Determination of the overall migration from silicone baking moulds into simulants and food using 1H-NMR techniques

Different silicone baking moulds (37 samples) were characterized with respect to potential migrating substances using ¹H-NMR, RP-HPLC–UV/ELSD and GC techniques. In all cases cyclic organosiloxane oligomers with the formula [Si(CH₃)₂–O] _n were identified (n = 6 … 50). Additionally, linear, partly hydroxyl-terminated organosiloxanes HO–[Si(CH₃)₂–O] _n –H (n = 7 … 20) were found in 13 samples. No substances other than siloxanes could be detected, meaning the migrants mainly consist of organopolysiloxanes. Based on this knowledge, a ¹H-NMR quantification method for siloxanes was established for the analysis of both simulants and foodstuffs. Validation of the ¹H-NMR method gave suitable performance characteristics: limit of detection 8.7 mg kg^–1 oil, coefficient of variation 7.8% (at a level of 1.0 mg kg^–1 food). Migration studies were carried out with simulants (olive oil, isooctane, ethanol (95%), Tenax) as well as preparation of different cakes. From the 1st to 10th experiment, siloxane migration into cakes only slightly decreased, with a significant dependence on fat content. Migration never exceeded a level of 21 mg kg^–1 (3 mg dm^–2) and was, therefore, well below the overall migration limit of 60 mg kg^–1 (10 mg dm^–2). However, migration behaviour into simulants differed completely from these results.     

Evaluation of the effect of carvacrol on the Escherichia coli 555 metabolome by using H-NMR spectroscopy

Cultures of Escherichia coli 555 were grown at four levels of carvacrol (0–2 mM) and the E. coli endo-metabolome was extracted and measured by ¹H NMR spectroscopy. The results show that glucose concentration is going up with concentration of carvacrol and so do formate until the highest concentration is reached, from which point it suddenly decreases. This is interpreted as if the bacteria are increasingly unable to further metabolize glucose and as if the bacteria increasingly shifts with higher levels of carvacrol toward sugar fermentation as carbon source, until the level of carvacrol reaches a level (2.00 mM), where the E. coli must give up. Additionally, the multivariate Principal Component Analysis suggests that the adaptation occurring at sub-lethal doses of carvacrol is different from that occurring at higher doses.     

Assessing the association between phenolic compounds and the antioxidant activity of Brazilian red wines using chemometrics

The objective of this study was to evaluate the association among chemical parameters, the commercial value, and the antioxidant activity of Brazilian red wines using chemometric techniques. Twenty-nine samples from five different varieties were assessed. Samples were separated into three groups using hierarchical cluster analysis: cluster 1 presented the highest antioxidant activity towards DPPH (68.51% of inhibition) and ORAC (30,918.64 μmol Trolox Equivalents/L), followed by cluster 3 (DPPH = 59.36% of inhibition; ORAC = 25,255.02 μmol Trolox Equivalents/L) and then cluster 2 (DPPH = 46.67% of inhibition; ORAC = 19,395.74 μmol Trolox Equivalents/L). Although the correlation between the commercial value and the antioxidant activity on DPPH and ORAC was not statistically significant (P = 0.13 and P = 0.06, respectively), cluster 1 grouped the samples with higher commercial values. Cluster analysis applied to the variables suggested that non-anthocyanin flavonoids were the main phenolic class exerting antioxidant activity on Brazilian red wines.     

Effects of noble rot on must composition and aroma profile of Amarone wine produced by the traditional grape withering protocol

The effects of noble rot on the overall quality of Amarone wine, a “Passito” dry red wine, produced by a traditional withering grape process are poorly understood. Wines obtained from healthy and selected grapes infected by noble rot were compared. Validation of the experimental plan was carried out by determining glycerol and gluconic acid content, laccase activity and microbial analysis of the musts. Botrytis cinerea infection produced significant variation in esterase and β-glucosidase activity of grape must. Aroma analysis in healthy and botrytised wines was carried out by SPE extraction followed by GC–MS quantification. A decrease of several fermentative esters was observed in botrytised wine, while wine produced from healthy grapes showed a higher fatty acid content. Molecules such as 1-octen-3-ol, phenylacetaldehyde and furaneol were positively linked to the noble-rotten grapes. Interestingly, γ-nonalactone and 4-carbethoxy-γ-butyrolactone increased, while sherry lactones decreased in botrytised wine. The strong increase of N-(3-methylbutyl)acetamide was related to B. cinerea grape infection.     

