How chickens live changes the taste of their eggs

Scientists in Japan have found that the way chickens live changes the taste of their eggs. A group led by Professor Tsuyoshi Shinmura of Tokyo University of Agriculture and Technology, a university in Tokyo, the capital of Japan, announced the finding on August 31, 2026. Scientists from Kagoshima University, Kyoto University, Nippon Veterinary and Life Science University, and Azabu University also worked on the study. It was published in the science journal^*1 npj Science of Food on August 27.

Some chickens live in cages. Others are cage-free^*2 and can walk around on the floor. The scientists put cages and a cage-free area in the same room. All the chickens ate the same food. For five years, the scientists compared the chickens and their eggs. More than 100 people ate the eggs as pudding^*3 and as chawanmushi^*4, and they said which they liked. The scientists also studied the yolk^*5, the egg white, and the chickens' blood, and they looked at how the chickens' livers^*6 worked.

The chickens in cages could not move much. Because of this, more fat went into their blood and into the yolk, and their eggs tasted creamy. This was easy to taste in the pudding. But these eggs also had more of the things that make a bitter taste, so people liked them less.

The cage-free chickens moved a lot. Their egg white had more amino acids^*7, which give food a savory^*8 taste and a sweet taste. In chawanmushi, these eggs tasted rich and smooth.

The food was the same, so only the way of living changed the chickens' bodies. These changes went through the blood into the eggs and changed the taste. The scientists say that each kind of egg is good for different dishes.

Around the world, more people want farms to be kind to animals, and more countries are stopping the use of cages. But cage-free eggs cost more, so people wanted to know if they are really better. In earlier studies, cage-free chickens also ate grass and insects. Because of this, nobody could see the difference that came from the way of living alone. This new study shows that difference.

1. *1 journal: a magazine where scientists print their studies
2. *2 cage-free: not kept in a cage; free to walk around
3. *3 pudding: a soft, sweet dish made with eggs, milk, and sugar
4. *4 chawanmushi: a soft, warm Japanese dish made from eggs and soup, cooked in a cup
5. *5 yolk: the yellow part of an egg
6. *6 livers: a part inside the body that cleans the blood and helps use food
7. *7 amino acids: very small things in food that the body uses to build itself; they can also give food taste
8. *8 savory: a rich, full taste like meat or soup, not sweet