The Boston Beer Company has announced a voluntary product recall in the US.

The brewer, which last month posted a strong set of results for 2007, said yesterday (7 April) that a run of 12oz bottles of its Samuel Adams beer may contain "small grains or bits of glass".

The affected products are embossed on the base of the bottles with the letter 'N' followed by the number '35' followed by the letters 'OI', and are being recalled following routine quality control inspections at the company's Cincinnati brewery. The facility supplies around 25% of Boston Beer's bottles.

"We are disappointed and disturbed by this development, and we are doing everything we can to address the situation," said company founder and brewer Jim Koch "We are deeply disappointed that these bottles did not meet our quality standards.

"Because of these bottles supplied to us from an outside vendor, we didn't live up to our drinker's expectations. Our brewers, management, and all employees remain committed to doing everything possible to resolve this situation quickly, and to ensure the safety of our drinkers and the quality of our beer."

In March, Boston Beer reported full-year net profit of US$22.5m in 2007, up from $18.2m a year earlier. Sales for the year also improved, rising to $341.6m from $285.4m. The company warned, however, that it is facing overall production cost increases in 2008, currently estimated to be between 12% and 16% over full year 2007.