Using <Superscript>1</Superscript>H and <Superscript>13</Superscript>C NMR techniques and artificial neural networks to detect the adulteration of olive oil with hazelnut oil

The lack of any official analytical method to detect the adulteration of olive oil with a low percentage of hazelnut oil is explained by the similarities in the chemical compositions of both kinds of oils. To counter this problem, an artificial neural network based on ¹H-NMR and ¹³C-NMR data has been developed to detect olive oil adulteration, and the results from this ANN are presented here. A training set consisting of hazelnut oils, pure olive oils, and olive oils blended with 2–20% hazelnut oils was used to design and train a multilayer perceptron with 100% correct classifications. This mathematical model was also validated using an external validation set of blend samples (3–15%) and genuine samples. The detection limit of the model was around 8%.     

Diffusion of NaCl in meat studied by (1)H and (23)Na magnetic resonance imaging

The effect of sodium chloride (NaCl) diffusion into meat was investigated. Proton and sodium magnetic resonance imaging were used to determine the diffusion behaviour of brine (NaCl) in porcine Longissimus dorsi and semitendinosus. NaCl diffusion was visualized through images and diffusion coefficients were determined to be in the range 3-7×10(-10)m(2)s(-1), which is in agreement with values reported in the literature. The diffusion coefficient was found to increase during curing, suggesting microstructural changes in the meat. A supplementary experiment proved that the diffusion behaviour of sodium chloride in regions of meat with connective tissue/fat is distinctive from regions with pure myofilament tissue, as anticipated. Apparent diffusion coefficient (ADC) maps showed that meat microstructures shrunk when cured with 20% (w/w) NaCl brine. ADC across (⊥) the main muscle fiber direction decreased more than ADC along (‖) the main muscle fiber direction. The greater shrinkage in the direction across muscle fibers suggests that the curing induced shrinkage of the transverse structures rather than reduction in longitudinal structures.     

Phosphorylation of proteins by dry-heating in the presence of pyrophosphate and some characteristics of introduced phosphate groups

Various proteins and dextrin were phosphorylated by dry-heating in the presence of pyrophosphate, and phosphate bonds characterised. The basic proteins were more highly phosphorylated than acidic proteins by dry-heating in the presence of pyrophosphate. The phosphorylated poly-l-lysine hydrobromide (PP-PLy) and lysozyme (PP-Lz) were more highly dephosphorylated than phosphorylated dextrin and ovalbumin (PP-OVA) by phosphatases, and the dephosphorylation of PP-PLy was much higher than that of PP-Lz. The phosphate bonds in all phosphorylated samples were stable during heating at 120 °C. The ³¹P NMR spectral data suggested that different types of phosphate bonds were introduced, and the N–P bond was suggested in PP-PLy. Some phosphorylated tryptic peptides from PP-Lz and PP-OVA were detected by mass spectrometry analysis. Furthermore, the introduced phosphate linkages in peptides from PP-Lz and PP-OVA were identified.     

Influence of variety and commercial yeast preparation on red wine made from autochthonous Hungarian and Canadian grapes. Part I: phenolic composition

Eight wines were made from two Canadian hybrid grape varieties (Maréchal Foch, Baco Noir) and two Hungarian Vitis vinifera varieties (Kadarka, Lemberger). One half was kept untreated; the other half received a commercial yeast preparation (OptiRed^®) before fermentation. Significant differences were found between varieties for basic measures of wine quality, including pH, titratable acidity, ethanol, colour density, hue and total phenolics. Quercetin was identified only in Maréchal Foch and Baco Noir wines, and quercetin-glucoside only in Baco Noir. Varietal differences were also found in the concentrations of the 11 other colourless phenolic monomers measured, especially gallic acid, protocatechuic acid, tyrosol, caftaric acid, catechin, caffeic acid, GRP, epicatechin, p-coumaric acid, ferulic acid and trans-resveratrol. The Canadian wines had higher concentrations of the four anthocyanins measured (malvidin, delphinidin, petunidin and peonidin), higher anti-oxidative capacity, and were characterised by lower ratios of monomeric/polymeric phenolics. Addition of OptiRed^® had little impact on the basic measures of wine quality. Concentrations of gallic acid, protocatechuic acid, caftaric acid and catechin were, on average, 6% higher in wines made from OptiRed^®-treated musts. A trend was observed for all varieties in OptiRed^®-treated wines of a greater proportion of the procyanidins being presented as polymeric rather than monomeric phenolics.     

