Sushi and wasabi
Shizuoka Prefecture - largest producer of wasabi in Japan
Those living outside Japan are unlikely to know about the kind of region this wasabi is produced. The perfect environment for wasabi is a cool climate with extremely clean water, and the Izu region in Shizuoka Prefecture, which fulfills these requirements, is the largest producer of wasabi in Japan. I will now introduce wasabi-related photographs and effect-efficacy data obtained from Shizuoka Prefecture.
（Photos: Provided by farm producer in Izu, Shizuoka prefecture）
Wasabi is a plant of the brassicaceae family originating from Japan. Its scientific name is "Wasabia japonica Matsum" and the Chinese characters used for its name are: "山葵" (trans: 山 - mountain; 葵- hollyhock).
Wasabi cultivation methods are divided between "water-grown" and "soil-grown". The water-grown variety is used for raw consumption, while soil-grown wasabi is mainly used for processing such as wasabi pickles.
When wasabi is grated, it has a nasally-stimulating, pungent aroma. Its pungent ingredient is the volatile mustard oil type - "isothiocyanate (ITC)" - and when the mustard oil glycoside contained within wasabi's cells is physically broken-down during the grating process, hydrolysis of the mustard oil glycoside occurs due to the activity of the oxygen present in wasabi, and mustard oil is produced, thus explaining the aroma.
Within the mustard oil of wasabi, the most abundant ingredient is "allyl mustard oil", which makes up approximately 90%. Approximately 0.3g of this oil is contained per 100g of raw wasabi.
Besides allyl mustard oil, there are also a large number of other mustard oils. For example,
The "sawa (mountain stream) aroma", which is the unique taste of "sawa-wasabi", is caused by ω-Methylthioalkyl mustard oil.
Since the bactericidal property of pungent ingredients such as allyl mustard oil was reported by Koch et al in 1882, it has been discovered that wasabi has many activities including vitamin B1 synthetic enhancement capability, vitamin C stabilization capability, orexigenic effect, antiparasitic effect, and a digestion absorption effect.
Former University of Shizuoka Professor, Morita, discovered that wasabi had antibacterial activity against the widely feared O-157 strain of the E.coli bacteria. Additionally, it was found that it has extremely high antibacterial activity against various types of foodborne pathogenic bacteria such as Staphylococcus aureus, Vibrio parahaemolyticus, and its role as a cancer-prevention method was acknowledged because it breaks down burnt substances believed to cause cancer.
Further, Professor Kinae of the University of Shizuoka is researching the synergistic effect of tea and wasabi ingredients, and there is a high degree of expectation that intermingling these ingredients will have an even higher cancer preventative effect.
Another fact discovered is that wasabi has antioxidant activity protecting against fat content oxidation within a living organism that can cause aging and disease.
Reasons behind the sushi boom
The Japanese have known first-hand about the effect and efficacy of the wasabi aroma for many years, and have integrated it into Japanese food. It has been used particularly as an essential accompaniment to the Japanese flagship foods - sushi and sashimi (raw fish).
When considering the background behind sushi's boom across the globe; the essentially good taste of sushi would have to be given as the top reason, followed by its status as a health-food supporting the longevity of the Japanese people. Also I would like worldwide fans of sushi to acknowledge once again that the fact which the combination of sushi and wasabi have now been scientifically-proven.
People interested in wasabi should refer to the Japanese homepage - "Shizuoka ken mikan engei ka (in Japanese) - Shizuoka Prefecture Tangerine Horticultural Department - ".