Dried Foods - Dried Foods

Japanese: 乾燥食品 - かんそうしょくひん

Foods that have been dried by reducing the moisture content of fresh foods, either naturally in the sun or by artificial means such as hot air or freezing. Drying has a very long history. The original purpose of drying was simply to store food, but today it is often used to bring out flavors that cannot be enjoyed in raw foods, and to reduce the weight of foods by removing moisture, thereby lowering transportation costs.

[Tomomi Kono]

history

In the Neolithic period, when humans lived in the mountains and fields in search of food, it is believed that they preserved food by drying it in the sun. In an era when food production was left to nature, drying preservation is thought to have been an important means of regulating food supply and demand. Food can be dried without any equipment, so no containers have been found in ruins, and there is no evidence of dried foods. However, it is known that dried meat products existed in pre-Christian Egypt and the Inca Empire, and in Japan, during the Nara period, products such as kitai, which is whole, dried bird and animal meat, and suwayari, which is fish meat that is cut into small pieces, salted, and then dried, were already in existence, which are thought to have been influenced by China. In addition to these, there were also dried seafood, dried fish, dried abalone, dried abalone, as well as dried vegetables and fruits.

Additionally, frozen tofu (koya tofu), which is made by freezing tofu outdoors during the cold season and then drying it, is also an excellent dried food.

[Tomomi Kono]

nature

Fresh foods have poor preservation properties due to their high water content, but if the water content is reduced to 40% or less, the activity of enzymes in the food slows down, the growth of microorganisms is also suppressed, and the food is relatively resistant to deterioration. Dried foods take advantage of this property, but on the other hand, the oxidation caused by oxygen in the air becomes greater, which is difficult to prevent. Proteins also gradually denature, and when cooked, they often have a bad mouthfeel. Fats also change significantly due to oxidation, causing unpleasant odors, and some lipid peroxides combine with amino acids to turn yellowish brown, causing what is known as scorching. Scorching not only reduces the flavor of the food, but can also cause diarrhea and discomfort when eaten.

[Tomomi Kono]

kinds

There are various methods for drying food, but currently the methods listed in the table below can be listed.

Recently, research has been conducted on preventing the deterioration of food color, taste, and aroma due to drying, and new drying methods have been developed to replace natural drying. Vacuum drying is a method that minimizes the effects of air, light, and heat, which cause quality deterioration during drying. Among these, vacuum freeze drying is particularly excellent and is widely used as an ingredient in various processed foods. In addition, to make dried foods easier to rehydrate, powdered foods are processed into porous granules or dispersants are added. In addition, bleaching agents such as sulfurous acid are sometimes added to prevent discoloration during drying. For vegetables, a method such as pressure puffing has been developed to prevent the hardening of plant fibers due to freezing and drying, in which the tissue is made porous by lightly pressurizing and heating the food and then suddenly releasing the pressure. This method is mainly used for root vegetables and thick-fleshed vegetables such as carrots, potatoes, and onions.

[Tomomi Kono]

keep

Dried foods are susceptible to deterioration due to moisture absorption and air during storage, so they are stored in sealed packaging containers, vacuum-packed, or even by replacing the air in the container with nitrogen gas. The fat content in dried foods is particularly susceptible to change, so oxygen scavengers and antioxidants are sometimes used to prevent this.

[Tomomi Kono]

"Fundamentals and Applications of Dried Foods" by Mitsuo Kamewada, Hiromichi Hayashi, and Shigeru Tsuchida (1997, Saiwai Shobo)

Drying methods and major dried foods [Table]
©Shogakukan ">

Drying methods and major dried foods [Table]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

生鮮食品を、天日により自然に、または温風、凍結など人工によって水分を減少させ、乾燥状態にした食品類。その歴史は非常に古い。乾燥の目的は、初めは食品の貯蔵だけであったが、今日ではそのほか、乾燥によって、生(なま)では味わえない風味を出したり、水分を除くことで重量を減らして輸送などの経費を下げるためにも行われることも多い。

［河野友美］

歴史

人類が山野に食糧を求めて生活していた新石器時代には、とってきた食糧を天日乾燥して保存していたと推定される。食品の生産が自然まかせであった時代には、乾燥保存は重要な食糧需給の調節手段であったと考えられる。食品の乾燥は器具なしでできるため、遺跡から容器などが発見されないので、乾燥食品の実証資料がない。しかし紀元前のエジプトやインカ帝国に肉類の乾燥品のあったことは知られているし、日本でも、奈良時代にはすでに中国からの影響を受けたと思われる、鳥獣肉を全身まるのまま乾燥した腊(きたい)、魚肉を細かく切って塩漬けにしたのち干した楚割(すわやり)などがあった。このほか、海産物を干した、干し魚、のしあわび、干しあわびなどや、野菜、果実などを干したものもあった。

　また寒中に豆腐を屋外で凍結したのち乾燥した凍り豆腐（高野豆腐）も、優れた乾燥食品の一つである。

［河野友美］

性質

生鮮食品は水分を多く含むため保存性に乏しいが、水分を40％以下にすると、食品中の酵素の働きが緩やかになり、微生物の繁殖も抑えて比較的変質しにくくなる。乾燥食品はこの性質を利用したものであるが、一方、空気中の酸素による酸化作用が大きくなり、これを防ぐことがむずかしい。また、タンパク質も徐々に変性をおこして、料理した場合、口あたりの悪くなることが多い。脂肪も酸化による変化が大きく、不快臭の原因となるほか、過酸化脂質の一部はアミノ酸と結合して黄褐色を呈し、いわゆる油焼けの原因となる。油焼けをおこすと、味の低下だけでなく、食用により下痢や不快感を呈することもある。

［河野友美］

種類

食品の乾燥は種々の方法があるが、現在では表のような方法をあげることができる。

　最近は、乾燥による食品の色、味、香りなどの低下を防止する研究が進み、自然乾燥にかわって新しい乾燥法もできてきた。減圧乾燥は、乾燥の際に品質低下の原因になる空気、光、熱などの影響をなるべく受けないようにした方法で、そのなかでも凍結真空乾燥がとくに優れ、各種加工食品の材料として広く利用されている。また、乾燥食品をもどりやすくするためのくふうとして、粉末状のものでは、多孔質の粒状に加工するとか、分散剤のようなものを添加することも行われている。また、乾燥中の変色を防ぐため、亜硫酸などの漂白剤を添加することもある。野菜では、凍結や乾燥による植物繊維の硬化を防ぐため、軽く加圧加熱したあと急激に圧力を抜き、組織を多孔質にしたのち乾燥するプレッシャーパフなどの方法も開発され、ニンジン、ジャガイモ、タマネギなど主として根菜類や肉厚な野菜類に用いられる。

［河野友美］