Accurate localization of apples is the key factor that determines a successful harvesting cycle in the automation of apple harvesting for unmanned operations. In this regard, accurate depth sensing ...or positional information of apples is required for harvesting apples based on robotic systems, which is challenging in outdoor environments because of uneven light variations when using 3D cameras for the localization of apples. Therefore, this research attempted to overcome the effect of light variations for the 3D cameras during outdoor apple harvesting operations. Thus, integrated single-point laser sensors for the localization of apples using a state-of-the-art model, the EfficientDet object detection algorithm with an mAP@0.5 of 0.775 were used in this study. In the experiments, a RealSense D455f RGB-D camera was integrated with a single-point laser ranging sensor utilized to obtain precise apple localization coordinates for implementation in a harvesting robot. The single-point laser range sensor was attached to two servo motors capable of moving the center position of the detected apples based on the detection ID generated by the DeepSORT (online real-time tracking) algorithm. The experiments were conducted under indoor and outdoor conditions in a spindle-type apple orchard artificial architecture by mounting the combined sensor system behind a four-wheel tractor. The localization coordinates were compared between the RGB-D camera depth values and the combined sensor system under different light conditions. The results show that the root-mean-square error (RMSE) values of the RGB-D camera depth and integrated sensor mechanism varied from 3.91 to 8.36 cm and from 1.62 to 2.13 cm under 476~600 lx to 1023~1100 × 100 lx light conditions, respectively. The integrated sensor system can be used for an apple harvesting robotic manipulator with a positional accuracy of ±2 cm, except for some apples that were occluded due to leaves and branches. Further research will be carried out using changes in the position of the integrated system for recognition of the affected apples for harvesting operations.
Mycotoxins are the secondary metabolites secreted by different types of fungi to which humans can get exposed mainly via ingestion. Patulin (C7H6O4) is a polyketide lactone produced by various fungal ...specifies, including Penicillium expansum as the main producer. P. expansum can infect different fruits and vegetables yet it has preference to apples in which they cause blue rot. Therefore, apples and apple-based food products are the main source of Patulin exposure for humans. Patulin was first identified in 1943 under the name of tercinin as a possible antimicrobial agent. Although it is categorized as a non-carcinogen, Patulin has been linked, in the last decades, to neurological, gastrointestinal, and immunological adverse effects, mainly causing liver and kidney damages. In this review, the characteristics of and possible human exposure pathways to Patulin are discussed. Various surveillance and toxicity studies on the levels of Patulin in various food products and effects of Patulin on cells and animal models have been documented as well. Importance of epidemiological studies and a summary of the possible toxicity mechanisms are highlighted with a case study. The commonly used control methods as described in the literature are also discussed to guide future researchers to focus on mitigating mycotoxins contamination in the food industry.
•Proposing an improved YOLO-V3 network processed by DenseNet method.•Realizing the detection of apples in three different growth stages in orchards.•Realizing real-time detection of apples in high ...resolution images.•Realizing the detection of apples under occlusion and overlap conditions.
Real-time detection of apples in orchards is one of the most important methods for judging growth stages of apples and estimating yield. The size, colour, cluster density, and other growth characteristics of apples change as they grow. Traditional detection methods can only detect apples during a particular growth stage, but these methods cannot be adapted to different growth stages using the same model. We propose an improved YOLO-V3 model for detecting apples during different growth stages in orchards with fluctuating illumination, complex backgrounds, overlapping apples, and branches and leaves. Images of young apples, expanding apples, and ripe apples are initially collected. These images are subsequently augmented using rotation transformation, colour balance transformation, brightness transformation, and blur processing. The augmented images are used to create training sets. The DenseNet method is used to process feature layers with low resolution in the YOLO-V3 network. This effectively enhances feature propagation, promotes feature reuse, and improves network performance. After training the model, the performance of the trained model is tested on a test dataset. The test results show that the proposed YOLOV3-dense model is superior to the original YOLO-V3 model and the Faster R-CNN with VGG16 net model, which is the state-of-art fruit detection model. The average detection time of the model is 0.304s per frame at 3000 × 3000 resolution, which can provide real-time detection of apples in orchards. Moreover, the YOLOV3-dense model can effectively provide apple detection under overlapping apples and occlusion conditions, and can be applied in the actual environment of orchards.
•The 5-HT level was higher in the pulp than in the peel.•The distribution of 5-HT in apple fruits was skewed.•MdT5H5 may play an important role in the synthesis of 5-HT in apple.•5-HT accumulated ...gradually during apple fruit development.•The bagging reduced the 5-HT content in apple fruits.
Serotonin (5-hydroxytryptamine, 5-HT), a tryptophan derivative, is an important functional component in fruits. Although 5-HT was found in most fruits, the accumulation characteristics of its biosynthesis in apple fruits remain unclear. Here, we conducted a large-scale survey of 148 apple fruits in 5-HT content, and investigated the biosynthesis differences of 5-HT. Our results displayed a broad skewed normal distribution of 5-HT in apple fruits. 5-HT accumulated in all tissues of apple plants, with the highest content in the seeds and the higher content in the pulp than that of the peel. A significant increase of 5-HT at ripening stage was observed in the fruits with high 5-HT content, however, the 5-HT content did not change significantly during fruit development in the fruits with low 5-HT content. The bagging reduced the 5-HT biosynthesis compared to the fruits exposed to light conditions. In addition, the expression level of MdT5H5 was positively correlated with the 5-HT content, suggesting that MdT5H5 may play a key regulatory role in the 5-HT biosynthesis in apple fruits.
