Terahertz imaging for non-invasive classification of healthy and cimiciato-infected hazelnuts.

The development of new non-invasive approaches able to recognize defective food is currently a lively field of research. In particular, a simple and non-destructive method able to recognize defective hazelnuts, such as cimiciato-infected ones, in real-time is still missing. This study has been designed to detect the presence of such damaged hazelnuts. To this aim, a measurement setup based on terahertz (THz) radiation has been developed. Images of a sample of 150 hazelnuts have been acquired in the low THz range by a compact and portable active imaging system equipped with a 0.14 THz source and identified as Healthy Hazelnuts (HH) or Cimiciato Hazelnut (CH) after visual inspection. All images have been analyzed to find the average transmission of the THz radiation within the sample area. The differences in the distribution of the two populations have been used to set up a classification scheme aimed at the discrimination between healthy and injured samples. The performance of the classification scheme has been assessed through the use of the confusion matrix on 50 samples. The False Positive Rate (FPR) and True Negative Rate (TNR) are 0% and 100%, respectively. On the other hand, the True Positive Rate (TPR) and False Negative Rate (FNR) are 75% and 25%, respectively. These results are relevant from the perspective of the development of a simple, automatic, real-time method for the discrimination of cimiciato-infected hazelnuts in the processing industry.

Minty aroma compounds in red wine: Development of a novel automated HS-SPME-arrow and gas chromatography-tandem mass spectrometry quantification method.

A novel automated method was developed for the quantitative determination of nine terpenoids that could contribute to the minty notes of red wine bouquet. The method couples headspace SPME-Arrow extraction with GC-MS/MS analysis. PDMS/DVB fiber was chosen for the extraction and an ionization energy of 30 eV permitted to optimize the analyte detection. The optimal sample preparation consists of a two-fold dilution of the wine sample with addition of 4 g of sodium chloride while the most suitable extraction conditions take place at 50 °C for 1 h. The method shows good linearity, intraday variations between 2 and 25%, interday variations between 7 and 23% and recoveries between 80 and 119%. The method exhibits the required low detection (between 3 and 60 ng/L) and quantification (between 6 ng/L and 200 ng/L) limits. These limits have permitted the quantification of the pool of minty terpenoids in fourteen red Bordeaux wines.

Influence of microbial communities on the chemical and sensory features of Falanghina sweet passito wines.

Natural (N) as well as starter inoculated (S, inoculated with Saccharomyces cerevisiae M3-5; CZS, Candida zemplinina T13, Zygosaccharomyces bailii NS113 and Saccharomyces cerevisiae M3-5) fermentations of Falanghina must from dehydrated grape were monitored. Culture dependent analyses and amplicon-based high-throughput sequencing targeting 18S rRNA and 16S rRNA genes were used to monitor the fungal and bacterial communities (8 sampling points during 65 days). The resulting wines were subject to both sensory evaluation and volatile organic compounds analysis. Fungal community of un-inoculated musts (N) at beginning of the fermentation was mainly represented by Aureobasidium, Cladosporium, Sclerotinia, while Candida, Debaryomyces, Hanseniaspora, Metschnikowia, Pichia, Saccharomyces and Zygosaccharomyces showed a very low occurrence. The dominance of Hanseniaspora vineae and/or Hanseniaspora uvarum was clear up to 29th days of fermentation. S. cerevisiae occurred in all the phases but become dominant only at the end of the process. The odour profiles as evaluate by Quantitative Descriptive Analysis (QDA) highlighted a significant impact of the fungal populations on the olfactory profiles of the wines. Raisins, dried fruits, Sherry and liqueur were stronger in both S and CZS, while N was mostly discriminated by solvent/chemical and floral features. Outcomes underpin the impact of microbiota on the chemical and odour traits of Falanghina passito wines.

Alternative Methods to SO2 for Microbiological Stabilization of Wine.

The use of sulfur dioxide (SO2 ) as wine additive is able to ensure both antioxidant protection and microbiological stability. In spite of these undeniable advantages, in the last two decades the presence of SO2 in wine has raised concerns about potential adverse clinical effects in sensitive individuals. The winemaking industry has followed the general trend towards the reduction of SO2 concentrations in food, by expressing at the same time the need for alternative control methods allowing reduction or even elimination of SO2. In the light of this, research has been strongly oriented toward the study of alternatives to the use of SO2 in wine. Most of the studies have focused on methods able to replace the antimicrobial activity of SO2 . This review article gives a comprehensive overview of the current state-of-the-art about the chemical additives and the innovative physical techniques that have been proposed for this purpose. After a focus on the chemistry and properties of SO2 in wine, as well as on wine spoilage and on the conventional methods used for the microbiological stabilization of wine, recent advances on alternative methods proposed to replace the antimicrobial activity of SO2 in winemaking are presented and discussed. Even though many of the alternatives to SO2 showed good efficacy, nowadays no other physical technique or additive can deliver the efficacy and broad spectrum of action as SO2 (both antioxidant and antimicrobial), therefore the alternative methods should be considered a complement to SO2 in low-sulfite winemaking, rather than being seen as its substitutes.

