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There are so many aspects of seafood processing that it’s not possible to cover them all in this column. So I contacted various experts and asked them what aspects of seafood processing were receiving high interest lately.
Michael T. Morrissey (phone 503-325-4531), chair-elect of the IFT Seafood Technology Division and Director of the Oregon State University Seafood Laboratory in Astoria, said that his laboratory is actively working in a number of areas, including high-pressure processing (HPP) of oysters. He is working under a National Sea Grant award with the oyster industry and the manufacturer of HPP equipment, Flow International Corp., Kent, Wash., looking at optimizing HPP, determining how long it can extend shelf life, and determining how it affects sensory characteristics.
The oyster industry is one of the most traditional industries and hasn’t changed much in 100 years, Morrissey said, but it is forward-thinking now. One of the most exciting areas, he said, is high-pressure processing of oysters. It is now well-known that high pressure can kill Vibrio parahaemolyticus and other pathogenic organisms.
HPP is already being used on a small scale commercially to process oysters. As mentioned in the September 1999 Processing column, Motivatit Sea Foods, Inc., Houma, La., is using Flow International’s “Fresher Under Pressure” technology to market Motivatit’s Gold Seal oysters. In the process, the oysters are placed into holding vats where the hydrostatic pressure is increased to 30,000–40,000 psi. The process reduces harmful bacteria to nondetectable levels and extends the shelf life, while preserving the taste and texture.
An interesting discovery during HPP of clams, mussels, and scallops was the fact that if the whole shellfish in its shell is placed under the high pressure, the adductor muscle detaches and the shellfish releases its muscle from its shell, essentially shucking itself.
Traditionally, Morrissey said, the adductor muscle is cut by hand with a sharp knife. It is not the nicest type of job. There is a problem getting good help, and it is seasonal. With a machine to shuck oysters, the industry would save money and headaches. Microwaves can be used to open oyster shells, but they give a heat treatment that alters the sensory characteristics. HPP doesn’t produce heat.
Michael Voisin (504-868-7191), Vice-President at Motivatit Foods, said that his company has been studying use of HPP on oysters, clams, mussels, scallops, shrimp, crabs, and crab meat but at the moment is focusing on commercial molluscan shellfish and is marketing oysters under the Gold Seal brand in Las Vegas and markets in the southeast and West Coast. The products include oyster meat, shucked, frozen on the half shell, and in-shell, the latter with a plastic shrink band that holds the shell closed so it doesn’t lose its liquor. The company is using a small commercial unit manufactured by Flow International 18–20 hr/day to process 8–12,000 lb/day, depending on the product—raw in-shell, frozen half shell, or meat. The company plans to install another unit, doubling production, by March.
According to Edmund Ting (253-813-3346,) Vice President of Research and Development at Flow International, the technology also works well in processing clams, mussels, crayfish, shrimp, and scallops although it is not being used commercially on them as yet. Studies are continuing in conjunction with OSU.
Morrissey also said that there is revitalized interest in time-temperature control, using superchilled temperatures, to extend shelf life of fish. This involves primarily bringing the fish to temperature as quickly as possible aboard the fishing vessel and maintaining it at 30ºF for several days, during offloading, and through distribution. This can extend the prime or top-notch quality of fish from the current 4–5 days to 7–8, and the normal shelf life from the current 14 days to 18–20, giving more breathing room for fish distribution.
He also said that supplies of wild ocean-caught fish are pretty well maxed out and there will be a shift to better utilization of harvested fish and increased use of by-products. He added that there is more activity in aquaculture of catfish, oysters, and shellfish but only limited ocean finfish culture in the United States. Problems in the U.S. are with regulations, siting, land costs, and environmental concerns. Worldwide, aquaculture has expanded over the past 10 years. Now there is as much aquacultured salmon as wild salmon. He foresees an increase in aquaculture over the next several decades, with half of seafood production worldwide through aquaculture by 2030.
Don Kramer (907-274-9691), President of Pacific Fisheries Technologists and Professor of Seafood Technology, University of Alaska-Fairbanks School of Fisheries and Ocean Sciences (UAF SFOS), said that compared to other food industries, the seafood industry has a continuing problem regarding uniform quality when harvesting wild stock.
