Effects of Moisture Content and Impact Energy on the Cracking Characteristics of Walnuts

Abstract

A study was conducted to determine the effects of moisture content and energy of impact on the cracking characteristics of walnuts. A sample of fresh harvested walnuts was divided into four portions and conditioned under sunshine for different time durations to obtain different levels of moisture content [9.2-29.7%, wet basis (w.b.)]. An impact test apparatus was used to apply different impact energies in the range of 0.13-1.11 J to samples with different moisture content. Data obtained on the quantity of fully cracked and unbroken kernel, fully cracked but broken kernel and uncracked nuts were used in the computation of the nuts cracking characteristics. Results showed that moisture content, impact energy and interaction effects of these two variables have significant effect on the walnuts cracking characteristics. Full cracking of nuts increased with impact energy and decreasing moisture content. The optimum moisture content for cracking walnuts that gave the best result combination of high whole kernel yield and low kernel breakage was found to be about 16%. The optimum impact energy for cracking was found to be about 1.01 J (1.01 ± 0.1 J). The results of this study show that development of a centrifugal impact cracker, which uses impact to crack walnuts, is possible. In the designing of the walnut cracker, the radius and speed of the cracker should be such that create impact energy and velocity of about 1.01 J and 11 m/s, respectively, and walnuts should be conditioned to the moisture content of about 16% for optimum efficiency.

Mechanical damage to green and red lentil seeds

“…(), Shahbazi (), Shahbazi et al. () and Shahbazi (). An aluminum drop bar was inserted into a steel tube had 4 mm diameter holes from 5 to 60 cm with 5 cm intervals.…”

“…The impact test device use to apply impact to seed samples was similar to impact test devices used by Kim, Opara, Hampton, Hardacre, and MacKay (2002), Shahbazi et al (2012), Shahbazi (2013), Shahbazi et al (2014) and Shahbazi (2014). An aluminum drop bar was inserted into a steel tube had 4 mm diameter holes from 5 to 60 cm with 5 cm intervals.…”

Crushing Susceptibility of Vetch Seeds Under Impact Loading

“…The laboratory apparatus used to impact seeds, operated in a way similar to the impacting energy instruments used by Kim et al (2002), Oluwole et al (2007), Shahbazi et al (2012) andShahbazi (2014). A schematic diagram of the impact test apparatus is shown in Fig.…”

Mechanical properties and finite element analysis of walnut under different cracking parts

“…When compression experiments of walnut were completed, the shell thickness of walnut at different positions (top, middle and bottom) were measured by using the digital caliper, as shown in Figure 1, and the mean value of shell thickness was 1.53 mm. In addition, the sphericity coefficient of walnut were calculated by using the Equation (1) [24] , and the mean value of S p was 0.91.…”

“…Sharifian et al [7] investigated the mechanical behaviors of walnut by compression tests to determine the effects of moisture content, loading speed, loading position on the rupture force, specific deformation, and absorbed energy. And the quantitative relationships between cracking conditions and mechanical properties of walnut were determined by compression or impact tests [8][9][10][11] . Furthermore, researches on the macro mechanical properties of other nut crops such as macadamia nut [12] , almond nut [13] and hazelnut [14] , also have been widely studied by mechanical experiments, and the results indicated that physical characteristics (moisture content, size, shape, shell thickness) and technological parameters (loading force, compression direction, and loading speed) have significant effects on the mechanical properties of nut crops in terms of the rupture force, deformation, and rupture energy.…”