Survey Study of Lipid Effect on Nisin Nanoliposome Formation and Application in Pasteurized Milk as a Food Model

The use of bacteriocins, mainly nisin, is one of the most significant preservation technologies in the food industry. Nisin encapsulation can improve stability and homogenous distribution in food matrices. In this study, liposomes of four various lipids (lipoid S 100, lipoid S PC-3, lipoid S PC, and lipoid PC (DPPC)) were prepared by dehydration-rehydration method, and compared for entrapment efficiency, and lipid with the highest entrapment efficiency (DPPC) was characterized. The inhibitory effects of encapsulated (DPPC nanoliposomes) and free nisin on the spoilage of pasteurized milk were also studied. All experiments were performed in triplicate. Entrapment efficiency ranged from 14% (lipoid S 100) to 49% (DPPC). DPPC nanoliposomes were large unilamellar vesicles (LUV), and had an asymmetric oval shape (elliptical) with a mean diameter of 136 nm. It was revealed that pasteurized milk spoilage was delayed by both free and encapsulated nisin, but free nisin (with 38 days) was significantly more efficient in comparison with encapsulated nisin (14 days)

Karakterizacija jogurta s dodatkom Lacticaseibacillus rhamnosus kao protektivne kulture protiv kvasaca i plijesni

Lactic acid bacteria (LAB) play a very important role as natural bio-preservatives in foods. Accordingly, the inhibitory effect of Lactobacillus rhamnosus (L. rhamnosus) on 4 fungi species of Yarrowia, Penicillium expansum (P. expansum), Saccharomyces cerevisiae (S. cerevisiae), Aspergillus niger (A. niger), Kluyveromyces lactis (K. lactis) was investigated. Then P. expansum was selected as the most important contaminant mould in yoghurt to study the use of L. rhamnosus to reduce selective spoilage of P. expansum in yoghurt. Also, the effect of this bioprotective culture on the count of starter bacteria and some characteristics of yoghurt was determined. L. rhamnosus (106 cfu /mL) was inoculated into the milk along with yoghurt starter bacteria, so that four samples were produced T0 (L. rhamnosus = 0, P. expansum = 0), T1 (L. rhamnosus = 106 cfu/mL, P. expansum = 0), T2 (L. rhamnosus = 0, P. expansum = 105cfu/mL); T3 (L. rhamnosus = 106 cfu/mL, P. expansum = 105cfu/mL). All samples were analysed for pH, acidity, viscosity, syneresis, microbial (survival of Streptococcus thermophilus and Lactobacillus bulgaricus and P. expansum) and overall acceptability. L. rhamnosus had an inhibitory effect on the survival of P. expansum (p<0.05) but was not able to completely control it. L. rhamnosus in T3 sample had an inhibitory effect from the first day to the end of storage. Furthermore, during the storage, the survival of yoghurt starter bacteria in probiotic yoghurt samples was higher than the control (p<0.05). T3 had lower pH, viscosity and overall acceptability score compared to the control and its syneresis was higher (p<0.05). In general, the addition of 106 cfu/mL of L. rhamnosus did not have a complete inhibitory effect on P. expansum (105 CFU/mL) until the end of storage time.Bakterije mliječne kiseline (BMK) igraju vrlo važnu ulogu kao prirodni biokonzervansi u hrani. Prema tome, istražen je inhibicijski učinak Lactobacillus rhamnosus (L. rhamnosus) prema 4 vrste Yarrowia kvasaca i plijesni: Penicillium expansum (P. expansum), Saccharomyces cerevisiae (S. cerevisiae), Aspergillus niger (A. niger), Kluyveromyces lactis (K. lactis). Zatim je P. expansum odabran kao najvažniji kontaminant iz roda plijesni u jogurtu kako bi se istražila upotreba L. rhamnosus za selektivno smanjenje kvarenja jogurta uzrokovanog navedenim sojem plijesni. Također je određivan učinak ove biozaštitne kulture na broj starter bakterija i neke karakteristike jogurta. L. rhamnosus (106 cfu/mL) inokuliran je u mlijeko zajedno s jogurtnom starter kulturom pri čemu su proizvedena četiri uzorka T0 (L. rhamnosus = 0, P. expansum = 0), T1 (L. rhamnosus = 106 cfu/mL, P. expansum = 0), T2 (L. rhamnosus = 0, P. expansum = 105 cfu). /mL); T3 (L. rhamnosus = 106 cfu/mL, P. expansum = 105 cfu/mL). U svim uzorcima je određivana pH vrijednost, viskoznost, sinereza, mikrobiološki parametri tj. preživljavanje Streptococcus thermophilus, Lactobacillus bulgaricus i P. expansum, te ukupna prihvatljivost. L. rhamnosus je inhibiraio preživljavanje P. expansum (p<0,05), ali ga nije mogao u potpunosti kontrolirati. L. rhamnosus je u uzorku T3 pokazao jak inhibicijski učinak od prvog dana do kraja skladištenja. Nadalje, tijekom skladištenja preživljavanje sojeva jogurtne starter kulture u uzorcima probiotičkog jogurta bilo je veće od kontrolnog (p<0,05). T3 je imao niži pH, viskoznost i ukupni rezultat prihvatljivosti u usporedbi s kontrolnim uzorkom, a sinereza mu je bila viša (p<0,05). Općenito, dodavanje 106 cfu/mL L. rhamnosus nije u potpunosti inhibiralo rast soja P. expansum (105 CFU/mL) tijekom perioda skladištenja jogurta

