Are you actually using inverted commas " xxx" around "scones orange" or just scones orange ... I tried your search across the EYB online recipes
I find that without inverted commas/ quote marks I get searches returned that have orange and scone in the recipe title n=142; with inverted commas/quotes I get 0 recipes returned in an online EYB library search.
If i use scones oranges (-zest) I get 135 returns (no inverted commas /quote marks, but using brackets around the minus zest element solely..
If I use scones oranges -zest I get 27,125 recipes returned : so maybe its a function of the search string you adopt. Your -zest needs to be in brackets, if you use quote marks it seems to bring up recipes with "zest" in the title or in ingredients - that is, it ignores your minus sign
Using EYB's Filters : selecting filters under baking "bread and buns sweet"; and under ingredient, citrus "oranges", and then searching for scones I get 120 recipes; adding in (-zest) I get 113 recipes; if I use scones zest I get 7 recipes ;-)
So maybe consider using boolean search modifiers???
But that's just based on decades of research across numerous libraries/internet/databases & not from a technical database wizard.. so no doubt EYB techies will have a much better response ;-)