Aim of study: This study present a theoretical model that allow establishing the proper relationship between forces and diameters that take part in sealing for ensuring an adequate closure during storage time, and obtained the optimum stopper diameter for a proper sealing performance when modifying bottleneck diameter.Area of study: The proposed model is of interested to the whole cork value chain from forest owners to natural cork stoppers manufacturers.Material and methods: The optimum cork stopper diameter depends mainly on stopper quality and the compression rate applied in the bottling operation. In this study, we establish the stopper diameter when reducing bottleneck diameter, applying a compression rate of 33% when corking, and for natural cork stoppers which quality allows to recover its initial diameter to 96% after 24 h since compression.Main results: For a bottleneck diameter of 18 mm, the value of the stopper diameter should be at least of 22.3 mm, and for a bottleneck diameter of 17 mm, the value of the stopper diameter should be at least of 20.3 mm.Research highlights: These results try to solve one of the main worries of natural cork stopper manufacturers, which is the scarcity of raw cork suitable for manufacturing them. However this study is also of interested to forest owners because the increment of cork suitable for natural cork stoppers manufacturing means an increment in cork value.Key words: bottling; corking; compression force; compression rate; diameter recovery; relaxation force; relaxation ratio.Abbreviations used: Ds (Cork Stopper Diameter); Dg (Caliper Diameter the Corking Machine); Db (Bottleneck Diameter); Dr (Recovered Diameter); Fc (Compression Force); Fr (Relaxation Force); CR (Compression Rate); RR (Relaxation Ratio); RD (Diameter Recovery).
Influence of cutting direction of cork planks on the quality and porosity characteristics of natural cork stoppers