Isolation of a Penicillin Acylase Producing E.coli and Kinetic Characterization of the Whole Cell Enzyme Activity

ABSTRACT Penicillin acylase (EC 3.5.1.11) has been a target of study for a long time because of its pivotal role in the deacylation of the penicillin into the 6-aminopenicillanic acid (6-APA) and the side-chain organic acids. This property of penicillin acylase has been exploited commercially for large scale production of 6-APA, which is the key intermediate in the manufacture of semi-synthetic penicillins. Due to the worldwide demand for semi-synthetic penicillins, production of 6-APA has been increased up to 7000 tons in recent years. In this study, Sixty-five strains of E. coli were investigated for penicillin acylase activity using fluorescamine method. The 6-aminopenicillanic acid formed in the reaction mixture was developed on thin layer chromatography. One-minute beta-lactamase test was carried out to follow any trace of penicillinase activity. Only one sample designated as E.coli PPA78 was found to be penicillin acylase producer. The optimal pH and temperature of penicillin acylase activity of the whole cells were determined to be 8.0 and 57°C, respectively. Km value and activation energy of the enzymatic hydrolysis reaction of penicillin G by intracellular enzyme were estimated as 0.004 mmol and 6.2 Kcal/mol, respectively. Iran. Biomed. J. 6 (2 &amp; 3): 93-96, 200

A finite element model for extension and shear modes of piezo-laminated beams based on von Karman's nonlinear displacement-strain relation

Piezoelectric actuators and sensors have been broadly used for design of smart structures over the last two decades. Different theoretical assumptions have been considered in order to model these structures by the researchers. In this paper, an enhanced piezolaminated sandwich beam finite element model is presented. The facing layers follow the Euler-Bernoulli assumption while the core layers are modeled with the third-order shear deformation theory (TSDT). To refine the model, the displacement-strain relationships are developed by using von Karman's nonlinear displacement-strain relation. It will be shown that this assumption generates some additional terms on the electric fields and also introduces some electromechanical potential and non-conservative work terms for the extension piezoelectric sub-layers. A variational formulation of the problem is presented. In order to develop an electromechanically coupled finite element model of the extension/shear piezolaminated beam, the electric DoFs as well as the mechanical DoFs are considered. For computing the natural frequencies, the governing equation is linearized around a static equilibrium position. Comparing natural frequencies, the effect of nonlinear terms is studied for some example

