NE1008: Assuring Fruit and Vegetable Product Quality and Safety Through the Handling and Marketing Chain
- Duration:
- October 01, 2002 to September 30, 2007
- Administrative Advisor(s):
-
Steve Goodwin
(MAS)
- NIFA Reps:
-
D. Ramkishan Rao
Statement of Issue(s) and Justification:
The goal of this project is to develop and improve rapid and non-destructive methods and technology for assessing, retaining, and assuring quality, safety, and integrity of fruits and vegetables through the marketing chain.Annually, fruits and vegetables generate 25 billion dollars in farm income (Anon, 2001). They account for approximately 25% of the cash receipts of all crops grown in the United States while occupying only about 2.6% of the acreage devoted to cropland (Nichols, 1996). Furthermore, fruits and vegetables are an essential part of a healthy diet. The health benefits of compounds such as antioxidants and flavenoids, found in abundance in fresh fruits and vegetables, are becoming increasingly apparent.
As fruits and vegetables make their way from the producer to the consumer, they are sorted, stored, transported, processed, and packaged. With each step, their economic value increases. Annual sales of fresh produce alone exceed $95 billion (www.Fresh-Cuts.org). It is essential that the quality of this valuable resource be maintained. This, in brief, is the major focus of this proposal.
Although the system that delivers fruits and vegetables to the consumer works well, it is still vulnerable to the influences of population pressures, global competition, outbreaks of food-borne illness, and labor shortages. Furthermore, there are still opportunities for improving the efficiency of the system. While estimates of losses vary, it is not uncommon for the produce departments in grocery stores to experience losses of 10% because their produce spoils, contains undetected defects, or deteriorates in quality before it can be sold. Even if only 5% of the fresh produce were lost, the annual economic value of those losses would be nearly $5 billion.
Control of pathogens, resulting in food-borne illness and now the threat of bio-terrorism, is a critical issue that needs to be addressed. The fresh-cut industry, producing products that are not subject to conventional pasteurization methods, has been expanding rapidly. This industry accounts for 10-12 billion dollars in sales on an annual basis, about 10% of the total fresh produce market. New techniques are needed that rapidly identify the presence of pathogens on produce, as well as techniques to eliminate these pathogens.
NE-179 multi-state researchers have helped to improve existing technologies, such as color sorting. They are also developing new quality detection technologies such as: machine vision for the detection of bruises, surface defects and insect presence; x-ray scanning and magnetic resonance sensing for the detection of internal defects; and near infrared detection of soluble solids content (related to sweetness and quality). Accomplishments have included development of a color chart for improved color sorting of cherries, improvement of specifications for lighting of grading stations, and development of a device for orientation of apples grown in the eastern United States. (Note: Apples grown in the eastern United States cannot be oriented effectively using equipment routinely used for apples grown on the west coast.) Sharing of data, such as physical properties of fruits and vegetables, is also being promoted through the development of an Internet web site where links to data and reports issued by participating stations can be easily accessed.
Several NE-179 projects have involved cooperation among stations. For example, Cornell (New York) and the Appalachian Fruit Research Station (West Virginia) worked together in the development of the orientation device for eastern apples. They presently have a cooperative project on bruise detection by means of a combination of visible and near infrared radiation (multi-spectral imaging). The Fruit Research Station also evaluated detection of internal defects in apples by sponsoring and providing apples for an x-ray detection study at the University of Georgia and a magnetic resonance study at Purdue University (Indiana).
The project has sponsored two international conferences that brought together researchers working in the area of quality sorting. The first was conducted in Spokane, Washington in 1993 and the second in Orlando, Florida in 1996. Papers and discussion summaries from both of these meetings were published in proceedings. Interaction with processors, packers and growers was facilitated by means of tours held in conjunction with these meetings.
NE-179 also promotes the interaction of researchers with growers, processors and packers. Much of this interaction occurs during tours held in conjunction with each annual meeting. Researchers are able to visit facilities and dialogue with managers and others who are aware of the current concerns of the industry. Industry consultants, representatives of commodity groups and equipment manufacturers, and scientists from state and federal laboratories have attended NE-179 conferences and annual meetings. Their participation allows them to share their ideas and perspectives. Another example of NE-179s interaction with industry is the 1995 survey of apple packers and processors in which members conducted for the purpose of evaluating their satisfaction with current sorting systems and their needs for the future. The responses of 25 fresh pack firms and 7 processors were summarized and made available to NE-179 representatives so that they could gain a better understanding of the needs and concerns of the apple packers and processors.
