Donatella Albanese

Effect on orange juice of batch pasteurization in an improved pilot-scale microwave oven.

The effects on orange juice batch pasteurization in an improved pilot-scale microwave (MW) oven was evaluated by monitoring pectin methyl-esterase (PME) activity, color, carotenoid compounds and vitamin C content. Trials were performed on stirred orange juice heated at different temperatures (60, 70, 75, and 85 degrees C) during batch process. MW pilot plant allowed real-time temperature control of samples using proportional integrative derivative (PID) techniques based on the infrared thermography temperature read-out. The inactivation of heat sensitive fraction of PME, that verifies orange juice pasteurization, showed a z-value of 22.1 degrees C. Carotenoid content, responsible for sensorial and nutritional quality in fresh juices, decreased by about 13% after MW pasteurization at 70 degrees C for 1 min. Total of 7 carotenoid compounds were quantified during MW heating: zeaxanthin and beta-carotene content decreased by about 26%, while no differences (P < 0.05) were found for beta-cryptoxanthin in the same trial. A slight decrease in vitamin C content was monitored after MW heating. Results showed that MW heating with a fine temperature control could result in promising stabilization treatments.

Evolution of quality parameters during red wine dealcoholization by osmotic distillation

Osmotic distillation technique was used for the total dealcoholization of a red wine (Aglianico grape variety) up to 0.19 vol.%. The dealcoholization process was performed in subsequent cycles which gave rise wine samples at different alcoholic degrees. The effect of processing on the main chemical and physical properties of Aglianico wine was evaluated. Among wine samples, no significant differences (p<0.05) of oenological parameters such as pH, total acidity were found. Similarly, the total phenolic, flavonoids and tartaric esters content and the composition of organic acids did not show significant differences (p<0.05) during the process. On the contrary, colour intensity and tonality of wine samples changed significantly when the alcohol reduction was over the 6.5 vol.%. Finally, the total dealcoholized wine showed properties similar to Aglianico wine except for the volatile compounds, which decreased over 98%. Hence, flavour enrichment may be required to produce a pleasurable and delicious non alcoholic beverage from wine.

An ultrasound technique for monitoring the alcoholic wine fermentation

In this paper an ultrasonic technique, usually used in non-destructive-testing (NDT), is applied to the monitoring of alcoholic wine fermentation. This technique consists in placing a test tube, containing the analyzing fluid, between two matched ultrasonic piezoelectric transducers, one used as transmitter and the other as receiver. The transmitter generates an ultrasonic wave in the liquid sample which is received by the receiver; the attenuation and the delay of the received signal in respect to the transmitted one are used to characterize the testing fluid. As first experiments this technique was applied to some test solutions of saccharose in water, ethanol in water and of both solvents in water, in order to evaluate the method applicability and resolution. Best results are obtained by the propagation velocity measurement, with a resolution less than 2%. The method was then applied to monitor the wine fermentation: the propagation velocity in the must was measured every day and the results were related to chemical analyses. The obtained results show that the propagation velocity has the same behaviour of the saccharose concentration, putting in evidence the possibility of monitoring the process state by measuring the ultrasound propagation velocity.

A highly sensitive impedimetric label free immunosensor for Ochratoxin measurement in cocoa beans

In this work the development and optimization of an impedimetric label free immunosensor for the detection of Ochratoxin A (OTA) is reported. Two antibody immobilization methods (oriented and not oriented) were compared highlighting a lower limit of detection (5pg/ml) for the not oriented immobilization but a closer linear range in contrast to oriented anti-OTA immunosensors which showed linearity in the range of 0.01-5ng/mL OTA. The analysis of the Atomic Force Microscopy (AFM) images showed two different nanostructures indicating that the use of oriented immobilization created a more ordered and highly dense antibody surface. Finally the oriented immunosensor was used to quantify OTA in spiked cocoa bean samples and the results were compared with those registered with competitive ELISA kit. The immunosensor was sensitive to OTA lower than 2μg/kg that represents the lower acceptable limit of OTA established by European legislation for the common food products.

Screen printed biosensors for detection of nitrates in drinking water

Amperometric screen printed nitrate reductase by Escherichia coli biosensors have been developed to detect nitrate ions. The effects of two different immobilization procedures of NaR and mediator (Azure A and Methyl viologen MV) to increase the performances (response time, sensitivity, stability) of the nitrate sensor have been studied. The best performances were registered by nitrate biosensor developed with a simultaneous cross-linking of enzyme and MV mixed BSA in in satured glutaraldehyde vapour. This biosensor showed the capability to detect nitrate residue levels lower than the European legislation one for a long storage stability (> 36 days) representing an applicable and cheap method for the analysis of nitrate ions in water and food samples.

