Powdered milk - Funnyu (English spelling) milk powder

Milk or skim milk is powdered and preserved by removing water. Milk made from milk is called "whole milk powder" or "whole fat milk powder," skim milk powder made from skim milk, whole milk powder with sucrose added is called "sweetened milk powder," and milk powder made by replacing ingredients or adding micronutrients mainly for infant nutrition is called "formulated milk powder." In addition, similarly dried products such as cream, buttermilk, and whey are also treated as similar products to milk powder. Historically, Marco Polo's "The Travels of Marco Polo" records that Mongolians made milk powder by drying milk in the sun, but industrial production is relatively new, with drum-type dryers beginning in the United States in 1903. In Japan, production began in 1917 (Taisho 6) by Wakodo, but it did not become widespread until the 1930s.

Manufacturing methods can be broadly divided into drum drying and spray drying. In the drum method, a steam-heated iron cylinder is rotated, milk is sprayed onto its surface to evaporate the water, and the remaining milk powder is scraped off. In the spray method, milk that has been concentrated to about 45% solids is turned into fine milky droplets in a drying tower and sprayed into hot air, instantly evaporating the water, and the milk powder particles are separated and collected. Milk powder made by the spray method is heated to a lesser extent than that made by the drum method, so there is less change in its components and it has good storage properties, and so the spray method is now commonly used.

Powdered milk is widely used as an ingredient in various dairy products, as well as in confectionery, bread, and prepared foods, but its suitability for use varies depending on the strength of the heat treatment used during production. Low-heat-treated powder is suitable for reduced dairy products such as reduced milk and cheese, while high-heat-treated powder is suitable for bread and chocolate production. Powdered milk has a low moisture content, so microorganisms do not grow and it can be stored at room temperature, but the fat in the powdered milk oxidizes over long-term storage, resulting in a loss of flavor. Skim milk powder can therefore be stored for about three years, while whole milk powder can only be stored for six months. For this reason, the air in the container of whole milk powder and prepared milk powder is replaced with nitrogen gas to prevent oxidation of the fat and improve shelf life.

[Kyoji Niinuma and Akiaki Wani]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

牛乳または脱脂乳から水分を除去し、粉末状にして保存性を高めたもの。牛乳からつくったものを「全粉乳」または「全脂粉乳」、脱脂乳からつくったものを「脱脂粉乳」、全粉乳にショ糖を加えたものを「加糖粉乳」、主として乳児栄養の見地から成分を置換したり、微量栄養素を添加したものを「調製粉乳」という。このほかクリーム、バターミルク、ホエイなどを同様に乾燥したものも、粉乳の類似品として取り扱う。歴史的にはマルコ・ポーロの『東方見聞録』に、モンゴル人が天日でミルクを乾燥させて粉乳をつくっているとある記録が古いが、工業的には比較的新しく、1903年にアメリカでドラム式乾燥機による生産が始められた。日本では1917年（大正6）和光堂によって生産が開始されたが、本格的な普及は1930年代に入ってからである。

　製造方法はドラム乾燥法と噴霧乾燥法に大別される。ドラム法は、蒸気で加熱された鉄製の円筒を回転させ、その表面に牛乳を散布して水分を蒸発させ、残った粉乳をかき取る方法である。噴霧法は、あらかじめ固形分45％程度に濃縮した牛乳を、乾燥塔で微細な乳滴状にして熱風中に噴霧し、瞬間的に水分を蒸発させたのち、粉乳粒子を分離回収する方法である。噴霧法でつくられた粉乳は、ドラム法に比べ加熱の程度が少ないため、成分の変化が少なく保存性もよいので、現代では噴霧法が一般に用いられている。

　粉乳は種々の乳製品の原料となるほか、製菓、製パン、調理食品の原料としても広く用いられるが、粉乳製造のときの熱処理の強さによって使用適性が異なる。低熱処理粉は還元牛乳、チーズなどの還元乳製品、高熱処理粉は製パン、チョコレート製造などに適している。粉乳は低水分のため微生物は生育せず、常温で保管できるが、粉乳中の脂肪が長期保存中に酸化して風味の低下をもたらす。したがって脱脂粉乳では約3年間の保存期間に耐えるが、全脂粉乳では6か月である。このため全脂粉乳や調製粉乳では、容器中の空気を窒素ガスで置換し、脂肪の酸化を防いで保存性を高める方法が行われている。

［新沼杏二・和仁皓明］

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