Narezushi

It is believed that the original Narezushi (Hinezushi in Noto) was not soaked in vinegar but took at least one year of ripening. However, currently, Narezushi is often eaten within two to fourmonths after initiation of ripening. 

3 Free amino acid and organic acid levels In Narezushi 

The pH of Aji no susu is within the range of 3.9. 3, with main organic acid as lactic acid (3.1-8.6g/l(X)g). In addition, volatile short-chain fatty acids, such as acetic acid (0.1-0.6 g/100 g), were detected. The highly concentrated lactic acid is characteristic of Narezushi that rich in rice (carbohydrate). The concentration of lactic acid in the Narezushi (Aji no susu) made from horse mackerel and fermented for 1 year was higher than that in Fumzushi and Saba (mackerel) narezushi made in Fukui Prefecture. Butyric acid and propionic acid, which are considered the main causative factors for the characteristic odour of Fumzushi and Kusaya, were hardly detected. 

Currently, Japanese sushi is prepared by placing a slice of fresh fish on hand-shaped vinegar rice. It is considered that Narezushi is an origin of the cnrrent Sushi. Sushi will have vinegar added instead of waiting for the accumnlation of lactic acid. 

The aromatic compounds in Narezushi made from horse mackerel, which shows various durations of fermentation, were analysed by a Headspace GC/MS system. The content was higher and the kinds of aroma constituents were present more in the fish meat part than in the rice part. Contents of acetic acid (4100-6500ng eqnivalent to BHT/g) and l-penten-3-ol (980-2900ng equivalent to BHT/g dried small sardines smell) 

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Kiyohara, M., Koyanagi, T., Matsui, H., Yamamoto, K., Take, H., Katsuyama, Y, et al. (2012). Changes in microbiota population during fermentation of Narezushi as revealed by pyrose-quencing analysis. Bioscience Biotechnology and Biochemistry, 76,48-52. 

Traditional fermented fish products are also made in Europe and Africa. For example, SurstrGmming, which is marketed in Sweden, is made from herring and anits a strong smell after spontaneous fermentation in cans without sterilization. Feseekh is made in Africa from mullet or other fishes by salting and fermentation. Since the 1950s, several studies about Southeast and East Asian culture and their traditional foods had been reported by Shinoda (1970). These reports speculate about the propagation of Narezushi, salted and fermented fish with cooked rice. Ishige and Ruddle (1990) indicated in their report entitled Research on fish sauce and Narezushi that the distribution of Narezushi and fish sauce production are correlated to paddy-rice culture in Monsoon Asia. 

Narezushi Fish, rice, salt Fermented fish-rice Japan... 

Figure 16.1 Distribution of the Narezushi line and Izushi line in Japan.

In the Ishikawa Prefecture, Izushi-type fermented foods, including Kaburazushi and Daikonzushi, remain in the Kaga district, which is an urbanized region. On the other hand, old-type Narezushi is made in Noto, which is a rural area that follows traditional cultures. Ishiru is made in Noto, as previously mentioned. These facts correspond to the findings obtained by Ishige and Ruddle (1990) indicating that rice paddy cultivation is deeply associated with fish sauce and Narezushi. 

The process of preparing Narezushi in Noto is as follows (Figure 16.6) (1) the giUs, guts and eyes of the fresh fish are removed (2) the fish is salted (3) the fish is soaked in diluted vinegar (4) the prepared fish and cooked rice are filled in a barrel and... 

LAB, such as lactobacilli and lactococci are the predominant microbiota in Aji no susu Narezushi made from horse mackerel), which is either produced in each family or was commercially available. Most of the samples (1.5 to timonths of ripening) contained 8 log cfu/g LAB, indicating that Aji no susu is a typical lactic acid-fermented food (Kuda et al., 2009). In products fermented at least one year, the amount of LAB decreases to approximately 6 log cfu/g. Mold occurs on the lid of some barrels. These fungi might have a role in the development of the unique taste of Aji no susu. 

The materials and recipe of Daikonzushi are similar to those of other Izushi-type products made in the Tohoku region and Hokkaido. Originally, old-type Narezushi was mainly prepared from freshwater fishes in inland or mountain areas. The Izushi-type products are made mainly from marine fishes in plains and urban areas. From the viewpoint of the association with Izushi-type products, such as Shihhe, in Korea, this is an interesting fermented food culture. 

Ishige, N., Ruddle, K. (1990). Research on fish sauce arid Narezushi (Gyosho to Narezushi no Kenkyu). Tokyo Iwanami-Shoten (in Japanese). 

Kanno, T., Kuda, T., An, C., Takahashi, H., Kimura, B., (2012). Radical scavenging capacities of saba-narezushi, Japanese fermented chub mackerel, and its lactic acid bacteria. LWT-Food Science and Technology, 47, 25-30. 

Kuda, T., Yano, T. (2010). Lactic fermented food with fish - Noto narezushi and Kaga kabu-razushi. Japanese Journal of Food Microbiology, 27,185-195. 

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