Mechanical behavior of pumpkin fruits subjected to compression during maturation

Acácio Figueiredo Neto,Nelson Cárdenas Olivier,Francisco De Assis Cardoso Almeida,Alan Christie Silva Dantas,Marcos Antonio Silva Irmão

doi:10.1590/s1983-40632013000300003

Acácio Figueiredo Neto, Nelson Cárdenas Olivier + Show 3 more

Open Access

https://doi.org/10.1590/s1983-40632013000300003

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Abstract

During handling operations, many problems that reduce the quality of vegetables may occur. Mechanical injuries are the leading cause of postharvest losses for the pumpkin, and can take place at any point of the production chain. This study aimed at evaluating the pumpkin fruits behavior, during their ripening stages, on the values of maximum compression force for fixed deformations, and determining the proportional deformability modulus of the fruits under compression at the repose position. Fruits were harvested at 15, 30, 40, 50 and 60 days after flowering and uniaxially compressed between two parallel plates. The results allowed to conclude that both the required compression force and the proportional deformability modulus increased during the maturation course, reaching a maximum force of 1,778 N and a maximum deformation modulus of 164 MPa, after 30 days. After this period, both the maximum force and the modulus values decreased, reaching 1,514.8 N of maximum force and a modulus of 132.09 MPa, after 60 days of ripening. Over the course of a longer maturation time, the fruit firmness increased, therefore requiring an increase in the maximum load to achieve greater deformation. The ideal period for harvest and transport of 'Jacarezinho' pumpkin fruits was set from 30 to 40 days after anthesis.

Highlights

The origins of pumpkin lie in the central region of Mexico
The worst kinds of damage are caused mainly during the handling process for transportation by trucks, in bulk or in boxes (Yam-Tzec et al 2011). Considering those aspects and the scarcity of theoretical information on the mechanical properties of pumpkin fruits, this study aimed at evaluating the influence of the maturity stage on the values of maximum compression force for fixed deformations, as well as determining the proportional deformability modulus for pumpkin fruits subjected to compression at the repose position
The mechanical property of pumpkin fruits increased along their maturation course, reaching a maximum value at 30 days after anthesis

Summary

Introduction

The origins of pumpkin lie in the central region of Mexico. It is a tropical species, whose production is favored by high temperatures. Belonging to the Cucurbitaceae family and the Cucurbita genus (Sasaki et al 2006), it presents varied shapes and sizes, and can be harvested at different maturation stages, even before reaching its definite size. For industrial use, the fruit must be harvested when already ripe, or when the stem is dry and the skin hard (Silva 2009). Its fruit often goes through a series of mechanical injuries, from the moment they are harvested until consumption, and, depending on their susceptibility, the damage caused may compromise the end quality, reaching losses as great as 25% of the overall production, an amount that justifies a greater.

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