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From: Food Quality & Safety magazine, August/September 2012

Artturi Virtanen's Silage Preservation System Innovated Farming

by Lori Valigra

Nobel laureate Artturi Ilmari Virtanen (1895-1973)—a Finnish biochemist with the rare distinction of having both the 1449 Virtanen asteroid and the lunar crater Virtanen named after him—applied his specialty to the agriculture and dairy industries. Even so, his work to improve nutrition chemistry and the quality of animal products rippled up the food chain to humans. He made key contributions to preserving fresh fodder for cows during the long winters of his native country, also using that knowledge to develop a system to preserve Finnish butter and making it an international delicacy after World War II. He also improved our understanding of raw food digestion in the body by studying the release of enzymes.

He is most known, however, for a method he developed to preserve grain silage by increasing its acidity. It is called AIV (his initials) silage, and it led to his Nobel Prize. The technique is an additive sprayed on stored grains to raise their acidity, thus stopping the excessive fermentation that destroys both the stored grain and its nutritional value.

Focus on Chemistry

According to his biography in Nobel Lectures on the website of the Nobel Prize—which he won in 1945 for his work and inventions in agricultural and nutrition chemistry—Virtanen was born in Helsinki on Jan. 15, 1895 to his father Kaarlo Virtanen and mother Serafiina Isotalo. He was educated at the Classical Lyceum at Viipuri, Finland.

After completing schooling there, he studied chemistry, biology, and physics at the University of Helsinki, where he earned a master of science degree in 1916 and a doctor of science degree in 1919. In 1920 he continued his studies with work in physical chemistry in Zurich under Georg Wiegner, followed by work in bacteriology in 1921 under Christian Barthel in Stockholm. From 1923-1924 he studied enzymology in Stockholm with Hans von Euler-Chelpin, who later shared the 1929 Nobel Prize in chemistry. But in 1923, Virtanen’s interest turned to biochemistry.

In his professional career, he was first assistant in the Central Laboratory of Industries at Helsinki from 1916-1917, and then a chemist at the Laboratory of Valio of the Finnish Cooperative Dairies’ Association from 1919-1920. He married botanist Lilja Moisio in 1920, and had two sons, Kaarlo and Olavi. Kaarlo later became a mathematician, but Olavi followed in his father’s footsteps in chemistry. In 1921 Virtanen became director of the Valio laboratory, and in 1931 he headed the Biochemical Research Institute at Helsinki.

In 1931, after having served as a docent in chemistry at the University of Helsinki since 1924, and where he was known for his lectures on the chemistry of life, he was appointed professor of biochemistry at the Finland Institute of Technology at Helsinki, and then at the University of Helsinki in 1939. He also worked in the Butter Export Association’s lab, which became a laboratory of the university. In 1930 the university’s Institute for Biochemistry was founded, and he worked there until his death. Virtanen died on Nov. 11, 1973, from complications related to fracturing his hip two weeks earlier. He holds honorary degrees from the universities of Lund, Paris, Giessen, and Helsinki, the Royal Technical College at Stockholm, and the Finland Institute of Technology.

In the early 1900s Virtanen was one of the first scientists to notice that raw foods contained healthy enzymes, and postulated that the enzymes literally burst open when they entered the body, thus aiding in the digestive process.

Science on the Farm

Virtanen bought a farm near Helsinki in 1933, giving him the opportunity to test some of his scientific results in the real world. He regarded the overproduction of food to be only a temporary phenomenon. He loved living simply, never owning a car, smoking or drinking alcohol.

His interest in chemistry appears to go back to his seven brothers, four of whom died in childhood. He used chemistry to research the cause of his brothers’ deaths, according to Wikipedia, and determined that they probably died of a Vitamin A deficiency. He linked that to the fact that his family was poor and drank fat-free milk.

His academic research started in 1924 with a focus on the phosphorylation of hexoses. Virtanen showed that the phosphorylation of sugar is the first step in many fermentation reactions in which the sugar is broken into simpler molecules like alcohol or acetic acid. If fermentation continues, the final product is carbon dioxide. The next year, in 1925, he researched nitrogen-fixing bacteria in the root nodules of leguminous plants. He also figured out how to improve butter preservation by adding disodium phosphate to prevent acidic hydrolysis, and the method continued to be used in Finland for several decades. His research from 1925-1932 included the AIV fodder preservation method, which he patented in 1932.

The AIV silage method, drawn from his observations of plant decay, improved the storage of green fodder, which is especially important over long winters in a cold country like Finland. Fodder for cattle is typically stored as silage, which is made from larger pieces of fodder shredded into small pieces and fermented to remove the oxygen, which prevents rotting. The AIV process includes increasing the acidity of newly stored greens, stalks, and grain by adding dilute hydrochloric or sulfuric acid. That, in turn, prevented excessive and harmful fermentation. The process also was shown to have no adverse effects on the fodder’s nutritional value or on the animals that eat it. The milk produced by the cattle that grazed on the fodder was indistinguishable chemically and in its vitamin content from the milk produced by cattle that ate fresh grain, hay, and plants. Another aim of his work was to produce milk that had the same vitamin content regardless of the season of the year. The AIV fodder process became so popular and useful to European farmers that it garnered the Nobel Prize.

Virtanen also developed a similar system that he used to preserve butter by applying chemistry and enhancing the pH factor through additional salt. That discovery helped boost the Finnish economy following World War II by making the country’s butter an international delicacy.

In the early 1900s Virtanen also was one of the first scientists to notice that raw foods contained healthy enzymes, and postulated that the enzymes literally burst open when they entered the body and thus aided in the digestive process.


Lori Valigra is a frequent writer for Food Quality. Reach her at lvaligra@gmail.com.

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