RSS Aggregator with keyword filtering

Is there an RSS Aggregator plugin that can filter based on a keyword? I tried out Feedwordpress, but that plugin only filters on a category, tag, or author.

An example is if I am doing a blog on ‘toast’ and I just want to aggregate stories on toast, I want the plugin to scan the RSS for the keyword ‘toast’. The article may use categories or tags such as ‘breakfast’ and thus a category or tag filter will not work.