Ensuring the safety and longevity of food products is a major priority in the meat industry. This paper focused on assessing the soybean-glycinin (SBG) impact on the quality and shelf-life of beef Musculus longissimus thoracis et lumborum (LTL) steaks and their potential in-vivo adverse consequences on foodborne pathogens and quantitative minimum biocidal values. Over 15 chilling-days at 4 °C, fresh LTL-steaks were fortified with either 1 mg/g of SBG (SBG1) or 0.5 mg/g (SBG0.5) and compared to control for physicochemical, oxidative, and microbiological attributes. Antibiotic-susceptible pathogens, Staphylococcus aureus, Salmonella enterica, and Escherichia coli were suppressed by 0.98 mg/mL of SBG, whereas antibiotic-resistant Salmonella enterica and Escherichia coli required higher biocidal dosages of 50 and 6.25 mg/mL, respectively. SBG-fortification kept LTL-steaks’ pH below borderline until day 12, increased water-holding capacity, reduced cooking loss at the storage end, and significantly improved tenderness (p < 0.05). LTL-steaks’ lightness, redness, and chroma were statistically unaffected by SBG1.0-fortification compared to the control; however, there were notable growing-patterns during the last two storage-periods (p < 0.05). Except the sixth- and ninth-day storage-periods, SBG1.0-fortification increased the LTL-steaks yellowness and hue compared to the control, indicating brighter, less red meat (p < 0.05). SBG-fortification had a dose-dependent antioxidant and bactericidal impact on both native microflora and inoculated pathogens, Listeria monocytogenes and Salmonella. Conclusively, SBG-fortification activities to improve LTL-steaks oxidative stability and shelf-life beyond 15 days and to inhibit inoculated-pathogens growth by one log CFU/g above or below the inoculation dose, validating SBG as a promising feasible meat preservation strategy.