Mealiness assessment in apples and peaches using MRI techniques

Analyzing the Quality Parameters of Apples by Spectroscopy from Vis/NIR to NIR Region: A Comprehensive Review

Spectroscopic methods deliver a valuable non-destructive analytical tool that provides simultaneous qualitative and quantitative characterization of various samples. Apples belong to the world's most consumed crops and with the current challenges of climate change and human impacts on the environment, maintaining high-quality apple production has become critical. This review comprehensively analyzes the application of spectroscopy in near-infrared (NIR) and visible (Vis) regions, which not only show particular potential in evaluating the quality parameters of apples but also in optimizing their production and supply routines. This includes the assessment of the external and internal characteristics such as color, size, shape, surface defects, soluble solids content (SSC), total titratable acidity (TA), firmness, starch pattern index (SPI), total dry matter concentration (DM), and nutritional value. The review also summarizes various techniques and approaches used in Vis/NIR studies of apples, such as authenticity, origin, identification, adulteration, and quality control. Optical sensors and associated methods offer a wide suite of solutions readily addressing the main needs of the industry in practical routines as well, e.g., efficient sorting and grading of apples based on sweetness and other quality parameters, facilitating quality control throughout the production and supply chain. This review also evaluates ongoing development trends in the application of handheld and portable instruments operating in the Vis/NIR and NIR spectral regions for apple quality control. The use of these technologies can enhance apple crop quality, maintain competitiveness, and meet the demands of consumers, making them a crucial topic in the apple industry. The focal point of this review is placed on the literature published in the last five years, with the exceptions of seminal works that have played a critical role in shaping the field or representative studies that highlight the progress made in specific areas.

Fusion of acoustic sensing and deep learning techniques for apple mealiness detection

Mealiness in apple fruit can occur during storage or because of harvesting in an inappropriate time; it degrades the quality of the fruit and has a considerable role in the fruit industry. In this paper, a novel non-destructive approach for detection of mealiness in Red Delicious apple using acoustic and deep learning techniques was proposed. A confined compression test was performed to assign labels of mealy and non-mealy to the apple samples. The criteria for the assignment were hardness and juiciness of the samples. For the acoustic measurements, a plastic ball pendulum was used as the impact device, and a microphone was installed near the sample to record the impact response. The recorded acoustic signals were converted to images. Two famous pre-trained convolutional neural networks, AlexNet and VGGNet were fine-tuned and employed as classifiers. According to the result obtained, the accuracy of AlexNet and VGGNet for classifying the apples to the two categories of mealy and non-mealy apples was 91.11% and 86.94%, respectively. In addition, the training and classification speed of AlexNet was higher. The results indicated that the suggested method provides an effective and promising tool for assessment of mealiness in apple fruit non-destructively and inexpensively.

Use of Magnetic Resonance Imaging in Food Quality Control: A Review

Modern challenges of food science require a new understanding of the determinants of food quality and safety. Application of advanced imaging modalities such as magnetic resonance imaging (MRI) has seen impressive successes and fast growth over the past decade. Since MRI does not have any harmful ionizing radiation, it can be considered as a magnificent tool for the quality control of food products. MRI allows the structure of foods to be imaged noninvasively and nondestructively. Magnetic resonance images can present information about several processes and material properties in foods. This review will provide an overview of the most prominent applications of MRI in food research.

Detection of cold injury in peaches by hyperspectral reflectance imaging and artificial neural network

Peaches in cold storage may develop chill damage, as symptomized by deteriorated texture and lack of juice. To examine fruit quality, we established a hyperspectral imaging system to detect cold injury, and an artificial neural network (ANN) model was developed for which eight optimal wavelengths were selected. Between normal and chill-damaged peaches, significant differences in fruit quality parameters and the spectral response to correlating selected wavelengths were observed. Evidencing this relationship, the correlation coefficients between quality parameters and the respective spectral response of eight selected wavelengths were -0.587 to -0.700, 0.393 to 0.552, 0.510 to 0.751, and 0.574 to 0.773. With optimal representative wavelengths as inputs for the ANN model, the overall classification accuracy of chill damage was 95.8% for all cold-stored samples. The ANN prediction models for quality parameters performed well, with correlation coefficients from 0.6979 to 0.9026. This research demonstrates feasibility of hyperspectral reflectance imaging technique for detecting cold injury.