NE-179 is a vital link between the fruit and vegetable industry and researchers who are developing machines and systems for assessing and retaining the quality of these commodities. NE-179 is accomplishing this by means of tours of processing and packing facilities, discussions with processors and packers held during the tours, industry surveys, sponsorship of international conferences, and the publication of the proceedings of these conferences. NE-179 fosters cooperation among participating stations as demonstrated by several joint research projects and the sharing of test samples among stations. They continue to address concerns of the industry by evaluating techniques and systems that can be used to improve product quality, reduce waste, and maintain or expand the United States share in a global market.
Related, Current, and Previous Work:
The literature contains information about the use of rapid sensing techniques and technologies for detection of internal quality constituents and internal defects. The proposed research will expand upon the research literature in these areas, both in terms of development of new sensing techniques and technologies as well as the application of existing sensing techniques and technologies to new types of produce.Work was started on the design of a PCR-based biosensor to detect Salmonella in alfalfa sprout irrigation water (Jackson et al., 2001). A small thermal cycler was designed using a thermoelectric unit and an embedded controller. Amplified DNA was measured in a specially designed optical head using fluorescent markers and laser excitation with emphasis on semi- microfluidic components because of the need to test larger sample volumes. A real-time PCR for Salmonella was developed to work in the sensor. Currently, control of the thermal cycler is being optimized and methods of integration with the optical sensor are being considered. Calibration will be done with different serovars of Salmonella in distilled water and sprout irrigation water.
Technological developments and changes in user needs requires periodic reassessment of sensors for measuring fruit and vegetable quality. A list is needed of quality attributes that users would like to measure if suitable sensors were available. Especially valuable would be an understanding of the impacts expected at other business links of a food distribution chain if new sensors are implemented at any link. Simulation models and games of postharvest operations would help managers improve understanding of interactions within the chains.
The laser puff firmness detector developed at Georgia can rapidly measure firmness of fresh produce without direct contact. Expanded use is expected if procedures are simplified and on-line applications are made feasible.
Research on electrolyzed (EO) water at Georgia started about 4 years ago and focused on finding safe, effective, economic, and practical means of controlling food-borne pathogens as food moves from the farm, through postharvest operations, and onto the table at home. Research findings (Kim et al., 2000; Park et al., 2001a,b) indicated that EO water can be used as a non-thermal method to inactive food-borne pathogens.
The U. of Georgia has studied feasibilitiy of using x-ray for internal disease detection for the past 12 years. Watercore in apples, bruises in apples occurring prior or during harvest and diseases in onions can be determined with 90%+ accuracy and with less than 10% false positives. Work is in process to couple the internal inspection process with various optical indicators through cooperation with commercial firms.
In cooperation with personnel from the CA station, a limited number of green coffee bean samples were separated by geographic place of culture using NIR spectroscopy (unpublished). Numerous samples from various origins need to be scanned to develop a robust technique.
Several studies have demonstrated that proton magnetic resonance (1H-MR) can be used for measurement of quality and composition of fruits, vegetables, and nuts. (Ni and Eads, 1992, 1993ab; Tollner and Hung, 1995; McCarty et al., 1995; Zion et al., 1995). Chen et al., (1989) used a high-field (85.35 MHz) spectrometer to obtain magnetic resonance images of a variety of fruits and vegetables. When images were examined, the location of seeds or pits were detected, and also the presence of voids, worm damage, bruises, and dry regions. Jung et al. (1998) reported that low-field 1H-MR could be used to detect watercore and internal browning in apples. However, low-field 1H-MR would only be useful for quality sorting of fruits and vegetables if internal defects can be detected rapidly, as fruit is moving on a belt or stopped instantaneously. Chen et al. (1996) demonstrated that a relatively high-field 1H-MR sensor (85.35 MHz), in which Fourier transform of the signal was possible, could measure oil content of avocados moving on a specially designed conveyor belt at speeds up to 250 mm/s. Similar experiments should be conducted with a low-field MR sensor to determine whether the low-field techniques used successfully for stationary fruit will work on moving fruit.
