Search

SynopsisObjective The aim of this study was to prove the capability of β-cyclodextrin (β-CD) to interact with some representative molecules responsible to cause body malodour, such as carboxylic acids, thiols and steroids, present in sweat and body secretions. Methods The association constants in guest-CD were determined by 1H-NMR spectroscopy for thiols and steroids such as 3-mercapto-1-hexanol, androstenone, androstenol and androsterone, and pH-potentiometric titration for acetic acid, l(+) lactic acid, isobutyric acid, isovaleric acid and 3-hydroxy-3-methyl-hexanoic acid. Results All considered systems are able to interact with relatively weak association constants with β-cyclodextrin, in a 1 : 1 host–guest ratio. Conclusion From these findings, it is possible to conclude that β-CD is capable to interact with different components present in the sweat and body secretion, forming inclusion complexes. For this reason, β-CD could be a component of body care formulations, such as deodorants.

Parmigiano–Reggiano (P–R) cheese is still one of the most valuable Protected Designation of Origin (PDO) cheeses of Italy. The rind percentage (from 12% to 50%), the ripening (from 13 to 31 months), the moisture content and the differences between true P–R and competitors were determined by means waveguide spectroscopy. Preliminary tests were carried out in the 2–20 GHz frequency range (with a span of 1 GHz) to investigate which 1 GHz frequency range contains most information on the rind percentage and on the months of ripening. Partial Least Squares (PLS) regression was used to predict rind percentage, months of ripening and moisture in the previously selected frequency ranges (2–3, 5–6 and 17–18 GHz for the rind percentage; 2–3, 5–6 and 16–17 GHz for the months of ripening). Moreover, Soft Independent Modelling of Class Analogy (SIMCA) analysis was used to discriminate the samples according to the rind percentage. Principal component analysis (PCA) was used to discriminate true P–R cheese from competitors. PLS models ( test set validation ) showed R 2 values up to 0.944 (root mean square error of prediction in test set validation, RMSE p = 3.4%), 0.966 (RMSE p = 1.2 months) and 0.786 (RMSE p = 0.99%) for the prediction of rind percentage, months of ripening and moisture percentage, respectively. As a result only a part of the prediction of rind percentage and ripening can easily be attributed to the moisture. For each considered frequency range, all samples belonging to the classes characterized by 12% and 50% of rind were correctly classified. Competitors were clearly separated from P–R cheese by the PCA analysis of the spectral signals and their moisture was predicted with a R 2 values up to 0.942 ( test set validation ). In this case, the discrimination power can be mainly attributed to moisture content.

Soluble solids content (SSC) and Magness–Taylor flesh firmness (MTf) of “Hayward” kiwifruits were non-destructively assessed by means of a waveguide, that houses the fruit, connected to a sweeper oscillator and a spectrum analyzer. A preliminary test was conducted with a plastic fruit filled with solutions with different SSC values in the frequency range from 2 to 20 GHz (with a step of 1 GHz). The best linear correlations ( R 2 up to 0.987) between electric signals and SSC solutions in the above described test were found in the 2–3 GHz and 15–16 GHz steps. These steps were used for the dielectric measurements on kiwifruit samples during storage of 28 days at 14 °C. Partial least squares (PLS) regression were then used to predict SSC and MTf from these acquired spectra. In “test set” validation, PLS models showed R 2 values up to 0.804 (RMSE = 0.98 °Brix) and 0.806 (RMSE = 8.9 N) for the prediction of SSC and MTf, respectively.

In the present research, a method based on admittance measurements able to assess total solids and fat contents (%) in nine different liquid whole egg products was set up. By means of a tetrapolar platinum cell connected to a signal conditioning circuit, an alternating current generator and a data acquisition system, the effect of 15 different combinations of frequencies of the oscillating field (10, 100, 500, 1000 and 5000 Hz) and input voltage levels (1, 1.5 and 2 V) on the estimation of the total solids and fat contents were analyzed. The influence of the temperature solution on the electrical measurements was also assessed. The best estimations were obtained at 1000 Hz and 1 V (R^2 = 0.998; SE = 0.14%) for the total solids content and at 5000 Hz and 1 V (R^2 = 0.995; SE = 0.19%) for the fat content. For both parameters, the measurements conducted at 10 Hz appeared affected by the polarization occurring at the electrodes-solution interface. The admittance of the liquid whole egg products linearly increased with the temperature, and a temperature coefficient θ at 20 °C of about 2.1 was calculated. These excellent results encourage an industrial application of the technique for a rapid and economic assessment of the total solids and fat contents in the liquid egg products.