Effects of milk fat composition, DGAT1, and SCD1 on fertility traits in Dutch Holstein cattle

Recently, selective breeding was proposed as a means of changing the fatty acid composition of milk to improve its nutritional quality. Before implementing such breeding objectives, effects on other economically important traits should be investigated. The objectives of this study were to examine 1) the effect of milk fat composition, and 2) the effect of polymorphisms of DGAT1 and SCD1 genes on female fertility in commercial Dutch Holstein-Friesian cattle. Data on 1,745 first-lactation cows were analyzed by fitting linear mixed models. We found that higher concentrations of trans fatty acids within total milk fat negatively affected reproductive performance. Furthermore, results suggested a potential effect of the DGAT1 polymorphism on nonreturn rates for insemination 28 and 56 d after the first service. Our results can be used to assess the correlated effects of breeding for improved milk fat composition on reproduction, thereby allowing for better evaluation of breeding programs before implementation.     

The role of acidity,sweetness, tannin and consumer knowledge on wine and food match perceptions

The purposes of this study were to (1) explore significant differences in perception of match for a variety of food and wine styles; (2) evaluate the impacts of wine sweetness level, wine acidity level, and wine tannin level on perception of match; and (3) investigate the impact of food and wine expertise on perceived level of match. The highest perceived wine matches for each food item were: Sauvignon Blanc and chêvre, Chardonnay and brie, Cabernet Sauvignon and spicy Italian salami, and Port and milk chocolate. Wine sweetness, acidity, and tannin levels all significantly impacted the level of match with certain food items. Food and wine expertise also significantly impacted the level of match, indicating differences between the more expert and novice participants in the role wine sweetness, acidity, and tannin had on level of match.     

Effects of variation in porcine MYOD1 gene on muscle fiber characteristics, lean meat production, and meat quality traits

Three single nucleotide polymorphisms (SNPs) in the porcine MYOD1 gene were used for association analysis and haplotype construction to evaluate the effects of their substitution. Four hundred and three pigs of Yorkshire and Berkshire breeds were used. The mRNA expression levels of MYOD1 were examined. The g.489C>T and g.1264C>A SNPs were significantly associated with several muscle fiber characteristics, the loin eye area, and lightness. Particularly, animals having hetero-genotypes of both sites showed good performance both in lean meat production and meat quality traits. The results of haplotype substitution were similar to the associations of individual SNPs. Moreover, the 2 SNPs had significant effects on mRNA expression. Therefore, the g.489C>T and g.1264C>A SNPs in MYOD1 may be meaningful DNA markers that can be used for improving important porcine economic traits.     

Statistical study of the influence of fungicide treatments (mancozeb,zoxamide and copper oxychloride) on heavy metal concentrations in Sicilian red wine

The aim was to assess the influence of mancozeb, zoxamide and copper oxychloride fungicide treatments on Mn, Zn, Cu, Cd and Pb concentrations in Sicilian red wines, grapes, marcs and grape stalks. The experimentation was carried out over two crop years: 2003 and 2004. Trace metals analysis was performed by derivative stripping chronopotentiometry, which allowed detection of concentrations lower than 1 ng g^?1. The data obtained gave evidence that the levels of Mn and Zn in wines from plots treated with zoxamide–mancozeb were about threefold higher than those observed in the control. Wines treated with Cu oxychloride had a significant increase in Cu(II) concentrations with respect to the control; in particular, samples from 2004 showed a 50% increase in Cu levels. Furthermore, as shown in a previous paper, the fungicides treatments studied led to a moderate increase in Pb(II) and Cd(II) levels in treated samples with respect to the control. Wines from 2004 had higher Cu and Pb amounts than wines from 2003; but the concentrations of all the other metals were similar. Statistical analysis of the data by linear discriminant analysis (LDA) and the Kruskal–Wallis test confirmed that both zoxamide–mancozeb treatments and copper oxychloride treatments exerted a significant influence on Mn(II), Zn(II) Cu(II), Pb(II) and Cd(II) concentrations in wines, grapes, marcs and grape stalks samples from both the studied vintages.     