Nondestructive measurement of fruit and vegetable quality

We review nondestructive techniques for measuring internal and external quality attributes of fruit and vegetables, such as color, size and shape, flavor, texture, and absence of defects. The different techniques are organized according to their physical measurement principle. We first describe each technique and then list some examples. As many of these techniques rely on mathematical models and particular data processing methods, we discuss these where needed. We pay particular attention to techniques that can be implemented online in grading lines.

Nondestructive detection of internal bruise and spraing disease symptoms in potatoes using magnetic resonance imaging

Magnetic resonance imaging (MRI) was applied to detect nonvisible internal bruise and spraing symptoms and to get insight on the chemical and anatomical causes of such defects. Cultivar Saturna with internal bruise and cultivar Estima with spraing symptoms were investigated by comparison of different MR images as proton density-, T(1)- and T(2)-weighted images and T(2) maps. In all these types of MR images, it was possible to identify internal bruise and spraing spots in the potatoes, where these phenomena were present. When combining the information in the MR images, the interior of the internal bruise was characterised as being very dry (low signal in the proton-weighted image) with a small amount of highly mobile water in the shell around the bruise (high signal in T(2)-weighted image and high relaxation time in T(2) map). The spraing spots were more diffuse; however, the dry interior and highly mobile water around the spraing dots were somewhat similar to the appearance of internal bruise but resembled more the appearance of human tumour tissue than bruise disorders in, for example, fruits. In conclusion, this study demonstrated that MRI can detect nonvisible internal bruise and spraing symptoms in potatoes, which has not been published before. MRI may, therefore, be an appropriate method for detecting and for studying developmental changes of such disorders and related disorders during postharvest storage in future experiments.

Application of MRI to monitor the process of ripening and decay in citrus treated with chitosan solutions

Chitosan is a biopolymer, which has numerous applications in agriculture and agroindustries. Coating fruit and vegetables with chitosan has some positive advantages for the long-term storage of foods, because the film of chitosan provides a kind of an active package, which allows a gradual release of preservatives, thus inhibiting fungal growth and maintaining the external appearance of the fruit for a longer time In this study, two varieties of citrus, Fortune mandarins and Valencia oranges were coated with Biorend(R) (IDEBIO S.L., Salamanca, Spain) (a compound whose active molecule is chitosan), to investigate its effect on maturity, decay, and damage, and therefore, to find a better method for the long term storage of fruit. The effect of chitosan as a fungistatic was also studied. To that end, the fruit was maintained in a damp storage room, ideal conditions for the growth of fungi. The magnetic resonance imaging (MRI) technique was used to monitor the process of ripening and decay in the citrus fruit that had been coated with chitosan. The dissolution of the chitosan on the mandarins and oranges produced excellent results in terms of percentage of weight loss, MRI, and visual appearance.

MRI and x-ray CT study of spatial distribution of core breakdown in ‘Conference’ pears

Two non-destructive tomographic techniques, X-ray CT imaging and magnetic resonance imaging (MRI), were applied to study the development of core breakdown disorder in 'Conference' pears (Pyrus communis cv. Conference). This disorder, which is characterized by brown discoloration of the tissue and development of cavities, is induced by elevated CO(2) and decreased O(2) levels during controlled atmosphere storage. Tomographic images of pears stored for 10 months under disorder inducing conditions, were acquired with both techniques and compared to the actual slices. Both X-ray and MRI were able to differentiate between unaffected tissue, brown tissue and cavities. A simple image-processing program, based on threshold values, was developed to determine the area percentage of affected and unaffected tissue as well as the cavity and core area per slice. For all three imaging techniques the area percentage brown tissue per slice increased with the diameter of the pear, but was systematically underestimated by 12% and 6% for, respectively, X-ray and MRI, compared to the actual slices. The area percentage cavity corresponded very well for all techniques. It was also found that the contours of the brown tissue were parallel to the fruit boundaries, suggesting a relation between the disorder symptoms and gas diffusion properties of the fruit. It was concluded that MRI is the most appropriate technique to study the development of core breakdown disorder during postharvest storage in future experiments.