Bioelectrical impedance analysis (BIA) is increasingly being applied to fish to measure body composition non-destructively, in order to guage things like fat percentage and fish quality.
Similar to how scales found in health clubs measure the body mass indexes of humans, BIA technology measures fish to determine impedance, which lends itself to the calculation of a fish's body fat percentage.
Devices of this type typically determine impedance through an array of four rod-type electrodes that run a light electrical current through the body of the fish. In contrast to a strong current, which would move directly through cells, a light current works its way around the cells. If the space contains water, the current is conducted well; if it contains lipids (fats), it conducts electricity poorly. How well the current moves through the device determines how much fat is present.
In order for those measurements to indicate fat percentage, samples must be collected on each target species in order to match the impedance readings with sampled fat percentages determined by a different method. The location for placing the electrodes used by the tool also varies by species, as different species store fat in different parts of the body.
Even with this data, there are additional variables – such as temperature and reproductive state – that may throw off the result unless accounted for. The devices are meant for use on fresh fish only, but can also be used to identify fish that have been previously frozen.
As more aquaculture operations adopt BIA devices, three companies and their offerings have emerged as forerunners in the realm: Distell in Fauldhouse, West Lothian, Scotland; Certified Quality (CQ) Foods, Inc. in Clinton Township, Michigan, U.S.A.; and Yamato Scale Co., Ltd. in Akashi City, Hyogo Prefecture, Japan.
Each company has approached creating these tools in different ways, with different features.
Distell has two models of its “Fish Fatmeter” available. Model FM 692 is the standard commercial model, for use with larger fish species. In contrast to the four protruding rod electrodes of its competitors, it has a head consisting of a micro-strip transmission line sensor that detects the water content of the sample. The device comes pre-calibrated for four fish species, that can be specified by the buyer from over 60 available.
According to Distell, usage is simple: the device is held with two hands, the sensor is pressed to the fish, and a button is pushed. The machine can take multiple samples from different parts of a fish and average them, with up to 1,000 data sets capable of being stored. That data can be transferred via cable to the USB port of a PC to view in an Excel file. The device has an internal battery that is charged by an included charger via the data port. The advertised price, excluding tax, is GBP 5,685 (USD 8,016, EUR 6,617). Rental and installment payment plans are available, the company said.
Model FM 992 has a smaller sensor head for use with smaller fish species. It can also be used on larger fish species, but there is a slight degradation in accuracy, according to Distell. The model is slightly cheaper, and sells for GBP 4,650 (USD 6,554, EUR 5,412).
Another product from Distell, the Torrymeter, can assess the freshness of fish on a scale of 18 (best) to 1. Different from the Fatmeter, it has four electrodes, and costs GBP 2,125 (USD 2,998, EUR 2,473). Competing makers combine the fat and freshness measuring functions into a single device.
CQ Foods, Inc., meanwhile, offers the Certified Quality Reader (CQR), based on a BIA device that is U.S. Food & Drug Administration (FDA) approved for human use to measure body fat and body composition – the Quantum V from RJL Systems. The hardware, firmware, and software have been adapted to measure animal health and quality of protein foods such as chicken and fish. Both CQ Foods and RJL Systems are headquartered in the same Michigan town.
Another unit, the Waterproof CQR, is designed for use at-sea on fishing vessels, CQ Foods said. The Small Fish Form Factor is a handheld waterproof wired attachment to measure small fish. There is also a similar Scallop Form Factor, the company said.
The electrodes of the CQR are spring-loaded and are meant to be partly depressed to ensure firm contact, even on an irregular fish shape, according to the firm. Readings for salinity, quality, and fat content can be given from the same device. The CQR device also displays a “group” setting, which is customizable by the user and can include, for example, boat names or suppliers, to allow easier breakdown and analysis of the readings. Data is transferred via cable, CQ Foods said.
The company’s Analytical Monitoring Program (AMP) is a customizable cloud-based dashboard that can be used to sort and manipulate the data. The AMP is meant to help identify which suppliers are meeting quality goals. CQ Foods said it can help to identify and eliminate problems in fish as part of a long-term quality improvement program, rather than just rating individual fish.
The CQR was introduced in 2015, and has built up a track record with Alaskan salmon processors. The introductory price at that time was around USD 5,000 (EUR 4,093), but the company is now promoting a lease program.
The last product, The Fish Analyzer by Yamato Scale – based in Akashi City, Hyogo Prefecture, Japan – is easier to hold and easier to pay for than its competitors, but lacks some features that would be desirable in a formal quality improvement program outside of Japan, most notably the ability to download data to a PC, according to the developer.
Yamato Scale Deputy Commercial Weighing Solutions Executive Manager Shuichi Okabe told SeafoodSource that the device as sold in Japan has Bluetooth capability to transfer data. However, the chip the company uses on the device in Japan is not approved for use in the U.S. because it has not been cleared by the Federal Communications Commission (FCC) regarding radio frequency interference, Okabe said. The company is planning to switch to an FCC-approved Bluetooth chip, but until it does, the download function is not available outside of Japan.
Unlike its competitors, which have a boxlike form, the Fish Analyzer has a vertical handgrip with the four rod-type electrodes below and an LCD display screen above (competitors use LED displays). To measure small fish, an adapter (included) with a closer electrode pattern can be placed over the standard rod electrodes.
The model being marketed overseas, the DFA110 Pro, gives both a fat percentage and a quality reading, expressed as a letter: A, for best, through to D. It comes loaded with calibrations for 20 fish species, and locations for placing the electrodes vary by species.
“We are successful in Japan selling these to fishery cooperatives who want to brand their catch,” Okabe said.
It is common in Japan to create a premium regional brand, often with a minimum fat percentage, to ensure good flavor. For the overseas market, the company plans to focus on fish farms that export.
The DFA110 Pro is also one of the cheaper options, selling for under JPY 150,000 (USD 1,413, EUR 1,155), but is currently available only in the domestic Japanese market.
Photo courtesy of Yamato Scale