Currently, blueberry growers are averse to using the less persistent, environmentally safe insecticides because the risk is high (i.e., if a detectable level of maggots is present then the processor could reject the entire crop from a given field). If infested blueberries could be removed by a combination of technologies and equipment based on near infrared spectroscopy (NIRS), then novel less contaminating control tactics might be adopted by growers. In 1996, Ridgway and Chambers reported on methods using reflectance mode NIRS to detect external and internal insect infestation of wheat. They were able to detect insect protein and/or chitin at low levels (0.01% by weight) as well as moisture differences in the infested wheat samples as compared to control, non-infested samples. Ridgway and Chambers (1998) used NIRS, in conjunction with spectral subtraction methods, to detect insects inside wheat kernels. Ridgway and Chambers (1999) furthered their previous detection work by examining which particular wavelengths are crucial for detection of infestation of wheat and found two wavelengths (982 and 1014 nm) were key for identification, making an in-process-line system more efficient.
For the past two crop seasons the ME station has collaborated with an entomologist in experiments funded by Wild Blueberry Commission of Maine that show infestation detection in blueberries via NIRS. The entomologist led artificial infestation experiments to obtain a higher percentage (approximately 30 %) of infested berries than can be expected by chance under normal field conditions. Preliminary NIRS work performed during the 2001 season showed evidence of wavelength ranges that allow detection of maggot infestation in blueberries in the range of 600-1400 nm, similar to data findings by other researchers studying infestation detection (Ridgway and Chambers 1996; Dowell et al. 1998; Dowell et al. 2000).
Other researchers successfully developed a spectral image database to use with discriminate analysis and/or neural networks to characterize quality attributes for various agricultural commodities (Baker et al. 1999; Carlini et al. 2000; Tarkosova and Copikova 2000; and Thygesen et al. 2001). Others have been able to develop in-process-line equipment using spectral image discriminate analysis as a foundation (Dowell et al. 1999; Osborne and Kunnemeyer 1999; Ridgway and Chambers 1999; and Walsh et al. 2000). Based on this information, we believe there are data treatment and analysis methods that will yield a small number of wavelengths (focus wavelengths) to concentrate discriminate analysis.
Studies (Lu, 2001; Lu et al., 2000) show that NIRS gives good predictions of the sugar content (or soluble solids) of apples and cherries. Relatively good predictions on firmness were also obtained for cherries, but the results for apples are not satisfactory. The different firmness predictions between apples and cherries could be due to the fact that cherry fruit are softer than apples and, thus, are easier for light to penetrate and scatter in the fruit tissue. Absorption and scattering are the two basic phenomena as light interacts with the fruit. Absorption is closely associated with the concentration of certain chemical constituents, such as sugar, moisture, protein, and chlorophyll. On the other hand, scattering properties offer insight into the composition, density, and tissue structure (Birth, 1986). NIRS only provides approximate quantifications of light absorption in a sample through measurement of either reflectance or transmittance. If both absorption and scattering properties can be measured and separated, more information about the fruit will be obtained, which can lead to improved predictions on fruit quality attributes. Therefore, we propose a new sensing technique using imaging spectroscopy (or hyperspectral imaging) to determine the absorption and scattering properties of apple fruit and relate them to fruit firmness, sugar content, and/or acid.
Hyperspectral imaging is a relatively new technique that combines the features of imaging and spectroscopy to obtain both spectral and spatial information from an object. A NIR hyperspectral imaging system was developed to detect both new and old bruises on apples. The system was able to detect up to 94% new and old bruises on apples. The spectral region between 1000 nm and 1340 nm was most appropriate for detecting apple bruises. The optimal number of spectral bands was between 20 and 40 with the corresponding wavelength resolution between 8 nm and 17 nm.
Current practice in the sweet potato industry relies on manual grading of roots as they proceed down a packing line. Thirty to 50 workers scan sweet potatoes and remove those with size discrepancies, disease, deformities, injuries, and abrasions. Automated grading systems have not been adopted due to low throughput capacity, marginal performance, and high cost. Recent advances in biometrics and machine vision technology promise to mitigate these shortcomings. Low cost digital imaging systems coupled with sophisticated pattern recognition algorithms can quickly identify low grade sweet potato roots and trigger a separation mechanism. Visual spectra from the camera can be combined with information from other sensors such as NIR to improve system performance.
Multiple images taken from different locations permit a 3-D model of the object to be constructed in memory with distortions of perspective removed. Fuzzy discriminators and ANN can be trained to distinguish between grades based upon different criteria.
