## 2 Influence of UV-C on the Physical and Mechanical Properties of Different Crops
### Mechanical Properties  
Mechanical properties of harvested vegetables and fruits are important characterization throughout processing, storage, and consumption. Mechanical properties may be defined by cell structure and are dependent on the physical state, flow properties, and porosity. In the light of measurements, force-deformation methods are commonly used in textural or mechanical properties of solid foods, fresh vegetable/fruit, and their derivatives in their solid state. The basic mechanical properties that are determined from the force-deformation includes rupture force, toughness, cutting force, shear force, and strength [79], which are effective for different purposes, such as product standardization, transportation, handling, and design purposes as well. If we take account of the dimension of a product in the mechanical testing, stress-strain characterization, for example, can be used and some important properties can be obtained from the result of this test, such as yield strength, Young's modulus, ultimate strength, and modulus of elasticity. Recent research conducted intensive work on mechanical changes of UV-C irradiated strawberries at a varied irradiation dose of 0.8, 2, and 4 kJ\(\cdot\)m\({}^{-2}\) by changing the storage duration from 0 to eight days at 0 \({}^{\circ}\)C. Resistance to compression, crush resistance, and distance to tissue failure attributes dropped significantly during storage. According to the author, the resistance to compression was higher at a lower UV-C dose. At 2 kJ\(\cdot\)m\({}^{-2}\) and 4 kJ\(\cdot\)m\({}^{-2}\), tissue deformation reported a higher value [80]. In the latest work on the effect of UV-C irradiation on some of the mechanical characteristics of blueberries _'O'Neal'_ a puncture test was performed at UV-C intensities of 5.3, 8.3, and 11.4 kJ\(\cdot\)m\({}^{-2}\), exposure time of 7, 11, and 15 min, and storage time from 0 to 15 days. According to the report, mechanical parameters were not affected by UV-C treatments until 15 days of storage time when irradiated samples showed higher values of rupture force, deformation, and weight loss [81]. In a related study, a compression test (stress -strain) was performed on UV-C exposed fresh-cut apples at an exposure time of 10, 15, and 25 min and UV-C intensity at 5.6, 8.4, and 14.1 kJ\(\cdot\)m\({}^{-2}\). True stress and deformability modulus were noticeably reduced at lower exposure time and UV-C dose [63]. The effect of UV-C on the mechanical characterization as well as the dimensions (length, width, and height) of _Faba_ bean during storage was studied by considering various UV-C exposure times (0, 30, 60, and 90 min) and during storage periods of 0, three, six, and nine months. The result indicated that main dimensions, mass and bulk volume, and true volume were decreased by increasing the storage period and decreasing ultraviolet irradiation time. UV-C irradiation time increased with reducing the storage time, although, length and thickness decreased slightly. From this research, very important mechanical tests, such as shear force and shear penetration, were also investigated on the UV exposed _Faba_ bean. The authors described the decrement of both the sheer force and penetration force of seed as UV-C exposure time increased during the given storage time [82]. The mechanical properties of different UV-C irradiated plant commodities are briefly presented in Table 1.