Classification of fermented cocoa beans (cut test) using computer vision

Fermentation of cocoa beans is a critical step for chocolate manufacturing, since fermentation influences the development of flavour, affecting components such as free amino acids, peptides and sugars. The degree of fermentation is determined by visual inspection of changes in the internal colour and texture of beans, through the cut-test. Although considered standard for evaluation of fermentation in cocoa beans, this method is time consuming and relies on specialized personnel. Therefore, this study aims to classify fermented cocoa beans using computer vision as a fast and accurate method. Imaging and image analysis provides hand-crafted features computed from the beans, that were used as predictors in random decision forests to classify the samples. A total of 1800 beans were classified into four grades of fermentation. Concerning all image features, 0.93 of accuracy was obtained for validation of unbalanced dataset, with precision of 0.85, recall of 0.81. Although the unbalanced dataset represents actual variation of fermentation, the method was tested for a balanced dataset, to investigate the influence of a smaller number of samples per class, obtaining 0.92, 0.92 and 0.90 for accuracy, precision and recall, respectively. The technique can evolve into an industrial application with a proper integration framework, substituting the traditional method to classify fermented cocoa beans

Magnetic Field Effects on the Head Structure of Protostellar Jets

We present the results of 3-D SPMHD numerical simulations of supermagnetosonic, overdense, radiatively cooling jets. Two initial magnetic configurations are considered: (i) a helical and (ii) a longitudinal field. We find that magnetic fields have important effects on the dynamics and structure of radiative cooling jets, especially at the head. The presence of a helical field suppresses the formation of the clumpy structure which is found to develop at the head of purely hydrodynamical jets. On the other hand, a cooling jet embedded in a longitudinal magnetic field retains clumpy morphology at its head. This fragmented structure resembles the knotty pattern commonly observed in HH objects behind the bow shocks of HH jets. This suggests that a strong (equipartition) helical magnetic field configuration is ruled out at the jet head. Therefore, if strong magnetic fields are present, they are probably predominantly longitudinal in those regions. In both magnetic configurations, we find that the confining pressure of the cocoon is able to excite short-wavelength MHD K-H pinch modes that drive low-amplitude internal shocks along the beam. These shocks are not strong however, and it likely that they could only play a secondary role in the formation of the bright knots observed in HH jets.Comment: 14 pages, 2 Gif figures, uses aasms4.sty. Also available on the web page http://www.iagusp.usp.br/preprints/preprint.html. To appear in The Astrophysical Journal Letter

Effect of glycerol and corn oil on physicochemical properties of polysaccharide films : a comparative study

The aim of this work was to evaluate the influence of glycerol and corn oil on physicochemical properties of polysaccharide-based films. The polysaccharides used were galactomannan from Gleditsia triacanthos and chitosan. Fourier-transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis were performed, together with determinations of moisture content, solubility, water vapor permeability and mechanical properties. Structure–properties relationships were established, relating the two polysaccharides’ structures with the way they interact with water, other film’s constituents (glycerol and oil) and the resulting properties. The presence of glycerol and corn oil originated a more hydrophilic structure and a decreased affinity of the film matrix to water, respectively, in both polysaccharides. However, the two polysaccharides presented different behaviors in terms of glass transition temperature, water vapor permeability and elongation-at-break that have been related with the particularities of their structure: while for the galactomannan the specific sorption sites for water are the O–H groups, for chitosan those are O–H and/or NH2 groups. The present work provides insight regarding the physicochemical properties of polysaccharide-based films and established relationships with polymers’ structure, showing that the two polysaccharides studied here have adequate properties to be used as packaging materials for specific food applications.Miguel A. Cerqueira gratefully acknowledge his fellowship (SFRH/BPD/72753/2010) to the Fundacao para a Ciencia e Tecnologia (FCT, Portugal), and Bartolomeu W. Sousa was recipient of a fellowship from the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES, Brazil)

Confronting Vegard's rule in Ge1-x Sn (x) epilayers: from fundamentals to the effect of defects

