## 3 Results and Discussion
### Total Phenolic Content and Antioxidant Activity
#### 3.1.1 Pineapple Shell
The storage time (24 h) in the whole samples, compared to the raw material (DPPH: 25.73 \(\pm\) 0.97 \(\mu\)mol Trolox g\({}^{-1}\) dry matter; FRAP: 25.59 \(\pm\) 0.76 \(\mu\)mol Trolox g\({}^{-1}\) dry matter; ABTS: 29.05 \(\pm\) 0.83 \(\mu\)mol Trolox g\({}^{-1}\) dry matter), showed increases of 17%, 18%, and 20% in the antioxidant activity when evaluated by the methods of DPPH (30.01 \(\pm\) 0.84 \(\mu\)mol Trolox g\({}^{-1}\) dry matter), FRAP (30.26 \(\pm\) 0.60 \(\mu\)mol Trolox g\({}^{-1}\) dry matter), and ABTS (34.80 \(\pm\) 0.44 \(\mu\)mol Trolox\(\cdot\)g\({}^{-1}\) dry matter), respectively (\(p<\) 0.05). In the case of storage time 48 h, there was a decrease in antioxidant activity by all methods (Figure 2). Globally, sample treatments at a temperature of 40 \({}^{\circ}\)C were more efficient in increasing antioxidant activity than treatments with temperatures of 30 \({}^{\circ}\)C, regardless of the method used to determine antioxidant activity (Figure 2). The treatments at 40 \({}^{\circ}\)C in whole pineapple shell did not present significant differences in antioxidant activity measured by DPPH (38.95-39.36 \(\mu\)mol Trolox g\({}^{-1}\) dry matter), although there has been a significant increase (\(p<\) 0.05) in the antioxidant activity by the FRAP (44.72-44.77 \(\mu\)mol Trolox g\({}^{-1}\) dry matter) and ABTS (45.17-46.02 \(\mu\)mol Trolox\(\cdot\)g\({}^{-1}\) dry matter) methods, between the storage time 0 h (DPPH: 39.29 \(\pm\) 0.27 \(\mu\)mol Trolox\(\cdot\)g\({}^{-1}\) dry matter; FRAP: 39.53 \(\pm\) 0.78 \(\mu\)mol Trolox g\({}^{-1}\) dry matter; ABTS: 41.94 \(\pm\) 0.85 \(\mu\)mol Trolox\(\cdot\)g\({}^{-1}\) dry matter) and the longest storage times (24 h and 48 h). In wounding shell samples, the heat treatments at 40 \({}^{\circ}\)C did not show significant differences between 0 h (DPPH: 25.57 \(\pm\) 0.69 \(\mu\)mol Trolox\(\cdot\)g\({}^{-1}\) dry matter; FRAP: 33.43 \(\pm\) 0.54 \(\mu\)mol Trolox\(\cdot\)g\({}^{-1}\) dry matter; ABTS: 31.37 \(\pm\) 0.88 \(\mu\)mol Trolox g\({}^{-1}\) dry matter) and 24 h storage time, and decrease for 48 h storage time (DPPH: 23.08 \(\pm\) 0.87 \(\mu\)mol Trolox\(\cdot\)g\({}^{-1}\) dry matter; ABTS: 29.43 \(\pm\) 0.80 \(\mu\)mol Trolox\(\cdot\)g\({}^{-1}\) dry matter) in antioxidant activity by any of the methods studied (\(p<\) 0.05). [PERSON] et al. (2011) [33] have also studied the effect of wounding and heat treatment as abiotic stresses on other fruits and vegetables. Carrots (_Daucus carota_), when subjected to stress from wounding and hyperoxia, function as bio-factories of caffeoylquinic acids. Carrots with stress caused by wounding and stored for 48 h at 20 \({}^{\circ}\)C showed an increase of \(\pm\)287% in the total phenolic content. The accumulation of stress-induced total phenolic content in carrots is influenced by the signalling molecules of reactive oxygen species. The application of wounds promoted an increase in total phenolic content and also of antioxidant activity in carrots stored at 20 \({}^{\circ}\)C for 48 h, and the accumulation of total phenolic content was intensified with an increase in the intensity of the wound. The shredded carrots stored under air showed a higher increase in the value of antioxidant activity (-240%) than samples before storage. [PERSON] and [PERSON] (2012) [7] studied the effect of wounding on phenolic compounds in carrots and found that more intense damages with 4 days of storage at 15 \({}^{\circ}\)C increased the phenolic content by 2.5 times compared to whole samples. The most severe wound in the tissues produced a more accentuated response, which developed a higher synthesis of phenolic compounds and antioxidants. Wounding is thus an economical process that can be used to enrich fresh products with phenolic compounds and antioxidants [3].