Delineating the synergistic effect of radio frequency and acidic pH regulation on the shelf life and quality of semi-dried noodles

This study aimed to investigate the effect of radio frequency (RF)-synergized pH regulation on the shelf-life and quality of semi-dried noodles. A comprehensive analysis was conducted on microbial, quality and microstructural characteristics. The addition of 0.4 % monosodium fumarate reduced the pH of semi-dried noodles from 5.88 to 4.75, and extended their shelf-life to 7 d. Moreover, RF treatment significantly (P < 0.05) reduced the initial mold and yeast to 0 lg CFU/g, and extended the shelf-life to 5 d. Furthermore, RF-synergized acidic pH significantly (P < 0.05) reduced the initial total plate count from 2.99 lg CFU/g to 2.27 lg CFU/g while significantly (P < 0.05) reducing the initial mold and yeast to 0 lg CFU/g, thus prolonging the shelf-life to 15 d. The combined treatments increased bound water contents (A₂₁) from 0.982 to 0.987, and decreased its relaxation time (T₂₁) from 2.656 ms to 1.520 ms. Furthermore, RF-induced protein polymerization and textural improvement compensated for the acidic pH-induced quality deterioration of semi-dried noodles. This resulted in an increased protein network junction and enhanced textural stability of semi-dried noodles following combined treatments. Therefore, the synergistic treatment of RF and acidic pH regulation is a potential preservation technology in semi-dried noodles.