Application of oleaster leaves (Elaeagnus angustifolia L.) essential oil and natural nanoparticle preservatives in frankfurter-type sausages: An assessment of quality attributes and stability during refrigerated storage

The effects of oleaster leave essential oil (OLEOs: 1000 and 2000 ppm) in combination with nisin nanoparticles (200 ppm) and ε-polylysine nanoparticles (2000 ppm) on the physicochemical, microbiological and sensory properties of the emulsion-type sausages without added chemical nitrite/nitrate salts were evaluated during 45 days of storage. Nanoparticle attributes were assessed, including encapsulation efficiency (EE%), zeta potential, nanoparticles size, FTIR analysis, and thermal stability (DSC). Overall, ε-PL nanoparticles (ε-PL-NPs) were thermally more stable and showed higher EE% (91.52%) and zeta potential (37.80%) as compared to nisin nanoparticles (82.85%) and (33.60%), respectively. The use of combined ε-PL-NPs (2000 ppm) + Ni-NPs (200 ppm) with oleaster leaves essential oil (2000 ppm) resulted in a higher pH value (5.88), total phenolic content (10.45 mg/100 g) and lower TBARS (2.11 mg/kg), and also decreased total viable bacteria (1.28 Log CFU/g), Clostridium perfringens (1.43 Log CFU/g), E. coli (0.24 Log CFU/g), Staphylococcus aureus (0.63 Log CFU/g), and molds and yeasts (0.86 Log CFU/g) count in samples at day 45 in comparison to the control (120 ppm nitrite). The consumers approved sensory traits in nitrite-free formulated sausages containing ε-PL-NPs and Ni-NPs combined with OLEOs.