Deck and Stikeleather (1994) evaluated the performance of a semi-automated sorting system for sweet potatoes which employed a video camera with a touchscreen monitor to improve worker safety. More than 200 million pounds of blueberries are sorted annually in the US based upon visual observation by humans on inspection lines or with equipment that measures surface color. Sensing of maturity in blueberries using optical density measurements has been used by researchers. Surface color will not distinguish between ripe vs. overripe berries. Light transmitted through a just ripe berry appears red and shifts to a dark blue as the berry becomes overripe. The transmitted light wavelength is closely related to anthocyanin pigments, sugars, acids, and ultimately to fresh shipping quality.
For a large sample of berries with various levels of maturity, spectrographs of individual berries were obtained statically and while the berries were moving across a light source. Each berry was chemically assayed for soluble solids (SS), pH, and titratable acidity (Acids). Based upon this data set, proprietary image processing algorithms were developed to classify the berry spectrograph to its SS/Acids ratio. Preliminary results were encouraging. Future work will focus on applying this classification method to multiple lanes of moving fruit that will be imaged using a single area scan digital camera. Real time digital signal processors will be used to extract image intensity and wavelength features. An ANN will fuse extracted wavelength features into a final classification of under ripe (green), ripe or overripe. Final prototype integration will be achieved utilizing current commercial sorting berry transport equipment from SBIR Phase II funding.
Postharvest handling and storage for perishable commodities work includes research into how temperature, humidity, and mix of atmospheric gases can affect the shelf life and appearance of sweet potatoes. Methods (both pre- and postharvest) that might positively effect storage life and the appearance of sweet potatoes are being determined. This work included field studies, design and testing of several harvesting aids and particularly development of a computerized method for determining levels of skin adhesion. Roots with high skin adhesion resist the damage of abrasion found in handling.
Visible and NIR spectral imaging has detected over 20 surface defects on over 11 cultivars of eastern US apples (Upchurch et al. 1994; Throop et al 1995, Aneshansley et al 1997, Throop et al 1997). Current and proposed work will continue visible and NIR spectral imaging for internal defects (worm holes, water core and other internal defects) (Throop et al. 1994a, 1994b; Upchurch et al 1997) and will include collaborations with Zedic Industries and the USDA Appalachian Fruit Research Center in implementing new X-ray imaging technologies to detect internal defects. A high speed (5 apples/sec) inspection station using both visible/near infrared spectral imaging has been developed and evaluated. The same collaboration is in the initial phases of developing a system to inspect internal defects on a high speed handling system using x-rays.
Biosensor technologies are being developed that can be applied to a variety of food safety issues. There is work on rapid multi-analyte biosensors, micro-cell lysis system, integrated optoelectronic microsystems for biological agents that can be used to assure food safety (Baeumner et al 1996, 1998, 2001). This work is aimed at biological warfare agents, Dengue virus serotypes, and also food pathogens such as C. parvum and E. coli which are important for food safety. Spectroscopic studies similar to those used for surface defects could also be used for food safety issues.
We have developed a variety of handling and orienting systems for the processing of inspecting apples for surface defects with the Appalachian Research Center (Throop et al. 2001, Patent 08/491,805 (1996), Patent 08/735,511 (1996). These techniques can and are being refined and expanded in order to inspect apples for other types of quality issues at high speed.
Although much work has been done with Universal Testing Machines on the texture of fruits and vegetables, Dynamic Mechanical Analyzers (DMA) are unique in that rheological data can be obtained during continuous heating or cooling of fruits and vegetables, as well as under isothermal conditions. Earlier we studied the effects of heating on the modulus of Russet Burbank and Yukon Gold potato discs. During the next period, we will conduct studies on apples, grapes, and other fruits and vegetables with regard to the role of composition on the storage modulus.
The loss of fruit firmness during storage is caused by the action of hydrolytic enzymes on the cell wall polysaccharides. Recent studies indicate that beta-galactosidase is the enzyme most likely to be responsible for apple softening. Research results show an inverse relationship between the beta-galactosidase activity and apple firmness. Further research is needed to study the effects of cultivar and crop year on fruit firmness and beta-galactosidase activity. The enzyme will be purified and characterized.
