at different ripening stages (green mature, breaker and red) were evaluated. Herein we report the global composition, mineral and trace element contents, and the most relevant physicochemical parameters of each variety of pepper collected in 2 consecutive years. Both pepper varieties showed a similar chemical composition, except in vitamin C content, which resulted to be about 70% higher in Fresno de la Vega peppers. Red ripe fruits were high in total carbohydrates, fructose, glucose, sucrose, fat (64.5, 29.14, 25.57, 2.94, 1.79/100 g dry weight, respectively) and total soluble solids (6.83°Brix). Ascorbic acid content also increased progressively during ripening, reaching a mean value of 1.81 mg/100 g dry weight for Fresno de la Vega peppers. Potassium was the most abundant of the analyzed elements in the all samples, followed by phosphorus, magnesium, calcium and sodium. The order of the levels of the trace elements was iron > manganese > zinc > copper.

PRACTICAL APPLICATIONS

This report underscores the potential value of two traditional varieties of Spanish peppers and provides information on their composition during ripening to decide the proper harvesting time, which can be useful in the food industry.     

Influence of cephalosporins on the coagulation time of yogurt made from ewes’ milk

Ceftiofur and cephalexin were independently added to ewes’ milk at three different concentrations 50, 100 and 150 µg/kg. Spiked milk was used to produce yogurt and the acidification of the yogurt during incubation was then studied. Ceftiofur showed significant delays in the pH decrease rate at all concentrations assayed, but no significant delays occurred with cephalexin. When these antibiotics were administered intramuscularly to lactating ewes, from which the milk was used to make yogurt immediately after the corresponding withdrawal periods, absence of residues and pH delays were not observed during the yogurt fermentation in the presence of any antibiotic.