Post‐harvest physiological deterioration in several cassava genotypes over sequential harvests and effect of pruning prior to harvest

• Published in: International journal of food science & technology Vol. 56; no. 3; pp. 1322 - 1332
• Main Authors: Luna, Jorge, Dufour, Dominique, Tran, Thierry, Pizarro, Mónica, Calle, Fernando, García Domínguez, Moralba, Hurtado, Iván M., Sánchez, Teresa, Ceballos, Hernán
• Format: Journal Article
• Language: English
• Published: Oxford Wiley Subscription Services, Inc 01-03-2021
• Subjects: Cassava; Deterioration; Dry matter; Dry matter content; fresh market; Genotypes; Independent variables; Physiological effects; Physiology; post‐harvest losses; Pruning; Roots; scopoletin; Seasonal variations; shelf life; Storage
• ISSN: 0950-5423; 1365-2621
• DOI: 10.1111/ijfs.14711

Cassava roots have a short shelf life due to a process known as post‐harvest phyisological deterioration (PPD). Roots need to be consumed or processed no more than 3 days after harvest. PPD results in large losses that affect mostly women selling roots in fresh markets of sub‐saharan Africa. Althoug PPD is a very important problem, little progress has been made overcoming it. This is in part because of the complexities related to PPD. Several metabolic processes are trigered as soon as roots are harvested and have been linked to PPD. Environmental conditions, particularly at harvest time, have a strong impact as well. The graph depicts PPD in four different varieties harvested at many different times during a two years period. It is clear that genetic factors and harvesting time strongly influence PPD. Our research analizes the relationship between PPD, dry matter content (DMC), a key factor defining the price of cassava roots and scopoletin content (from harvest through seven days of storage). Not a single model can explain PPD, confirming the complexity of the problem. Some trends, however have been found. Pruning plants one or two weeks before harvest reduce DMC and PPD. Chemical tretreatment of plants before harvest with products that inhibit respiration may be a feasible approach to reduce PPD but may affect cooking quality of the roots.
Summary
Consumers, traders and processors consider post‐harvest physiological deterioration (PPD) an important constraint. In Experiment 1, PPD was assessed three consecutive years in roots from five genotypes through seven storage days. PPD, scopoletin and dry matter content (DMC) was recorded during storage. Year, genotype, duration of storage and their interactions were significant. PPD was associated with duration of storage period, DMC and scopoletin contents. Ambient moisture and temperature during storage influenced PPD. In Experiment 2, roots from seven clones were harvested 10 months after planting from 30 consecutive biweekly plantings. PPD was assessed 0, 2 and 7 days after harvest. In 13 harvests, roots from plants pruned six days earlier were also evaluated. Results indicated large seasonal variation across genotypes. Pruning reduced PPD and DMC. Complex and contrasting relationships among the variables analysed were found. There is no uniform model explaining the relationship between PPD and the independent variables considered.