Radical Scavenging Activity

Radical scavenging activity (RSA) from apple peel extract was determined according to Mditshwa et al. [9]. In triplicates, 15 μL of 3-fold diluted crude extract was added to 735 μL of 50% methanol followed by 750 μL 2,2-diphenyl-1-picrylhydrazyl (DPPH) (0.1 mM) solution. The mixture was incubated for 30 min in the dark at room temperature before measuring the absorbance at 517 nm using a UV–visible spectrophotometer (Thermo Scientific Technologies, Madison, WI, USA). Ascorbic acid concentration was used to generate a calibration curve, and RSA in the extract was extrapolated from the calibration curve. The RSA was expressed as the mean (millimolar) of ascorbic acid equivalent per milligram of dry matter (mM AAE/mg DM).

#### 2.2.5. Statistical Analysis

The experimental design was a completely randomized design with three factors (storage treatment, storage duration, and shelf life). Analysis of variance (ANOVA) was done using SAS software (SAS Enterprise Guide 7.1) and means were separated by least significant difference (LSD; *p* = 0.05), according to Bonferroni (Dunn) *t*-test. Relationship among the measured parameters was determined by subjecting data to the Pearson correlation test in XLSTAT software version 2012.04.1 (Addinsoft, Paris, France). GraphPad Prism software version 8.4.3 (GraphPad Software, Inc., San Diego, CA, USA) was used for graphical presentations.
