Simona Benedetti

Evaluation of the antioxidant power of honey, propolis and royal jelly by amperometric flow injection analysis.

In this paper is described the applicability of a flow injection system, operating with an amperometric detector, for measurement in rapid and simple way the antioxidant power of honey, propolis and royal jelly. The proposed method evaluates the reducing power of selected antioxidant compounds and does not require the use of free radicals or oxidants. Twelve honey, 12 propolis and 4 royal jelly samples of different botanical and geographical origin were evaluated by the electrochemical method and the data were compared with those obtained by the DPPH assay. Since a good correlation was found (R(2)=0.92) the proposed electrochemical method can be successfully employed for the direct, rapid and simple monitoring of the antioxidant power of honeybee products. Furthermore, the total phenolic content of samples was determined by the Folin-Ciocalteau procedure and the characteristic antioxidant activities showed a good correlation with phenolics (R(2)=0.96 for propolis and 0.90 for honey).

Monitoring of alcoholic fermentation using near infrared and mid infrared spectroscopies combined with electronic nose and electronic tongue

Effective fermentation monitoring is a growing need due to the rapid pace of change in the wine industry, which calls for fast methods providing real time information in order to assure the quality of the final product. The objective of this work is to investigate the potential of non-destructive techniques associated with chemometric data analysis, to monitor time-related changes that occur during red wine fermentation. Eight micro-fermentation trials conducted in the Valtellina region (Northern Italy) during the 2009 vintage, were monitored by a FT-NIR and a FT-IR spectrometer and by an electronic nose and tongue. The spectroscopic technique was used to investigate molecular changes, while electronic nose and electronic tongue evaluated the evolution of the aroma and taste profile during the must-wine fermentation. Must-wine samples were also analysed by traditional chemical methods in order to determine sugars (glucose and fructose) consumption and alcohol (ethanol and glycerol) production. Principal Component Analysis was applied to spectral, electronic nose and electronic tongue data, as an exploratory tool, to uncover molecular, aroma and taste modifications during the fermentation process. Furthermore, the chemical data and the PC1 scores from spectral, electronic nose and electronic tongue data were modelled as a function of time to identify critical points during fermentation. The results showed that NIR and MIR spectroscopies are useful to investigate molecular changes involved in wine fermentation while electronic nose and electronic tongue can be applied to detect the evolution of taste and aroma profile. Moreover, as demonstrated through the modeling of NIR, MIR, electronic nose and electronic tongue data, these non destructive methods are suitable for the monitoring of must-wine fermentation giving crucial information about the quality of the final product in agreement with chemical parameters. Although in this study the measurements were carried out in off-line mode, in future these non destructive techniques could be valid and simple tools, able to provide in-time information about the fermentation process and to assure the quality of wine.

Head space sensor array for the detection of aflatoxin M1 in raw ewe's milk.

A novel screening method was developed for simple and rapid detection of aflatoxin M1 contamination in raw ewes milk samples without the need for sample pretreatment. The method was based on the use of a commercial head space sensor array system constituted by 12 metal oxide semiconductor sensors, 10 metal oxide semiconductor field-effect transistor sensors, and a pattern recognition software. Twenty-four raw milk samples collected from two different groups of ewes fed with a formulated feed that contained increasing amounts of aflatoxin B1 and six noncontaminated ewes milk samples were analyzed. The results obtained by using the head space sensor array, processed by statistical methods, made it possible to group the samples according to the presence or the absence of aflatoxin M1. Sample classification was in complete agreement with the aflatoxin M1 content measured by an enzyme-linked immunosorbent assay procedure. This is the first report, to our knowledge, of detection of aflatoxin M1 in ewes milk by a multisensor array.

Polymer Composites Containing Gated Mesoporous Materials for On-Command Controlled Release

Polyamidic nanofibrous membranes containing gated silica mesoporous particles, acting as carriers, are described as novel hybrid composite materials for encapsulation and on-command delivery of garlic extracts. The carrier system consists of MCM-41 solids functionalized in the outer surface, with linear polyamines (solid P1) and with hydrolyzed starch (solid P2), both acting as molecular gates. Those particles were adsorbed on electospun nylon-6 nanofibrous membranes yielding to composite materials M1 and M2. FE-SEM analysis confirmed the presence of particles incorporated on the nylon nanofibers. The release of the entrapped molecules (garlic extract) from the P1, P2, M1, and M2 materials was evaluated using cyclic voltammetry measurements. Electrochemical studies showed that at acidic pH P1 and M1 were unable to release their entrapped cargo (closed gate), whereas at neutral pH both materials release their loading (open gate). Dealing with P2 and M2 materials, in the absence of pancreatin a negligible release is observed (closed gate), whereas in the presence of enzyme the load is freely to diffuse to the solution. These newly developed composite nanomaterials, provide a homogeneous easy-to-handle system with controlled delivery and bioactive-protective features, having potential applications on pharmacology, medical and engineering fields.