Global age-sex-specific mortality, life expectancy, and population estimates in 204 countries and territories and 811 subnational locations, 1950–2021, and the impact of the COVID-19 pandemic: a comprehensive demographic analysis for the Global Burden of Disease Study 2021

Background Estimates of demographic metrics are crucial to assess levels and trends of population health outcomes. The profound impact of the COVID-19 pandemic on populations worldwide has underscored the need for timely estimates to understand this unprecedented event within the context of long-term population health trends. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 provides new demographic estimates for 204 countries and territories and 811 additional subnational locations from 1950 to 2021, with a particular emphasis on changes in mortality and life expectancy that occurred during the 2020–21 COVID-19 pandemic period. Methods 22 223 data sources from vital registration, sample registration, surveys, censuses, and other sources were used to estimate mortality, with a subset of these sources used exclusively to estimate excess mortality due to the COVID-19 pandemic. 2026 data sources were used for population estimation. Additional sources were used to estimate migration; the effects of the HIV epidemic; and demographic discontinuities due to conflicts, famines, natural disasters, and pandemics, which are used as inputs for estimating mortality and population. Spatiotemporal Gaussian process regression (ST-GPR) was used to generate under-5 mortality rates, which synthesised 30 763 location-years of vital registration and sample registration data, 1365 surveys and censuses, and 80 other sources. ST-GPR was also used to estimate adult mortality (between ages 15 and 59 years) based on information from 31 642 location-years of vital registration and sample registration data, 355 surveys and censuses, and 24 other sources. Estimates of child and adult mortality rates were then used to generate life tables with a relational model life table system. For countries with large HIV epidemics, life tables were adjusted using independent estimates of HIV-specific mortality generated via an epidemiological analysis of HIV prevalence surveys, antenatal clinic serosurveillance, and other data sources. Excess mortality due to the COVID-19 pandemic in 2020 and 2021 was determined by subtracting observed all-cause mortality (adjusted for late registration and mortality anomalies) from the mortality expected in the absence of the pandemic. Expected mortality was calculated based on historical trends using an ensemble of models. In location-years where all-cause mortality data were unavailable, we estimated excess mortality rates using a regression model with covariates pertaining to the pandemic. Population size was computed using a Bayesian hierarchical cohort component model. Life expectancy was calculated using age-specific mortality rates and standard demographic methods. Uncertainty intervals (UIs) were calculated for every metric using the 25th and 975th ordered values from a 1000-draw posterior distribution. Findings Global all-cause mortality followed two distinct patterns over the study period: age-standardised mortality rates declined between 1950 and 2019 (a 62·8% [95% UI 60·5–65·1] decline), and increased during the COVID-19 pandemic period (2020–21; 5·1% [0·9–9·6] increase). In contrast with the overall reverse in mortality trends during the pandemic period, child mortality continued to decline, with 4·66 million (3·98–5·50) global deaths in children younger than 5 years in 2021 compared with 5·21 million (4·50–6·01) in 2019. An estimated 131 million (126–137) people died globally from all causes in 2020 and 2021 combined, of which 15·9 million (14·7–17·2) were due to the COVID-19 pandemic (measured by excess mortality, which includes deaths directly due to SARS-CoV-2 infection and those indirectly due to other social, economic, or behavioural changes associated with the pandemic). Excess mortality rates exceeded 150 deaths per 100 000 population during at least one year of the pandemic in 80 countries and territories, whereas 20 nations had a negative excess mortality rate in 2020 or 2021, indicating that all-cause mortality in these countries was lower during the pandemic than expected based on historical trends. Between 1950 and 2021, global life expectancy at birth increased by 22·7 years (20·8–24·8), from 49·0 years (46·7–51·3) to 71·7 years (70·9–72·5). Global life expectancy at birth declined by 1·6 years (1·0–2·2) between 2019 and 2021, reversing historical trends. An increase in life expectancy was only observed in 32 (15·7%) of 204 countries and territories between 2019 and 2021. The global population reached 7·89 billion (7·67–8·13) people in 2021, by which time 56 of 204 countries and territories had peaked and subsequently populations have declined. The largest proportion of population growth between 2020 and 2021 was in sub-Saharan Africa (39·5% [28·4–52·7]) and south Asia (26·3% [9·0–44·7]). From 2000 to 2021, the ratio of the population aged 65 years and older to the population aged younger than 15 years increased in 188 (92·2%) of 204 nations. Interpretation Global adult mortality rates markedly increased during the COVID-19 pandemic in 2020 and 2021, reversing past decreasing trends, while child mortality rates continued to decline, albeit more slowly than in earlier years. Although COVID-19 had a substantial impact on many demographic indicators during the first 2 years of the pandemic, overall global health progress over the 72 years evaluated has been profound, with considerable improvements in mortality and life expectancy. Additionally, we observed a deceleration of global population growth since 2017, despite steady or increasing growth in lower-income countries, combined with a continued global shift of population age structures towards older ages. These demographic changes will likely present future challenges to health systems, economies, and societies. The comprehensive demographic estimates reported here will enable researchers, policy makers, health practitioners, and other key stakeholders to better understand and address the profound changes that have occurred in the global health landscape following the first 2 years of the COVID-19 pandemic, and longer-term trends beyond the pandemic

