Effect of ε-Poly-Lysine on Preservation of Boiled Noodles

Abstract

The preservative effect of ε-poly-lysine (PL) was investigated under different PL concentrations and temperatures when PL was added to boiled noodles in a simple wrapper. (1) At 20°C, pH of boiled noodles with PL was almost constant during 6-day storage time. On the other hand, pH of noodles without PL (control) decreased from 6.4 to 4.0 after 2 days. (2) At 20°C, viable cell counts gradually increased from 10²/g to 10³/g-10⁵/g during 6 days in the presence of 0.25% to 1.0% of PL, but the counts of control rapidly increased to more than 10⁶/g after 2days. (3) Yeast and mold counts in the samples with PL increased gradually from 10²/g to 10⁴/g-10⁵/g during 6days at 20°C. On the other hand, those of the control showed an increase to 10⁶/g or over after 2 days. (4) About 75% of PL remained in boiled noodles after cooking for 15min in boiling water. (5) The above results showed that the addition of PL was able to prolong shelf-life of boiled noodle for a few days as compared with non-added noodles.