Comprehensive and systematic study challenging the application of Vegard's rule to germanium tin solid solutions grown on germanium buffer layers and 100 silicon substrates is presented. The binary's lattice parameters, composition and respective uncertainties are determined through x-ray diffraction via reciprocal space mapping technique employing newly developed software. The tin content is confirmed by Rutherford backscattering spectrometry and energy dispersive x-ray spectroscopy. The statistical agreement between the tin contents derived by the different structural characterization techniques suggests the binary to follow generically the Vegard's rule in the range of low Sn molar fractions (<5%). Phase separation, Sn segregation, point defects, post-growing oxygen impurities, and deteriorated surface morphology are found to be relevant within the similar to 200 nm germanium tin films. Although, complex mechanisms triggering composition/strain heterogeneities are found in the analysed Ge1-x Sn (x) compounds, the deviation from the perfect crystals is suggested to be not enough to distort the in- and out-of-plane lattice parameters away from its empirical linear combination.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Plurianual Strategic Funding UID/FIS/50010/2019. F O acknowledges the FCT PhD Grant and thanks the Institut fur Halbleitertechnik, Universitat Stuttgart for hospitality. The authors acknowledge Professor J Schulze for providing the MBE facilities and the growing of the growing of the germanium tin films

Effects of moderate electric fields on aggregation of whey protein solutions and properties of edible films made thereof

Thermal processing may result in disruption of the native conformation of whey proteins, thus affecting their structure and functional properties. The aim of this work was to evaluate the effects of moderate electric fields on thermal aggregation of whey proteins and its subsequent effects on properties of edible films made from ohmic heated whey protein film forming solutions. Thermal aggregation of whey protein isolate was studied at 85 ºC up to 30 min through ohmic heating, under the presence of moderate electric fields ranging from 4 to 20 V/cm; this treatment was compared with conventional heating under identical temperature profiles. Results show that whey protein aggregation (measured by dynamic light scattering in terms of aggregate size) was found to decrease with the increase of electric field applied during ohmic heating; a maximum increase in whey protein aggregation of 45 nm was observed for treatments at 18 V/cm, while treatments at 4 V/cm and 0 V/cm (conventional heating) produced a maximum increase of 70 nm and 75 nm, respectively. Edible films prepared from ohmic heated film forming solutions present a decrease of about 10 %, when compared with films produced through conventional heating, for water vapor permeability. The presence of moderate electric fields during heating, apparently influences the denaturation and aggregation of whey proteins thus modifying the mechanisms of protein interactions in films formed from whey protein film forming solutions. Ohmic heating presents itself as a novel method for production of protein films

Seed extracts of Gleditsia triacanthos : functional properties evaluation and incorporation into galactomannan films

In this work, three different extraction procedures were performed in Gleditsia triacanthos seeds in order to obtain extracts that were characterized in terms of the yield of extraction, total phenolic content and antioxidant properties. The extracts have been shown to contain considerable amounts of phenolic compounds (between 4.93 and 12.34 mg galicacid g extract − 1) and antioxidant activity between 18.77 and 71.59%. Different concentrations of one of the extracts (extract presenting simultaneously the best values of total phenolic content, radical scavenging activity and the concentration of the compounds that caused a 50% inhibition of the radical scavenging activity) were incorporated into G. triacanthos galactomannan solutions and films were cast from these. A 2 2 full factorial design was done to evaluate the effect of the galactomannan and extract concentrations in film properties. Galactomannan concentrations ranging from 0.5 to 1.5% and extract concentrations ranging from 0 to 1.0%, were used and the evaluated film properties as: water vapour permeability, colour, total phenolic compounds content and antioxidant activity. This work has shown that G. triacanthos can be used not only as a source of galactomannan films suitable to incorporate antioxidant compounds for further application in the food industry but also as a source of the active compounds to be incorporated.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Brazil).Fundação para a Ciência e Tecnologia (FCT) - SFRH/BD/ 23897/2005; SFRH/BD/32566/200

Effects of electric fields on protein unfolding and aggregation : Influence on edible films formation

Electric fields application is receiving increased attention because of its uniform heating of liquids. The mechanisms of unfolding and aggregation of whey proteins during ohmic heating may influence properties of edible films made thereof. The aim of this work was to evaluate the effects of ohmic heating on physical and structural properties of whey protein edible films and compare them with those obtained by conventional heating. The results showed that ohmic heating determined less aggregation and lower concentration of free sulphydryls in film-forming solutions. Ohmic films were thinner, less permeable to water vapor and presented nearly the same mechanical properties of conventional films. Ohmic heating induced protein conformational changes by increasing the contents of -sheet structures in the film network. This work emphasized the effects of ohmic heating in unfolding and aggregation mechanisms of whey proteins during heat denaturation, which determined the production of protein edible films with distinctive properties.Fundação para a Ciência e Tecnologia (FCT)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Brazil