Zhihui Yu

Whole egg is a nutrient-dense matrix, yet its application in beverages is often constrained by poor colloidal stability and “eggy” off-flavor. This study elucidated dose-dependent effects of mixed lactic acid bacteria inoculation on the physicochemical properties, protein structural evolution, and flavor quality of a fermented whole-egg beverage (WEB). A 1:1 (V/V) mixture of L. delbrueckii subsp. bulgaricus and Streptococcus thermophilus (total viable count: (1.1 ± 0.1) × 109 CFU/mL) was inoculated into pasteurized whole egg beverage matrix at 0%, 1%, 3%, 5% and 7% (V/V), corresponding to groups WE, FWE-1%, FWE-3%, FWE-5% and FWE-7%. Fermentation proceeded at 42 °C for 4 h, followed by 36 h ripening at 4 °C. All samples were characterized using dispersion metrics, spectroscopy, electrophoresis, in vitro digestion, gas chromatography-ion mobility spectrometry, electronic nose, electronic tongue, and sensory evaluation. Fermentation acidified WEB, to pH 4.15–4.36, decreased relative turbidity (normalized to the control), and improved dispersion uniformity (minimum polydispersity index was 0.305 at 7%). Soluble protein content increased to 10.24–12.27 mg/g (vs. 2.53 mg/g in the control), and antioxidant capacity was enhanced, with 1,1-diphenyl-2-picrylhydrazyl radical and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) cation radical scavenging rates reaching 95.84% (FWE-5% group) and 82.14% (FWE-7% group), respectively. Second-derivative ultraviolet, intrinsic fluorescence, and Fourier transform infrared spectroscopy amide I redshift indicated protein conformational remodeling, supported by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showing progressive degradation of high-molecular-weight subunits. These changes improved nutritional functionality, with in vitro protein digestibility maximized at 3% inoculation. Flavor analyses revealed fermentation-driven reconfiguration of volatile and taste profiles, including aroma enrichment and reduced bitterness. Sensory results identified 3% inoculation as optimal, delivering the highest overall acceptability with balanced sourness and diminished eggy odor. This research provides a scientific basis for optimizing inoculation levels in fermented WEB and offers new perspectives for the development of functional egg-based fermented products.

Eggs, as a high-nutritional food, face challenges such as limited flavor diversity and high cholesterol content in their processed products. Lactic acid bacteria (LAB) fermentation has been introduced as a method to address these issues by reducing pH, producing organic acids, and facilitating enzymatic hydrolysis, thereby enhancing the flavor and nutritional quality of egg products. This review explores the effects of lactic acid fermentation on the physicochemical, flavor, and nutritional characteristics of egg products. Research indicates that LAB can effectively improve the flavor of egg products, reduce pH, and enhance protein solubility and gel characteristics. During fermentation, LAB regulate the production of flavor compounds through enzymatic systems while promoting protein breakdown to generate bioactive peptides, which confer health benefits such as immune enhancement and lipid reduction. Furthermore, extending fermentation time significantly influences the pH and flavor compounds of egg products. This review provides a theoretical foundation for the further development of fermented egg products and is of considerable importance in meeting consumer demand for healthier foods.

This research aims to investigate the effects of Staphylococcus xylosus YCC3 (Sx YCC3) and Lactobacillus plantarum MSZ2 (Lp MSZ2) on lipid hydrolysis and oxidation, the bacterial community’s composition, and the volatile flavor compounds in fermented sausage. The bacterial community was examined by plate counting and high-throughput sequencing. Differential flavor compounds in non-inoculated and inoculated sausages were identified by principal component analysis (PCA) and orthogonal partial least squares discrimination analysis (OPLS-DA). The results showed that the free fatty acid (FFA) content was increased after inoculating with Sx YCC3 or Lp MSZ2. The pH, peroxide value (POV), thiobarbituric acid reactive substances (TBARS) value, lipoxygenase activity, and the counts of Enterobacteriaceae were lower in the inoculated sausage than in the non-inoculated sausage. The bacterial inoculation enhanced the competitiveness of Staphylococcus and Lactobacillus and restricted the growth of unwanted bacteria. The OPLS-DA revealed that (Z)-hept-2-enal, (E)-2-octenal, 1-nonanal, octanal, and 1-octen-3-ol were common differential flavor compounds that were found in the inoculated sausages but were not found in the non-inoculated sausages. A positive correlation was observed between the differential flavor compounds and the relative abundance of Staphylococcus or Lactobacillus, or the FFA content. Our results indicated that inoculation with Sx YCC3 or Lp MSZ2 can improve fermented sausages’ flavor by enhancing their bacterial quality and increasing their FFA content.