Charlie Li 2016-06-29 04:31:33
In the past three decades, U.S. blueberry production has increased more than four-fold, accounting for almost 60% of world production. The production area has expanded to more than 25,000 ha (61,000 acres), with a total production of 239 million kg (527 million lb) and a farm gate value close to a billion dollars. This large increase is primarily driven by the well-documented health benefits of blueberries, especially their high concentration of antioxidants. However, most highbush blueberries destined for the fresh market are still hand harvested. This is because as much as 78% of mechanically harvested blueberries develop bruise damage, making them unacceptable for long-term cold storage and fresh consumption. This low-quality fruit can only be sold at half the price of fresh-market fruit, so it’s relegated to blueberry jellies, baked goods, and other processed foods. Therefore, reducing fruit bruising has become a top priority for blueberry growers because product quality is directly related to profitability and to the long-term sustainability of the industry. As a matter of fact Blueberries invariably interact with various machine parts and surfaces during harvest, postharvest handling, and transport. These interactions cause bruises and reduce fruit quality. During packing, the fruit interacts with several contact points as the blueberries are dumped onto the conveyer and then moved through various transition points between different segments of the conveyer system. In the past, the impacts caused by mechanical handling could only be evaluated by assessing the quality of blueberries after the handling process due to the lack of effective sensing tools. If a small sensing instrument were available to quantitatively measure the mechanical impacts caused by harvesters, packing lines, and transport vehicles, the resulting information would be quite valuable for blueberry growers, researchers, and equipment manufacturers. However, although the concept of so-called “instrumented spheres” is not new—the earliest instrumented sphere was developed in the early 1990s—most commercially available instrumented spheres are the size of an apple (>50 mm diameter), and none of them can be readily used for small fruits like blueberries. To address this need, my research assistants Pengcheng Yu and Rui Xu and I have developed two iterations of the Berry Impact Recording Device (BIRD) over the past six years. In essence, the BIRD sensor is an independent wireless data logging sensor with a spherical shape and size, weight, and surface similar to a blueberry. As a result, as it passes through the handling process (e.g., mechanical harvest, packing, and transport), it is subjected to the same stresses as a real blueberry—while quantitatively measuring and recording all the impacts using accelerometers and a microprocessor installed inside the sphere. The impact data are saved in a memory chip, and a rechargeable battery powers the device. The first-generation BIRD sensor (BIRD I) had a diameter of 25.4 mm and weighed 14 g. The second-generation BIRD sensor (BIRD II) is smaller, with a diameter of 21 mm, and weighs just 6.9 g. In addition to the reduction in size and weight, BIRD II contains other major improvements, such as using the USB interface for both communication and recharging, which eliminates the previous interface box. Sensor success The sensor has been successfully used to measure the impacts created by mechanical harvesters and packing lines, which has not been done before. For example, the BIRD sensor revealed that the catch plates on a rotary harvester account for more than 30% of all the mechanical impacts imposed on a typical blueberry. Thus, a significant reduction in bruising could be achieved by modification of the catch plates, such as by reducing the fruit falling height or making the catch plates softer. Overall, the sensor approximates a real blueberry closely enough to allow us to better understand how blueberries interact with different machine parts within the harvester, and which parts create the most impacts. Better understanding of how the harvester interacts with the fruit will lead to better harvester designs and better quality fruit for the fresh market. The BIRD sensor has also been used to measure mechanical impacts on almost two dozen commercial packing lines in the U.S. and Chile. The data collected by the BIRD sensor revealed that most impacts occurred at transfer points between conveyer belts, and the highest impacts happened when the sensor dropped onto a hard surface, such as stainless steel or hard plastic. Padding the transfer points proved to be effective in reducing the impacts. The impacts measured by the BIRD sensor were correlated to fruit firmness and bruising. Based on this correlation, several large impacts were identified that caused bruise damage to the fruit. Most of the small impacts at the transfer points may not cause bruise damage, but their cumulative effect could cause bruising and significantly increase the bruising rate. Present work Currently, our group is developing the third-generation BIRD sensor. The sensor will be refined by further reducing its size and weight and by adding several new functions, such as apps for mobile devices so that the BIRD sensor can be configured and the data can be viewed instantaneously in the field on a smartphone. One unique feature of the BIRD sensor: it is the first device of its kind for studying small fruits. In addition to blueberries, it can be used to study cranberries, cherries, and olives, to name a few. It has drawn great interest from industry, not only in the U.S. but also in South America and Australia. Our group hopes to develop the sensor technology from a lab prototype to a robust engineering product that can ultimately be commercialized, benefiting more stakeholders. The first two iterations of the BIRD sensor were funded by a USDA NIFA Specialty Crop Research Initiative (SCRI) grant and a grant from the U.S. Highbush Blueberry Council. The third-generation BIRD is funded by another NIFA SCRI grant and is a large, multifaceted project (http://scri.engr.uga.edu). The overall goal of this NIFA SCRI project is to develop a new semi-mechanical harvest-aid system for efficient fruit harvesting for the fresh market. This system should be affordable to small and medium-size blueberry farms, ergonomically effective for workers, and compliant with all food safety standards. Meanwhile, other advanced sensor technologies will be developed to help blueberry breeders select blueberry cultivars for mechanical harvestability. I am currently leading a multidisciplinary research team (engineering, plant science, economics, and microbiology) with members from the University of Georgia, USDA-ARS, Michigan State University, University of Florida, Penn State University, Washington State University, North Carolina State University, Oregon State University, and Mississippi State University. Ultimately, our goal is to develop technologies to help make the blueberry industry more profitable and sustainable in the competitive global marketplace. ASABE member Changying “Charlie” Li, Professor, Bio-Sensing and Instrumentation Laboratory, College of Engineering, University of Georgia, Athens, USA, firstname.lastname@example.org.
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