Acıbadem Mehmet Ali Aydınlar University, Faculty of Health Sciences 3-10.11.
2023
Department of Nutrition and Dietetics
FOOD CHEMISTRY and ANALYSIS I
EXPERIMENT: DRY MATTER DETERMINATION
For dry matter determination, the incubator usage method is generally used. Additionally, dry
matter determination can be made by distillation method and electrical conduntance mothod.
Although the electrical conductance method gives very quick results, the incubator method is
preferred for sensitive work.
REQUIRED DEVICES AND MATERIALS
- Weighing containers
- Incubator
- Analytical scale
- Desiccator
- Pliers
- For some foods, blender, grater, etc. grinder (like wheat grain)
The drying container and lid to be used in the analysis should not contain moisture. For this
purpose, it is dried by keeping it in an oven preheated to 135°C for half an hour. Then, it is
placed in a desiccator using forceps and cooled. Again, with the help of forceps, the container
is tared (m1) on an analytical balance (±0.001 g precision). This process is called constant
weighing. Approximately 3-5 g of sample is weighed into the tared container, in accordance
with the sample to be analyzed (m2).
It is important that the weighed sample is homogeneously spread and has fine particles. For this
purpose, the following preliminary processes are applied before weighing:
- Solid samples, such as cheese, are grated and taken as the semi-solid samples below.
- Cream cheese, yogurt, etc. Semi-solid samples are mixed with quartz sand to ensure their
homogeneous distribution and increase their surface area. For this purpose, quartz sand is
placed in the drying container beforehand, dried together with the drying container, and remains
in the drying container throughout the entire analysis. When tareing the container, it is taken
along with the sand.
- In grains, grains larger than 1.7 mm must be milled.
** After weighing m2, if a better spread is desired in the weighing container, some water can
be added to dissolve/spread the sample. The added water will evaporate during drying in the
incubator and will not be included in the calculation.
The weighed samples are left to dry in the oven at the following temperatures and times. The
lid of the drying container should be positioned open during drying.
Acıbadem Mehmet Ali Aydınlar University, Faculty of Health Sciences 3-10.11.2023
Department of Nutrition and Dietetics
For grains and products ………. 130-133°C, 2-3 hours
For milk and dairy products ………… 100-105°C, 2-3 hours
For meat and meat products…………… 100-105°C, 2-3 hours
For fruits and vegetables ………… 100-105°C, 2-3 hours
Honey and candied fruits ………... 70°C, 6-8 hours
At the end of the specified period, the lids are closed again and placed in the desiccator using
forceps/tongs. After cooling, weighing is done. Then, it is dried for another half hour, cooled
again and weighed. According to literature, the drying process continues until the difference
between two weighings does not exceed 0.1%. The final weighing is noted as m3.
ATTENTION!
• When drying foods with high sugar or fat content (e.g. grains, meat products), low
temperatures such as 70°C should be selected. These products decompose above this
temperature. When they decompose, the outflow of water is blocked.
• Air flow in the incubator provides more effective drying. For this purpose, the air hole
of the incubator should be partially opened or a vacuum oven should be used.
• Oven drying method is not suitable for spices that are rich in volatile compounds.
Toluene distillation method is used.
• Oxidation occurring in unsaturated fats increases the dry matter ratio with the effect of
temperature during drying.
CALCULATION AND RESULT
m2 – m3
R= * 100
m2 - m1
R = Amount of humidity (%)
m2 = First weighing (g)
m3 = Last weighing (g)
m1 = Tare of the container (g)
TDM = 100 - R
TDM = Total Dry Matter (%)
Acıbadem Mehmet Ali Aydınlar University, Faculty of Health Sciences 3-10.11.2023
Department of Nutrition and Dietetics
REFERENCES
1. TS 1135 (ISO 712)
2. Temel Gıda Analizleri kitabı, Doç. Dr. Vildan Uylaşer, Prof. Dr. Fikri Başoğlu, 2011,
Gıdalarda Nem ve Kuru madde tayini, sf.8-12.
Study Questions:
1. 1. What does the desired amount of dry matter in foods mean? Discuss the relationship
between dry matter amount and nutrition according to the literature.
2. 2. Is there a determined dry matter amount for wheat flour according to the Turkish
Food Codex? Does this amount vary depending on flour types?
3. Is there a determined amount of dry matter in the Turkish Food Codex for cheese and its
products?
GOOD LUCK ….
Lec. Sena ORUÇ
Res. Asst. Gamze Ayakdaş
Acıbadem Mehmet Ali Aydınlar University, Faculty of Health Sciences 3-10.11.2023
Department of Nutrition and Dietetics
EXPERIMENT:
PURPOSE OF THE
EXPERIMENT:
CALCULATIONS:
Acıbadem Mehmet Ali Aydınlar University, Faculty of Health Sciences 3-10.11.2023
Department of Nutrition and Dietetics
DISCUSSION AND
CONCLUSION:
