The headspace O2 of all the treatment samples remained below 0.01% and the O2 indicator stayed pink throughout the storage despite the exhaustion of the scavenging capacity, especially the samples with smaller OS size and/or poorer O2 barrier material. The aerobic microorganisms continued to respire on the limited ingress O2 through polymeric packaging walls, depleting headspace O2 and keeping the O2 indicator pink.