Bird flu has caused egg prices to surge and has impacted the availability of eggs.Substitutes, such as applesauce, can be used in baking instead.I made brownies using applesauce, tofu, chia seeds, mayonnaise, and aquafaba to varying results.With the price of eggs reaching historic highs and supply wavering due to the bird flu, it could be worth considering egg substitutes when making meals at home.I tried making a classic box of Betty Crocker brownies with different substitutes to see which is best for baking.I used five common egg replacements recommended by vegans and home cooks: applesauce, silken tofu, mayonnaise, chia seeds, and aquafaba, which is the liquid found in a can of beans or legumes, such as chickpeas.Through this experiment, I hoped to find a cheaper alternative to eggs that could still hold up in the recipe.Here's how the five egg alternatives compared.To easily compare the results of the different egg substitutes, I used the same brownie mix for each batch: the Betty Crocker's Fudge mix.The classic mix offers a fudgy and rich brownie. Kristine Villarroel/Business Insider For this test, I used Betty Crocker's Fudge brownie mix. Each box was $2.99.The classic fudge mix calls for 1/2 a cup of oil, 2 tablespoons of water, and two eggs.The first egg alternative I tried was applesauce.Applesauce is a common replacement for eggs in baked goods. Kristine Villarroel/Business Insider One 24-ounce jar of Mott's applesauce was $2.Since applesauce works as a binder and an emulsifier, according to Business Insider's egg replacement chart, it should provide moisture and body to baked goods like brownies.I had used applesauce in baking, but never with boxed mixes.Applesauce works well holding ingredients together, but doesn't help with helping baked goods rise. Kristine Villarroel/Business Insider I had previously made oat cookies with applesauce, but I had never tried it in a box mix.To replace the two eggs in the brownies, I used 100 grams of applesauce, which is just over a 1/3 cup.The mix appeared runny and lumpy.The applesauce texture showed in the brownie mix. Kristine Villarroel/Business Insider I first mixed the applesauce with water and then added the oil, but it didn't seem to fully incorporate.When I poured the batter into a lined baking pan, the mix still had some oil floating on top.In the pan, I could see some of the oil creep up in the corners. Kristine Villarroel/Business Insider Since it wasn't fully emulsified, the applesauce mix seemed to separate a bit in the pan. After pouring it in, I saw some of the oil appearing in the corners.After baking, the same problem persisted I could see the oil bubbling up from the brownie.The oil seemed to separate and float at the top of the brownie. Kristine Villarroel/Business Insider I cooked each batch of brownies in this test at 350 degrees Fahrenheit for 35 minutes or more as needed.At the 35-minute mark, the applesauce brownies still looked undercooked, so I left them in the oven for an additional 10 minutes. Even then, the brownies still seemed a little undercooked when I cut them.The applesauce brownies felt oily and flat.The brownies felt a little undercooked. Kristine Villarroel/Business Insider Despite being cooked for the appropriate time, the brownies seemed undercooked on the inside maybe they could've benefited from staying in the oven a few extra minutes so the mix could solidify a bit more.However, when it came to the taste, they were fudgy and rich and didn't have any apple taste.The second egg alternative I tried was silken tofu.Tofu is a protein-rich replacement. Kristine Villarroel/Business Insider One 16-ounce container of tofu was $2.99.I used 160 grams to replace two eggs just under a third of the pack which added about 7 grams of protein to the brownies.The tofu intrigued me the most.I had never used tofu in baking. Kristine Villarroel/Business Insider While I'm familiar with tofu from being a vegan in the past, I had never used it in baking, so I was intrigued by its potential.The silken tofu was very soft, and it was a little challenging to drain the water from the container without the tofu also falling out.The tofu emulsified better than the applesauce.After mixing thoroughly, the tofu blended nicely in the mix. Kristine Villarroel/Business Insider I first mixed the tofu with the 2 tablespoons of water and then added the oil. The tofu seemed to emulsify a lot better than the applesauce.At first, white clots of tofu were a little intimidating, but after mixing it more, they blended nicely.The brownie batter was a little thicker than when I had used applesauce.The tofu made for a thicker, smoother batter. Kristine Villarroel/Business Insider The mix was thicker than the applesauce, but it was also smoother.The tofu brownie looked promising.The brownie looked shinier and more cooked. Kristine Villarroel/Business Insider Out of the oven, the tofu brownie had a nice shiny layer on top.It had also risen a lot more than the applesauce brownies and didn't look as oily.The tofu brownies were light, although a bit crumbly.The tofu had an almost cake-like texture. Kristine Villarroel/Business Insider Having risen a little more than the applesauce brownies, the tofu brownies had more of a cake-like texture and were a lot lighter.They were a little crumbly not dry but I didn't mind it too much