Impedimetric Label-Free Immunosensor on Disposable Modified Screen-Printed Electrodes for Ochratoxin A

An impedimetric label-free immunosensor on disposable screen-printed carbon electrodes (SPCE) for quantitative determination of Ochratoxin A (OTA) has been developed. After modification of the SPCE surface with gold nanoparticles (AuNPs), the anti-OTA was immobilized on the working electrode through a cysteamine layer. After each coating step, the modified surfaces were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The capacitance was chosen as the best parameter that describes the reproducible change in electrical properties of the electrode surface at different OTA concentrations and it was used to investigate the analytical parameters of the developed immunosensor. Under optimized conditions, the immunosensor showed a linear relationship between 0.3 and 20 ng/mL with a low detection limit of 0.25 ng/mL, making it suitable to control OTA content in many common food products. Lastly, the immunosensor was used to measure OTA in red wine samples and the results were compared with those registered with a competitive ELISA kit. The immunosensor was sensitive to OTA lower than 2 μg/kg, which represents the lower acceptable limit of OTA established by European legislation for common food products.

Aglianico wine dealcoholization tests

Abstract In the recent years, there has been a growing interest in partial or total dealcoholization of alcoholic beverages. The demand for drinks with low levels of alcohol is attributable both for health reasons and for the desire to reduce alcohol consumption in new generations. This research aims to produce a dealcoholized wine with less than 0.5% alcohol-by-volume from Aglianico. Dealcoholization tests were carried out by plant working on direct osmosis, equipped with a membrane contactor and some temperature sensors and automatic control of the process phases. The fixed alcohol content was achieved with 5 cycles, under mild condition. Chemical-physical and aromatic composition was evaluated in feed (wine) during the dealcoholization process.

Winemaking Process Monitoring Based on a Biosensor Automatic System

This paper proposes an automatic measurement system for monitoring of biological processes using amperometric biosensors in flow injection analysis. Whereas this kind of measurement usually requires intervention of human experts, the proposed system allows full automation of the measurement process. Both flow injection and analyte concentration measurement processes are managed without human interactions. In this paper, a first prototype of the system customized for winemaking process monitoring is described and characterized.

Kinetics of carotenoids degradation and furosine formation in dried apricots (Prunus armeniaca L.)

The kinetics of carotenoid and color degradation, as well as furosine formation, were investigated in apricot fruits during convective heating at 50, 60 and 70°C. Degradation of carotenoids and color, expressed as total color difference (TCD), followed a first and zero order kinetic, respectively. The activation energy (Ea) for carotenoids degradation ranged from 73.7kJ/mol for 13-cis-β-carotene to 120.7kJ/mol for lutein, being about 91kJ/mol for all-trans-β-carotene. Violaxanthin and anteraxanthin were the most susceptible to thermal treatment. The furosine evolution was fitted at zero order kinetic model. The Ea for furosine formation was found to be 83.3kJ/mol and the Q10 (temperature coefficient) varied from 1.59 to 4.14 at the temperature ranges 50-60°C and 60-70°C, respectively.

Quality Attributes of Low-Alcohol Top-Fermented Beers Produced by Membrane Contactor

The practice of dealcoholization is used nowadays to reduce the alcohol content in beverages, and osmotic distillation seems to be a convenient membrane process due to its mild operating conditions. The focus is on the quality of final beverage which may lack in taste, flavor, and body. The aim of this work was to evaluate the quality attributes of low-alcohol beers, dealcoholized by osmotic distillation and using stripping solutions specific for the beverage composition. Two types of top-fermented beer were used: Weiss beer, with a very fruity aroma and strong phenolic content, and Bitter beer, with a malt aroma. Regarding the stripping solutions, they were obtained by dilution of the original beer with water, in order to limit the volatile compound loss during the process. Moreover, low-alcohol Weiss beer was also produced by using carbonated stripping solutions (i.e., saturated with CO2 at ambient pressure). The results highlighted that color, bitterness, total phenols, and antioxidant activity were unchanged in the low-alcohol beers but volatile compounds were reduced to a different extent. The lower vapor pressure of some volatile compounds (i.e., 2-phenylethanol, aldehydes) can explain their retention in beer. The carbonation of stripping solutions did not significantly reduce CO2 loss, but aldehydes and total alcohols were better retained in low-alcohol Weiss beer. Esters and other volatile compounds were reduced so that the low-alcohol beer may result with a weak sensory profile, which can be compensated by a re-addition of CO2 before bottling.