Ali Topcu

Detoxification of aflatoxin B1 and patulin by Enterococcus faecium strains

Aim of the present study was to investigate the detoxification of aflatoxin B(1) and patulin from aqueous solution by probiotic culture of Enterococcus faecium M74 and commercial culture of E. faecium EF031. The effect of the bacterial viability, incubation time and pH of the medium on the binding ability was tested. Also, binding stability was determined by washing the bacteria-mycotoxin complexes with phosphate buffer saline. Both M74 and EF031 strains have the ability to remove aflatoxin B(1) and patulin. While M74 removes 19.3 to 30.5% of aflatoxin B(1) and 15.8 to 41.6% of patulin, EF031 removes 23.4 to 37.5% of aflatoxin B(1) and 19.5 to 45.3% of patulin throughout a 48 h incubation period. The removal of aflatoxin B(1) and patulin was highest at pH 7.0 and 4.0, respectively. The stability of the aflatoxin B(1) and patulin complexes formed with the bacterial strains was found to be high. The viability of the bacteria did not have any significant effect on the detoxification of aflatoxin B(1) and patulin. Detoxification properties of E. faecium could represent new strategies for a possible application in the human diet and animal feed.

Rapid analysis of sugars in honey by processing Raman spectrum using chemometric methods and artificial neural networks

The aim of this study was to quantify glucose, fructose, sucrose and maltose contents of honey samples using Raman spectroscopy as a rapid method. By performing a single measurement, quantifications of sugar contents have been said to be unaffordable according to the molecular similarities between sugar molecules in honey matrix. This bottleneck was overcome by coupling Raman spectroscopy with chemometric methods (principal component analysis (PCA) and partial least squares (PLS)) and an artificial neural network (ANN). Model solutions of four sugars were processed with PCA and significant separation was observed. This operation, done with the spectral features by using PLS and ANN methods, led to the discriminant analysis of sugar contents. Models/trained networks were created using a calibration data set and evaluated using a validation data set. The correlation coefficient values between actual and predicted values of glucose, fructose, sucrose and maltose were determined as 0.964, 0.965, 0.968 and 0.949 for PLS and 0.965, 0.965, 0.978 and 0.956 for ANN, respectively. The requirement of rapid analysis of sugar contents of commercial honeys has been met by the data processed within this article.

The effect of Ramadan on maternal nutrition and composition of breast milk

Background: There are many advantages of breast milk for infants. Many factors can affect the volume and composition of breast milk. One of them is the maternal diet. The objective of this study is to determine the effect of Ramadan fasting on maternal nutrition and breast milk composition.

Determination of whey adulteration in milk powder by using laser induced breakdown spectroscopy

A rapid and in situ method has been developed to detect and quantify adulterated milk powder through adding whey powder by using laser induced breakdown spectroscopy (LIBS). The methodology is based on elemental composition differences between milk and whey products. Milk powder, sweet and acid whey powders were produced as standard samples, and milk powder was adulterated with whey powders. Based on LIBS spectra of standard samples and commercial products, species was identified using principle component analysis (PCA) method, and discrimination rate of milk and whey powders was found as 80.5%. Calibration curves were obtained with partial least squares regression (PLS). Correlation coefficient (R(2)) and limit of detection (LOD) values were 0.981 and 1.55% for adulteration with sweet whey powder, and 0.985 and 0.55% for adulteration with acid whey powder, respectively. The results were found to be consistent with the data from inductively coupled plasma - mass spectrometer (ICP-MS) method.

A high sensitive assay platform based on surface-enhanced Raman scattering for quantification of protease activity

In this study, a new, sensitive, and rapid assay was developed to quantitatively measure the proteolytic enzyme activity using the surface-enhanced Raman scattering (SERS) probe. Two different shapes of gold nanoparticles, gold nanosphere and nanorod particles were produced. SERS label, comprising self-assembled monolayers (SAMs) of Raman reporter molecule (5,5-Dithiobis (2-Nitrobenzoic acid), DTNB), was coated on the surface of the nanoparticles. Two different SERS-based analysis platforms were designed using gold-coated glass slide and polystyrene microtiter plate. The calibration curves were obtained by plotting the intensity of the SERS signal of symmetric NO(2) stretching of DTNB at 1326 cm(-1) vs. the protease concentration. The effects of nanoparticle geometry and assay platform on the protease assay were investigated and the best working combination of the parameters was selected as rod shaped SERS probe and gold-coated glass slide. The correlation between the protease activity and SERS signal was found to be linear within the range of 0.1-2 mU/mL (R(2)=0.979). The limit of detection (LOD) and limit of quantification (LOQ) values of the validated method were found as 0.43 and 1.30 mU/mL, respectively. The intra-day and inter-day precisions of the method, as relative standard deviation (RSD), were determined as 2.5% and 3.6%, respectively. The developed method was successfully applied for quantitative analysis of the commercial enzyme preparate that is used in cheese making process. It was also used for investigation of substrate specificity of protease enzyme towards the casein and bovine serum albumin. The proposed method has a flexibility to try different substrates for the detection of various enzyme activities.

Monitoring multiple components in vinegar fermentation using Raman spectroscopy.

