# Investigation of the Maturity Changes of Cherry Tomato Using Magnetic Resonance Imaging
## 1 Introduction  
Fresh agricultural produce needs quality measurement and monitoring for various processing. Most agricultural produce are not harvested at the same stage of maturity due to their biological and environmental differences. While modern mechanical harvesting for produce decreases production costs, it also increases the need for proper sorting of agricultural products. Even hand-picked produceneeds to be sorted based on quality. Generally, produce quality factors are classified as external or internal. Size, shape, surface color, defects, and bruises can be categorized as external quality factors and internal voids, solids, disorder, and composition can be categorized as internal quality factors. Harvested products have different internal structure due to variations in environmental growing conditions, different maturity states, and various physiological disorders. Qualitative analysis related to the changes of internal physicochemical states and structure are crucial in agricultural products' grading based on internal factors. Many internal quality attributes are hard to detect by nondestructive methods. Many researchers have worked to utilize suitable imaging techniques for acquiring measures of internal quality factors for agricultural produce nondestructively. Quality factors were measured using the optical, acoustical, thermal, and electromagnetic properties of agricultural produce [1]. Among those nondestructive methods, nuclear magnetic resonance (NMR) and X-ray-based imaging techniques can provide true internal cross-section images of various agricultural and food produce [2; 3; 4; 5]. Magnetic resonance imaging (MRI), utilizing NMR properties of target samples, is a versatile tool to investigate most agricultural produce. Having high moisture content, agricultural products yield strong signals when applying an MRI technique. [PERSON] et al. [6] applied a MRI technique to monitor the ripening of mangoes. They found that signal intensity of the pericarp region in magnetic resonance (MR) images varied with ripening stage. [PERSON] et al. [2] investigated fresh Korean ginseng for internal quality evaluation and concluded that the age identification of ginseng is possible using one-dimensional image analysis of MR images. [PERSON] et al. [7] used MRI to detect seeds and freeze-damage in mandarins and found that the signal intensity of seeds and freeze-damaged regions was weaker than the signal intensity in normal tissue regions. [PERSON] et al. [8] investigated the tissue structure change to evaluate the effect of storage conditions on kiwi fruits and found water migration in the direction of the outer region in the pericarp during storage. [PERSON] et al. [4] intensively reviewed various MRI techniques for food and agricultural products. They explained the contrast of MR images being varied with physicochemical differences in foods and agricultural products. Also, they mentioned that MRI has the capabilities of not only the evaluation of maturity and quality but also the understanding of relating physiological processes. Tomato ripening stage is classified into 6 stages by color: green, breaker, turning, pink, light red, and red. Tomato ripening is associated with internal structure and chemical changes [9]. It is difficult to quantify internal structure changes during ripening. Many researchers have investigated the physicochemical changes during ripening and storing of tomatoes with NMR-based techniques. [PERSON] et al. [10] studied macroscopic structure changes of tomatoes during ripening. They found that the pericarp structure changed significantly compared with the internal tissues. [PERSON] et al. [11] investigated the seasonal physicochemical changes of cherry tomatoes with MRI techniques, and spin-spin and spin-lattice relaxation times measured in the morphological tissues were closely related to seasonal physicochemical changes of cherry tomatoes.