Potential of phytic acid in synergy with sodium chloride as a natural-borne preservative to inactivate Escherichia coli O157:H7 and inhibit natural microflora in fresh noodles at room temperature
Hary Yu, Min Suk Rhee
Abstract
The increase in consumer demand and the high cost of maintaining a cold chain during distribution emphasize the need for preservative technology to ensure the microbiological quality of fresh noodles with a moisture content of 32–40%. However, few studies have been conducted to increase the storage stability of fresh noodles by using a preservative with a significant inhibitory effect against microorganisms and/or minimizing the use of synthetic antimicrobial agents. This study aimed to propose a synergistic natural-borne antimicrobial that could interact with NaCl, an essential component of noodles, for extended preservation of fresh noodles at room temperature. NaCl (0–1.6% (w/w) based on the total weight of the noodle dough) and phytic acid (0–1.0% (v/w)) were applied to fresh noodles. The bactericidal effect on Escherichia coli O157:H7 and the inhibitory effect on the indigenous microflora were assessed within 21 days at 30 °C. After cooking fresh noodles, physicochemical/textural and sensory characteristics (whiteness, pH, water activity; hardness, adhesiveness, springiness, chewiness; appearance, odor, overall acceptance) were further evaluated as objective and subjective quality parameters. In fresh noodles preserved with 0.6% phytic acid and 1.6% NaCl, the E. coli O157:H7 population was eliminated below the detection limit (>5.8 log reduction; P < 0.05) within 4 days of storage. This preservative significantly inhibited ( P < 0.05) the mesophilic bacterial and total yeast/mold counts naturally present in fresh noodles for 12 days, while the largest antimicrobial activity was observed in noodles supplemented with 1.0% phytic acid combined with 1.0–1.6% NaCl. Although the objective parameters were significantly affected by the preservatives, analysis of the subjective parameters demonstrated that all samples were slightly or moderately favored by the panelists ( P > 0.05). Considering the normal range of objective parameters for fresh noodles, the optimal preservative was determined to be 0.6% phytic acid and 1.6% NaCl. This study suggests the potential use of phytic acid as a natural-borne preservative that combines with NaCl in fresh noodles and exerts a synergistic effect. The developed method is expected to be applicable to extending the shelf life of other grain-based foods containing NaCl as an essential ingredient. • Preservative was developed with synergy of phytic acid and essential ingredient, NaCl. • The inoculated E. coli O157:H7 was reduced (>5.8 log) within 4 days at 30 °C. • Growth of indigenous microflora was significantly inhibited within 12 days at 30 °C. • The preservative improves the storage stability (ca. 7 days) at room temperature. • Cooked noodles (0.6% phytic acid + 1.6% NaCl) showed no sensory difference.