Use site: in Google to narrow your results. You can use site: to search within websites. Find the base URL of a site (pepsi.com, for example). In Google, type your keywords, then use site:pepsi.com. Google will only search within Pepsi's website. For example, if you are interested in the amount of calories in Pepsi products you could search calories site:pepsi.com and results will look something like this:
If you are searching for scholarly information about a particular brand you might try adding your search terms in front of site:edu to find articles published by educational institutions. For example, if you are interested in the Walmart brand you could search walmart brand site:edu to get results something like this:
