The chemical quality of frozen Vietnamese Pangasiushypophthalmus fillets

1. The chemical quality of frozen
Vietnamese Pangasius
hypophthalmus fillets ( catfish)
Done by : Reem Omair
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2. Catfish
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*www.gloryal.com

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4. Introduction
• Pangasius hypophthalmus is mainly produced in
Asian countries such as Bangladesh, Vietnam,
Malaysia, Indonesia and China.
• Vietnam is the largest Pangas-producing country.
• Catfish is widely exported due to great
acceptability, affordable cost, and white meat.
• It was ranked the sixth favorite fish species in the
United States in 2011 .
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5. Spoilage indicators
• Ammonia is resulting from the bacterial or enzymatic
degradation of protein, which increases in fishes
during storage.
• Biogenic amines (BAs) are produced, mainly, by
exogenous decarboxylase enzymes.
BAs may result in severe toxicological effects.
BAs may react with nitrates resulting in
nitrosamines, which are carcinogenic
compounds
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6. • Malondialdehyde (MDA) is a secondary product
from lipid oxidation. This compound in high amounts
decreases the paraoxonase (PON1) level.
• Methyl mercury is the molecular form from mercury
(Hg) most detrimental for fish species and humans
due to their great toxicity.
• Polyphosphate is an additive that enhances water
binding of fish flesh.
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7. Sampling
• Ten frozen samples of commercial Pangasius
fillets were purchased at different supermarkets
in Rio de Janeiro,Brazil, and transported to the
laboratory.
• All analysis were made three times.
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8. Analysis
Proximate composition
• Moisture was determined by using a drying oven at 100–
105°C until constant weight.
• Protein content was estimated by the Kjeldahl method.
• Ash content was determined after incineration in a muffle
furnace (550°C).
• Total lipid content was determined by the Soxhlet
extraction method and the petroleum ether solvent.
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9. Polyphosphate
• Polyphosphate concentration was determined
through the microcolorimetric method.
• The reading was performed with UV/visible
SmartSpec™ Plus spectrophotometer.
• Results were reported in total concentrations of
pyrophosphate and tripolyphosphate (expressed
as g 100 g−1 P2O5)
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10. Ammonia and pH
• The quantitative determination of ammonia was
adapted according to the colorimetric method.
• Measurement was performed immediately with
UV/visible SmartSpec™ Plus spectrophotometer.
• Results were expressed in μg NH3 g−1.
• The pH values were measured using a digital pH
meter .
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11. Biogenic amines
• Biogenic amines (putrescine, cadaverine,
histamine, spermine, and spermidine) were
determined based on reverse-phase HPLC.
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12. Lipid oxidation
• Malondialdehyde values were determined using
the distillation method and a 2-thiobarbituric
acid.
• measurement was performed with UV/visible
SmartSpec™ Plus spectrophotometer.
• Results were expressed in mg MDA kg−1
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13. Mercury
• Total Hg was determined using a Direct Mercury
Analyzer
• Results were expressed in mg kg−1.
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14. Results and disscusion
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18. References
• Guimarães CFM, Mársico ET, Monteiro MLG, Lemos M, Mano
SB, Conte Junior CA. The chemical quality of frozen Vietnamese
Pangasius hypophthalmus fillets. Food Science & Nutrition.
2016;4(3):398-408. doi:10.1002/fsn3.302.
• Dambrosio, A., Normanno, G., Storelli, A., Barone, G., Ioanna, F.,
Errico, L., Centoducati, G. and Storelli, M. M. (2016), Aspects of
Vietnamese Sutchi Catfish (Pangasius Hypophthalmus) Frozen
Fillet Quality: Microbiological Profile and Chemical Residues..
Journal of Food Safety, 36: 532–536. doi:10.1111/jfs.12273
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