Mycotoxins are abiotic hazards produced by certain fungi that can grow on apples. Consequently, their prevalence in apple and appple products may be relatively high. In this study, 205 healthy apples ...and 104 rotten apples from three provinces of China (Liaoning, Hebei and Shandong), as well as 107 apple products purchased from Chinese local and online markets, were used to analyze 7 mycotoxins. The results showed that none of the mycotoxins were found in healthy apples. Six mycotoxins (patulin, alternariol, alternariol monomethyl ether, altenuene, tentoxin and tenuazonic acid) were detected in rotten apples and apple products, and patulin was the most common and frequent one. Contamination levels of patulin, altenuene, tentoxin and tenuazonic acid were significant difference in different parts of rotten apples among three provinces. Mycotoxin co-occurrence was common in rotten apples and apple products, and the rates of rotten apples and apple products contaminated by two or more mycotoxins were 73.08% and 4.67%, respectively.
•Apple and Apple products from China were investigated 7 mycotoxins.•Healthy apples were not contaminated by any mycotoxins.•PAT was the most frequent mycotoxin in both rotten apples and apple products.•Simultaneous presence of two to six mycotoxins was found for the rotten apples and apple products.•Provincial differences were observed in different parts of rotten apples.
Apples are not only a foodstuff, but also a raw material for many industrial production fields, and the market demand is constantly increasing. The Loess Plateau is one of the world’s largest ...apple-producing areas, with about 85% are aged orchards (more than 20 years old), facing problems such as poor soil water retention, degradation of tree strength, and declining yield and quality, etc., so do aged orchards in other regions of the world, and study on improving quality and increasing yield of aged orchards is of great significance to the sustainable development of the apple industry. Here, 6 treatments (2, 4, 6, 8, 10 and 12 kg/plant) were designed in the experiment to study the effects of biochar on yield and quality in aged apple orchards. The study showed that: biochar could improve soil water retention, but caused the soil alkalization; biochar could improve apple quality and increase yield, T3 and T4 were of better quality, and T3 had the highest yield. Comprehensive analysis, T3 is the optimal scheme. The results not only provide a reference for aged orchards worldwide, but also have great significance for the sustainable development of the apple industry.
This study attempted to eradicate Apple stem pitting virus (ASPV) and Apple stem grooving virus (ASGV) from virus‐infected in vitro shoots of apple rootstocks ‘M9’ and ‘M26’ using shoot tip culture ...and cryopreservation. In shoot tip culture, shoot tips (0.2 mm in length) containing two leaf primordia failed to show shoot regrowth. Although shoot regrowth rate was the highest in the largest shoot tips (1.0 mm in length) containing four leaf primordia, none of the regenerated shoots was virus‐free. Shoot tips (0.5 mm in length) containing two and three leaf primordia produced 100% and 10% of ASPV‐free shoots, respectively, while those (1.0 mm) containing four leaf primordia were not able to eradicate ASPV. ASGV could not be eradicated by shoot tip culture, regardless of the size of the shoot tips tested. In cryopreservation, shoot tips (0.5 mm in length) containing two leaf primordia did not resume shoot growth. Although 1.0‐mm and 1.5‐mm shoot tips gave similarly high ASPV‐free frequencies, the latter had much higher shoot regrowth rate than the former. Very similar results of shoot regrowth and virus eradication by shoot tip culture and cryopreservation were observed in both ‘M9’ and ‘M26’. Histological observations showed that only cells in upper part of apical dome and in leaf primordia 1–3 survived, while other cells were damaged or killed, in shoot tips following cryopreservation. Virus immunolocalization found ASPV was not detected in upper part of apical dome and leaf primordia 1 and 2, but was present in lower part of apical dome, and in leaf primordium 4 and more developed tissues in all samples tested. ASPV was also detected in leaf primordium 3 in about 16.7% and 13.3% samples tested in ‘M9’ and ‘M26’. ASGV was observed in apical dome and leaf primordia 1–6, leaving only a few top layers of cells in apical dome free of the virus. Different abilities of ASPV and ASGV to invade leaf petioles and shoot tips were also noted.
Apples are seasonal fruits, and thus after harvesting apples of optimal picking maturity, it is important to prepare them properly for storage and to ensure proper storage conditions in order to ...minimize changes in the chemical composition and commercial quality of the apples. We studied the quantitative composition of triterpenic compounds in the whole apple, apple peel and apple flesh samples before placing them in the controlled atmosphere (CA) chambers, and at the end of the experiment, 8 months later. HPLC analysis showed that highest total amount of triterpenic compounds (1.99 ± 0.01 mg g−1) was found in the whole apple samples of the ‘Spartan’ cultivar stored under variant VIII (O2—20%, CO2—3%, N2—77%) conditions. Meanwhile, the highest amount of triterpenic compounds (11.66 ± 0.72 mg g−1) was determined in the apple peel samples of the ‘Auksis’ cultivar stored under variant II (O2—5%, CO2—1%, N2—94%) conditions. In the apple peel samples of the ‘Auksis’ cultivar stored under variant I (O2—21%, CO2—0.03%, N2—78.97%) conditions, the amount of individual triterpenic compounds (ursolic, oleanolic, corosolic, and betulinic acids) significantly decreased compared with amount determined before the storage. Therefore, in the apple flesh samples determined triterpenic compounds are less stable during the storage under controlled atmosphere conditions compared with triterpenic compounds determined in the whole apple and apple peel samples.
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