Properties of low-fat ultra-filtered cheeses produced with probiotic bacteria

Probiotics are live microorganisms that in certain numbers may confer a health benefit on the host. Nowadays, there are many dairy products on the market, especially fermented milks, with probiotics, and their popularity is rising. The aim of this article was to investigate the viability of commercial probiotic bacteria (Lactobacillus acidophilus LAFTI(center dot)L10 i Bifidobacterium lactis LAFTI(center dot)B94, DSM, Netherland) as well as their influence on the changes of composition, pH, proteolysis, microbiological status and sensory properties of low-fat ultra-filtered (UF) cheeses within 2 months of ripening. Low-fat cast ultra-filtered (UF) cheeses were produced according to the defined production procedure by mixing UP milk protein powder, skim milk and cream, without (control cheese A) and with adjunct probiotic culture (cheese B). The compositional parameters (milk fat, proteins and dry-matter content), pH, proteolysis parameters (water soluble nitrogen, nitrogen soluble in 5% PTA, urea and SDS PAG electrophoresis), as well as the numbers of starters and probiotic bacteria, were determined during ripening. In addition, sensory evaluations of cheeses were performed throughout the ripening time. A significant influence of probiotic strains on the composition, pH and primary proteolysis of cheese during ripening was not found. The counts of commercial probiotic bacteria were maintained at high levels (> 10(7) cfug(-1)) during the overall ripening period, as a prerequisite of their therapeutic effects. The adjunct probiotic cultures enhanced the rate of secondary proteolysis, which was shown by the significantly higher levels of PTAN/TN of experimental compared to the control cheeses. The sensory evaluation showed that the overall aroma of low-fat cheeses was remarkably improved by the addition of the probiotic cultures used. Based on the results it can be concluded that the low-fat UF cheeses differ in good dietetic and functional properties as well as very acceptable sensory properties, and can be used as carriers of probiotics

Primena tehnika elektronske mikroskopije u proučavanju sireva

Four types of electron microscopes, i.e. scanning electron microscope, cryo-scanning electron microscope, transmission electron microscope and environmental scanning electron microscope, as well as confocal laser scanning microscope, as a representative of light microscopy that is nowadays frequently being used in analyzing milk origin nutrition, are discussed. The differences between these categories of microscopes are presented here. The advantages in analyzing milk products are discussed. General methods of preparation of biological samples for all types of electron microscopes are introduced, as well as specific methods for preparation of cheese samples. Representative micrographs of different cheese samples are discussed. Use of the electron microscopy plays an important role in nutrition research, especially concerning microstructure. Electron microscopy will probably become a significant tool in future research of food. .U radu se analiziraju načini rada, kao i konstrukcija četiri tipa elektronskih mikroskopa: skenirajućeg elektronskog mikroskopa; krio-skenirajućeg elektronskog mikroskopa; transmisionog elektronskog mikroskopa i envajromental skenirajućeg elektronskog mikroskopa, kao i konfokalno lasersko skenirajućeg mikroskopa, predstavnika svetlosne mikroskopije, koji se trenutno najviše koriste za analizu namirnica mlečnog porekla. Prikazane su razlike između pojedinih kategorija mikroskopije, ukazano je na prednosti i mane u pogledu analiziranja namirnica različitog porekla. Prikazane su opšte metode pripreme bioloških uzoraka za sve vidove elektronske mikroskopije, metode pripreme uzoraka sireva, kao i prikazi mikrografija. Primena elektronske mikroskopije ima značajnu ulogu u proučavanju namirnica, posebno njihove mikrostrukture. Istraživanje strukture će verovatno postati važna komponenta budućih biotehnoloških istraživanja i koristiće se za posmatranje strukturalnih promena namirnica.

Role of ERK1/2 Activation In Thrombin-Induced Vascular Smooth Muscle Cell Hypertrophy

It is well recognized that the proliferation of vascular smooth muscle cells (VSMCs) is a key event in the pathogenesis of various vascular diseases, including atherosclerosis and hypertension. It is generally considered that the phosphorylation/dephosphorylation reactions of a variety of enzymes belonging to the family of mitogen-activated protein kinases (MAPKs) play an important role in the transduction of mitogenic signal. We have previously shown that among extracellular signal-regulated protein kinases (ERKs), the 42 and 44 kDa isoforms (ERK1/2) participate in the cellular mitogenic machinery triggered by several VSMCs activators, including thrombin. ERK1/2 activation by G-protein-coupled receptors (GPCRs) has been shown to be Ca2--dependent and to require the transactivation of epidermal growth factor receptor (EGFR). In addition, it is generally admitted that variations of the intracellular Ca2- concentration ([Ca2-] i) play an important role in the transduction of mitogenic signal. Recently, we have shown that in thrombin-stimulated VSMCs, EGFR-independent activation of ERK1/2 activation could occur when agonist-induced ([Ca2-] i) elevation was reduced. This review examines recent findings in ERK1/2 signaling pathway that have been identified as critically important mediator of VSMCs hypertrophy and vascular diseases. Future investigations should now focus on the mechanisms of MAPK activation which might therefore represent a new mechanism involved in the antiproliferative effect revealed in this review

