Let's take a step back. Just about no site is worldwide in relevance because each locality is different. A website with English content is not very helpful to Chinese speaking people in Asia. Even if you have an English language site it is not equally relevant to American & UK audiences because they speak a common but still different language. In the UK people eat crisps but Americans call them potato chips. 1/5/13 in South Africa is May 1st, 2013 and in America it is January 5th, 2013. Countries and even the regions within countries can have differences that makes it very hard for a site to be relevant worldwide. This is a big reason why Google tries to personalize the SERPS for each location.
If you want to attract a wider audience from around the world here are some tips to start with:
1) Go with .com, it is often seen as the most generic of tlds
2) Consider placing country specific content in country specific folders or subdomains
3) Develop backlinks from relevant sites in each country (if you can't convince those sites to link to you then you probably won't convince Google you are relevant either)
4) Double check your keywords and their synonyms. Biscuits can refer to cookies or bread rolls depending on your region. Google likes to see relevant content with the right keywords.