Harvesting of wild fish is subject to management decisions regarding the time and place to harvest. Wild fish, especially salmon, are often not harvested at their highest intrinsic quality. As salmon near their spawning grounds, their lipid is used to produce eggs and sperm, the protein content decreases, and the moisture content increases. So the farther from the spawning stream the salmon are harvested, the higher the quality. Since management decisions are often made to preserve the stock, the processing plant receives a wide variation in quality.
Producing consistent quality is harder for wild fish than for other muscle food sources such as cattle, and for aquacultured fish. So quality issues are much more of a problem, especially since the increase in aquacultured fish, particularly high-quality salmon, is causing the market to demand increased quality. There is a need to harvest the fish and get them to the processing plant very quickly.
There is ongoing research in universities, such as the UAF Fisheries Industry Technology Center in Kodiak, Alaska. Other states have similar programs, he said. However, he added, government laboratories that used to do seafood research have been phased out in the U.S., Canada, and the United Kingdom, so it is up to university and industry labs to carry on, especially regarding handling and development of underutilized species.
Kramer and Edward Kolbe at OSU had earlier published a manual on cold storage facilities and are now working on a manual on freezing.
There is also a lot of interest in using antibacterial compounds to lower bacterial counts on equipment and fish, Kramer said. Two approaches being actively promoted are use of ozone and use of chlorine dioxide. Both have the potential to reduce the bacterial load and extend shelf life.
Clarence W. de Silva (604-822-6291), Professor in the Dept. of Mechanical Engineering at the University of British Columbia, Vancouver, Canada, has been applying sensor technology, “intelligent control,” and various other mechanisms to the cutting, inspecting, and grading of fish and fish products. Much of the funding comes from the Natural Sciences and Engineering Research Council of Canada (NSERC), which sponsors his Chair in Industrial Automation.
One of the problems in salmon fishing is wastage, he said. Dressing salmon (cutting off the head) accounts for the largest percentage of waste in preparing salmon for canning. The industry in British Columbia generally uses an “iron butcher,” a heavy-duty steel machine designed about 100 years ago. The fish approaches the machine on a conveyor, and a sliding foot (indexer) drops onto the fish, slides along the body until it engages the gill fin (collarbone), and pushes the fish to the cutter, a guillotine-type rotating blade. The machine thus aligns the gill fin with the cutting blade, but there’s no feedback and positioning errors can occur. If the sliding foot slides over the gill, the machine would chop only part of the head. Conversely, if the sliding foot doesn’t reach all the way to the gill fin, the machine would chop off more meat.
To overcome this problem, de Silva has been working with B.C. Packers, Ltd., Vancouver, to develop a new prototype machine, shown with de Silva in the photo above. It uses machine vision and a servo-controlled hydraulic cutter and reduces waste from 6% to 1%. The old machine handles two salmon/sec, and the new one can do as well or better. It takes only ½ sec to position and cut fish. It has “intelligent” self-tuning features. It also withstands the plant environment and washdown better. The machine has been tested on thousands of fish under actual plant conditions, and plans are being discussed about commercial development of the prototype.
De Silva and his associates have also been working on automating the grading of herring roe, which is exported to Japan as a delicacy. Currently, roe is graded manually on a conveyor belt or grading table with three people on each side removing the bad roe. It goes very fast, so they’re bound to leave some bad roe behind, he said, but if the Japanese find any bad roe in a batch, they downgrade the whole batch and its price. The problem is to maintain accuracy and repeatability, as well as be able to easily change standards. For example, if a customer decides in mid-season to change the specs for grade 1 from 15-cm-long roe to 14-cm-long roe, it’s hard for humans to differentiate them, and it’s very hard to retrain humans. Therefore, machine grading would be more accurate, consistent, and repeatable.
So, again with B.C. Packers, Ltd., his team developed a machine that uses machine vision to determine the size, shape, and color of roe, tell whether there are bloodstains or blood spots, and estimate the weight accurately. It can also determine the texture (firmness) on the basis of the color. The machine is also equipped to use ultrasound to give a texture profile, but as yet it causes a bottleneck in the production process. An ultrasound impedance profile shows which parts of the roe are firm and which are not. The image features can be correlated directly with overall grade, size, color, shape, and texture. It can also be used to grade on the basis of weight and size, and the grades can also have subgrades, such as large, medium, and small. Commercial development of the machine is now being negotiated.