The ripening of white brined cheeses made with commercial and potential autochthonous probiotic strains

The white brined cheeses are the most popular cheeses with the long tradition of production and consumption in Serbia. Modern medical research studies indicate the importance of diet in the maintenance and improvement of health. In this regard, for the last decades, there is rapid growth of food products with dietetic and functional properties, including products with probiotic bacteria, which could be beneficial for human health. Milk products, including cheeses, represent a good base for the development of new products with functional properties, especially those with probiotic bacteria. The effects of commercial and autochthonous strains of lactic acid bacteria on the composition and proteolysis of white brined cheeses were studied throughout 30 days of ripening. Cheese A was produced with commercial strains (LL 50 A and MY 721, DSM, Netherlands) Lactococcus lactis ssp. lactis, Lactococcus lactis ssp. cremoris and probiotics Lactobacillus acidophilus and Bifidobacterium lactis and cheese B with autochthonous strains Lactococcus lactis ssp. lactis 563, Lactococcus lactis ssp. cremoris 565 and potential probiotics Lactobacillus plantarum 564. The rate of proteolysis was analyzed by the water and 5% phosphotungstic acid soluble nitrogen fractions, as well as by SDS and UREA PAG electrophoresis. The viability of probiotic strains during cheeses ripening was also determined. A significant influence of different starter and adjuncts bacteria on the composition was not found. The proteolysis rate was significantly different (p lt 0.05) between cheeses made with different starter cultures, due to different proteolytic activity of bacteria used. The viability of adjunct probiotic bacteria in both cheeses were maintained on the high level during the overall ripening period that are necessary for acquirement of their therapeutic effects. Cheeses made with autochthonous bacteria showed a higher rate of secondary proteolysis, as well as higher flavour scores, and were more acceptable than cheese made with commercial probiotic bacteria

Role of PI3K/AKT, cPLA2 and ERK1/2 Signaling Pathways in Insulin Regulation of Vascular Smooth Muscle Cells Proliferation

Vascular smooth muscle cells (VSMCs) respond to arterial wall injury by intimal proliferation and play a key role in atherogenesis by proliferating and migrating excessively in response to repeated injury, such as hypertension and atherosclerosis. In contrast, fully differentiated, quiescent VSMCs allow arterial vasodilatation and vasoconstriction. Exaggerated and uncontrolled VSMCs proliferation appears therefore to be a common feature of both atherosclerosis and hypertension. Phosphorylation/dephosphorylation reactions of enzymes belonging to the family of mitogen-activated protein kinases (MAPKs), phosphatidylinositol 3-kinase (PI3K) and protein kinase B (Akt) play an important role in the transduction of mitogenic signal. We have previously shown that among extracellular signal-regulated protein kinases (ERKs), the 42 and 44 kDa isoforms (ERK1/2) as well as Akt and cytosolic phospholipase 2 (cPLA 2) participate in the cellular mitogenic machinery triggered by several VSMCs activators, including insulin (INS). The ability of INS to significantly increase VSMCs proliferation has been demonstrated in several systems, but understanding of the intracellular signal transduction pathways involved is incomplete. Signal transduction pathways involved in regulation of the VSMCs proliferation by INS remains poorly understood. Thus, this review examines recent findings in signaling mechanisms employed by INS in modulating the regulation of proliferation of VSMCs with particular emphasis on PI3K/Akt, cPLA2 and ERK1/2 signaling pathways that have been identified as important mediators of VSMCs hypertrophy and vascular diseases. These findings are critical for understanding the role of INS in vascular biology and hyperinsulinemia

Influence of autochthonous lactic acid bacteria on the proteolysis, microstructure and sensory properties of low fat UF cheeses during ripening

The influence of commercial bacteria Lactococcus lactis ssp. lactis and Lactococcus lactis ssp. cremoris (cheese A) and combinations of autochthonous lactic acid bacteria (LAB) strains Lactobacillus paracasei ssp. paracasei 08, Lactococcus lactic ssp. cremoris 656, Lactococcus lactis ssp. lactis 653 (cheese B and C) on composition, proteolysis, microstructure and sensory properties of low fat cheeses during ripening was investigated. Low fat cast ultra-filtered (UF) cheeses were produced according to the defined production procedure by mixing UF milk protein powder, skim milk and cream. Significant influence of different LAB strains on composition, primary proteolysis and microstructure was not found. Cheeses made with autochthonous LAB showed a higher rate of secondary proteolysis, as well as higher flavour scores, and were more acceptable than control cheese