Google has updated the recipe schema markup help documents to remove all references to time ranges for food prep, cook time and total time as a supported field type. Now you need to specify a singular time, and no longer provide time ranges.
What changed. Google wrote that it “removed guidance about specifying a range for the cookTime, prepTime, and totalTime properties in the Recipe documentation. Currently, the only supported method is an exact time; time ranges aren’t supported. If you’re currently specifying a time range and you’d like Google to better understand your time values, we recommend updating that value in your structured data to a single value (for example, "cookTime": "PT30M").”
Old docs. the old documentation had references to using minimum and maximum time frames for the range of time it takes to prepare and cook the dish. Here is an old screenshot from the totalTime field about the mix and max ranges:
Now there are only references to using a singular and fixed time without any ranges.
Why we care. If you use recipe schema markup on your pages and have time ranges in that markup, you will want to adjust those ranges to use singular and fixed times. One would assume the Search Console reports will soon show errors for the use of ranges but you should jump on this and modify any uses of ranges in your markup.