Machine vision was used to evaluate quality features of apples (Tao et al. 1995a; Heinemann et al. 1995) potatoes (Deck et al. 1995; Tao et al. 1995b; Heinemann et al. 1996), and mushrooms (Heinemann et al., 1994). Later work included development of a measurement procedure for sugars in juices, detection of cholesterol, tenderness of meat, microorganisms of fruit surfaces, and evaluation of the quality of honey.
NIR, MIR, FIR, UV-vis, and florescence spectroscopy have been used to measure composition, contamination, molecular structure, color, texture, and other physical properties of food and agricultural materials. Most of the past applications of spectroscopy in food and agricultural systems focused on NIR, and UV-vis spectroscopy. MIR spectra using fourier transform infrared (FTIR) spectroscopy has been used to study the functional chemical groups in a variety of food systems (Van de Voort, 1993; Chen et al., 1998). With the advent of photoacoustic spectroscopy (PAS) analysis of complex systems is possible (Yang and Irudayaraj, 1998).
Applications of ultrasound include study of emulsions, fruit freshness, meat tenderness, etc. (Henning et al., 1994; Gestrelius, 1994; Mizrach et al., 1994). Despite advances of ultrasonic sensing, only a fraction of its potential has so far been exploited and adopted in food manufacturing.
Fundamental understanding of the physics of impact damage in fruits and vegetables is being established. Instrumentation for measuring key parameters is being developed at the research level. Basic requirements for conditioning of several key commodities are being established. The next steps include development of condition systems and monitoring instrumentation for commercial use.
Fundamental microwave and RF energy relationships for controlling navel orange worm, Indian meal moths, codling moths while maintaining fruit and nut quality are being established. Future work will extend this knowledge to include fruit flies, scale-up the protocol for insect control in in-shell walnuts for industrial implementation, expand research to include almonds and pistachios, and continue protocol development to control insects in tree fruits, especially cherries and apples.
CRIS search results show several research projects doing work in this area. However, most of these are projects with investigators that are participants in this NE-179 project. In addition to those, here is a summary of projects in related areas with non-NE-179 participants:
Project VAK-2000-00295 is an SBIR project investigating combining machine vision with electronic and optical components to assess on-line non-destructive apple firmness. Project CALK-9800290 investigated NIR transmittance for measuring internal composition of several types of fruit such as sugar concentration in mandarins. Project FLA-LAL-03646 is assessing sensor techniques applicable to non-destructive determination of internal quality of fresh citrus fruit and correlating sensor measurements with standard quality indices of fresh citrus. Project COLK-9603703 is an SBIR project to produce a high performance multi-spectral processor that will evaluate color distribution and a number of defect types in agricultural products and will be evaluated using apples. Project CA-D-XXX-5909-SG investigated the use of NMR for evaluating internal quality factors of fruits and vegetables. Project 1270-44000-005-03T developed non-destructive sensing technology to determine the quality of fruits using imaging and NIR spectrophotometry techniques. Project 5325-44000-003-01T investigated line-scanning x-ray for the detection of defects in apples, such as larvae holes, water core, core rotting, and internal browning.
Other areas less directly related to the NE-179 objectives are more numerous, and some samples are cited here. Project MER-1999-03621 is evaluating the feasibility of an impedance-based ethylene sensor for the determination of fruit quality and storage life. Project RI-00-1999-03656 developed a biosensor for food pathogens such as and compared it to standard piezoelectric and fluorescent immunosensors. Project MDR-9702102 is investigating use of biosensor for detection of S. Aureus enterotoxin in foods. Broader systems approaches to safety for apple juice processing are found in project 1935-41420-007-00D and for fresh cut products in project LAB03470.
Objectives
- Define and measure the physical, mechanical, optical, and other properties of fruits and vegetables and their functional relationships to quality, and establish a database of these properties. (CA, HI, NY-C, GA, ARS-MI, ME, MI, NC, NY-G, WA)
- Develop, evaluate and apply rapid non-destructive sensor technology for quantitative measurement of fruit and vegetable quality. (CA, MI, ARS-MI, PA, IN, NY-C, GA, NC, MD, WA, HI, ME)
- Develop, evaluate, and apply rapid sensing technologies to assure food safety including bio-security, purity, and integrity of produce. (CA, PA, MI, NY-C, GA, WA)
- Integrate sensor technologies with handling and storage systems to retain post harvest quality in fruits and vegetables. (NY-C, GA, NC, CA, HI, PA, WA)
