At Belinca we are dedicated to scallops. We also develop other markets, one of them is mahi mahi. Here goes a story about being wrongfully accused of soaking frozen mahi portions with chemicals.
Late 2013 we shipped over 600,000lbs of frozen Peruvian mahi portions to one specific customer on the East Coast. As importer of record they did the right thing by sampling through a commercial lab in the US for net weight, micro, counts, etc. Testing incoming product is a sign of good practice and it says something about the importer.
P = A x [C / D] but C and D are wrong
P cannot be determined because C and D are wrong. This very mistake was at the center of a test to determine whether frozen mahi portions are soaked or not. Testing with the flawed formula was done by a commercial laboratory in the USA on behalf of my customer.
I knew we shipped unsoaked, chemical-free mahi mahi. But the lab results of the importer came back differently. I was shocked when I learned that the results suggested we soaked the mahi with phosphates. I was determined to get to the bottom of the claim, and in the end I succeeded to prove that the lab results were fatally flawed. We did not soak the mahi, the method used by the private laboratory was based on the critical error of using the wrong values for C and D.
Mahi is a wild caught, migrating fish. This explains why mahi is caught in many places including Peru, Hawaii, Taiwan , Vietnam, Indonesia, Oman, and South Africa. Phosphorus is a vital nutrient in the ocean. The natural phosphorus levels of mahi fluctuate. It fluctuates depending on eating patterns and the phosphorus levels in the ocean during the migration paths of mahi schools.
The lab used the following methodology. First they determined the phosphorus level of the mahi we shipped to Miami. This level was compared to an expected phosphorus level. If the phosphorus level of our mahi was higher then the expected phosphorus level, the lab chemist considered the additional phosphorus as added phosphates. Simply said: when the phosphorus level of our exported fish is higher than the expected phosphorus level, they concluded we soaked the mahi with phosphates. One would expect the private lab to take into account moisture levels as well, but they didn’t. The lab report said “added phosphates” and we were (wrongly) accused of having shipped phosphated mahi.
The lab calculated the expected phosphorus level as following:
P = expected phosphorus level
P = A x (C / D)
A = protein % of the Peruvian mahi we exported to Miami.
The static values of C and D are published in the USDA Nutrient Database. These values are supposedly based on a mahi sample USDA took in September 1987. The origin of this mahi is unknown: catch area unknown, processing methods unknown, … nothing is known about the mahi sample behind the values C and D. However, things are much worse ! I contacted the USDA Resarch Leader and this is what she answered: Our protein value is from a single sample in a 1958 published paper on Hawaiian fish, and the P value is imputed, likely based on the P in a similar species. Public USDA records showed that the mahi values were based on a sample of September 1987. But the science lead of USDA confirmed that the protein value goes back to a publication of 1958 and that the phosphorus value is likely… imputed ? Protein calculation in the 21st century has improved a lot since 1958. Which serious commercial lab in 2013 would test for soaked mahi using unreliable data of 1958 ?
C = mahi phosphorus level according to the publication of 1958 = fixed value of 143.
D = mahi protein level according to the publication of 1958 = fixed value of 18.50.
C / D = 7.72972973
One of the lab sheets came back as following:
(i) Our Peruvian mahi sample had 19.60% protein.
(ii) The expected phosphorus is 152 mg/100gm (19.60 x 7.72972973).
(iii) The actual phosphorus level of our mahi sample was 206 mg/100gm.
Conclusion made by private lab in the USA: we added phosphates because 206mg > 152mg. And this was how the outrageous accusation of seafood fraud started.
It was perfectly possible for the natural phosphorus level in our mahi to be higher compared to 1958 publication. With natural I refer to the natual, not-artificially-added phoshates. A higher natural phosphorus level does not imply that phosphates were added. Phosphorus levels drop during the production process. This phenomen is explained by the Aquatic Food Products Lab at the University of Florida. The longer the process of filleting and freezing takes, the lower the phosphorus levels. Higher natural phosphorus levels are therefore found in quickly processed mahi. Those who visited our plant in Peru knew very well that the production process was very fast. One could reasonably conclude that our mahi samples had naturally higher (than expected) phosphorus values.
Additionally, when phosphates are used, moisture is added. When % moisture increases, % protein decreases. Interestingly enough our sample that was supposedly soaked had a higher % protein compared to the 1958 data ! It didn’t make sense at all: if we soaked the mahi, how could it be that our protein level was higher ? Soaked mahi should show a lower protein % and our mahi had a higher protein level.
One does not require a PhD in marine chemistry to understand that phosphorus levels vary in the ocean both geographicaly and over time. Consequently, phosphorus levels of mahi depend on the phosphorus levels in the ocean during the migratory traject in combination with feeding patterns plus the residence time in ice and time spent in processing. The longer the fish is exposed to ice or water the more moisture will increase in the product and this will reduce the amount of total phosphorus mainly by dilution but also by leaching.
Regarding the 1958 publication: what was the phosphorous contents in that catch area at the time ? Is it possible that these levels were lower than the current phosphorus levels in the Peruvian catch areas? What about the migratory traject of the sampled mahi ? What is the phosphorus content of the food the USDA mahi sample fed on ? Was the mahi of 1958 processed quickly to prevent phosphorus leach ? None of these questions could be answered.
The initial private lab of the importer tested for added phosphates using the wrong formula. Because C and D in “P = A x [C / D]” are unreliable values, the result P cannot be guaranteed. I stronly objected to the phosporus test and the importer retested with a different lab using the cromatography method. The new results came in and we were immediately acquitted of any wrongdoing. No added phosphates were detected. Our mahi was not soaked. Chromatography is the only reliable scientific test to check for added phosphates in mahi mahi. Ion chromatography will separate the natural phosphates (monophosphates or orthophosphates) from the added ones such as diphosphates, tripolyphosphates and hexametaphospahtes. If any of these are found then added phosphates were used.
I called the chemistry manager and tried to explain that her phosphorus test is totally wrong. She defended her method refering to her PhD degree and the fact she had been doing this test for many years so who was I to question her methodology ? She appealed to authority in lieu of logic and that underminded her thinking.
Q.E.D.