As with many things in our walk, there are various levels of strictness that one might seek to adhere to concerning the removal of leavening from our homes.
Some Jews sell their homes to a Gentile for a dollar and then buy it back again after the Feast of Unleavened Bread has ended, thus circumventing the requirement to remove leaven from their homes. Some would only take their yeast and any leavened bread products and set them in out in the woods in a sealed container until after the feast of Unleavened Bread has ended, and then take all of it back in their house again. To me, both of these are attempts to circumvent the commandments of Yahweh, and are attempts to find “loopholes in the law.”
My desire is to be a man after Yahweh’s heart in all things, and even though I may not be where I need to be, I think it’s good to desire and pursue that attitude.
Probably most believers seek to eliminate some basic leavening agents and any foods containing them. The most common leavening agents are yeast, Sodium Bicarbonate (baking soda), and Baking powder. If that’s where you are comfortable and don’t feel a conviction to do anything more than that, then I don’t judge you.
So, what are the leavening agents? Well, if you just want to go with the big ones, you can say yeast, baking soda and leavened bread. But if you are like me, you want to try to be more diligent and get rid of all possible leavening agents, following the spirit of the law, the principles, not just the rigid code. But we want to do so without adding to the law either, so there is where it can get a little muddy at times. It takes discernment.
Suppose a man tells his son to not go over the fence, but then his son finds a way to go under the fence, did he obey his father? He obeyed the rigid code, but he did not follow the spirit of his father’s law. His father did not want him to go over the fence.
So if Yahweh tells Israel to not eat leavened bread, and to get rid of all the leavening, with no leavening to be seen in all their dwellings, but then I go and find some other substances, such as baking soda, or baking powder, or a whole host of other things that can cause bread to rise, and then I eat it, I am not following the spirit of Yahweh’s law.
So what about the baking soda in my house. I may not be keeping it for the purposes of causing bread to rise, I am keeping it for the purposes of cleaning my floors, or to put in my refrigerator to keep the odor down, can I then keep the baking soda in my house, even though it is indeed a leavening agent in every way that yeast is a leavening agent?
I can’t say that for sure that you are 100% in violation of the principles of the Torah, because you aren’t using it as a leavening agent. Just as the yeast floating around your house isn’t being used as a leavening agent until it comes into contact with bread. For this reason, some people even go ahead and keep the yeast packets in their home since it isn’t currently leavening anything.
Others may counter this by saying that while it isn’t currently leavening anything, it is there for the purposes of leavening bread just as the sour dough ball was in the houses of the Israelites for leavening bread… so throw it out.
If you are unsure of where to stand on this, my advice would be to err on the side of caution, for we don’t want to get in the practice of doing things that keep us from having a clear conscience.
So if we want to be really technical about it, there are a number of chemical and ingredients in our modern world that can be found in foods which are used as leavening agents. For me, I want to eliminate both yeast and anything that could be in my bread that is functioning as a yeast substitute. My desire is to avoid circumventing Yahweh’s command by enjoying a “yeast-like” bread that, while it may not contain yeast, nevertheless the end result is pretty similar.
One thing I like to keep in mind that this is all a spiritual exercise. It is representing the diligence needed to get the sin out of our lives. And the more complicated this world is, and the further it departs from Yahweh, the more difficult this can often be.
So here is a list of potential leavening agents. Some of them you may almost never see in any ingredient list. You can choose to take this as far as you feel the conviction to do.
I encourage you to do your own research on these ingredients. You might find that this list is too extreme, while others want to be more diligent about it. Our goal is that we would fulfill the commandment to rid ourselves of leavening. Yahweh sees our hearts.
Some items may contain a symbol on them that indicate they are free of leavening agents, according to the standard in Orthodox Judaism. I’m not sure how strict they are in comparison to this list, but I do know that some things marked kosher for Passover will have Sodium Bicarbonate (Baking soda). Personally, for this reason I would not trust it. Here is the symbol:

Now here is the list of potential leavening agents:

*See https://en.wikipedia.org/wiki/Chorleywood_Bread_Process
**See https://en.wikipedia.org/wiki/Leavening_agent#Other_leaveners
And here is a PDF version of the chart for you to download and print: