Detection of the adulteration of olive oils by solid phase microextraction and multidimensional gas chromatography

The presence or absence of filbertone in 21 admixtures of olive oil with virgin and refined hazelnut oils obtained using various processing techniques from different varieties and geographical origins was evaluated by solid phase microextraction and multidimensional gas chromatography (SPME–MDGC). The obtained results showed that the sensitivity achievable with the proposed procedure was enough to detect filbertone and, hence, to establish the adulteration of olive oil of different varieties with virgin hazelnut oils in percentages of up to 7%. The very low concentrations in which filbertone occurs in some refined hazelnut oils made difficult its detection in specific admixtures. In any case, the minimum adulteration level to be detected depends on the oil varieties present in the adulterated samples. In the present study, the presence of R- and S-enantiomers of filbertone could be occasionally detected in olive oils adulterated with 10–20% of refined hazelnut oil.     

Evaluation of the spiral plating method for the enumeration of microorganisms throughout the manufacturing and ripening of a raw goat's milk cheese

A statistical comparison of the spiral plate count (SPLPC) and the standard plate count (SPC) methods for enumeration of microorganisms in raw goat's milk cheese throughout its manufacturing and ripening was carried out. Enumeration of mesophiles, lactic acid bacteria (presumptive lactococci, presumptive leuconostocs, and presumptive lactobacilli), Micrococcaceae, Enterobacteriaceae, and molds and yeasts was carried out for milk, curd, and 2-, 5-, 10-, 17-, and 27-day-old cheeses. Average counts for the SPLPC and SPC methods differed by less than half of a log cycle for all microbial groups studied (range of difference, -0.1386 [mesophiles] to +0.4397 [presumptive lactobacilli]). The results of the SPLPC method compared favorably with the results of the SPC procedure for mesophiles, presumptive lactococci, presumptive leuconostocs, Enterobacteriaceae, and molds and yeasts (the variance between replicate platings was close to 0.005, and correlation coefficients were >0.9). Correlation coefficients were lower for Micrococcaceae (r = 0.824) and presumptive lactobacilli (r = 0.670). Analysis of variance showed that the plating method was a significant factor (P < 0.05) for presumptive lactobacilli counts. In general, results from the SPLPC method compared favorably with results from SPC procedure in the enumeration of microorganisms in goat cheese throughout its manufacturingand ripening processes. However, the suitability of the SPLPC method depends mainly on the microbial group studied.     

Hot water and organic acid interventions to control microbiological contamination on hog carcasses during processing

Pork skin and muscle tissue were washed with water at temperatures from 25 to 80 degrees C. Water temperatures of 65 and 80 degrees C resulted in greater population reductions of Enterobacteriaceae on pork muscle tissue than lower water temperatures. There was no observable effect of water temperature on population reductions of Enterobacteriaceae on pork skin. Water temperatures of 55, 65, and 80 degrees C reduced the populations of Enterobacteriaceae on inoculated scalded carcasses processed in a university abattoir by 1 to 1.5 log/cm2. Following the water wash with an organic acid rinse resulted in further numerical reductions in populations, although these were not statistically different from the water wash alone. The jowls of both scalded and skinned carcasses processed in a commercial establishment were directly inoculated with a fecal material slurry and then processed with organic acid rinsing only, hot water washing only, or a combination of hot water washing followed by organic acid rinsing. The hot water and acid treatment reduced the populations of mesophilic aerobic bacteria and Escherichia coli by approximately 2 log cycles on both scalded and skinned hog carcasses. The combined treatment resulted in 60% of the scalded carcasses and 40% of the skinned carcasses with undetectable levels of E. coli after direct fecal inoculation of the carcasses. Hot water washing followed by organic acid rinsing can significantly improve the microbiological quality of pork carcasses.     

Study of the inhibitory effect of hydrophobic fluorescent markers on the enzymic coagulation of bovine casein micelles: action of TNS

The interaction of 2-(p-toluidinyl) naphthalene-6-sulfonate (TNS) with casein micelles (CM) was studied by fluorescence spectroscopy. Fluorescence emission spectra of the complex showed blue shift and intensity enhancement of TNS fluorescence, suggesting the insertion of the marker in low polarity regions of CM. An energy transfer process between the proteins and the marker was detected, showing that most of the TNS binding sites were in the proximity of CM fluorescent residues. TNS inhibited the aggregation step of CM enzymic coagulation, producing probably a decrease of size and amount of aggregates formed. This effect could not be related only to changes in CM net charge, but also possibly to the occupancy of surface hydrophobic regions by the marker. About a 20% decrease in the TNS fluorescence intensity was observed during the proteolytic step of coagulation which could be attributed to release of the marker from its binding sites located in the CM external layer. A bound TNS release was also observed during the initial time of the aggregation step, probably by removal of the bound marker from contact regions between aggregating particles upon their collisions. A further increase, related to the aggregation step, could indicate the uptake of the marker by new hydrophobic sites created in the complex structure of the clusters. The results pointed to the participation of surface hydrophobic regions of renneted CM in their aggregation process.     