because of the nice lightness the brownie had.The third egg alternative I tried was mayonnaise.Mayonnaise is made from eggs and oil. Kristine Villarroel/Business Insider Mayonnaise, which is made from eggs and oil, made sense as an egg replacement, although I wasn't very fond of the idea.One 8-ounce jar of Hellmann's mayonnaise was $3.99, making this alternative the most expensive per serving.I wasn't too excited to use mayonnaise in baking.I was the most skeptical about the mayonnaise. Kristine Villarroel/Business Insider While I can enjoy mayonnaise in savory dishes, the idea of using it for brownies was a little daunting. I wasn't looking forward to it, but I was open to having my mind changed.I used 6 tablespoons of mayo to replace the two eggs.The mix was the thickest.The mayonnaise made the brownie batter thicker than the rest of the alternatives. Kristine Villarroel/Business Insider I first mixed the mayonnaise with the water and then added the oil, and it seemed to emulsify really well.The mayonnaise brownies didn't look promising.The mix seemed to separate. Kristine Villarroel/Business Insider Pouring it in the pan, the mix did not look as smooth as when I had used other egg alternatives. It was also the thickest, so I had to spread it out.The brownies had trouble baking.The brownies took twice as long to cook. Kristine Villarroel/Business Insider When I first checked on the brownies at the 35-minute mark, the mix was still completely liquid.I let them cook until they solidified for an extra 30 minutes, 10 minutes at a time, and checked until they looked done.When I pulled them out of the oven, oil was bubbling through the flat top.The mayonnaise brownie was my least favorite.I thought it had a weird flavor, but it could've been more of a mental block. Kristine Villarroel/Business Insider The mayonnaise brownie was extremely oily and a little too chewy and hard.I also thought it had a bit of a weird flavor, but that might have been more of a mental block on my part.Next up: chia seeds.A two-pound bag of the seeds was $8.88. Kristine Villarroel/Business Insider The chia seeds seemed expensive at $8.88 for a 2-pound bag, which was the only one I could find at the store.Still, the large bag meant the cost per serving was actually lower than the mayonnaise.I was familiar with using them in baking.I had baked with chia seeds before and usually found it to make recipes more crumbly. Kristine Villarroel/Business Insider I had used chia seeds in baking before, so I knew going in that it usually meant recipes turned out more crumbly than expected.I first mixed 2 tablespoons of seeds with 6 tablespoons of water to make a "chia egg" it took about five minutes for the mixture to settle in a gelatinous texture.I then mixed it with water and then the oil.The mix was a little thick but smooth.You could still see the seeds in the mix. Kristine Villarroel/Business Insider Although you could still see the seeds, the mix itself was smooth and not too dry.The mix was runny enough to spread out on the pan.Unlike the mayonnaise batter, the chia seeds still made for a smooth mix. Kristine Villarroel/Business Insider Although textured, the mix was still smooth and runny enough to cover the pan without me spreading it.The chia brownies looked lighter and crispier than some of the other batches.The chia brownies had a nice crispy edge. Kristine Villarroel/Business Insider When I took them out of the oven, the brownies didn't seem to have any oil bubbling through and had a nice crispy edge and top.The chia brownies were crunchy and fudgy.The chia seeds added a crunch to the brownies. Kristine Villarroel/Business Insider With a nice crispy top and fudgy bottom, the chia brownies were my favorites by far. They were the perfect balance of rich and crunchy.The chia seeds also added a fun crunch to the brownie, and I really enjoyed the texture.The fifth and final egg alternative I tried was aquafaba.I had heard of aquafaba as an egg white replacement but had never used it. Kristine Villarroel/Business Insider Aquafaba, the liquid leftover from cooking chickpeas, is supposed to help with emulsifying, binding, and leavening, making it the most complete replacement, at least on paper.One can of chickpeas was $1.25, making this the cheapest alternative. I used 6 tablespoons of the liquid to replace two eggs.I was excited to try aquafaba, although a bit scared.The chickpea liquid was thick and runny, like watered-down egg whites. Kristine Villarroel/Business Insider I had never used aquafaba, and while I had heard a lot of good things about it, I was a bit uncertain about how these would turn out.Filtering out the liquid, I had to remove some chickpea skins from the aquafaba, which had a thick, watery texture, like watered-down egg whites.When mixed, the liquid turned a white color.It also became lighter and egg-white-like. Kristine Villarroel/Business Insider I first mixed the aquafaba with water and then added the oil. While mixing it, the liquid became white and lighter. I was afraid of over-beating it, so I stopped once it felt like a liquid egg mixture.This mixture was the runniest of them all.The aquafaba mixture was thin and runny. Kristine Villarroel/Business Insider While it emulsified well and the oil didn't seem to separate, the mixture was very runny, more than the other alternatives.