Development of a diagrammatic scale for the evaluation of postharvest physiological deterioration in cassava roots

Marcela Tonini Venturini,Eder Jorge De Oliveira,Leandro Ribeiro Dos Santos

doi:10.1590/s0100-204x2015000800004

Marcela Tonini Venturini, Eder Jorge De Oliveira + Show 1 more

Open Access

https://doi.org/10.1590/s0100-204x2015000800004

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Abstract

Abstract:The objective of this work was to develop a scale to assess the severity of postharvest physiological deterioration (PPD) of cassava roots, and to validate this scale for accuracy and reproducibility estimates. A diagrammatic scale (0 to 100%) for the damaged roots was analyzed according to precision, accuracy, and reproducibility. Seven evaluators (four with experience and three without it) quantified the PPD severity, with or without the scale, considering 150 roots with different levels of PPD. Without and with the use of the scale, respectively, the inexperienced evaluators obtained coefficients of determination (R2) from 0.76 to 0.86 and 0.87 to 0.92, and the experienced evaluators obtained R2 from 0.90 to 0.96 and 0.96 to 0.97. The values of the intercept (a) obtained by both the experienced and inexperienced evaluators who did not use the scale were all significant, while after using the scale, only two evaluators got values that were not significantly different from one. Evaluation reproducibility between the evaluators ranged from 0.61 to 0.91 for the inexperienced ones and from 0.83 to 0.95 for the experienced ones. The proposed diagrammatic scale was considered appropriate to estimate the severity of PPD in cassava roots, and can be used to identify sources of tolerance to postharvest deterioration.

Highlights

Cassava (Manihot esculenta Crantz) plays an important role in the global food diet because of its high energy content, ease of cultivation, relatively low incidence of pests and diseases, tolerance to drought and to acidic soils, and flexibility of harvesting, characterizing it as an important crop for food security in some countries (Sánchez et al, 2006)
Losses caused by postharvest physiological deterioration (PPD) may occur during various stages of the production chain, making it difficult to estimate the overall losses, field observations indicate losses of more than 60% when roots have not been taken for processing three days after harvest
The PPD processes involved the production of reactive oxygen species (ROS) related to the aerobic respiration

Summary

Introduction

Cassava (Manihot esculenta Crantz) plays an important role in the global food diet because of its high energy content, ease of cultivation, relatively low incidence of pests and diseases, tolerance to drought and to acidic soils, and flexibility of harvesting, characterizing it as an important crop for food security in some countries (Sánchez et al, 2006). Cassava roots have a short shelf life, due to a rapid process of postharvest physiological deterioration (PPD), which makes it unpalatable and commercially unfeasible 24 to 48 hours after harvesting (Sánchez et al, 2006; Morante et al, 2010). Due to the high perishability of cassava root, caused by PPD, the economic losses are inevitable, negatively impacting the supply of roots as a raw material for fresh or industrial consumption. Losses caused by PPD may occur during various stages of the production chain, making it difficult to estimate the overall losses, field observations indicate losses of more than 60% when roots have not been taken for processing three days after harvest. The PPD processes involved the production of reactive oxygen species (ROS) related to the aerobic respiration. ROS is able to start the signal transduction cascades which activate defense‐related gene expression and immediately cause cellular damage, by rapidly oxidizing cellular components (Zidenga et al, 2012)

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