Brian E. Farkas (919-513-2096), Assistant Professor of Food Engineering at North Carolina State University, Raleigh, said that he and colleagues S. Andrew Hale and Tyre C. Lanier are conducting research on tuna processing, sponsored jointly by StarKist Seafoods, Inc., the USDA National Needs Fellowship program, and the North Carolina Sea Grant Program.
Farkas said that the U.S. canned tuna industry processed more than 220,000 tons of fish in 1997 to produce 37 million cases of light-meat tuna, the majority from skipjack (Katsuwonas pelamis), accounting for nearly $1 billion in gross sales. However, the increase in variety and availability of other pre-prepared foods has led to a decline in consumption of canned tuna, forcing the tuna industry to seek improvements in product quality and yield, principally through product formulation technologies and improvements in purse seine vessel operations.
In 1997, Farkas and Hale, under a U.S. Dept. of Agriculture National Needs Award, entered into a joint research partnership with StarKist Seafoods, Inc., Newport, Ky., to improve canned tuna quality and yield through process engineering at the cannery level. Lanier joined the partnership in 1998 under a North Carolina Sea Grant Industrial Fellowship Award to conduct additional research on skipjack muscle biochemistry with a focus on enzymatic degradation during cannery processing.
The four-year project focuses on determining how the cannery unit operations of thawing, precooking, cooling, cleaning, and can filling interrelate and ultimately affect the final product quality. The results will be used to develop a control algorithm to maximize quality and yield.
The researchers are (1) using numerical simulation to determine optimum conditions for freezing, thawing, precooking, and cooling of whole tuna; (2) determining the governing mechanisms for mass transfer in whole and particulate tuna and the relationship between changes in physical properties and protein biochemistry; and (3) identifying and determining the kinetics of the enzymes responsible for proteolytic degradation, one of the primary causes of quality loss. They are then putting all this information together to develop a process sensing and control strategy that considers not only the status of specific process setpoints, but also the condition of the incoming raw material and intermediary product at each unit operation.
Starkist has provided the researchers with funding and plant facilities in which to test their hypotheses and gather data on-line under actual processing conditions.The company has also provided its expertise in tuna processing and information on consumer desires. Starkist has been implementing the research team’s recommendations during the project, with an increase in yield and quality.
Farkas and Hale have also been working on developing a new method for thermal processing of blue crabs. A common and serious problem with steam processing of blue crabs is the large temperature differences found within the retort during heatup and cooling. This leads to severe overprocessing, quality loss, and low yield. They have developed a modified process involving evacuation of the retort followed by steam backflushing as a precook treatment. This modified process greatly reduces the disparity in temperature distribution. It has been proven on a pilot scale, with results showing up to a 50% reduction in cook time and a nearly homogenous temperature distribution across the retort.
The crabs are placed into a basket and pushed into the retort. The steam gets evenly and quickly distributed through the mass of crabs, without overcooking those toward the outside of the mass. Retort venting is the key, Farkas said. A commercial-scale unit is being built now for installation at Washington Crab Co., Washington, N.C., during this year’s blue crab season. The rectangular vessel features modular steam inlet and exhaust capabilities, a liquid-ring vacuum pump capable of rapid evacuation of the vessel, stainless-steel construction, sanitary piping for simple breakdown and cleaning, and a distributed data acquisition system used to monitor retort performance.
Tyre Lanier (919-515-2964), Professor of Food Science at NCSU, is also working, along with Research Associate Joseph Simunovic and graduate student Alexander Riemann, on an improved method for testing surimi gelation quality by microwave cooking. The gelling quality, and ultimately the value, of a particular batch of surimi produced at sea or in land-based plants is determined by a standard method that involves producing a model cooked gel for rheological testing. The gel is usually made in the form of a cylinder, 1–1.5 in in diameter, which is cooked in a water bath. Heat-stable proteinases are often present in surimi, however, which may weaken the texture if the heating rate is sufficiently slow. Processors have noted that the gelling performance of surimi in the manufacture of crab analog is often better than that measured by the standard test, because of the greater diameter of the product being cooked during testing (crab analog is rapidly cooked by steam in 2-mm-thick sheets).
