Changes in the oxidative metabolism of cassava (Manihot esculenta Crantz) roots associated with cultivation managements

Abstract

The sweet cassava root age and pre-harvest managements can modulate the oxidative metabolism and provide a longer shelf life. Moreover, the evaluation of enzymes envolved in oxidative protection regarding the phenolic metabolism can be an additional approach to understand how the cultivation affects the post-harvest physiological deterioration tolerance in sweet cassava roots. Thus, the aim of this study was to evaluate the oxidative enzymatic protection associated to oxidation mediate by PPO and POD, in response to population density and harvest time of sweet cassava roots, cv. "Mossoró". The roots were cultivated in field conditions in the Brazilian Semiarid, under irrigation. The experimental design was a randomized complete block with three replications. Treatments corresponded to four harvest times (240, 300, 360, 420 days after planting -DAP) and four population densities (10,000, 12,500, 15,000 and 17,500 plants ha -1 ). Sweet cassava roots were sampled and the total soluble phenol content as well as soluble protein content were measured. Also, polyphenol oxidase (PPO), peroxidase (POD), superoxide dismutase (SOD), catalase (CAT) activity was evaluated. The roots showed higher total soluble phenol content at 300 and 360 DAP and higher protein content at 240, 300 and 360 DAP, for all densities avaluated. Planting densities extremes, of 10,000 and 17,500 plants ha -1 , resulted in higher levels of phenolics compounds and SOD activity. However, did not promote difference in the levels of soluble proteins. There was a significant reduction at PPO, SOD and CAT activity with late harvest, which did not occur for POD activity. Therefore, younger roots have higher oxidative enzymatic protection when compared to older roots in Semiarid conditions.

Association of preharvest management with oxidative protection and enzymatic browning in minimally processed cassava

“…Factors related to cultivation that can easily be modified, such as the harvest age and population density, promote changes in plants, both in morphology and postharvest quality attributes (Andrade et al, ; Leskovar, Agehara, Yoo, & Pascual‐Seva, ; Simões et al, ). Recently, some field strategies have been reported to delay PPD in unprocessed cassava roots (Zainuddin et al, ).…”

“…In this study, the authors reviewed superficially the effects of pruning, which increases the sugar/starch ratio and limits scopoletin accumulation, and furthermore they suggested that PPD should be evaluated at different harvest ages, indicating that this factor affects the postharvest quality of the roots. Andrade et al () demonstrated that at high harvest ages, the freshly harvested roots had lower enzyme activities and lower metabolite contents related to oxidative protection, such as SOD, CAT, and phenolics. However, how the age of harvesting and other management issues in the field affect PPD in the conservation of minimally processed cassava roots, remains to be determined.…”