IP Datacast over DVB-H has been adopted as a core technology to build complete end-to-end mobile broadcast TV systems. In order for this technology to be successful in the market, provisioning of acceptable QoE (Quality of Experience) to the users, as well as a wide range of business models to the service providers, is essential. In this paper, we analyze the channel zapping time, which is an important metric to measure QoE for mobile broadcast TV services. In particular, we clarify primary components that determine the channel zapping time for protected services in IP Datacast over DVB-H. Our analysis is based on the data gathered during the trial service of the OMA-BCAST Smartcard profile in Singapore, Asia. Based on the analysis, we show that a significant reduction in channel zapping time can be achieved by optimizing the transmission parameters related to the key derivation time and the synchronization time between the content stream and the key stream.