6 research outputs found
IVLAB - Advanced Processing Image System
This paper describes the image processing tasks developed under a R&D project(iVLab project), between the Faculty of Engineering of Oporto University and anindustrial machinery equipment leader in the production of equipments for the corksector. The main objective of the project was to develop a system capable ofclassifying cork stoppers in different classes according to their surfacecharacteristics; therefore, using grey scale image processing and patternrecognition techniques it was possible to develop a system able of learning eachclass characteristics and, afterwards, make its classification in different classes
Cork structural characteristics and their influence on the oxygen ingress through wine stoppers
Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia - ULCork structural characteristics and their influence on the oxygen ingress through wine stoppers
were studied aiming to contribute to an increased added-value of the natural cork stoppers.
The surface porosity features of cork stoppers can differentiate the three main commercial
classes used nowadays: the porosity coefficient was 2.4%, 4.0% and 5.5% for premium, good
and standard stoppers, respectively. Image analysis also distinguished defects in the cork
structure: empty ant gallery; Coroebus undatus F. larvae gallery; and wetcork. Several
predictive classification models of stoppers into quality classes were built using the results
from cork stoppers surface characterization and a simplified model using the main
discriminant features i.e. porosity coefficient and the RGB colour-type variables was
presented.
X-ray tomography was used as a non-destructive technique to study the internal structure of
natural cork stoppers, allowing the visualization of some defects inside the cork stopper. After
characterization, the natural cork stoppers were used as closure of bottles and oxygen
diffusion measurements were made along time. The kinetics of oxygen transfer was similar
and could be adjusted to logarithmic models. On average 35% of the overall oxygen ingress occurred in the first 5 days, 59% in the 1st month and 78% in the first 3 months.
Microtomography images (voxel size of 50 µm) allowed the observation of lenticular channels
development and geometry, and the quantification of void and high density regions (HDR)
fractions. The evidence that the void fraction of lenticular channels in the innermost part of
the cork stopper inserted in the bottle was strongly related to the oxygen ingress in the first
month after bottling can be used for quality enhancement of natural cork stoppers with
incorporation of performance requirement