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p r a c t i c a l w i n e r y & v i n e ya r d J a n U a r y 2 0 1 5 39 P A C K A G I N G ture of 20±1 oC and constant relative humidity of 65±1%. 5 Oxygen transmission kinetics through closures and their OTR The kinetics of oxygen ingress through different closures into bottled wine stored horizontally and vertically for 36 months is shown in Figures 1 and 2. Results showed that only the control (bottle sealed by flame) was completely air-tight, other closures allowed wine oxygenation. It was observed that the oxygen ingress kinetics have different phases, which vary according to type of closures. 4,5 For cylindrical closures such as corks and synthetic, there is an initial phase of one month where the oxygen pickup is much more important than in the following months of storage. This phase is likely a result of oxygen introduced at bottling due to the "piston effect" during the descending movement of closures into the bottleneck. In addi- tion oxygen is expelled from the closure into the bottle after compression and insertion. In the second phase, cylindrical clo- sures display oxygen ingress at a more consistent rate. Their transmission is a result of either permeation through the closure, or diffusion of gases retained in the compressed closure. Permeation is seen as a steady transmission where diffusion is limited by the gas and pres- sure found in the compressed closure. The total oxygen ingress in this phase is extremely dependent on the inherent oxygen transmission characteristics of each closure type. With the screw cap closures, the apparent entry of oxygen into wine (first); two "technical" cork stoppers (Twin Top and Neutrocork); one syn- thetic closure, Nomacorc classic clo- sure (43 x 22 mm) and four screw cap (Saran-tin liners) closures (Stelvin, Auscap, Cospak, and CSA). An airtight bottle containing a reduced indigo car- mine solution, sealed by flame, was used as a control. All bottles were sealed and then stored horizontally and vertically under constant tempera- manny@boutes.com Figure 2: Kine cs of oxygen ingress through screw cap closures into wines bo les stored horizontally during 36 months. Error bars represent the standard devia on of 4 replicates. 0.3 0.8 1.3 1.8 2.3 2.8 0 6 12 18 24 30 36 O 2 (mL) Horizontal storage (Months) Stelvin Auscap Cospak CSA Figure 2. Kinetics of oxygen ingress through screw cap closures into wine bottles stored in horizontal position during 36 months. Error bars represent the standard deviation of four replicates.