QDoes wasabi have antibacterial effect?

It has the effect of holding growth of bacteria.
It is known that wasabi and mustard have the effect of suppressing growth of bacteria, and people used these for sashimi etc. in old times. This is because the components of spiciness and aroma (Allyl isothiocyanate) holds the growth of food poisoning bacteria and holds the growth of mold and yeast.

QWhy do tears ooze when eating and smelling wasabi?

Allyl isothiocyanate, which is the component of spiciness, is highly volatile and tears come out because nasal mucosa membrane is stimulated by eating and smelling the wasabi.
Also, they say this stimulation moderately activates the brain.

QWhen dissolving powdered wasabi, with water or warm water gets spicier?

When mixing with warm water around 40 degrees C (104F), the pungent component is generated well. It is due to the temperature range where the enzyme myrosinase that generates pungent component reacts most active.

QHow should I store wasabi before and after opening?

It is important to follow the instruction on the package to store the product because the spiciness and aroma are delicate. You can enjoy product until the best before date, if it has been stored according as the instruction before opening. Once it is opened, use as soon as possible. Please refer following reminders;
  • Shelf stable wasabi paste
    It can be stored at a room temperature before opening. Once opened, remove air in the container, close the cap firmly and keep it refrigerated.
  • Wasabi powder
    Put in an airtight container such as food storage container or bag with zipper, and store in cool dry place away from direct sunlight.

QHow should I store wasabi powder mixed with water?

After mixing, put it in an airtight container to hold flavor / spiciness and store in a refrigerator. By reducing the contact with the air by wrapping with plastic film, changes in flavor, spiciness and color will be little.
However, because pungency is volatile, it will be weaken as time goes along after mixing, so please use as soon as possible.