The combined effect of free or encapsulated ethanolic cashew leaf extract and high-pressure processing (HPP) on shelf-life extension of refrigerated Nile tilapia slices

Cashew (Anacardium occidentale L.) leaf extract (CLE) has been known as an excellent source of antioxidant and antimicrobial agents. To enhance the stability, encapsulation via chitosan-tripolyphosphate complexation can be the promising approach. Moreover, high pressure processing (HPP) can be employed along with CLE or CLE encapsule (CLE-E) to increase efficacy in the preservation of fish slices. CLE and CLE-E were prepared and characterized, and they were used at different concentrations (200 and 400 mg kg- 1) in combination with HPP at 200 MPa for 5 min to treat Nile tilapia slices. The quality of treated slices was monitored during storage at 4 degrees C for 18 days. CLE-E had homogeneous particle size distribution and a low dispersion index (0.21) with encapsulation efficiency of 88.21 %. It had a positive zeta potential (38.22 mV) and an average particle diameter of 254.10 nm. The CLE-E also still exhibited antioxidant and antibacterial activities. During the storage, Nile tilapia slices treated with CLE-E at 400 mg kg- 1 combined with HPP (CLE-E-400-HPP) had total viable count below the limit (106 CFU g- 1) for up to 15 days, whereas the control could be stored for only 6 days. The CLE-E-400-HPP sample also showed low lipid oxidation, and its fatty acid profile was maintained. Based on 9-point hedonic test, the CLE-E-400-HPP sample was still sensorially acceptable after 15 days. The use of CLE-E at 400 mg kg- 1 in combination with HPP (200 MPa, 5 min) was recommended for the treatment of Nile tilapia slices, in which shelf life could be prolonged up to 15 days at 4 degrees C.