Identification of cocoa butter equivalents added to cocoa butter I. An approach by fatty acid composition of the triacylglycerol sub-fractions separated by Ag+-HPLC

 Separation of the six sub-fractions of triacylglycerols (TAG) from cocoa butter, three cocoa butter equivalents (CBEs: calvetta, choclin and coberine) and their mixtures was carried out by silver ion high-performance liquid chromatography. The percentage fatty acid composition of all these sub-fractions was then measured by high-resolution gas chromatographic analysis of the methyl esters of the constitutive fatty acids. In particular, the percentage quantities of all acids in the fully saturated sub-fraction of pure fats and some of their mixtures were evaluated as a function of the percentage CBEs added to cocoa butter in order to devise multiple regression models. The aim was to obtain statistical tools for the identification and/or quantification of added CBEs. The results obtained show the effectiveness of TAG sub-fraction percentage fatty acid composition data for the purposes of research, as well as the potential use of stereospecific analysis of the same sub-fractions. In fact, the stereospecific analysis of TAG fractions from cocoa butter and CBEs already carried out has enabled observation of the different distributions of various fatty acids in the glycerol backbone of TAG from cocoa butter and the CBEs under study, and this will certainly result in the development of more powerful and discriminating statistical models. Received: 12 August 1997 / Revised version: 19 December 1997     

Commiphora myrrha (Nees) Engl. extracts: evaluation of antioxidant and antiproliferative activity and their ability to reduce microbial growth on fresh‐cut salad

With the aim to develop natural preservatives displaying also chemopreventive activity, different Commiphora myrrha (Nees) Engl. extracts were studied. Myrrh essential oils, obtained by steam distillation and microwave‐assisted hydrodistillation, and several other extracts, obtained by sequential procedures with petroleum ether (PE), ethanol, ethyl acetate and butanol, have been screened for their antioxidant (DPPH· scavenging assay) and antiproliferative activity (on both nontumour and colon cancer cell lines) without previous purification. Considering that the colon cancer cell lines were more sensitive to PE and ethanol extracts, the latter of which showed the highest antioxidant activity (EC50 = 0.160 ± 0.008 mg mL^?1), both have been selected for further antibacterial/antifungal activity tests using an antimicrobial diffusion test and a growth inhibition test on salads. Results showed that the ethanol extract possessed the higher antibacterial and antifungal activity. Compared to untreated product, fresh‐cut salads treated with these two myrrh extracts displayed a significant lower bacterial growth. Although further investigation is required, these promising results offer hints as how to improve the shelf life of fresh‐cut salad.     

Anthocyanin profile of red fruits and black carrot juices,purees and concentrates by HPLC‐DAD‐ESI/MS‐QTOF

A fast and reliable method for anthocyanin extraction and identification by HPLC‐DAD‐ESI/MS‐QTOF was used to analyse the anthocyanin composition of commercial red fruit juices (blackberry, redcurrant and pomegranate), purees (strawberry, cherry and raspberry) and concentrates (elderberry, blueberry and red grape). The anthocyanin profile of black carrot juice is also reported. The extraction and analysis method allowed us to detect and quantify a wide range of individual anthocyanins in a simple and rapid way. Pelargonidin‐3‐glucoside was detected in redcurrant for the first time and petunidin‐3‐galactoside quantified for the first time in blueberries. Considering the health benefits that have been associated with anthocyanin consumption, all these fruit and vegetables processed products could appear as a good source of this group of phytochemical compounds for their direct consumption or their use as ingredients for the design of new food product or food supplements.     

Short communication: Space allocation in intensive Mediterranean buffalo production influences the profile of functional biomolecules in milk and dairy products

The aim of the present study was to determine if space allocation influenced the concentration of biomolecules in buffalo milk and dairy products. Intensively housed buffaloes (n = 96) were randomly assigned to 2 groups according to days in milk, parity, and milk yield: group S10 had a space allocation of 10 m² per buffalo and group S15 had a space allocation of 15 m² per buffalo. Individual milk yield was recorded daily. Twice a month, a bulk milk sample was collected for each group, as well as whey, ricotta, and mozzarella cheese, to assess cheese yield and to conduct HPLC-electrospray ionization-tandem mass spectrometry, milk antioxidant activity, and cell viability analyses. We tested milk extracts from the 2 groups in vitro to evaluate their efficacy in counteracting endothelial oxidative damage induced by high glucose. We evaluated reproductive function in 28 buffaloes from each group using the Ovsynch-timed artificial insemination program. We observed no differences in milk quantity or quality in terms of fat, protein, or lactose, and reproductive function did not differ between the 2 groups. Compared with group S10, group S15 had higher concentrations of carnitine (56.7 ± 1.1 vs. 39.8 ± 0.7 mg/L in milk and 40.9 ± 0.8 vs. 31.7 ± 0.7 mg/L in whey), acetyl-l-carnitine (51.9 ± 0.3 vs. 39.7 ± 0.7 mg/L in milk and 41.1 ± 1.7 vs. 28.7 ± 2.6 mg/L in whey), propionyl-l-carnitine (34.8 ± 1.0 vs. 21.0 ± 0.9 mg/L in milk and 26.9 ± 0.8 vs. 17.6 ± 1.2 mg/L in whey), glycine betaine (23.1 ± 1.9 vs. 13.5 ± 1.6 mg/L in milk and 10.7 ± 0.4 vs. 7.9 ± 0.5 mg/L in whey), and δ-valerobetaine (24.2 ± 0.5 vs. 16.7 ± 0.5 mg/L in milk and 22.0 ± 0.9 vs. 15.5 ± 0.7 mg/L in whey). Group S15 also had higher total antioxidant activity than group S10 (56.7 ± 1.9 vs. 46.4 ± 1.13 mM Trolox equivalents). Co-incubation of high-glucose-treated endothelial cells with milk extracts from group S15 improved cell viability compared with cells treated with high glucose only; it also reduced intracellular lipid peroxidation (144.3 ± 0.4 vs. 177.5 ± 1.9%), reactive oxygen species (141.3 ± 0.9 vs. 189.3 ± 4.7 optical density units), and cytokine release (tumor necrosis factor-α, IL-1β, IL-6). Greater space allocation was associated with higher levels of biomolecules in buffalo milk. This could have been the result of improved welfare in buffaloes that were allocated more space.