2.5 Sapota fruit quality analysis
The weight of individual fruit, pulp and peel weight (g) was determined with the help of an analytical balance while a digital display vernier caliper was used to measure fruit diameter and length (mm). Uniform matured fruits were harvested randomly from each treatment and transported to the laboratory. After washing in tap water, fruits were allowed to ripen at the ambient room temperature. Fifteen uniformly ripened fruits from each treatment were peeled and deseeded to separate fruit pulp to evaluate quality parameters. The fresh fruit juice was obtained by filtering the pulp through a three-layered muslin cloth to determine TSS and TA. Vitamin C, reducing, non-reducing and total sugars were determined using fresh fruit pulp. For antioxidants enzyme assay and total phenol content, the pulp was homogenized and stored at 4 °C to prevent enzymatic browning until further analysis.
The portable refractometer was used to determine TSS after calibration with distilled water and it was expressed in oB. TA was estimated using 0.1N NaOH using phenolphthalein indicator until a pink color persisted (AOAC, 1990). Vitamin C, total soluble sugars content and reducing sugar content in the pulp were determined by following the protocol developed by AOAC (2005), DuBois, et al. (1956) and Somogyi (1952), respectively. Total antioxidants activity in the fruit samples was estimated using FRAP assay as per method given by Sreeramulu et al., (2009). The total phenol content was determined by following the protocol of Malick & Singh (1980).