Walnut meal protein as a promising fat mimetic in low-fat ice cream: mechanisms and quality control during storage

BACKGROUND Reducing dietary fat intake has become a prevalent health pursuit. In this study walnut meal protein (WP) with a protein content of 90.43% was utilized as a fat mimetic to optimize formulation, investigate component interaction mechanisms, and assess the storage quality of low-fat ice cream. RESULTS Sensory evaluation and melting rate were used as indicators. The optimal processing conditions were determined to be a cream-to-WP ratio of 21:7, skimmed milk powder addition of 4.30%, and guar gum (GG) addition of 0.06%. Compared to the control sample, the WP and GG samples showed that the WP-GG mix exhibited a smaller particle size, higher absolute zeta potential and viscosity, and lower surface tension. This suggests that the WP and GG mix can synergistically form a stable protein–polysaccharide composite gel network. Laser scanning confocal microscopy images confirmed that the WP-GG sample mix exhibited a markedly dense and homogeneous structure. After 6 weeks of frozen storage, the WP-GG sample demonstrated the highest overrun, the lowest melting rate, and the lowest hardness. At week 6, the syneresis rate was 70.42 ± 0.65% ( P < 0.05), indicating the best freeze–thaw stability. Furthermore, short-term storage test results showed that on day 9 the peroxide value and acid value of the WP-GG sample were only 1.48 ± 0.09 mmol kg −1 and 1.92 ± 0.07 mg g −1 , respectively. This confirmed that the steric hindrance between WP and GG maximally delayed lipid oxidation, effectively maintaining the oxidative and flavor stability of the ice cream. CONCLUSION This research provides a theoretical basis for the high-value utilization of WP and the development of low-fat ice cream. © 2026 Society of Chemical Industry.