Marcelo Lazzarotto

Differentiation of wines according to grape variety using multivariate analysis of comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detection data

Headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry detection (GC×GC/TOFMS) was used to analyse the volatiles in five types of wines elaborated with grapes of Cabernet Sauvignon, Merlot, Chardonnay, Sauvignon Blanc and Pinot Noir varieties. Fisher ratio, principal component analysis (PCA) and stepwise linear discriminant analysis (SLDA) were used to develop a discriminant model and, as a result, 12 volatile compounds enabled differentiation and classification of wines according to grape cultivars. A detailed examination of GC×GC/TOFMS data showed that the use of one-dimensional gas chromatography with a mass spectrometric detector (1D-GC/MS) would probably result in misidentification of some of these 12 compounds, as they showed partial coelution with other components in the first chromatographic dimension.

Main differences between volatiles of sparkling and base wines accessed through comprehensive two dimensional gas chromatography with time-of-flight mass spectrometric detection and chemometric tools

The main changes in the volatile profile of base wines and their corresponding sparkling wines produced by traditional method were evaluated and investigated for the first time using headspace solid-phase microextraction combined with comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry detection (GC×GC/TOFMS) and chemometric tools. Fisher ratios helped to find the 119 analytes that were responsible for the main differences between base and sparkling wines and principal component analysis explained 93.1% of the total variance related to the selected 78 compounds. It was also possible to observe five subclusters in base wines and four subclusters in sparkling wines samples through hierarchical cluster analysis, which seemed to have an organised distribution according to the regions where the wines came from. Twenty of the most important volatile compounds co-eluted with other components and separation of some of them was possible due to GC×GC/TOFMS performance.

Brazilian Dioscoreaceas starches

Abstract Determination of the characteristics of native starches is crucial in order to select their best application in various industrial fields. Thus, two different types of non-traditional native starches from the Dioscoreaceas species (Dioscorea sp. and Dioscorea piperifolia Humb. var. Wild) were studied regarding their thermal, structural and rheological properties. The results were contrasted with traditional commercial starch sources (potato, cassava and corn). From the thermogravimetric results (TG/DTG), D. piperifolia starch obtained the highest thermal stability of the samples, except for potato starch. Furthermore, using differential scanning calorimetry and viscoamylograph profiles (RVA), it was found that the Dioscoreaceas starches presented a higher onset (To) temperature and susceptibility to retrogradation. They also showed lower values in relation to relative crystallinity, which was calculated from their X-ray patterns and tendency to white (L*) colour. The shapes of the Discoreaceas starch granules were determined using electron microscopy; it was found that as the potato starch the Dioscoreaceas starches showed a wide range of particle size.

Nanotechnology applied to improve functionality in food

Abstract Functional foods are one of new trends for the food industry and nanotechnology can be useful for enrichment of food or parts of the food with natural bioactive compounds. Besides the introduction of nutraceuticals into food, nanotechnology may allow the protection of the functional compounds against degradation, and, furthermore, improve their bioavailability. Nanocapsules of biomacromolecules can be employed for entrapment of sensitive hydrophobic nutraceuticals with partial protection against photochemical degradation to enrich food products without modifying sensory properties. Insoluble fibers from plants can be employed to improve intestinal tract and decrease cholesterol and sugar absorption into blood. Besides, nanoparticles or nanofibers would be useful for jellification or emulsions, which have great potential for beverage applications associated with delivery of bioactives. However, some nanomaterials, mainly inorganic crystalline ones, may have toxic effects in the body and proper steps should be taken before recommending them for industrial applications. There are many processes for obtaining nanomaterials, which may belong to either bottom-up and top-down approach. This chapter focuses on some of these aspects along with some perspectives.

Electronic parameters of cation complexation by calixarene ionophores

The Gibbs energy of extraction experiments of ionophoric calixarenes with alkali metals from the literature have been correlated with electronic parameters of their “monomeric” structures calculated by AM1, PM3 and PM7 algorithms: energies of molecular orbitals and charge densities of oxygen and nitrogen atoms. We observed general correlations of the extraction constants with the charge on the carbonyl oxygen and specific correlations with MO-energy using the covalent term of the Klopman–Salem equation. The correlations for calixarenes with 5 and 6 phenolic units were very poor, and we attributed to the structural flexibility, which allow different optimized conformations for metal binding.

