The chemical quality of frozen Vietnamese Pangasius hypophthalmus fillets

The aim of the present study was to evaluate the chemical quality parameters regarding frozen Pangasius hypophthalmus specimens from Vietnam. The proximate composition, pH, ammonia, biogenic amines (BAs), total mercury (Hg), malondialdehyde (MDA), and polyphosphate were determined. The moisture, protein, lipid and ash values were between 83.83-85.59, 12.51-14.52, 1.09-1.65, and 0.76-2.38 g 100 g(-1), respectively. Fraud by excessive polyphosphate addition was detected in 30% of the samples whereas Hg above the recommended limit was observed in 50% of the samples. With regard to compounds from the degradation process, low concentrations of individual BAs and pH values were found in this study and ranged from 5.88 to 6.18, except for samples with polyphosphate >1 g 100(-1) (pH > 7.00) were observed in the present study. However, ammonia concentration indicated that a degradation process initiated in 80% of the samples (0.12-0.34 NH 3 g(-1)) and 20% of the samples (1.87-1.94 μg NH 3 g(-1)) were in an advanced deterioration process. Furthermore, MDA values (1.21-7.88 mg kg(-1)) suggested some failures, mainly during transportation and/or storage. We concluded that quality control measures must be implemented on the Pangasius production chain to improve the quality of products provided to consumers worldwide.