The effect of artisanal processing methods on lysine content in selected fish species from different lakes in Uganda

Abstract

Background: Lysine is one of the essential amino acids required in the human diet. However, it is easily lost when fish is subjected to different processing methods which may compromise the human dietary requirements. Methods: We determined changes in lysine content of four fresh water fish species, namely Bagrus docmak, Rastrineobola argentea, Brycinus nurse and Distichodus niloticus. The fish were obtained from lakes Victoria, Kyoga, Edward and Albert in Uganda. Lysine was determined before (baseline) and after processing the four fish species using artisanal methods, namely sun-drying, salting, smoking and deep-frying. Results: The baseline lysine content varied significantly among fish species (6.1-17.6%). Lysine content of B. docmak from L. Victoria and Rastrineobola argentea from L. Kyoga reduced significantly by 43.2 and 55%, respectively, when deep-fried. Smoking also significantly reduced lysine content in R. argentea by 50%. Distichodus niloticus occurs in only L. Albert, and its lysine content decreased with processing method by 49.5% in deep-fried and 7.3% in sun-dried. Processing method did not significantly change lysine content of Brycinus nurse. Conclusion: Generally, the nutritional quality with regard to lysine content of four fish species was not significantly affected by three artisanal processing methods: drying, salting and smoking. However, deep-frying significantly reduced lysine content in three species which has a bearing on public health. In this regard, awareness creation among processors and consumers about deep-fried fish products would alleviate the nutritional insecurity attributed to deep-frying. In addition, modification of the existing artisanal processing methods is necessary to avert a possible predisposition to lysine deficiency.