Nitrofuran derivativses, firstly developed as a chemotherapeutic agent for human diseases, have been utilized as feed additives in the United States and as food preservatives in Japan.
AF-2 (2-(2-furyl)-3-(5-nitro-2-furyl) acryl amide) and AF-5 (3-amino-6-(5-nitrofuryl-2-ethenyl)-1, 2, 4-triazine hydrochloride), two new nitrofurans, have been found to have high antibacterial activity in vitro and very low chronic toxicity as compared with nitrofurazone (F) and nitrofuryl acryl amide (Z) which are currently being used as food preservatives in Japan.
In this study, preservative effects of these two new nitrofurans were tested in use with Kamaboko (fish cake), fish sausage and fresh fish. They showed strong preservative effects for these foods.
AF-2 and AF-5, both showed a preservative effect for Kamaboko at a 5 ppm ratio which was more effective than a 250 ppm ratio of Neofuraskin (trade name of powder sold by Ueno Seiyaku Co., containing 2% of F and 8% of Z). (Table 2. and 3). For fish sausage, AF-2 and AF-5 showed almost the same preservative effect. A 5 ppm ratio of AF-2 or AF-5 was as effective as a 250 ppm ratio of Neofuraskin. But the effect of AF-5 for these two kinds of foods was more varied than that of AF-2 during the experiments. (Fig. 1). This phenomenon might be caused by the instability of this compound in foodstuffs. When the fish were dipped in druged sea water, the preservative effect of AF-2 and AF-5 for fish was almost the same as that of chlorotetracycline, with AF-2 slighly more effective than AF-5. Both were far more effective than Z. (Table 5. and Fig. 2).