Knowledge of heat treatment for food
Features of roasting

Features and benefits of roasting "焙煎"

Roasting is one of heat treatment methods called "roast" and "dry roasting".
Even at home, you may cook sesame or soybeans with a frying pan.
At home you can apply kanji "炒る" or "煎る".
There is no big difference between the two methods of treatment, but "煎る" means stronger heat treatment than "炒る", that is, the meaning of burning becomes stronger.
In the meaning of kanji "煎" which is used in the word "焙煎", it may be said that "焙煎" so called roasting is a heat treatment method that has a strong meaning of burning rather strongly.

What is roasting "焙煎"
Heat treatment called roasting is a method of heating food materials without using a heat medium such as oil or water, and the roasting treatment will evaporate the moisture contained in the food ingredients and impart a fragrant flavor.
Besides that, proteins and foodstuffs such as proteins and carbohydrates such as starch may cause chemical reactions due to thermal energy during heating, which may change properties and flavor and flavor of foods.


What is the food to be roasted?
Heat treatment called roasting is used as one example of a cooking method for eating grain and seeds, as exemplified by sesame or soybean at the beginning, and foodstuffs such as coffee beans, cacao beans or tea leaves as it is It is sometimes used as a thermal processing method that makes it possible to eat foods that are not suitable as.
In foodstuffs that are roasted for the purpose of producing taste and flavor, if the temperature of roasting treatment and heating time are mistaken and burned too much, bitterness becomes too strong, so it is common for many cases to purchase processed ones is.
However, roasting can be done with cooking utensils at home, so some people roast food ingredients that can be eaten as raw, like sesame, changing at home according to their taste.
Roasted barley and tea leaves used for barley tea and roast tea may also be roasted again just before extraction for the purpose of increasing the flavor.
In recent years roasting machines for coffee beans for households have also been sold and it seems there are cases where roasting raw coffee beans themselves according to their taste.
The main items of roasted foodstuff are as follows.
  • Cereals such as rice (brown rice), barley, soybeans
  • Directly eating seeds such as peanuts, almonds, macadamia nuts, sesame seeds, ginkgo and so on
  • Seeds to be food ingredients such as coffee beans and cocoa beans
  • Tea leaf


Reactions and points that occur during roasting
In roasting heat treatment, roasting temperature, item temperature, heating time, cooling time are important factors.
Furthermore, it is important that evenly heat is applied to all ingredients during roasting, so the mixing state is also an important condition.
Although the roasting temperature and time will change depending on the ingredients and purpose, basically, you will add aroma by burning the ingredients and aroma components will stand out.
Temperature management concerning roasting has few published information, and each food manufacturer's know-how is packed.
However, in order to stably produce the quality of roasted foodstuffs in good condition, it is important to control the heating time by raising the temperature and cooling quickly to return to normal temperature.
If the roasting temperature is too high, it may result in excessive burning and strong bitterness or excessive color.
In addition, volatile components will be vaporized at all times while the temperature of the ingredients is high, so even if the roasting is finished in the ideal state, there is a possibility that necessary aroma components will disappear if it takes time to cool There is also.
Therefore, in order to reach the target temperature in a short time and quickly return to room temperature at the end of the roasting time, it is important to make a system that stirs effectively while not scratching food materials.


What are the characteristics of roasting in typical ingredients?
Cereals such as rice and barley, coffee beans and cocoa beans that are not used without roasting, and nuts with a lot of oil that require attention to conditions, etc. are characterized by heat treatment such as roasting in each ingredient I would like to explain.


●Brown rice tea(Genmaicha)
The history of brown rice tea is the beginning of putting the tea in the tea leaves by roasting the dried waste chips which occurred when cutting the New Year's mochi. It is thought the fragrant aroma and taste of the roasted brown rice is the decisive factor of brown rice tea.
In recent years, sencha is used as tea leaves, but originally it began to drink brown rice tea in order to deliciously drink tea leaves that fall short in quality such as tea leaves and roasted tea outside the standards.
Brown rice, white rice and glutinous rice are often used for roasted rice to be added, but roasted rice is mixed with tea leaves and roasted until becoming fox color is marketed as brown rice tea.
The taste and aroma of brown rice tea are said to be dependent largely on roasted rice.
Some roasted rice is mixed with explosives.
At our company we expand the brown rice and sell it under the name "flower", but since there is no particular influence on the taste, it is used by the tea maker from the glamorous appearance.


●Barley tea(Mugicha)
Although the name of tea is attached, tea leaves are not included at all, and it is barley tea to simmerize the roasted wheat as it is and to make it as a beverage.
Historically, it goes back to "barley tea" which became popular among the upper classes of the Heian era.
The barley that is extracted after roasting the fresh barley harvested in the early summer has good taste and aroma, and it has been drunk as a standard in the summer.
Depending on the preservation state, barley tea which became old in the late summer sometimes has a fragrance falling, there seems to be some families drinking with light frying and adding fragrance before extraction.


