Application of UV-C and modified atmosphere packaging to prolong the shelf life of parboiled Hokkien noodles : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology, Massey University, Manawatu, New Zealand

Abstract

Hokkien noodles is a popular pre-cooked alkaline noodle product that is widely consumed in Asia. Despite their nutritional and sensory appeal, the high moisture content limits shelf life to 1–1.5 days at room temperature. The main challenge affecting the shelf life of pre-cooked noodles is microbial spoilage. Nowadays, traditional chemical preservatives raise health and sensory concerns, driving demand for clean-label alternatives. Ultraviolet-C (UV-C) light treatment is an eco-friendly, non-chemical disinfection method, that has shown promise in inactivating microorganisms on food surfaces. However, UV-C treatment alone does not prevent recontamination. This study explores the synergistic effects of UV-C treatment and modified atmosphere packaging (MAP) in extending the shelf life of Hokkien noodles. UV-C effectively reduces surface microbial load, while MAP maintains a minimum oxygen level to inhibit microbial growth, particularly anaerobic and spoilage bacteria. Together, these technologies may ensure microbial safety and maintain the sensory quality of fresh noodles. By combining UV-C light and MAP, this research highlights the potential of this multi-hurdle method to meet modern consumer demands and improve the shelf life of commercial noodles. The current study was carried out in two stages to evaluate the effects of UV-C treatment and MAP on the shelf life and quality of pre-cooked Hokkien noodles. Phase one identified the optimal UV-C dosage with MAP to extend the shelf life of Hokkien noodles stored at 4 °C for 14 days. The pre-cooked Hokkien noodles were subjected to four different UV-C doses (50, 110, 126, and 220 mJ/cm²). Half of the samples were packaged under modified atmosphere packaging (MAP) conditions, while the remaining samples were not packaged under MAP. Standard plate count (SPC), yeast and moulds (Y&M), pH, and water activity were analysed for each dosage. Based on the findings in stage one, a UV-C dosage of 110 mJ/cm² combined with modified atmosphere packaging was selected for phase two experiments. This combination provided sufficient germicidal efficacy while preserving the texture (preventing breakage) of the Hokkien noodle product. In phase two, noodles were treated with the optimal UV-C dosage identified in phase one and stored under modified-atmosphere packaging conditions. Control samples were maintained as a baseline for comparison to evaluate the effects of the tested parameters on the treated samples. Their shelf life was evaluated over a 42-day storage period at 4°C. Physicochemical attributes and food quality changes of the noodle products were analysed for both UV-C-treated and control samples by assessing SPC, Y&M, EB, pH, colour, texture (springiness), and water activity. ANOVA revealed no significant differences in pH and water activity between control and UV-C-treated samples (p > 0.05). However, notable colour changes were observed due to non-enzymatic browning reactions, pigment degradation, and microbial activity, which stabilised over storage. Texture analysis showed a reduction in springiness throughout storage. The combined UV-C and MAP approach significantly enhanced microbial stability and extended shelf life. The combined application of UV-C treatment and MAP showed potential for improving the microbiological stability of Hokkien noodles during chilled storage. UV-C treatment effectively reduced surface microbial loads, while MAP suppressed oxygen-sensitive bacteria growth and preserved product texture. Chilled storage at 4 °C combined with lactic acidification to a pH of approximately 4.6 provided an additional hurdle to inhibit bacterial and fungal growth. Microbial analysis demonstrated the efficacy of the multi-barrier method in delaying the spoilage of commercial Hokkien noodles. However, the differences between the treated and control samples were relatively small. UV-C treatment did not substantially reduce microbial counts compared with the control under the conditions investigated. Furthermore, although MAP may influence microbial growth by modifying the package atmosphere, the standard plate count (SPC) method was conducted under aerobic conditions; therefore, the present study did not specifically assess strictly anaerobic bacteria. Overall, this study shows that integrating UV-C treatment and MAP is an effective multi hurdle preservation strategy for pre-cooked Hokkien noodles. The findings provide practical guidance for manufacturers seeking clean-label solutions to extend shelf life, enhance microbial safety, and maintain product quality within the fresh noodle product category. Further studies using anaerobic microbiological methods and longer storage periods are recommended to determine the potential contribution of MAP to controlling anaerobic bacteria and to confirm any shelf-life extension.