It could be that Google needs to be sent to your site again to recrawl it, especially if you set up your blog post SEO more recently.
You can resubmit your site map which will do the trick to get Google to come recrawl faster. Here's the link to our guide on how to do this.
Hope that helps!
for google rich snippets (structured data) you need to use mark ups. You can add them directly into your blog post when clicking the < > button. In our blog, we post mostly paleo recipes and use the mark ups for recipes: https://developers.google.com/search/docs/data-types/recipes
Heres an example of one recipe (4th position): https://www.google.de/?gws_rd=ssl#q=paleo+brot Just check our source code and you'll see the mark ups we used to display the image.