Moisture content as a critical factor: balancing microstructural integrity and cooking quality in frozen potato starch noodles

This study aimed to identify the optimal initial moisture content for frozen potato starch noodles (PSN) and to elucidate the underlying mechanism by which moisture regulates ice crystal formation, multi-scale structure, and cooking quality. PSN with moisture contents ranging from 45 % to 70 % were frozen at –30 °C for 6 h and subsequently evaluated. Compared to the control (PSN60, 60 % moisture), PSN₅₀ (50 % moisture) exhibited a 115.94 % increase in elongation at break (reaching 413.13 %) and a 2.69 % reduction in cooking loss. Low-field NMR revealed that PSN50 contained predominantly bound water, indicating limited free water available for ice crystallization. Moreover, PSN50 possessed a finer and more uniform porous structure, implying restrained ice crystal growth. X-ray diffraction and Fourier-transform infrared spectroscopy further demonstrated that 50 % moisture significantly promoted starch retrogradation, increasing crystallinity from 7.20 % to 10.39 %, and enhancing short-range molecular order. Meanwhile, a higher fractal dimension (α = 1.643) for PSN50 further confirmed a denser gel network. These results establish that a moisture content of 50 % optimally balances water availability, limits deleterious ice crystal formation, promotes structural ordering, and ultimately enhances the textural and cooking performance of frozen PSN. This work provides a clean-label strategy for quality improvement in frozen starch-based foods through intrinsic moisture regulation.