In this study, the utility of Raman spectroscopy (RS) with chemometric methods for quantification of multiple components in the fermentation process was investigated. Vinegar, the product of a two stage fermentation, was used as a model and glucose and fructose consumption, ethanol production and consumption and acetic acid production were followed using RS and the partial least squares (PLS) method. Calibration of the PLS method was performed using model solutions. The prediction capability of the method was then investigated with both model and real samples. HPLC was used as a reference method. The results from comparing RS-PLS and HPLC with each other showed good correlations were obtained between predicted and actual sample values for glucose (R(2)=0.973), fructose (R(2)=0.988), ethanol (R(2)=0.996) and acetic acid (R(2)=0.983). In conclusion, a combination of RS with chemometric methods can be applied to monitor multiple components of the fermentation process from start to finish with a single measurement in a short time.

Use of Raman spectroscopy for determining erucic acid content in canola oil.

This study presents a novel method to determine erucic acid in canola oil samples by using Raman spectroscopy and chemometric analysis. The oil mixtures were prepared at various concentrations of erucic acid ranging from 0% to 33.56% (w/w) through binary combinations of different oils. In order to predict erucic acid content, Raman spectroscopy and GC results were correlated by means of partial least squares analysis. High coefficient of determination values was obtained for both calibration and validation data sets, which are 0.990 and 0.982, respectively. The results of the present study reveal the potential of Raman spectroscopy for rapid determination (45s) of erucic acid in canola oil. Further research would be useful to improve the method to put it forward as an alternative to GC in the erucic acid analysis.

Nitrite and Nitrate Levels of Gingival Crevicular Fluid and Saliva in Subjects with Gingivitis and Chronic Periodontitis

ABSTRACT Objectives Nitrosative stress plays an essential role in the pathogenesis of periodontal disease. The aim of this study is to analyze the gingival crevicular fluid and saliva nitrite and nitrate levels in periodontally healthy and diseased sites. Material and Methods A total of 60 individuals including, 20 chronic periodontitis and 20 gingivitis patients and 20 periodontally healthy controls participated in the present study. Probing depth, clinical attachment level, bleeding on probing, gingival index and plaque index were assessed, gingival crevicular fluid (GCF) and saliva samples were obtained from the subjects, including 480 GCF samples and 60 unstimulated whole saliva samples. Nitrite and nitrate were analyzed by Griess reagent. Results Total GCF nitrite levels were higher in gingivitis and periodontitis groups (1.07 [SD 0.62] nmol and 1.08 [SD 0.59] nmol) than the control group (0.83 [SD 0.31] nmol) (P < 0.05) but did not differ significantly between gingivitis and periodontitis groups (P > 0.05). The difference in GCF nitrate level was not significant among the control, gingivitis and periodontitis groups (7.7 [SD 2.71] nmol, 7.51 [SD 4.16] nmol and 7.38 [SD 1.91] nmol). Saliva nitrite and nitrate levels did not differ significantly among three study groups. Saliva nitrate/nitrite ratios were higher in periodontitis and gingivitis groups than the control group. A gradual decrease in nitrate/nitrite ratio in GCF was detected with the presence of inflammation. Conclusions It may be suggested that nitrite in gingival crevicular fluid is a better periodontal disease marker than nitrate and may be used as an early detection marker of periodontal inflammation, and that local nitrosative stress markers don’t show significant difference between the initial and advanced stages of periodontal disease.

Statistical Modeling of β-galactosidase Inhibition During Lactose Hydrolysis

A statistical model approach called response surface methodology was used to describe the product and substrate inhibition effect on β-galactosidase enzyme during lactose hydrolysis. The effect of independent variables, namely the initial concentrations of lactose (73 – 146 mM), galactose (44 – 122 mM) and glucose (83 – 167 mM) on the reaction rate of β-galactosidase was evaluated. The enzymatic reaction rate was influenced by both combined and individual effects of all the substrate and products. Although, glucose acted as an activator at low lactose and low galactose concentrations, glucose caused the inhibition of β-galactosidase at higher concentrations of lactose and galactose. The effect of galactose concentration on β-galactosidase enzyme was in the direction of inhibition. At low lactose concentrations and high glucose concentrations, galactose concentration became more effective on the reaction rate.

Analysis of Daytime Variations in Gingival Crevicular Fluid: A Circadian Periodicity?

BACKGROUND Volumetric alterations in gingival crevicular fluid (GCF) are widely accepted to be associated with periodontal health/disease. The volume/flow of GCF was shown to be affected by an array of methodological factors. However, relatively limited information is available on whether GCF is subject to circadian rhythm. The main aim of the present study is to assess the possible presence/absence of GCF circadian rhythm. The impact of the sampling technique on daytime volumetric variations is also analyzed. METHODS The possible daily volumetric variations of GCF with 2-hour intervals (from 08:00 to 18:00 hours) were assessed in 100 tooth sites and 600 GCF samples. Only maxillary incisors were included to eliminate any potential volumetric differences due to tooth dimensions. To analyze the potential impact of sampling technique on GCF volume and daytime variations, at one site modified intracrevicular sampling technique (MIST) was used, whereas the contralateral site was sampled with a deep intracrevicular sampling technique (DIST). Clinical periodontal parameters of the GCF sites were also recorded. RESULTS No significant daily variations in GCF volume could be detected. Higher volumetric measures were observed in inflamed subgroups compared with healthy subgroups (P <0.05). MIST was equivalent to DIST with regard to mean GCF volumes and the possible daytime volumetric alterations. CONCLUSIONS Within the limits of the present study, it can be suggested that daytime variations did not have significant impact on GCF volume. The sampling methodology had no apparent impact on the circadian periodicity of GCF.