RESUMO
INTRODUCTION: Little is known about the effects of boiling on nutrient levels in fishes that have a relatively high phosphorus-to-protein ratio (PPR), which are important sources of omega-3 polyunsaturated fatty acids. We hypothesized that the beneficial effects of boiling for a shorter duration (15 min) on nutrient contents in fishes were similar to those of boiling for a longer duration (30 min), which has been shown to decrease the PPR in meat. METHODS: The protein, fat, and phosphorus contents and the PPR of three cooked fish species and their corresponding fish broths were chemically analyzed. The effects of boiling on changes in protein, fat, phosphorus, and the PPR was examined by comparing fish that were prepared with usual cooking methods (no boiling), boiled for 15 min, and boiled for 30 min. The nutrients in fish broths that were boiled for 15 min were also compared with those boiled for 30 min. FINDINGS: There were no significant differences in the changes in phosphorus, PPR, protein, and fat content in fish and fish broths prepared with the two boiling methods. In the fish boiled for 15 min, the phosphorus content was 24% lower (p = 0.001), and the PPR was 20% lower (p = 0.04) than those in nonboiled fish. Additionally, boiling for 30 min reduced the phosphorus content by 31% (p = 0.001), and the PPR by 27% (p = 0.04) compared to nonboiled fish, but the protein and fat contents were unchanged after both 15 and 30 min of boiling. DISCUSSION: The 15- and 30-min boiling methods resulted in a similar reduction in phosphorus and the PPR in fish, with minimal effects on protein and fat. A shorter duration of boiling is recommended to achieve better nutrient profiles in fishes consumed by dialysis patients.
