Grind or blend sample until homogenous. Analyse sample immediately after
preparation. If sample cannot be analysed on the same day, keep in screw-cap bottle in a
freezer. For samples intended for analysis of vitamins or other labile nutrients, flush sample with
nitrogen before storing.
2. Analysis
2.1 For dry sample: Thaw sample to room temperature. Mix sample thoroughly by
turning the tightly closed bottle up and down three times. Weigh accurately 3 – 4 g sample, in
duplicate, into a preweighed drying container (W2).
2.2 For liquid/wet/slurried sample: Mix sample thoroughly and weigh 5–15 g
slurried sample and 20 g for liquid sample into a pre-weighed drying container with acid washed
sand and stirring rod (W2). For liquid samples, dry to a consistency of a thick paste over a boiling
water bath before drying in an oven.
2.3 Place container with sample in the vacuum oven to 60-70°C < 25 mm Hg for 5-6
hours.
2.4 Transfer the container with the dried sample into a desiccator, cool for 30 min
and weigh (W3). Repeat the heating procedure until constant weight is obtained. Different in
weight between two consecutive weighing should not be more than 5mg.
2.5 Calculation
Moisture (g/100g) = (W2 –W3) x 100
(W2 –W1)
Total solid (%) = 100 - % moisture (w/w)
Where W1 = weight of container or empty dish (g)
W2 = weight of container + sample before drying (g)
W3 = weight of container + sample after drying (g)
3. DETERMINATION OF MOISTURE BY INFRARED EMITTER
Principle
The method is based on the drying of food sample under an infrared emitter and its mass
is recorded as a function of time. The water molecules in the food evaporate because they absorb
infrared energy, which causes them to become thermally excited. Moisture contents can be
determined rapidly using this equipment, e.g.10-25 minutes. When heating a sample, there are
two effects applied; radiation and convection. IR is mainly absorbed by water vapour particles
and uniformly penetrates all sample structure. IR drying methods are not officially recognized
for moisture content determinations because it is difficult to standardize the procedure. Even so,
it is widely used in industry because of its speed and ease of use.
Grind or blend sample until homogenous. Analyse sample immediately afterpreparation. If sample cannot be analysed on the same day, keep in screw-cap bottle in afreezer. For samples intended for analysis of vitamins or other labile nutrients, flush sample withnitrogen before storing.2. Analysis2.1 For dry sample: Thaw sample to room temperature. Mix sample thoroughly byturning the tightly closed bottle up and down three times. Weigh accurately 3 – 4 g sample, induplicate, into a preweighed drying container (W2).2.2 For liquid/wet/slurried sample: Mix sample thoroughly and weigh 5–15 gslurried sample and 20 g for liquid sample into a pre-weighed drying container with acid washedsand and stirring rod (W2). For liquid samples, dry to a consistency of a thick paste over a boilingwater bath before drying in an oven.2.3 Place container with sample in the vacuum oven to 60-70°C < 25 mm Hg for 5-6hours.2.4 Transfer the container with the dried sample into a desiccator, cool for 30 minand weigh (W3). Repeat the heating procedure until constant weight is obtained. Different inweight between two consecutive weighing should not be more than 5mg.2.5 CalculationMoisture (g/100g) = (W2 –W3) x 100(W2 –W1)Total solid (%) = 100 - % moisture (w/w)Where W1 = weight of container or empty dish (g)W2 = weight of container + sample before drying (g)W3 = weight of container + sample after drying (g)3. DETERMINATION OF MOISTURE BY INFRARED EMITTERPrincipleThe method is based on the drying of food sample under an infrared emitter and its massis recorded as a function of time. The water molecules in the food evaporate because they absorbinfrared energy, which causes them to become thermally excited. Moisture contents can bedetermined rapidly using this equipment, e.g.10-25 minutes. When heating a sample, there aretwo effects applied; radiation and convection. IR is mainly absorbed by water vapour particlesand uniformly penetrates all sample structure. IR drying methods are not officially recognizedfor moisture content determinations because it is difficult to standardize the procedure. Even so,it is widely used in industry because of its speed and ease of use.
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