Lanier and Simunovic, in conjunction with Industrial Microwave Systems Inc., Research Triangle Park, N.C., developed a new method of cooking test gels. It utilizes a patented cylindrical microwave reactor that assures a uniform energy distribution during cooking. Heating rates in forming the test gel now can equal those of the crab analog line, despite the greater product diameter of the test gel, and performance of a surimi batch on-line can thus be better predicted. This method of cooking the test gel will also give surimi seafood manufacturers a better means of evaluating test formulations for new ingredient evaluation without the need to test on-line.
Lanier is also working with Herbert O. Hultin of the University of Massachusetts Marine Station in Gloucester and Jae W. Park of OSU on a new acid-aided process patented by Hultin for manufacturing surimi. The national cooperative two-year project funded by Sea Grant will begin this year to more thoroughly investigate the chemistry of the process and the stability and properties of the product.
The current method for producing surimi, Lanier said, involves only water washing and dewatering, yielding a concentrate of myofibrillar proteins with a large loss of water-soluble components. It is applied primarily to lean, light-fleshed species because fatty species produce a dark-colored product prone to lipid oxidation in storage. The new process is somewhat similar to that for producing soy protein isolate. All the fish proteins, both salt soluble (myofibrillar) and water soluble (sarcoplasmic), are first solubilized by adding acid (rather than by alkali in the case of soy proteins); the unstable membrane lipid fraction is largely removed; and then the fish proteins are reprecipitated by adjusting the pH. The more rigorous leaching process leads to a lighter color, so this acid-aided process allows even fatty, dark muscle species to be utilized. There is also less loss of protein and thus higher surimi yield, and wastewater can be reused because of its lower solids content.
Apparatus for splitting pistachios. U.S. patent 6,009,799, filed 5/23/1007, issued 1/4/2000 to R.F. Lemos, assigned to Paramount Farms, Inc. Describes a system for splitting pistachios which have not naturally opened. An adjustable splitter assembly includes plungers driven by cams, which can slide on a rotating camshaft to allow snubbing of the plungers against the nuts. Cavities on the splitter jaw and plungers include relief holes to avoid crushing of the ends of the nuts and encourage an appropriate split. Cushions between the plungers and cam followers reduce impact on the pistachios.
Methods of processing bivalve molluscs. U.S. patent 6,010,397, filed 11/19/1997, issued 1/4/2000 to T.M. Adams et al., assigned to Gearhies Investments Ltd. Describes a method of processing bivalve molluscs that consists of filling a basket-like container with the molluscs and vibrating them within the container, thereby inducing them to close tightly under stress and compacting them together. A lid maintains the compact configuration of the molluscs, which are cooked by immersing the container into boiling seawater, then removed and plunged into chilled water to halt the cooking process. The molluscs are then blast frozen. Because the shells of the bivalve molluscs are tightly closed and better compaction is achieved by vibrating the molluscs than by compressing them, the shells are unable to open and the internal juices are retained within the shells throughout the cooking, chilling and freezing steps, thereby resulting in processed bivalve molluscs with greatly improved organoleptic qualities upon thawing.
Actinic process for cold pasteurization of fresh foods and beverages. U.S. patent 6,010,727, filed 12/31/1997, issued 1/4/2000 to R.A. Rosenthal, et al. Describes a process for sanitizing fresh foods and beverage products using multiple stages of exposure to different wavelengths of ultraviolet, near-infrared, and infrared light. The food product is exposed to IR light to inactivate enzymes responsible for decomposition; exposed to UV light at germicidal wavelengths to inactivate undesirable microorganisms; and, since the UV light causes a reduction in organoleptic qualities of the food, exposed to NIR light to restore the organoleptic qualities.
