Decoding Corn: What Part of Corn Has the Most Protein?

November 5, 2025 •

2 min read

Did you know that although corn is often considered a starchy vegetable, it is actually a whole grain? When considering its nutritional value, especially the question of what part of corn has the most protein?, understanding the kernel's anatomy is key to unlocking its health benefits.

Quick Summary

The corn kernel's protein is concentrated in the germ and aleurone layer, with the endosperm containing the bulk of the grain's weight but a lower protein percentage.

Key Points

Protein Concentration: The germ of the corn kernel contains a significantly higher percentage of protein by weight than the starchy endosperm.
Whole vs. Processed: Eating whole corn kernels or products like popcorn ensures consumption of the protein-rich germ and fiber-rich pericarp, unlike processed corn flour or grits.
Protein Quality: The germ's protein is nutritionally superior to the endosperm's, offering a more balanced array of essential amino acids.
Kernel's Nutrients: Beyond protein, the germ is also the source of most of the kernel's oils, vitamins, and essential minerals.
The Aleurone Layer: This lesser-known layer, located between the pericarp and endosperm, is also a protein-rich component of the kernel.
Pairing for Balance: To compensate for the endosperm's lack of certain amino acids, pair corn with complementary protein sources like legumes to form a complete protein.

Understanding the Anatomy of a Corn Kernel

To understand where corn stores its protein, you must first be familiar with the four main parts of a corn kernel: the endosperm, germ, pericarp, and tip cap. These distinct parts contribute differently to the kernel's overall nutritional composition. A typical corn kernel is roughly 80-83% endosperm, 10-11% germ, 5% pericarp, and 1% tip cap on a dry weight basis. The different ratios of these components are what cause the variation in nutritional density across the entire kernel.

The Kernel's Protein Powerhouse: The Germ

The answer to the question of where most of the protein in corn is concentrated lies within the germ. The germ accounts for approximately 11% of the kernel's dry weight and contains about 18.4% protein by weight, making it the most protein-dense part. It is also the source of nearly all the kernel's oil.

The Starchy Endosperm and its Protein

The endosperm is the largest part of the kernel and contains the second-highest amount of protein overall, though less concentrated than in the germ. The main protein in the endosperm, zein, is deficient in essential amino acids, particularly lysine and tryptophan. This results in lower protein quality compared to the germ.

The Aleurone Layer and Pericarp

Just inside the pericarp, the aleurone layer is also protein-rich, with a concentration of about 19%. The pericarp, the outer layer, is primarily fiber. The tip cap has minimal nutritional value.

The Impact of Processing on Corn's Protein Content

How corn is processed significantly impacts its final protein and nutrient composition.

Whole vs. Degermed Products

Whole Kernels: Eating whole corn includes the nutrient-dense germ and fiber-rich pericarp, providing the full protein content and better amino acid balance.
Degermed Products: Removing the germ and pericarp during processing for products like corn flour results in lower protein, fat, and fiber content.

Comparison of Corn Kernel Components

This table highlights the nutritional differences between the key parts of a corn kernel:


Chemical Component	Pericarp	Endosperm	Germ
Protein (%)	3.7	8.0	18.4
Ether extract (Fat) (%)	1.0	0.8	33.2
Starch (%)	7.3	87.6	8.3

Supplementing Corn for a Complete Protein Diet

Corn is not a complete protein source because its endosperm protein lacks sufficient lysine and tryptophan. Combining corn with legumes like beans or soybeans creates a complete protein profile with all essential amino acids.

Conclusion: Making the Most of Corn's Nutritional Value

The germ is the most protein-dense part of the corn kernel, while the endosperm provides a larger quantity of protein with lower quality due to missing amino acids. Choosing whole corn and pairing it with lysine-rich foods can create a balanced protein source. For more on maize nutrition, visit the Food and Agriculture Organization of the United Nations website.

Frequently Asked Questions

The germ, or embryo, has the highest percentage of protein by weight compared to the other parts of the corn kernel. It is a concentrated source of this nutrient.

Yes, the endosperm contains protein, but at a lower concentration than the germ. The protein in the endosperm, primarily zein, is also of lower nutritional quality due to a deficiency in essential amino acids like lysine.

Eating whole corn kernels provides all parts of the grain, including the protein-rich germ and fiber-rich pericarp. Corn flour is often made from the starchy endosperm only, resulting in a product with significantly less protein and fat.

QPM varieties are genetically developed types of corn with an improved amino acid balance. This is achieved by reducing the amount of the low-quality zein protein in the endosperm, making the overall grain's protein more balanced.

You can improve the protein quality of a corn-based diet by combining it with foods that supply the amino acids corn is missing. Pairing corn with legumes like beans or lentils is a traditional and effective method.

Yes, the aleurone layer is nutritionally important. It contains a relatively high concentration of protein and is also a source of water-soluble vitamins, though its total mass is small compared to the endosperm and germ.

Yes, the proteins in the germ have a higher nutritional value and a better-balanced amino acid profile compared to the proteins found in the endosperm.