Glycosylated whey protein (GWP) was prepared from whey protein and xylooligosaccharide by wet glycosylation method. Its advantages for use as a fat substitute were analyzed, and the application of this fat substitute in reduced-fat processed cheese was explored. The results showed that the optimal preparation conditions were determined as: xylooligosaccharide concentration of 6%, reaction temperature of 85 ℃ and reaction time of 2 h. The grafting degree of GWP prepared using these conditions was (29.28 ± 1.53)%, and a browning phenomenon occurred during the preparation process. Compared with whey protein, the contents of α-helix, β-fold, β-turn and random coil structures changed in GWP, and the water and oil-holding properties increased by 60.18% and 103.97%, respectively; the emulsifying capacity and emulsion stability increased by 30.81% and 13.57%, respectively. The surface of GWP was smoother. The surface hydrophobicity at pH 7.0 was 2.48 times higher than that of whey protein. After shearing at 10000 r/min for 10 minutes, the median particle diameter of GWP was 7.57 µm, and the stability of the solution was obviously improved, so that GWP could be used to simulate fat. The hardness of reduced-fat processed cheese with 60% butter replacement by GWP was significantly lower than that of full-fat processed cheese (P < 0.05), and the meltability increased significantly (P < 0.05), but the texture characteristics such as elasticity, chewiness and brightness value (L*) were not significantly different from those of full-fat processed cheese (P > 0.05), and the total sensory score was equivalent to that of full-fat processed cheese. These results proved that the glycosylated whey protein has a potential application as a fat substitute in reduced-fat food while guaranteeing that the quality of the product is good.

To enhance the functional properties of potato proteins (PP), this study investigated the effect of different ultrasonic treatments (at 0, 200, 300, 400, 500, and 600 W for 20 min) combined with pH shift on modifying the functional and structural properties of PP. Changes in the functional and structural properties of PP after modification were examined in terms of solubility, emulsifying and foaming properties, particle size, ζ-potential, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns, Fourier transform infrared spectra (FTIR), fluorescence spectra, free sulfhydryl content, and surface hydrophobicity, and the correlation between functional and structural properties was analyzed. The results showed that the solubility of PP increased from 24.84% to 90.74% after pH shift to pH 12 in combination with 500 W ultrasonic treatment. Moreover, the emulsifying activity index (EAI) was enhanced by 86.37%, and the foaming capacity (FA) by 31.24%. Additionally, notable alterations in the molecular structure were observed accompanied by a decrease in the average particle size from 452.05 to 89.63 nm and a reduction in the ζ-potential value from −24.64 to −32.57 mV. The secondary structure analysis showed that the α-helix content decreased while the β-sheet content increased. The free sulfhydryl content and surface hydrophobicity significantly rose (P < 0.05). The results of correlation analysis showed that the solubility, emulsifying and foaming properties were negatively correlated with the particle size, turbidity and ζ-potential but positively correlated with the free sulfhydryl content and surface hydrophobicity. In conclusion, ultrasonic treatment combined with pH shift can improve the functional properties of PP, thereby expanding its score of application in the food industry.

The anti-aging effects of four Bifidobacterium species (B. pseudospermum BP-1, B. longum BL-3, B. animalis BA-5 and B. infantis BI-38) on Caenorhabditis elegans were evaluated in terms of its lifespan, reproductive capacity, vitality, body shape, stress resistance, lipofuscin levels, antioxidant enzyme activity and malondialdehyde (MDA) content. The results showed that compared with the control group (Escherichia coli OP50), BA-5 and BI-38 effectively extended the lifespan of C. elegans (P < 0.05), while BP-1 and BL-3 had no significant effect on the lifespan of C. elegans (P > 0.05). Meanwhile, BA-5 and BI-38 did not impair the reproductive or locomotory capacities of C. elegans (P > 0.05), but could effectively enhance its pharyngeal pumping and reduce its body size (P < 0.05). BA-5 and BI-38 were able to enhance tolerance to heat or oxidative stress and thus prolong the lifespan of C. elegans (P < 0.05), significantly reduce lipofuscin accumulation and MDA content (P < 0.05), and significantly increase the activity of two antioxidant enzymes (catalase and superoxide dismutase) in C. elegans (P < 0.05). In conclusion, B. infantis BI-38 and B. animalis BA-5 had stronger anti-aging activity in vivo.