## 3 Results
### Total Polyphenols, Total Chlorophylls, and Antioxidant Activity  
Figure 1 shows the percentage retention of TPC, total chlorophylls, and antioxidant activity in all dried samples at different drying conditions. Avocado quality was shown to be diminished after IR drying, which implied that polyphenols and chlorophylls were degraded during IR drying of avocado pulp with various formulations. When the IR temperature was raised from 65 to 70 \({}^{\circ}\)C, the concentration of polyphenol and chlorophyll in the dried sample rose for each formulation (\(p<0.05\)). Then, if the IR temperature rose to 80 \({}^{\circ}\)C, both polyphenols and chlorophylls would dramatically decrease (\(p<0.05\) for AP and \(p>0.05\) for APM). Consequently, it was recognized that the impact of IR temperature on APM and AP was similar. When comparing TPC and total chlorophylls in avocado pulp formulations dried at 70 \({}^{\circ}\)C, it was discovered that APM had higher TPC and total chlorophylls retention than AP. The multifactor ANOVA showed that investigated factors and their interaction significantly impacted TPC (\(p=0.010\)) and TCC (\(p=0.004\)). In proportional relation to the changes in TPC and total chlorophylls, the antioxidant activity was highest at the IR temperature of 70 \({}^{\circ}\)C, and APM was also more antioxidant-active than AP. Figure 1: The retention of total polyphenols (**a**), total chlorophylls (**b**), and antioxidant activity (**c**) of avocado pulp powder obtained by infrared drying at different drying temperatures and formulations. [PERSON] and [PERSON] (2015) comprehensively reviewed the degradation of phenolic compounds during drying mainly due to the participation of the oxidation enzymes, namely polyphenol oxidases (PPOs), peroxidase (POD), and LOX [39]. As previously stated, LOX might be completely inactivated by IR drying avocado pulp. Some previous studies [40; 41; 42] reported the activity of PPOs and POD in avocado pulp. The PPOs in avocado pulp were more heat-resistant than those in other fruits and vegetables [43]. Under heat inactivation at 84 \({}^{\circ}\)C for 15 min, only around 0.2% of the relative activity of PPOs in avocado flesh was maintained [44]. [PERSON] et al. (2010) observed that fruit maturation, as well as changes in temperature and time, can reduce the activity of the POD soluble enzyme [42]. Water activity, in addition to heat inactivation, has a major impact on enzyme activity. Lower water activity was found to reduce enzyme activity. Thus, a considerable volume of water would accelerate enzymatic reactions, bringing about the loss of TPC at the start of the drying process. However, when water was promptly removed from the substances, the enzymes were rapidly inactivated [45]. The rate of reactions would rise with a higher IR temperature, causing more TPC loss, but the higher rate of moisture removal would reduce enzyme activity. On account of this, higher temperature or longer operation time could lead to higher TPC loss [46]. Therefore, the highest content of TPC was reached at 70 \({}^{\circ}\)C, which resulted from the complex interaction between the changes in biochemistry and physical chemistry of avocado pulp during IR drying. Between two avocado pulp formulations, APM preserved higher TPC more effectively than AP for each IR temperature. This is possibly because hydrocolloids worked as a coating material, creating a physical barrier to oxygen and light to protect against chemical and enzymatic degradation [47]. The degradation of chlorophyll could be caused by enzymatic and non-enzymatic reactions. For chemical degradation, Mg\({}^{2+}\) ions are replaced by two H\({}^{+}\) ions from the porphyrin ring to form pheophytin and pyropheophytin, under acidic or heat treatment or by the action of Mg-chelatase [48]. For enzymatic reactions, enzymes involved in the degradation of chlorophyll were characterized as chlorophyllase or POD. It was reported that suitable pretreatments, such as steam blanching, could effectively inactivate chlorophyllase [49].