Grain based extruded product and process of making. U.S. patent 6,010,732, filed 11/4/1997, issued 1/4/2000 to B. van Lengerich et al.; assigned to General Mills, Inc. Describes improved methods for preparing a grain-based extrudate such as a ready-to-eat cereal or snack product. The methods involve high screw speeds, short-barrel-length extruders, and short residence times. An at least partially ungelatinized grain-based material is fed to a cooker extruder having at least one rotating screw and a relatively short length:diameter ratio. The screw is rotated at least 700 rpm or higher to mix and heat and compress the material, which is then extruded through at least one die orifice to form a puffed extrudate with a density of about 10–100 g/L, a moisture content of 1.5–5%, and cell sizes of about 0.001–3 m2, with most being substantially less than 1.0 m2.
Some forthcoming meetings and courses on seafood processing
The 8th annual Oregon State University Surimi Technology School will be held at the OSU Seafood Laboratory in Astoria, Ore., on April 11–13, 2000. Lecture topics will include surimi chemistry; microbiology; acid-aided surimi manufacturing; freezing; chemistry and cryoprotection; proteolytic enzymes; rheology and texture; processing; starch; color; flavor technology; and surimi products, manufacturing, and marketing. Lecturers include Tyre Lanier, North Carolina State University; Robert Price, University of California-Davis; Herb Hultin and Steve Kelleher, University of Massachusetts; B.Y. Kim, Kyung Hee University; Pascal Guenneugues, Activ International; Bob Gordon, Givaudan-Roure; Carl Jaundoo, Roquette America; and OSU faculty members Jae Park, Edward Kolbe, Haejung An, Michael Morrissey, and Ron Wrolstad. More information is available from course director Jae W. Park (phone 503-325-4531, e-mail [email protected] or [email protected]) or www.orst.edu/dept/seafood/surimi.
The 3rd OSU Surimi Technology School in Bangkok will be held at the Thai Dept. of Fisheries on August 15–17, 2000. Lecture topics will include chemistry of fish proteins; microbiology of further processed seafood; cryoprotectants and starch; acid-aided surimi manufacturing; colors and flavorings; rheology and texture; HACCP system; tilapia surimi; enzymes in surimi gelation; and surimi manufacturing, new products, and new technologies. Lecturers will include Jae Park and Mark Daeschel, OSU; Carl Jaundoo, Roquette America; Mike Burns, Advanced Protein Technology; Herb Hultin, University of Massachusetts; Pascal Guenneugues, Activ International; Poonsap Virulhakul, Thai Dept. of Fisheries; Suwan Viratchakul, Khon Kaen University; and Jirawat Yong-sawatdigul, Suranaree University of Technology. More information is available from Jae W. Park (phone 503-325-4531, e-mail [email protected] or [email protected]) or www.orst.edu/dept/seafood/surimi.
The 2nd OSU Surimi Technology School in Europe will be held in Massey, France, in February 2001. Topics and lecturers are to be announced. More information is available from Jae W. Park (phone 503-325-4531, e-mail [email protected] or [email protected]) or www.orst.edu/dept/seafood/surimi.
The Pacific Fisheries Technologists (PFT) meeting on March 26–29, 2000, in Ketchikan, Alaska, will include tours to a salmon hatchery and two seafood processing plants and papers on such topics as processing technology, seafood marketing, by-products, seafood biochemistry, regulatory update, marine toxins, seafood safety, HACCP issues, aquaculture, microbiology, value-added products, fish handling technology, packaging technology, waste disposal, and environmental issues. More information is available from Don Kramer, PFT President, at the UAF SFOS Marine Advisory Program, Anchorage, Alaska (phone 907-274-9691, [email protected]), or seafood.ucdavis.edu/events/pft.htm.
Sheldon Jackson College will present a HACCP course, March 30–April 1, 2000, in Sitka, Alaska, following the PFT meeting. For more information, contact Liz Brown at 907-747-2554 or [email protected]. The college also has a 10-week seafood training course for those wanting to earn a certificate.
The UAF SFOS Marine Advisory Program will teach a oneweek course on smoking fish and HACCP in Anchorage, Alaska, at a date in 2001 to be announced. In February 2001, it will teach the Better Process School for seafood processors in Anchorage. For more information on these courses, contact Don Kramer at 907-274-9691 or [email protected].
