Use of lysozyme from chicken egg white as a nitrite replacer in an Italian-type chicken sausage
Authors: Abeyrathne Nalaka Sandun 
Published: October 2019

Background: Sodium or potassium nitrite is widely used as a curing agent in sausages and other cured meat products. Nitrite has strong antimicrobial and antioxidant effects and generates cured meat color. Nitrite, however, can react with secondary or tertiary amines in meat to form carcinogenic, teratogenic and mutagenic N-nitroso compounds. Several findings have been suggested that high consumption of processed meat may increase the risk of cancer, and emphasized that dietary nitrosamines are positively associated with cancer. Lysozyme is one of the major egg proteins that have antimicrobial and antioxidant characteristics. Therefore, lysozyme can be used in meat processing to prevent microbial growth and oxidative degradation in meat products during storage. This study is focused on evaluating the antimicrobial and antioxidant effects of lysozyme extracted from egg white as a replacer of nitrite in a cooked Italian-type chicken sausage.Methods: Four curing treatments including 100% nitrite (control), 100% lysozyme (treatment 1), 25% nitrite + 75% lysozyme (treatment 2) and 50% nitrite + 50% lysozyme (treatment 3) were used to prepare Italian-type chicken sausage samples. Recipe was developed with 64%  (w/w) meat, 17% (w/w) binder (bread crumble), 12% (w/w) ice, 4%  (w/w) vegetable oil, 2%  (w/w) salt, 1% (w/w) spices (chili, black pepper, cardamom). Prepared samples were cooked in an 80 °C smoke house to a core temperature of 65 °C and cooled in cold water to 20-25 °C subsequently packed in polyethylene and stored in a freezer (-18 °C). The antimicrobial effect lysozyme was tested using Escherichia coli and Salmonella. The growth of these pathogens at 0, 3 and 5 days of storage of spore inoculation was determined. The antioxidant activity of lysozyme was determined using the TBARS value during the 25 d storage period. The redness (a*), lightness (L*), and yellowness (b*) of sausages were analyzed using a Minolta color meter (CR 410, Konica Minolta Inc., Japan). The proximate composition (AOAC, 2002) of frozen (-18 °C) sausage samples and sensory properties of cooked samples were determined.Results: 50% nitrite + 50% lysozyme (treatment 3) was as effective as control (100% nitrite) in suppressing the growth of Escherichia coli, Salmonella and limiting lipid oxidation in the Italian-type chicken sausage. Treatment 3 was not significantly different from the control, for lightness (L*), redness (a*) and yellowness (b*) values (P > 0.05) but showed the best sensory characteristics among the treatments (p < 0.05). Moisture content of control sample was significantly higher (p < 0.05) than other treatments while crude protein, crude fat, crude fiber and ash content were not significantly differ each. In term of the cost, both treatment 3 and control have shown approximately equal values.Conclusion: This study demonstrated that lysozyme can be used as an effective nitrite replacer in the Italian-type chicken sausage. Replacing 50% of nitrate salt with 50% lysozyme did not show any negative effects in controlling microbial growth, preventing lipid oxidation, and color changes but improved the sensory characteristics.Keywords: Italian-type chicken sausage, nitrite, lysozyme, antimicrobial, antioxidant