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EFFECT OF COOKING METHOD ON PROXIMATE AND MINERAL COMPOSITION OF LAKE MALAWI TILAPIA ( Oreochromis karongae )
Sainani, H & Kapute, F
Abstract
Fish is a nutritious food and an excellent source of animal protein in the human diet
containing many vitamins and minerals that are essential for the human body. In Malawi,
fish is the major source of affordable dietary protein for humans. Lake Malawi tilapia
(Oreochromis karongae) locally known as Chambo, is the most preferred and highest
value commercial food fish species obtained from Lake Malawi. Several methods are
used to prepare/cook the fish viz.: boiling, deep frying in edible cooking oil, grilling,
and/or roasting over fire. However, the fact that cooking alters the nutrient content in
foods underscores the need to understand nutritional effects of different food
cooking/processing methods. This study investigated effect(s) of cooking fresh fish
(Lake Malawi tilapia) by boiling, roasting, pan frying and, using a locally made fireless
cooker) on its proximate (protein, fat, ash and moisture) and mineral (calcium,
magnesium, zinc, iron and phosphorus) composition. Highest and lowest values for crude
protein were reported in fish processed using the fireless cooker (64.3±0.2%) and
roasting (59.9±0.4%), respectively (P<0.05), against (64.4±0.3%) for the fresh fish
(control). Fish that were pan fried showed significantly higher crude fat content
(25.5±0.1%) (P<0.05) followed by samples prepared using the fireless cooker (15.3±0.1),
and lowest values were found in fish that were boiled (12.1±0.2%). Fish from the fireless
cooker had significantly high moisture content (10.6±0.1%), ash (17.1±0.3%), zinc
(0.0±0.0μg/g), phosphorus (2.6±0.0μg/g) and reasonably, more calcium (54.2±7.0μg/g)
and magnesium (0.5±0.0μg/g) (P<0.05). The lowest levels of minerals were recorded in
fish that were roasted: calcium (44.8±0.1μg/g), magnesium (0.5±0.0μg/g), zinc
(0.0±0.0μg/g) and phosphorus (2.0±0.1%) (P≥0.05). The results suggest that fish
processed in the fireless cooker were of higher nutritional quality principally due to the
relatively high content of the most needed nutrient - protein. Adopting and encouraging
use of the fireless cooker could also be a way of saving energy thus; curbing dependency
on fuel wood. The results also showed that cooking does not have significant effect on
minerals in fresh fish.
Keywords
Fireless cooker; boiling; roasting; pan frying; tilapia; Lake Malawi; Malawi
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