thank you I didn't have this book and could not find it in the internet yet. this term is used by the editor of my manuscript, recently! I didn't heard this term too. by the way I should to read more books or papers to find out what is extra caution!
I also am unfamiliar with the phrase "extra caution". An excellent text book for how to perform and analyze data for sensory evaluation is: "Sensory Evaluation Techniques" by Meilgaard, Civille, and Carr; 4th edition, 2006, CRC press.
I thought "extra caution" is a term that only I am not familiar with, so I asked it here. but now, I know that maybe it is not a technical method for sensory evaluation. so as you said its good idea asking the editor to explain more.
To my knowledge, "extra caution" means that you have done your best to eliminate any other sources of error before coming to a conclusion. For example, "extra caution" may be used when you are using panelists that may have the tendency to be "bias" towards the evaluated products. In this case, maybe you have used colored light bulbs to avoid the panelist from being influenced by the product appearance.
Just sharing my itsy bitsy knowledge, hope it helps.
My interpretation of using "extra caution" in sensory evaluation, would mean the researchers should be wary of influencing participant's "feelings" about a particular taste over another because humans are so impressionable that even the slightest hint that a person of authority prefers one taste over another might bias results of the study.
The short answer is having research assistants use a protocol and make sure they stick to it for all participants, i.e. no smiling, no adjectives in describing food. The key is consistency.