Physical characteristics of baru tree fruit aimed at kernel extraction

Abstract

The baru tree fruit has a sustainable economical potential. However, the shelling process to release the whole kernel, the most valued part of the fruit, is still performed in a rather inefficient way. The objective of this investigation was to determine the physical-mechanical properties of the fruit to understand its behavior during shelling. Fruit and nut were characterized by unit mass, dimensions, volume and bulk, and real densities. Compression tests up to endocarp disruption were performed to determine maximum force, corresponding deformation, and deformation energy. X-ray tomography was used to identify potential nut internal dimension changes, affected by the treatments. Whole fruits and nuts showed average unit mass values of 28.20 ± 0.99 g and 16.52 ± 1.67 g, respectively. Their average dimensions, such as length, width, and thickness were 52.40 ± 4.48 mm, 38.31 ± 4.05 mm, and 28.64 ± 3.67 mm, and 50.78 ± 5.57 mm, 34.65 ± 5.14 mm, and 21.36 ± 2.86 mm, respectively. Average bulk and real densities values were 519.33 ± 49.63 kg/m3 and 918.87 ± 77.77 kg/m3, and 517.14 ± 41.88 kg/m3 and 1072.00 ± 187.01 kg/m3, respectively. Considering all treatments, the average rupture force ranged between 7926.7 and 9284.4 N, with corresponding widthwise specific deformation of 5.1% and 6.6%, to release 100% whole kernels of the tested nuts. Up to maximum force, deformation energy values ranged between 6.55 and 9.26J. There was no evidence of treatments’ effect on the internal dimension. Based on its mechanical behavior, showing that it is possible to open the endocarp and release the whole kernel, it was concluded that the baru nut has mechanized shelling potential.