Brazilian Amazon white yam (Dioscorea sp.) starch

The functional properties of starch granules define its application in food and non-food industries. Thus, in this study we investigated thermal, rheological, structural and colour properties of the native and modified starch of the Amazon Dioscorea sp. (white yam) tuber. The Dioscorea sp. native starch was modified by applying single, simultaneous and combined modification agents (sodium hypochlorite, ultraviolet (UV) radiation and microwave irradiation). The thermogravimetric curves showed three main mass losses and increased thermal stability for the triple (NaClO + UV + microwaves) modified sample. The UV-irradiated samples required less energy (enthalpy) to gelatinize as registered by the differential scanning calorimetry. Performing modification using microwaves resulted in starches of highly viscous pastes as recorded by the rapid visco analyser. All the starch gel samples presented thixotropic behaviour, in which pseudoplastic characteristics were adequately described by Ostwald–de Waele and Herschel–Bulkley models. Rheological evaluation also revealed that one-step modified starches could produce stronger gels than the native one. Lower degree of relative crystallinity and a wide range of granule sizes were demonstrated by X-ray diffraction patterns and scanning electron microscopy. The colour measurement revealed the brightening and browning action of NaClO and microwaves, respectively.

A chemometric approach for moisture control in stingless bee honey using near infrared spectroscopy

Honey is a product that is often adulterated by the addition of water. Stingless bee honey naturally has a higher moisture content than that produced by the traditional Apis mellifera. In most countries, there is a lack of quality standards and methods to characterise and assure the authenticity of stingless bee honey, which demands for the development of fast methods to assess its main properties, avoiding potential fraud. Thus, this work aimed to develop a non-destructive moisture determination method for stingless bee honey based on diffuse reflectance near infrared spectroscopy combined with chemometrics. Thirty-two honey samples from four stingless bee species (Melipona quadrifasciata, Melipona marginata, Melipona bicolor and Scaptotrigona bipuncata) were used to develop calibration models using partial least squares regression analyses. Results revealed intense absorption bands in C–H, O–H and C–O vibrations in the spectra of stingless bee honey. The calibration model was used to predict the moisture content in honey from an external group. The prediction of the honey’s moisture showed good correlation (r2 = 0.93) with the refraction index method and an average error of 2.14%. The statistics variables for the calibration (R2 = 0.947, SEP = 1.005 and RPD = 4.3) revealed that this model can be used to predict the moisture from stingless bee honey and that near infrared spectroscopy is a reliable tool to be applied in quality control with rapid, simple and accurate results.

Induced effects by oxidation with potassium permanganate on the thermal, morphological, colorimetric and pasting properties of corn starch.

Introduction. Native starches are the most consumed polysaccharides in human diet. They are used in several industries as food, textile, pharmaceutic, etc. However due to some limitations starches should be modified chemically. Materials and methods. Corn starch modified with standard solutions of potassium permanganate (KMnO4) was analysed by simultaneous thermogravimetry-differential thermal analysis, differential scanning calorimetry, rapid viscoamylographic analysis, field emission gun-scanning electron microscopy/energy dispersive spectroscopy, X-ray powder diffraction and colorimetric analysis. Results and discussion. Corn starch was oxidised with KMnO4 at different concentrations (0.01; 0.02 and 0.05 mol L-1) at pH = 6.0 for 1 hour. (0.01; 0.02 and 0.05 mol L-1), pH = 6.0 for 1 hour. After filtered, washed and dried at 40 oC by 24 hours, the properties of the samples were investigated. Thermogravimetric curves showed an endothermic peak attributed to evaporation of water and two exothermic peaks, which refer to the decomposition and oxidation of organic matter until the formation of ash. A period of stability was observed, which decrease after modification. The gelatinisation of oxidised starch occurred at higher peak temperatures and also required higher gelatinisation enthalpy. The viscosity of the samples was significantly reduced and the relative crystallinity increased in proportion to the oxidant concentration used. Manganese and potassium content increased with the modification. There were no morphological changes after oxidation; however a darkening of the samples was identified due to the presence of potassium and manganese observed by energy dispersive spectroscopy (EDS). Conclusions. The obtained fluid paste with low retrogradation tendency suggests the application of oxidised starch in the paper industry.