Statistical study of the influence of fungicide treatments (mancozeb, zoxamide and copper oxychloride) on heavy metal concentrations in Sicilian red wine

The aim was to assess the influence of mancozeb, zoxamide and copper oxychloride fungicide treatments on Mn, Zn, Cu, Cd and Pb concentrations in Sicilian red wines, grapes, marcs and grape stalks. The experimentation was carried out over two crop years: 2003 and 2004. Trace metals analysis was performed by derivative stripping chronopotentiometry, which allowed detection of concentrations lower than 1 ng g^-1. The data obtained gave evidence that the levels of Mn and Zn in wines from plots treated with zoxamide-mancozeb were about threefold higher than those observed in the control. Wines treated with Cu oxychloride had a significant increase in Cu(II) concentrations with respect to the control; in particular, samples from 2004 showed a 50% increase in Cu levels. Furthermore, as shown in a previous paper, the fungicides treatments studied led to a moderate increase in Pb(II) and Cd(II) levels in treated samples with respect to the control. Wines from 2004 had higher Cu and Pb amounts than wines from 2003; but the concentrations of all the other metals were similar. Statistical analysis of the data by linear discriminant analysis (LDA) and the Kruskal-Wallis test confirmed that both zoxamide-mancozeb treatments and copper oxychloride treatments exerted a significant influence on Mn(II), Zn(II) Cu(II), Pb(II) and Cd(II) concentrations in wines, grapes, marcs and grape stalks samples from both the studied vintages.     

Accurate determination of the Ca activity in milk-based systems by Ca-ISE: Effects of ionic composition on the single Ca activity coefficient and liquid junction potentials

Calcium ion selective electrode (Ca-ISE) was found to underestimate the actual Ca²⁺ ion activity in simulated milk ultrafiltrate (SMUF) and milk. It is shown that the ionic compositional difference between conventional calibration solutions and milk type samples had a significant effect on the single Ca²⁺ activity coefficient, which generates the erroneous estimate of Ca²⁺ activities in SMUF and milk. This study tests new standards with ionic profiles similar to SMUF, aiming at the reduction of the errors generated by the compositional difference between conventional standards and milk samples. As a result, the new standards showed a significant improvement in the accuracy of Ca²⁺ activity and Ca²⁺ activity coefficient over the conventional standards. The systematic error is reduced from 20% to 5% for SMUF and from 44% to 15% for milk. In addition, the new standards generate liquid junction potentials that are practically insignificant.     

A study of the evolution of the physicochemical and structural characteristics of olive and sunflower oils after heating at frying temperatures

The evolution of the density, viscosity, oil/water interfacial tension and structure of vegetable oils after heating at frying temperatures was studied to explore the possibility of reusing waste vegetable oils as solid agglomerants for different purposes. Commercial olive and sunflower oils were heated at 150 and 225 °C in the time interval of 1–15 days to achieve a wide range of alteration degrees. Structural changes in the oils were monitored by FT-IR and ¹H NMR. Significant variations occur in the physicochemical and structural characteristics of these oils, which may affect their agglomeration capability, when they were heated at frying temperatures for periods above two days. Under these conditions, the viscosity of the oils increased very quickly, whereas their unsaturation degree decreased noticeably. Decreases in the relative intensities of the NMR spectra signals of the unsaturation-related protons were observed, those corresponding to the diallyl protons occurring much faster. Of the two vegetable oils studied, sunflower oil was found to be more sensitive to thermal treatment, undergoing greater changes in its properties, especially in viscosity, which may show a marked increase.     

