Research on nutrients

Milk protein

Focusing on the quality of milk protein
Meeting more and varied needs

Exploring the world of milk protein

Protein is one of the most important nutrients for our body, as evidenced by the ancient Greek word proteios meaning “primary” or “holding the first place.” The proteins that make up our body are repeatedly synthesized and broken down every day. In other words, muscles and skin are being synthesized or transformed gradually every day. The source of the synthesis is the protein obtained from our diet. There are various types of proteins, but among them, milk protein is known to have good digestion and absorption qualities and an excellent amino acid balance.
Milk protein is contained in various processed foods as well as in milk, and milk protein is used as an important nutrient especially in infant formula and liquid foods. Morinaga Milk has been researching milk protein for many years, and the results of such research are being applied to an ever growing variety of products.


Proteins are essential in our lives.

People often think that protein is taken to improve muscle strength, but that’s not the only reason. In addition to muscles, protein is a component of skin, nails, hair, blood, various other organs, and enzymes that control metabolism, and can be called the "source of the body." Protein is an essential ingredient we must have in our daily life to keep healthy.


Proteins are composed of 20 types of amino acids, nine of which are called essential amino acids and are considered to be particularly important. It is necessary to understand not only that a good protein is rich in these essential amino acids, but also how efficiently they are absorbed from the small intestine. In recent years, attention has been drawn to DIAAS, Digestible Indispensable Amino Acid Score.(Dietary protein quality evaluation in human nutrition: Report of an FAO Expert Consultation. 2013), which evaluates the quality of proteins by considering the difference in absorption rate of each amino acid. Morinaga Milk was one of the first to adopt these concepts and evaluate the various proteins our company offers. Data from the report are used in the product development research of Morinaga Milk, such as the design of the protein composition of Morinaga Hagukumi, an infant formula.

Casein and whey protein

Milk protein is a general term for proteins contained in milk, and can be broadly divided into two types: casein and whey protein. Both are high-quality proteins, but they have different characteristics depending on the amino acids of which they are composed and their absorption rate.
Casein, the main component of milk protein, accounts for about 80% of the protein. Casein contained in milk is characterized by being absorbed relatively slowly. Since it can maintain the amino acid concentration in the blood for a long time after ingestion and continuously suppresses the decomposition of proteins in the body, casein is expected to have the effect of suppressing the muscle breakdown during sleep if, for example, taken before going to bed.
Whey protein accounts for about 20% of milk protein and is known for its fast absorption rate. It also has a unique amino acid composition rich in branched chain amino acids (BCAA). Whey protein is well known as a raw material for the protein that athletes ingest. Since the amino acids that make up our muscles are also high in branched-chain amino acids (BCAA), whey protein being high content of BCAAs is beneficial for muscle growth. This whey protein is made primarily from whey, which is a by-product of cheese.

Understanding the quality of protein
by researching on breast milk

Milk protein has already permeated our daily lives and is taken in a variety of settings. Morinaga Milk also wants more people to know and understand these new benefits milk protein can provide. Through continuing research, we are creating products that take advantage of the characteristics of milk protein that are suitable for all generations and various lifestyles.

For example, in the case of infant formula, we need to know the difference in protein found in human breast milk and in cow’s milk. There are quantitative differences, such as how much protein is contained in milk, and qualitative differences, such as what kind of protein there is in milk. Cow’s milk contains about three times as much protein as breast milk, so Morinaga Milk began the development of infant formula by adjusting it to contain an amount of protein suitable for infants. More recently we have been focusing research on the quality of milk protein.

As explained earlier, there are two major types of milk protein, casein and whey protein. Both contain a large amount of amino acids necessary for infant growth. Casein is rich in methionine, phenylalanine, and histidine while whey protein is rich in cysteine, threonine, and tryptophan. For this reason, it is important to have a well-balanced mix of casein and whey protein.

For example, in Morinaga Hagukumi the ratio of casein and whey protein are adjusted. This product also contains peptides that are enzyme-digested whey protein. As a result, the amino acid balance of cysteine and tryptophan, which are abundant in whey protein, while the digestion and absorption of the protein is enhanced.


Types of amino acids

Types of amino acidsTypes of amino acids

Morinaga Milk disseminates the results of such milk protein nutrition research throughout the world, and also manufactures various milk protein raw materials at its German subsidiary MILEI GmbH for use by many childcare facilities and liquid food manufacturers internationally.


Milei Protein

MILEI GmbH is located in the southernmost dairy region of Germany. MILEI manufactures high-quality milk protein ingredients such as milk protein concentrate, whey protein concentrate, and micellar casein, some of which is also sold in Japan as MILEI Protein ®.


Morinaga Milk applies DIAAS for evaluation of the milk protein materials manufactured by MILEI. DIAAS indicates a ratio of the balance and absorption rate of amino acids to the protein in food. All of MILEI's milk protein materials have a high score of over 100, which shows that they are high quality proteins.


Power of milk protein for liquid foods for the elderly and people with health issues

Milk protein also plays an important role in liquid diets for people who cannot eat a regular diet due to advanced age or various diseases. Liquid diets must provide the necessary nutrition in spite of a limited intake. Therefore, milk protein, which is a high-quality protein, is an indispensable nutrient in the liquid diets provided by the Morinaga Milk Group.

Various milk protein ingredients are used in liquid foods. Casein has the ability to mix (emulsify) various nutritional components well. By utilizing the emulsifying action of casein in the production of liquid foods, it is possible to produce products containing high concentrations of various nutrients.

image of research


rakfea* Liquid food is a product of Clinico Co., Ltd., a company of the Morinaga Milk Group.

For the future

We are currently focusing on a research method called the indicator amino acid oxidation method*, which can measure the amount of protein required by living organisms. Further, we are researching qualities of various protein sources and these combinations.

Because the characteristics of milk protein vary depending on the manufacturing method, we would like to take advantage of these varying characteristics by combining them in new ways to create more beneficial products.

image of research

As professionals in the study of milk protein, the Morinaga Milk team will continue its research with the aim of contributing to the extension of healthy life expectancy, and will continue to provide new products suitable for all generations and various lifestyles. * Indicator amino acid oxidation method: An evaluation method that measures whether the amount of protein (amino acid) ingested is insufficient or excessive with respect to the amount of protein synthesis within the body. By estimating the amount of intake of protein and the amount needed by the body, we can project how much supplemental protein is needed. It is thought that a good quality, efficient protein is one which can efficiently provide the needed benefit in low volume.

Morinaga product containing milk protein developed by advanced technology (example)

As of March 2022