A comparative study between inhibitory effect of L. lactis and nisin on important pathogenic bacteria in Iranian UF Feta cheese

Introduction : In the present study, the inhibitory effect of nisin-producing Lactococcus lactis during co-culture and pure standard nisin were assessed against selected foodborne pathogenes in growth medium and Iranian UF Feta cheese. In comparison L lactis, not only proves flavor but also plays a better role in microbial quality of Iranian UF Feta cheese as a model of fermented dairy products.   Materials and method s: L. lactis subsp. lactis as nisin producer strain, Listeria monocytogenes, Escherichia coli and Staphylococcus aureus as pathogenic strains were inoculated in Ultra-Filtered Feta cheese. Growth curve of bacterial strains were studied by colony count method in growth medium and UF Feta cheese separately and during co-culture with L. lactis. Nisin production was determined by agar diffusion assay method against susceptible test strain and confirmed by RP-HPLC analysis method.   Results : Counts of L. monocytogenes decreased in cheese sample containing L. lactis and standard nisin, to 103 CFU/g after 7 days and it reached to undetectable level within 2 weeks. S. aureus counts remained at its initial number, 105 CFU/g, after 7 days then decreased to 104 CFU/g on day 14 and it was not detectable on day 28. E. coli numbers increased in both treatments after 7 days and then decreased to 104 CFU/g after 28 days. Despite the increasing number of E. coli in growth medium containing nisin, due to the synergistic effect of nisin and other metabolites produced by Lactococcus lactis and starter cultures, the number of E. coli decreased with slow rate . Discussion and conclusion : The results showed, L. monocytogenes was inhibited by L. lactis before entering the logarithmic phase during co-culture. S. aureus was also inhibited during co-culture, but it showed less sensitivity in comparison with L. monocytogenes. However, the number of E. coli remained steady in co-culture with L. lactis. Also, we found that, in all cheese samples, E. coli decreased slowly after 28 days which may be due to the synergistic inhibitory effects of nisin and other metabolites produced by L. lactis and starter culture strains. These conditions are compatible to UF Feta cheese making processes. The usage of L. lactis is more effective in terms of pathogenic inhibitory in comparison with free nisin. Using L. lactis as an adjunct starter culture can assist microbial quality improvement and prevent important pathogens, which may survive during food processing, because of the production of beneficial metabolites

Antioxidant activity and protective effects of Saccharomyces cerevisiae peptide fractions against H2O2-induced oxidative stress in Caco-2 cells