●Soybean (Kinako)
After roasting the soybean, it is a powder which is peeled and crushed into fine powder. The origin of the name of "Kinako" is "yellow powder", which is based on the color attached by roasting.
However, the color and flavor of the finely divided powder will change as raw materials are changed from soybeans, blue soybeans, black soybeans, and edamame.
Kinako produced from blue soybean is called "blue Kinako powder", "Uguisu Kinako" or "Uguisu powder", it becomes a powder of color as Uguisu bird.
Well, the meaning of roasting in the manufacture of kinako powder is not only color adjustment, but also the odor of raw soybean comes out, roasting gives fragrant aroma and sweetness.
The odor peculiar to soy flour is generated by the enzymatic reaction of soybean, but roasting will inactivate the enzyme and it will prevent the occurrence of smell.
Temperature against roasting temperature is not disclosed, but roasting method seems to have various methods.
If the enzyme is only inactivated, high temperature is not necessary, and conversely, if the temperature is too high, the yellow color approaches brown.
More than anything, if roasting conditions are too strong, isoflavones expected of soybeans will also be denatured.


●Beer (malt)
What is based on the amber color of beer is a brown pigment that roasts malt.
The malt is the main ingredient of beer and whiskey, which is obtained by immersing in water and applying heat to barley where roots are growing, stopping germination and drying with hot air.
The main purpose of heating to germinated barley is to stop the progress of germination, but if you just stop germination it is not necessary to heat up to high temperature treatment called roasting.
However, in reality, the browning reaction caused by hot air drying of malt, the so-called burning condition, greatly changes the color of the beer to be made.
Thin colored beer like Pilsner uses malt with light roasting condition, beer with strong color like stout and strong flavor is used malt (or barley) roasted until it becomes black.
The color and taste of various beers are decided by mixing malt (barley) of color and thin malt of thin color.


In recent years, there seems to be something called "green coffee" which is brewed without roasting raw coffee beans, but in general, drinks extracted from hot ground with roasted raw coffee beans is called coffee.
The roasted product temperature of coffee beans is generally roasted at a high temperature of 230 ° C to 250 ° C. However, in recent years, green coffee which does not roast because the health ingredients contained in coffee beans are inactivated by high temperature heating that means that it is a bit of a boom.
In the roasting of coffee beans, the degree of roasting is controlled such as shallow roast, medium roasted, deep roasted.
The purpose of this is to control the change and volatilization of components due to heat as well as add bitterness when extracting it, depending on the type of coffee beans, as the contents of ingredients that produce coffee peculiar taste such as acidity and astringent are different thing.
Of course, because the taste differs depending on the type of coffee beans, it seems that it is controlled by how much roasting of coffee beans you use is suitable for roasting.


●Chocolate and cocoa
After harvesting, fermented for about a week, roasted cacao beans dried in sunlight is used as a raw material.
It can be said that the roasted product temperature is relatively low from 110 ° C to 150 ° C and the burnt bitterness associated with roasting is small.
The bitterness of chocolate depends on the bitter ingredient called theobromine.
After washing and grinding roasted cacao beans, unnecessary substances from which husks such as hulls and embryos are generated are removed, and those ground to about 100 μm by grinding machine are called cacao powder and chocolate and cocoa raw materials It is a food ingredient.
Since cocoa beans contain a lot of lipids, roasting temperature will be suppressed when roasting at high temperature because lipids oxidize.


●Roasted Hojicha
Tea leaves of Japanese tea are heated to prevent oxidation and fermentation and increase extraction efficiency before drying and massaging.
Usually it is a heating method called steaming, but there is also a thing called Kamairi roasted tea and roasted in iron pots and pots. Ureshino tea in Kyushu is one of the famous Japanese tea as a Kamairi roasted tea.
The fact that roasting treatment is effective in the heat treatment of tea leaves is the manufacture of Hojicha.
Unlike green tea leaves that use young leaves, there are many cases where roasted tea made from grown leaves is used as a raw material.
Because the leaves are growing too much, the tannins are increased, so it is supposed that the tea that added aroma by suppressing astringency by roasting is Hojicha.
In the home, it seems that occasionally we use roasted tea leaves which have become older and have reduced flavor.


The image to roast almonds is strong, and there is an image like roasting any kind of nuts.
However, some nuts themselves can be eaten raw and there are cases where it is okay to heat as much as drying.
However, it is often accompanied by a peculiar odor and undesirable flavor, as is also known from the alias of the seeds, and it is more likely to be fried or roasted with oil to add fragrance, except for unnecessary taste.
The roasting of nuts is said to be good between 170 ° C and 180 ° C between cocoa beans and coffee beans.
Many nuts contain lipids, and if roasted at too high a temperature there is a possibility that the oil may be oxidized, and the necessary flavor may be flying.