Microbial and chemical properties of aji-no-susu, a traditional fermented fish with rice product in the Noto Peninsula, Japan

Abstract

Aji-no-susu is a Japanese fermented fish product prepared from salted horse mackerel Trachurus japonicus, and cooked rice. We studied the organic acid and free amino acid contents and microflora in 12 aji-no-susu products to clarify their features as a lactic-acid-fermented food. Salinity of the samples was approximately 7.0% (rice portion) and 6.0% (fish portion) (w/w). Water activity was approximately 0.9, and pH was approximately 4.4 and lower. In the rice portions, lactic acid content was very high (57 mg/g sample). The predominant amino acids were alanine (2.3 mg/g rice portion) and lysine (2.1 mg/g). In the case of long-fermented (4 and 12 months) aji-no-susu, a high content of gamma-aminobutyric acid (GABA, 1.5 and 1.4 mg/g) was detected. Total viable counts in rice and fish portions were 7.7 and 7.4 log colony-forming units (cfu)/g, respectively. The number of lactobacilli in the rice and fish portions was 7.3 and 7.1 log cfu/g, respectively. Yeasts were detected in eight samples. Furthermore, acidtolerant lactic acid bacteria (LAB) (Lactobacillus plantarum), GABA-producing LAB (Lactobacillus sp.), and halophilic or halo-tolerant yeast (Debaryomyces hansenii) were isolated and identified. Results in this study indicate that aji-no-susu is a typical traditional lactic-acid-fermented fish product.

Microbial population and physico-chemical composition of an African Fish based flavouring agent and taste enhancer

“…No significant difference (p>0.05) was recorded for lactic acid contents in all Lanhouin samples collected from market and processing sites within species but significant difference (p<0.05) was noted between species. Lactic acid contents in Lanhouin samples analysed were lower than those reported in other salted and fermented fish products (16 mg/g DM) (Kuda et al, 2002), salted fish (48.10 mg/g DM), fish sauce (aji-no-susu) (57.14 mg/g DM) (Kuda et al, 2009). Levels of acetic acid varied from 4.7 to 5.6 mg/g DM and 4.6 mg/g DM were determined for cassava fish and king fish Lanhouin samples respectively.…”

Pyrosequencing Analysis of Microbiota inKaburazushi, a Traditional Medieval Sushi in Japan

“…By contrast, the most ancient traditional sushi, narezushi, is made from salt-(and vinegar-)treated fish, and boiled rice is used instead of malted rice. Narezushi is fermented over a longer period than kaburazushi (exceeding 1 month), 2) and thus kaburazushi can be recognized as a mid-modern type. Lactic acid fermentation, accompanied by saccharification of starch by the malted rice, is responsible for the slight sweet-and-sour taste of the product.…”

Changes in Microbiota Population during Fermentation ofNarezushias Revealed by Pyrosequencing Analysis

“…These results are consistent with a previous report by Kuda et al, in which 32-40 mg/g of lactic acid was detected after fermentation had proceeded for about 1.5 to 2 months. 1) We also detected significant quantities of acetic acid (8.3 mg/g). This acid might be present as an artifact of the fish pretreatment process with vinegar, or it might be produced by heterofermentative L. brevis and L. plantarum.…”

“…The concentrations of the other organic acids detected did not vary significantly from those reported previously. 1) Changes in total bacterial population during ajinarezushi fermentation Finally, we evaluated the approximate total bacterial populations at each stage of fermentation by measuring the quantity of 16S rDNA by qPCR (Fig. 1).…”

“…1,2) Narezushi is made from salted fish and cooked rice, and is naturally fermented for more than 4 weeks at ambient temperature. In several areas in Japan, for example the Noto Peninsula in the Hokuriku region, preparation of narezushi as a preserved food or delicacy remains popular.…”