Products & Literature
SUPERSONIC MEAT TENDERIZING is accomplished by a noninvasive method in which boneless cuts of meat—particularly less-tender, lower-fat-content meat—in vacuum-sealed packages are lowered into a stainless-steel tank of water and are exposed to a supersonic shock wave created by a small explosive charge. The wave passes through the water and the meat, tenderizing it uniformly in a fraction of a second, without changing its appearance, texture, or flavor. Tests conducted by the U.S. Dept. of Agriculture have shown that the process is effective in tenderizing beef, pork, lamb, and chicken. For a copy of a 6-p brochure describing the system, contact Hydrodyne, Inc., 416 Ponce de Leon Ave., Suite 1601, Hato Rey, PR 00918 (phone 787-751-8336, fax 787-753-4755)—or circle 374.
PROCESSING OF DEBONED MINCED FISH OR CHICKEN can be viewed on the Web site of Stephen Paoli International Corp.(www.paolimeatrecovery.com). Clips from “one-step” demonstration videos allow the user to view processing, assembly, and cooking of products prepared on the company’s deboning, desinewing, and meat recovery machines. For more information, contact Stephen Paoli International Corp., 2531 11th St., Rockford, IL 61104 (phone 815-965-0621, fax 815-965-5393)—or circle 375.
BISCUIT SLICER/LOADER is capable of assembling 170 sandwiches/min. The sandwich assembly line can slice and collate biscuits and buns from 1-7/8 to 4.3 in in diameter and 7/8 to 3 in thick. Assembler/operators use simple arm and hand motions to complete sandwiches from a fixed meat patty storage bin and a synchronized biscuit-top conveyor. Completed twin packages are then ready for cartoning. For more information, contact Planet Products Corp., 4200 Malsbary Rd., Cincinnati, OH 45242 (phone 513-984-5544, fax 513-984-5580, www.planet-products.com)—or circle 376.
HYDRAULIC SAUSAGE STUFFERS, models 45 and 65/65S, feature a hydraulic piston drive that provides smooth, consistent pressure. The pressure and product flow are easily adjusted with a single control knob, and knee-pedal operation allows hands-free sausage making. For more information, contact Hollymatic Corp., 600 E. Plainfield Rd., Countryside, IL 60525 (phone 708-579-3700, fax 708-579-1057, www.hollymatic.com)—or circle 377.
SEPARATOR/CLASSIFIER TEST FACILITY can be used to separate or classify grains, cereals, pet foods, and other granular, powdered, or pelleted materials. The facility features process models and lab models of the separator/classifier, with automated bulk feed systems, dust collection, and variable-speed drives to provide multiple testing variations. Drying, cooling, and destoning options are available, as well as a wide selection of screen sizes for testing granulations as fine as 150 microns (100 mesh). For more in formation, contact Lorenz & Son Mfg. Co. Ltd., P.O. Box 1002, Cobourg, Ont., Canada K9A 4W4 (phone 905-372-2240 or 800-263-7782 in the U.S. or 800-263-1942 in Canada, fax 905-372-4456, www.lorenz-son.com)—or circle 378.
IN-LINE MIXERS efficiently provide high-speed blending of multicomponent solutions. They do not require an external pump, except for viscous fluids, and can be installed in both single-pass and continuous recirculation loop systems. Up to eight mixing heads can be combined on one mixer if maximum shear is required. For more information, contact Bematek, 12 Tozer Rd., Beverly, MA 01915 (phone 877-236-2835, fax 978-922-7801)—or circle 379.
HIGH-SPEED CHECKWEIGHER, the Cornerstone, is designed for ease and versatility while maintaining optimal production capacity. A built-in variable-speed drive and quick-release guide rails allow efficient product changeover. Critical part changeover, including belts, bearings, chains, guide rails, loadcells, and motors, takes less than 10 min. Users can set the checkweighing parameters that best suit their products. For more information or a copy of “Principles of Checkweighing,” contact Hi-Speed Checkweigher Co., Inc., 5 Barr Rd., Ithaca, NY 14850 (phone 800-836-0836, fax 607-257-6396)—or circle 380.
by NEIL H. MERMELSTEIN