Characterization of functional food additives from cashew apples (anacardium occidentale)

Abstract

In this study, cashew apple (Anacardium occidentale) was selected as a natural alternative against synthetic food additives. This study was divided into two sections, which were the optimization of the extraction of protease and secondary metabolites as meat tenderizers and food spoilages’ inhibitors, respectively. Both optimizations were made using Response Surface Methodology (RSM). In the meat tenderizing section, four studied variables, namely, pH, CaCl2 concentration, mixing time, and mass were chosen. The optimal crude protease extract (CPE) extraction conditions (R2 = 0.9803) for the highest protease activity were obtained at pH 6.34, 7.92 mM CaCl2 solution, 5.51 min mixing time, and 19.24 g sample mass. The validation test (n = 3) showed that there is no significant difference (Tukey test; p < 0.05) between the statistical (6.30 units/mL) and experimental (6.49 ± 0.23 units/mL) protease activity. The total protein content of the extract was 4.89 ± 0.10 mg/mL with specific activity of 1.29 ± 0.05 unit/mg. The CPE was successfully applied as a meat tenderizer by observing the increasing tenderness from 5.37 ± 1.12 mJ to 2.19 ± 0.55 mJ of force needed to deform meat, and decreasing protein band from over ~49.8 kDa to under ~22.4 kDa, after been treated with the CPE using texture analyser and SDS PAGE, respectively. In a concurrent study for food spoilages’ inhibitors, the secondary metabolites of cashew apple were extracted using SFE CO2 by optimizing pressure, time, and temperature. Optimal extraction conditions (R2 = 0.9858) that yield the highest DPPH radical scavenging activity (70.34%) were obtained at 288.98 bar, 66.21 min, and 36.98 °C. The statistical result was in reasonable agreement with the validation test (n = 3) of experimental (71.52 ± 0.67%) antioxidant activity. The dichloromethane fraction of the crude secondary metabolite extract (CSME) showed the IC50 value of 0.58 mg/mL and 0.08 mgGAE/mL of total phenolic content. The CSME showed antibacterial activity against Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus with 25.40 ± 0.05 mm, 20.80 ± 0.18 mm, and 7.20 ± 0.04 mm, respectively. A non competitive mixed inhibition type against tyrosinase, with IC50 value of 0.02 v/v of the extract in ethyl acetate. Based on GC MS, the most abundant of secondary metabolites identified was gamma elemene (67.30%). COSMO RS explains the extraction mechanism occurred in the SFE CO2 system. Gamma elemene satisfied Lipinski, Ghose, Veber, and Eagan drug likeness by ADME pharmacokinetic analysis and showed strong binding interactions against protein receptor (bacterial and tyrosinase).