**6. Antioxidant activity**

The compounds containing antioxidant activity inhibit and/or diminish the effects caused by free radicals, protecting the cells against the harmful effects of oxygenated and nitrogenous free radicals, formed during the oxidative process of the cells [49]. The evaluation of the antioxidant activity of plant material shall be determined by at least two methods, in order to obtain a slightly more complete context of this activity [50]. The use of ABTS colorimetric methods, together with DPPH, bring better reproducibility and sensitivity [51]. Given this, the antioxidant capacity of the raw extracts of the cocoa, cupuassu, pracaxi, and tucumã by-products was evaluated by the ABTS+ and DPPH methods, being performed in triplicate.

**Table 5** shows the antioxidant activities of CA, CP, PX, and TM extracts. According to the results, CP extract was the one that presented the best antioxidant activity, both by the ABTS+ and by the DPPH methods, while the CA presented the lowest values, determined by both methods. The four by-product extracts showed good results for the ABTS+ method.

These results were higher than those reported in the literature by Leong and Shui [52], who achieved values of the radical ABTS+ for some fruits, such as mango, passion fruit, pineapple, and guava that were 38.0; 5.5; 7.7; and 20.9 μM Trolox/g, respectively.

Studies have demonstrated that the ABTS<sup>+</sup> assay can be used to evaluate the antioxidant activity of a wide variety of substances [53], being commonly applied to determine the antioxidant activity in plants and based on the antioxidant capacity to neutralize the ABTS cation radical [54].

The antioxidant capacity values presented by different by-products CA, CP, PX, and TM, in addition to the vegetable sample difference, may also be related to different types of plant samples, which lead to different levels of phenolic compounds in extracts [55].

The results presented by the different by-products bring perspectives on the use of their antioxidant capabilities and may be better used in the development of new products.


#### **Table 5.**

*Values of antioxidant activity, by ABTS and DPPH methods, of raw extracts of CA [13], CP [10], PX [14], and TM [15].*