The input of a waveguide probe for shell eggs was connected to a sinewave sweeper oscillator and the signal at the output was captured by a spectrum analyser. A first analysis was carried out in the range from 3 to 20 GHz with a span of 1 GHz to investigate which 1 GHz frequency range contains most information for predicting the main quality indices of eggs during 15 days of storage. Simple linear regression models were therefore set up and the coefficient of determination was calculated. The absorbance spectra in the range thus identified (from 10.5 to 11.5 GHz) were used to predict the quality indices by means of an artificial neural network (ANN). The R 2 values of the obtained ANN in validation mode were 0.918, 0.854 and 0.912 for the air cell, the thick albumen height and the yolk index, respectively. The correlations between the quality parameters and tests carried out on albumen, yolk and plastic eggs for simulating the air cell showed how one index can be indirectly predicted through another one.

A resistive barrier discharge (RBD) prototype able to generate gas plasma at atmospheric conditions was set up. The discharge was electrically characterized and the plasma glow was analysed by optical emission spectroscopy. The decontamination power of the device was assessed on samples of shell eggs experimentally inoculated with Salmonella Enteritidis and Salmonella Typhimurium (5.5–6.5 Log CFU/eggshell) and placed in the treatment chamber. Different decontamination times (10, 20, 30, 45, 60 and 90 min) and relative humidity values (RH) of the gas mixture in the chamber (i.e. 35% and 65%, at 25 °C) were considered. All samples were treated in the plasma after-glow chamber where the measured temperature was not much higher than the room temperature, minimizing the risk of egg quality alterations. The discharge was characterized by a potential difference of about 15 kV; the emission spectra showed the presence of very reactive species such as the positive ion N 2 + and OH and NO radicals. After 90 min of treatment, reductions up to 2.5 Log CFU/eggshell and 4.5 Log CFU/eggshell were observed for S. enteritidis using air with low and high moisture contents, respectively. No significant negative effects of the gas plasma were observed on the egg quality traits.

The present study investigates the possibility of predicting the main quality indices of shell eggs by means of a dielectric technique based on a capacitor probe and a fully integrated RF circuit for measuring the amplitude and phase differences between two independent input signals. Samples of eggs were submitted to dielectric measurements in the range 50–500MHz after 1, 2, 4, 8, and 15 days of storage at room temperature (20 °C). Immediately after testing, the air cell and the thick albumen heights, the Haugh unit and the yolk index of eggs were destructively measured. Statistical models obtained by processing dielectric spectra and quality indices determined by means of partial least square (PLS) analysis showed coefficients of determination (R^2) values up to 0.996 for the time of storage, 0.876 for the air cell height, and 0.678 for the thick albumen height. Accurate predictions were also obtained for models based on selected narrow spectral regions.

Changes of the dielectric parameters of fresh hen eggs during storage were investigated for the development of a method to assess the main quality indices. Dielectric constant and loss factor were measured in the frequency range 20–1800 MHz using an open-ended coaxial probe on thick albumen and yolk of eggs after 1, 2, 4, 8 and 15 days of storage at room temperature. Tests were also carried out at the 9th day of storage to compare dielectric properties of thick and thin albumen. Statistical analysis was performed at 20, 100, 400, 900 and 1800 MHz. Thick and thin albumen showed slight differences in dielectric properties but significant only for the loss factor at 900 MHz. Dielectric constant and loss factor of yolk generally increased with the storage time. The maximum increment from the 1st to the 15th days of storage (22%,) was registered for the loss factor at 20 MHz. Methods based on the comparison between the experimental loss factor and calculated values by means of conductivity and frequency can potentially be used in predicting eggs’ age.