Soaring commodity prices will hurt soft drinks group Britvic's results this year.The company behind Tango and Robinsons, which also distributes Pepsi in the UK and Ireland, has increased its cost inflation guidance for 2011 to 9% to 11% from a previous estimate of 5% to 6%. "We have been adversely impacted by sharp recent increases in the price of PET (a plastic product derived from oil), steel and sugar," the company said.Britvic said the escalation in input costs comes after the completion of price negotiations with customers."Since our last update to the market we have witnessed a rapid and unprecedented uplift in the cost of key raw materials," chief executive Paul Moody said. "This has been driven by a shortage of supply to the market, where, for example, we have seen prices for PET, derived from oil, surge by around 20% in the last month alone."