Electronic Noses and Tongues

Electronic noses (e-noses) and electronic tongues (e-tongues) are sensor array devices that in combination with pattern-recognition systems can give useful information on the quality of food. Their basic principle is inspired by the neurophysiology of the senses of smell and taste. Subsequently, much time and effort are spent on methods that rapidly and automatically can estimate and measure these factors: e-noses and e-tongues offer an additional method. Analysis of multivariate data is also an essential part of these systems. This chapter examines the advances on electronic noses and tongues and their special applications to monitor food quality. In the first part, e-nose is presented and the different apparatus described in detail. In the second part, taste sensors are described in connection to batch and flow design. In the third part, the most common pattern-recognition techniques are briefly introduced. Recent applications of the e-noses and e-tongues in food and beverage are also reviewed.

Monitoring of autoxidation in LCPUFA-enriched lipid microparticles by electronic nose and SPME-GCMS.

Electronic nose and SPME-GCMS were used to monitor the autoxidation in long chain polyunsaturated fatty acid (LCPUFA)-enriched lipid microparticles produced by spray congealing with ultrasonic nebulization, during storage at 20 degrees C up to 6 weeks with sufficient air supply and limited air supply. Conjugated dienes and peroxide value as well as secondary lipid oxidation products were analysed to follow the course of autoxidation. Principal Component Analysis evidenced that only MOS sensors but not MOSFET sensors contributed to the discrimination of the samples and facilitated the ability of the electronic nose to distinguish the LCPUFA-enriched lipid microparticles into two groups according to the different oxidative status. The selected MOS sensor responses correlated well with quantitative dominating volatile compounds (propanal and hexanal) and with volatile compounds which have been associated with fishy and rancid off flavour (1-penten-3-one, 1-penten-3-ol, 2,4-heptadienal and 2,6-nonadienal). Bread mix supplemented with the LCPUFA-enriched microparticles was analysed as an example for a LCPUFA supplemented food. Data from the present study indicate that the electronic nose can be used as a sensitive tool to evaluate the lipid oxidative status of LCPUFA-enriched microparticles. In supplemented foods like bread mix, matrix-related changes, which occur in supplemented and non-supplemented samples, make a clear distinction more difficult.

Application of electronic senses to characterize espresso coffees brewed with different thermal profiles

Electronic senses were applied in order to evaluate the effect of brewing temperature on the sensorial properties of espresso coffees (ECs) produced by a bar machine of the latest generation able to work with constant, increasing and decreasing water temperature profiles. The obtained ECs were analyzed by e-nose, e-tongue and e-eye to depict their aroma and taste fingerprint and to evaluate the visual characteristics of foam. Physicochemical analyses were carried out to determine the extraction rate of typical EC components and to evaluate their antioxidant activity. The electronic devices coupled with multivariate statistical analysis demonstrated a good ability to discriminate and characterize coffee samples on the basis of their sensorial properties in relation to the brewing temperature. According to these results, electronic senses can be applied to assess the influence of the percolation parameters on the sensory attributes of ECs, thus resulting useful tools for the optimization of processing conditions.

Soybean-Enriched Snacks Based on African Rice

Snacks were produced by extruding blends of partially-defatted soybean flour with flours from milled or parboiled African-grown rice. The interplay between composition and processing in producing snacks with a satisfactory sensory profile was addressed by e-sensing, and by molecular and rheological approaches. Soybean proteins play a main role in defining the properties of the protein network in the products. At the same content in soybean flour, use of parboiled rice flour increases the snack’s hardness. Electronic nose and electronic tongue discriminated samples containing a higher amount of soybean flour from those with a lower soybean flour content.

Determination of ascorbyl 6-palmitate in food matrices by amperometric flow injection analysis

In this paper a rapid method based on a FIA (flow injection analysis) system with amperometric detection for the evaluation of ascorbyl 6-palmitate in foods is described. The selectivity of the proposed method is related to the low anodic potential applied to the working glassy carbon electrode (+0.1 V vs. Ag/AgCl) that leaves out interferences from ascorbic acid and phenolic compounds. By flow injection analysis, under optimised conditions, the calibration curve was linear in the range 0-20 mg l(-1) and the detection limit was 0.2 mg l(-1).

Application of the electronic nose in olive oil analyses

Publisher Summary It is possible to differentiate and classify extra virgin olive oil (EVOOs) from different geographical areas by using a commercial electronic nose and by applying multidimensional chemometric techniques. There is a growing emphasis and consensus that intelligent sensor arrays or electronic noses are most effective in the quality control of raw and manufactured products—for example, for determination of food freshness and maturity monitoring, shelf-life investigations, authenticity assessments of products and even microbial pathogen detection and environmental control. This application area is particularly important because the e-nose can be trained to recognize hazardous chemicals as well as odors. Furthermore, with respect to the human nose, the e-nose does not fatigue as easily, is less costly, and can travel easily into outer space. It also holds the promise of being much cheaper, smaller and easier to use and maintain than a mass spectrometer.