There's a list of laxative and constipating foods here if this helps :
https://babywhispererforums.com/index.php?topic=249922.0it helped me when I started my LO on solids.
One thing I will say though - if you are giving individual foods for a number of days (from what you said it sounds like a number of days with one food before trialling the next) this in itself can cause problems with gas and poo. For example I discovered with my LO that carrots made his poo firmer and if I had given him carrots for 3 days without other foods to balance that out he would have been badly constipated. I did not do 3 day trials on each food because we followed BLW and offered a range of foods from the get-go but I did learn from keeping a record (and reading that thread above) that if I gave him carrots I needed to also give him prunes. With those two foods I could balance out his poo so that if I saw it getting a bit too soft I would steam some carrots for his next meal (or make a stew with carrots in) and if it was too firm I'd give him a soft prune or two along with whatever meal he was having. It was a very natural way to keep his bowels in good shape. Now that he is older, and from my own eating habits I know there are certain foods we can only eat once per week or so otherwise we'd both get diarrhoea - a 3 day trial on such foods would have been disastrous but those same foods along with other foods is fine.
Not sure how old your LO is or if there is a high risk of allergies in your family which has led you to wanting to trial each food individually but usually these days people do not tend to do these 3 or 4 day trials any more (instead just totally avoid the foods unsuitable for babies such as honey etc). Something to think about.