Oxidative stress is one of the most causes of some severe diseases and the spoilage of foods. Protein hydrolysates containing antioxidant peptides are a suitable candidate to replace synthetic antioxidant. In the present study, the in vitro and cellular antioxidant properties of Saccharomyces cerevisiae protein hydrolysate and the peptide fractions have been reported. The peptide protective role was evaluated in H2O2-stimulated Caco-2 cells to consider cell viability, cellular lipid and protein oxidation, and the level of cellular antioxidant enzymes such as Catalase (CAT) and Glutathione-S-transferase (GST). The peptide fractions showed a significant ferric reducing antioxidant power (67.10-93.52 mu m FeSO4/mg protein), and < 3 kDa peptide fraction with 59.5% inhibitory effect on the 7th day, exhibited the most inhibitory activity toward linoleic acid peroxidation. Ultrafiltered fractions ( < 3 kDa and 3-5 kDa) significantly (P <= 0.05) decreased the levels of malondialdehyde (MDA) and protein carbonyl and the production of CAT and GST enzymes as protective responses of cells under oxidative stress by H2O2. This study confirms the antioxidant activity of yeast protein hydrolysate and peptide fractions and their potential to reduce cellular oxidative stress and thus validates their potential use as a valuable ingredient of functional foods

Risk assessment of isolated lactobacill from traditional Iranian dairy products

The application of probiotic starter cultures in fermented products is expanding in different communities. The genetic variation makes the effects of these bacteria different and unpredictable in different human societies. Therefore, the safety control and evaluation of their non-pathogenicity is of great importance and monitoring centers are required to closely monitor the safety of the bacteria used in food products. In this study, two strains of Lactobacillus isolated from dairy products of Ardabil (Heyran mountain road villages) and Khuzestan province (Behbahan city) in Iran were identified based on the biochemical and molecular properties through sequence analysis of 16S rRNA gene. Then, their safety was examined based on the international guidelines, especially the European :union: standard. The two identified strains included Lactobacillus fermentum (PTCC 1929) and Lactobacillus helveticus (PTCC 1930). The results showed the lack of gelatinase enzyme, inability of blood hemolysis, inability of amino acids decarboxylation and the lack of genes responsible for the invasive characteristics of pathogenic microorganisms including gelE, efaAfm , efaAfs , agg, ace, cylM, cylA, cylB. In addition, the results showed the sensitivity of both isolates to Penicillin, Ampicillin, Rifampicin and Tetracycline, and their resistance to Kanamycin and Ciprofloxacin. Lactobacillus fermentum was resistant to vancomycin, whereas Lactobacillus helveticus was susceptible to it. Since cases of antibiotic resistance are inherent according to scientific reports, the obtained results confirmed the potential application of these two isolated strains as starter in the fermented dairy products. It also confirmed the necessity of using safety assessment procedures for probiotic bacteria

In vitro and in silico studies of novel synthetic ACE-inhibitory peptides derived from Saccharomyces cerevisiae protein hydrolysate

The structure-function relation of YR-10 (YGKPVAVPAR) was investigated by synthesizing four structural analogs of that including YHR-10 (YGKHVAVHAR), GA-8 (GKPVAVPA), GHA-8 (GKHVAVHA), and PAR-3 (PAR). GA-8 (GKPVAVPA) was synthesized on the basis of simulated enzymatic gastrointestinal digestion performed by bioinformatics tools (expasy-peptide cutter). This study explains the molecular mechanisms for the interaction of synthetic peptides with ACE. The IC50 values of each were 139.554 +/- 2.3, 61.91 +/- 1.2, 463.230 +/- 3.56, 135.135 +/- 2.1, 514.024 +/- 5.86 mu M, respectively. Results indicated that Pro replacement with His in YR-10 and GA-8 increased ACE inhibitory activity respectively, by 55.63% and 70.82%. Removal of Tyr and Arg from respectively N and C terminal positions of YR-10, following in silico simulated gastrointestinal digestion caused the 3.31 fold decrease in ACE inhibitory activity. YHR-10 showed the best docking poses, and GHA-8 exhibited interaction with Zn2+. Lineweaver-Burk plots of most active peptides suggest that they act as noncompetitive inhibitors against ACE