The procedure of47,48 were used to determine the ash content. A heat resistant crucible was oven-dried at 105 °C for 1 h, cooled and weighed (W1). Then 2 g of the sample was put in a weighed crucible and re-weighed (W2), ashed at 250 °C for 1 h and then incinerated at 600 °C for 5 h in a muffle furnace. This was later cooled in a desiccator and then weighed (W3). The % ash was calculated as:

Crude protein was determined by the Kjeldahl method as described by47. Two grams of the sample was digested in a Kjeldahl digestion tube and boiled with 20 ml of concentrated sulphuric acid and a catalyst until the mixture was clear. The digested sample was filtered and put into 250 ml volumetric flask distilled water was added to make up to 250 ml. The aliquot (50 ml of 45% sodium hydroxide solution) was transferred into a 500 ml round bottom flask and distilled. A flask containing 100 ml 0.1NHCL was used to collect 150 ml of the distilled and then titrated against 20 ml NaOH. Methyl orange was used as the indicator and change of colour to yellow indicates the endpoint.

Nitrogen content (%) was calculated using the following formula:

where; N is the normality, Crude protein (%) was obtained by multiplying the nitrogen value by a factor of 6.25, % crude protein = nitrogen in sample × 6.25.

Five grams of the pulverized sample was extracted in 100 ml of diethyl ether by using an orbital shaker for 24 h. The extract was filtered and the ether extract was collected in a weighed beaker (W1). This was then equilibrated with 100 ml diethyl ether and shaken again for 24 h. The same beaker was used to collect the filtrate (W1). The content (ether) was concentrated to dryness in a steam bath and later dried in an oven at 40–60 °C. The beaker was then reweighed (W2). The crude fat content was calculated using the following formula:

This was determined as described by49 with little modification. A glass crucible containing 2 g of the sample and attached to the extraction unit, boiling 1.25% sulphuric acid and solution (150 ml) was then added. The sample was digested for 30 min, after which the acid was drained out, and boiling distilled water was used to rinse the residue four times. The residue was then rinsed using 100 ml of 1.25% NaOH solution. Finally, the crucible was removed from the extraction unit and oven-dried at 110 °C (Overnight), allowed to cool in a desiccator and weighed (W1). Ashing of the sample was then done in a muffle furnace at 550 °C for five hours cooled in a desiccator and reweighed (W2).

The percentage of crude fibre was calculated using the following formula:

Subtraction of total protein, moisture content, crude fibre, ash and crude fat from the total dry matter (100) gives the carbohydrate content as follow:

Energy value in Kilojoule per 100 g was calculated through the addition of the multiplied value for total carbohydrate, protein and crude lipid (ether extract), using the factor (16.736 kJ, 16.736 kJ and 37.656 kJ respectively) as follows:

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