Effects of Leuconostoc mesenteroides starter cultures on microbial communities and metabolites during kimchi fermentation

Kimchi fermentation usually relies upon the growth of naturally-occurring various heterofermentative lactic acid bacteria (LAB). This sometimes makes it difficult to produce kimchi with uniform quality. The use of Leuconostoc mesenteroides as a starter has been considered to produce commercial fermented kimchi with uniform and good quality in Korea. In this study, a combination of a barcoded pyrosequencing strategy and a ¹H NMR technique was used to investigate the effects of Leu. mesenteroides strain B1 as a starter culture for kimchi fermentation. Baechu (Chinese cabbage) and Chonggak (radish) kimchi with and without Leu. mesenteroides inoculation were prepared, respectively and their characteristics that included pH, cell number, bacterial community, and metabolites were monitored periodically for 40 days. Barcoded pyrosequencing analysis showed that the numbers of bacterial operational taxonomic units (OTU) in starter kimchi decreased more quickly than that in non-starter kimchi. Members of the genera Leuconostoc, Lactobacillus, and Weissella were dominant LAB regardless of the kimchi type or starter inoculation. Among the three genera, Leuconostoc was the most abundant, followed by Lactobacillus and Weissella. The use of Leu. mesenteroides as a starter increased the Leuconostoc proportions and decreased the Lactobacillus proportions in both type of kimchi during kimchi fermentation. However, interestingly, the use of the kimchi starter more highly maintained the Weissella proportions of starter kimchi compared to that in the non-starter kimchi until fermentation was complete. Metabolite analysis using the ¹H NMR technique showed that both Baechu and Chonggak kimchi with the starter culture began to consume free sugars earlier and produced a little greater amounts of lactic and acetic acids and mannitol. Metabolite analysis demonstrated that kimchi fermentation using Leu. mesenteroides as a starter was completed earlier with more production of kimchi metabolites compared to that not using a starter, which coincided with the decreases in pH and the increases in bacterial cell number. The PCA strategy using all kimchi components including carbohydrates, amino acids, organic acids, and others also showed that starter kimchi fermented faster with more organic acid and mannitol production. In conclusion, the combination of the barcoded pyrosequencing strategy and the ¹H NMR technique was used to effectively monitor microbial succession and metabolite production and allowed for a greater understanding of the relationships between the microbial community and metabolite production in kimchi fermentation.     

Influence of Dekkera bruxellensis on the contents of anthocyanins,organic acids and volatile phenols of Dão red wine

The anthocyanin, organic acid and volatile phenol compositions of red wine obtained from Touriga Nacional grapes growing in the Dão region (Portugal) were determined by HPLC/DAD, HPLC/UV and GC/FID, respectively. By these means, nine anthocyanic compounds (malvidin-3,5-O-diglucoside, cyanidin-3-O-galactoside, cyanidin-3-O-glucoside, peonidin-3-O-glucoside, malvidin-3-O-glucoside, delphinidin, cyanidin, pelargonidin and malvidin), six organic acids (ketoglutaric, tartaric, malic, quinic, lactic and shikimic acids) and two volatile phenols (4-ethylguaiacol and 4-ethylphenol) were identified and quantified. Malvidin-3-O-glucoside, the pair lactic plus shikimic acids and 4-ethylguaiacol were the main anthocyanin, organic acids and volatile phenol, respectively. The effects of nine different Dekkera bruxellensis strains on these chemical parameters were also evaluated. The results obtained indicate that some strains of D. bruxellensis yeast are able to cause deterioration of red wine from the Dão region during its maturation by the production of volatile phenols, namely 4-ethylphenol.     

Effects of menthol stereoisomers on the growth,sporulation and fumonisin B1 production of Fusarium verticillioides

Menthol is a naturally occurring cyclic terpene alcohol of plant origin from the Lamiaceae family. It has three chiral centres, implying eight possible different stereoisomers, which in turn define four pairs of enantiomers. This is the first work that reports on the stereoselective antifungal and antitoxigenic activities of the menthol stereoisomers on Fusarium verticillioides, with the (−)-menthol and (+)-menthol enantiomers found to be the most active inhibitors of fungal growth and sporulation. The results obtained suggest the importance of the presence of these substituents in the equatorial positions of menthol stereoisomers in the antifungal activity. The stereoisomer (−)-menthol, followed by (+)-menthol, were the most active compounds in the inhibition of fumonisin B₁ (FB₁) biosynthesis. The different antitoxigenic activities of (−)-menthol and (+)-menthol revealed that the molecular requirements to affect the FB₁ production were dependent not only on the presence of the substituents in the equatorial positions, but also on their spatial arrangements.