Earthy off-flavour in wine: evaluation of remedial treatments for geosmin contamination.

Seven treatments (activated charcoal, bentonite, PVPP, yeast cell walls, potassium caseinate, zeolite and grape seed oil) were evaluated for their efficacy in decreasing the concentration of geosmin, responsible for earthy off-flavour in wine. In the red wine the potassium caseinate and grape seed oil treatments decreased the concentration of geosmin by 14% and 83%, respectively, while in the white wine, the activated charcoal and the grape seed oil were able to decrease the concentration of geosmin by 23% and 81%, respectively. The effective treatments in decreasing geosmin also decreased aroma volatile compounds, most of all esters, responsible for fruity notes. Considering the OAVs (concentration/odour threshold) only the treatment with grape seed oil was able to decrease the relative contribution of geosmin to the profile of the odour active compounds, both in red and in white wine. Sensory analysis confirmed the efficacy of the grape seed oil as a remedial treatment.

Aroma composition of red wines by different extraction methods and Gas Chromatography-SIM/MASS spectrometry analysis.

One hundred and one volatile compounds, reported in literature as powerful odorants of wine, were quantified by Gas Chromatography-Selective Ion Monitoring/Mass Spectrometry (GC-SIM/MS) in Primitivo, Aglianico, Merlot and Cabernet Sauvignon red wines. Wine samples were extracted by 3 different extraction methods: 1) separation of the alcoholic fraction from the aqueous phase by salting-out and subsequent extraction by liquid-liquid micro-extraction with 1,1,2-trichlorotrifluoroethane (Freon 113); 2) extraction by liquid-liquid micro-extraction with dichloromethane; 3) solid phase extraction (SPE cartridge: 800 mg of LiChrolut EN resin) with pentane-dichloromethane (20:1) and dichloromethane. The selection of the ion fragments used for quantification was directly performed on a red wine sample. For each compound the area of the corresponding peak was normalized respect to the peak of the internal standard and then interpolated in a calibration curve obtained analysing a model wine solution (water, ethanol, tartaric acid and known amounts of analytes and of internal standard). The methods showed a good linearity: r2>0.990, except for farnesol (isomer a and c), octanal, decanal, furaneol and phenylacetic acid with 0.966 < or = r2 < or = 0.990. The 7 most powerful odorants were: beta-damascenone, acetaldehyde, maltol, ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, 3-methylbutanoic acid and acetal; 7 other slightly less important were: ethyl hexanoate, ethyl acetate, 1-octen-3-ol, butanoic acid, rose oxide, furaneol and sotolon. The Aglianico wines were characterised by the major fermentation compounds (esters, fatty acids and 2-phenylethanol), beta-damascenone, beta-ionone and linalool. The Primitivo wines were characterized by furaneol, methoxypyrazine, gamma-nonalactone and acetaldehyde, while Cabernet Sauvignon and Merlot wines principally by cask derivates (vanillin, (Z) 3-methyl-gamma-octalactone [(Z) wiskylactone], maltol and eugenol), some aldehydes and 3-isopropyl-2-methoxypyrazine.

Determination of furaneol (4-hydroxy-2,5-dimethyl-3(2H)-furanone) in some wines from Italian native grapes by Gas-Chromatography-SIM/MASS spectrometry.

Gas Chromatography-Mass Spectrometry (GC-MS) analysis by Selective Ion Monitoring (SIM) was applied to quantify 4-Hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF) in both red and white wines obtained from some Italian cultivar of Vitis vinifera. Wines were extracted by liquid-liquid extraction performed with 1,1,2-trichlorotrifluoroethane (Freon 113). The ion m/z 128 was used for quantification while the ion m/z 129 as qualifier. Precision, linearity and accuracy of the method resulted satisfactory. Results showed a significant variation in the concentration of furaneol in wine with grape variety. Generally, HDMF concentrations in white wines were lower than in red wines. Among white wines, Chardonnay resulted characterized by the highest concentration of HDMF. Among red wines the highest concentrations of HDMF were detected in Primitivo and Refosco varieties.