# Evaluation of Fruit and Vegetable Containers Made from Mulberry Wood (_Morus Alba_ L.) Waste
## 3 Results and Discussion  
The results of the flexion and density values of the mulberry branches compared to the woods used to make the plywood boards for packaging are shown in Table 1.  
A great variability of properties is observed in the mulberry branches, depending on the part of the branch where the measurements are made, observing a high fm, similar to that of the Scots pine and an Em similar to fast-growing cultivated woods. Scots pine also shows great variations, depending on the area of Spain where it has grown, and it presents a high degree of rigidity. The scanning electron microscope (SEM) image in Figure 3a corresponds to a tangential section of a one-year-old mulberry branch. The longitudinal fibers can be seen, surrounded by small holes. The energy-dispersive X-ray spectroscopy (EDS) results shown in Figure 3b indicates that the particles do not contain harmful metals or minerals that can contaminate food products; hence, its use as a food container is suitable. The results of the physical and mechanical tests conducted on the mulberry pruning waste particleboards are shown in Table 2. Conventional plywood boards were also tested as control samples, the results of which are also shown in Table 2.  
Mulberry particleboards are almost twice as dense as conventional plywood boards. The moisture content of the particleboards was 2.5%, which is less than wood and conventional plywood. This value is in accordance with the standard, which requires a moisture content of less than 20%. The MOR and MOE values are lower than for conventional plywood boards. The higher density and lower mechanical performance of mulberry particleboards make these boards of lower quality than those usually used to make this kind of containers. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Wood**} & **Density** & **Fm** & **Em** & \multirow{2}{*}{**References**} \\  & **(kg/m\({}^{3}\))** & **(N/cm\({}^{2}\))** & **(N/cm\({}^{2}\))** & \\ \hline Mulberry branches with bark & 445–630 & 27–40 & 550–1300 & This study \\ _Pinus sylvestris_ & 478–570 & 28–61 & 8700–11,598 & [48] \\ Poplar & 378 & 6.1 & 700 & [49] \\ Eucalyptus & 790 & 14.1 & 1655 & [49] \\ \hline \hline \end{tabular} Em. static bending modulus, fm: Static bending resistance.  
\end{table} 
Table 1: Properties of mulberry wood, Scots pine, poplar and eucalyptus. Figure 3: (a) Scanning electron microscope (SEM) image, (b) energy-dispersive X-ray spectroscopy (EDS) analysis. As seen in Table 2, the moisture content of mulberry boards is half that found in plywood boards, which can be considered an advantage. It is also observed that the TS (24 h) is greater than that of plywood, but it meets the requirements for type P3 boards [50] and can be used in humid environments because it is less than 25%. The results obtained for WA after 24 h are significantly better than those obtained for plywood. Finally, it can be seen that the mulberry boards have worse physical qualities than plywood since they have twice the density and the thickness swelling% is almost triple, although the water they absorb is similar. In Table 3, it can be seen that the modulus of rupture in flexion (MOR) and modulus of elasticity (MOE) values are lower in the mulberry boards than in the commercial plywood boards. According to the European standard (36), mulberry boards would be type P3: non-structural boards usable in humid environments. Compared to industrial plywood, these boards have much higher internal bonding and screw holding strength, although their flexural strength is significantly lower. In Table 3, it can be seen that, due to the higher density of mulberry particleboards, the average weight of the containers was 0.418 kg, around 32.7% higher than conventional containers, whose average weight is around 0.315 kg. The flexural strength of the container's base was tested considering a full weight of 2.5 kg. Therefore, the full container weight (P) is 2.5 + 0.418 = 2.918 kg. The weight (S) according to formula (1) is S = 4.377 kg.