Effects of olive leaf water extracts on physical properties of chicken breast sausage

Abstract

Olive leaf (Olea europaea L.) is an underutilized resource of olive tree but has a high polyphenol content, so it has the potential to be used as a food ingredient. In this study, we investigated the effects of olive leaf water extracts on the physical properties of chicken breast sausage (CBS). Olive leaf water extracts were prepared at 4 (OEx₄) and 80°C (OEx₈₀) from dried olive leaf powder and they were applied to CBS preparation within the concentration range 0.05 to 0.5% (w/w minced meat). OEx₄ had 32% lower polyphenol content than OEx₈₀. Water content, expressible water, breaking strength, and viscoelastic properties of CBS with OEx₄ and OEx₈₀ were measured. The analyses of the sausage physical properties showed that adding 0.1% OEx₄ increased the breaking stress (115%), breaking strain (68%), modulus of elasticity (20%), coefficient of viscosity (23%), and water-holding capacity (9%), and the enhancement effects of OEx₄ were much greater than those of OEx₈₀. The gel network of OEx₄-containing CBSs observed by scanning electron microscopy was finer and denser than that of the control CBS. Chemical analyses of the meat proteins showed that OEx₄ induces polymerization of myofibril proteins, especially myosin, via non-disulfide covalent bridges formed between amino and/ or thiol groups. These results indicate that the application of OEx₄ improves the sausage gel properties by inducing non-disulfide-type protein polymerization. This study supports the feasibility of OEx₄ as a new ingredient to improve the texture of gel products prepared from chicken breast minced meat.