Agriculture Reference
In-Depth Information
M ATERIALS AND M ETHODS
Materials
Sugar beets were obtained from “Senta” sugar factory (Senta, Serbia). Prior to
experiments, sugar beets were stored at 4 o C. Sugar beets were thoroughly washed with water
to remove soil and other debris. After peeling it was cut into long thin strips. The cossettes
thus obtained are usually about 3 mm to 4 mm thick and 4 cm to 5 cm long. The average
moisture content of the sugar beet was found to be 75% on a wet basis. Fresh cossettes were
placed in ascorbic acid solution (1%) in order to avoid non-enzymatic browning before
osmotic dehydration. Sucrose and sodium chloride were food grade commercial products and
purchased from local supermarket.
Osmotic Treatment
The osmotic dehydration was carried out in shaker fitted inside a thermostatically
controlled space. 250 ml beakers, filled with osmotic solution, were used as dehydration
vessels, in which samples (about 20 g) were placed. Sugar beet cossettes were totally
submerged in solution during the osmotic treatment, whilst the weight ratio between sample
and osmotic solution was 1:10, in order to avoid dilution of osmotic solution and subsequent
decrease of driving force for osmotic dehydration (Saputra, 2000). In each of the experiments
fresh osmotic solutions were used. At predetermined sampling time cossettes were taken out
and washed with fresh running water to remove excess solution. After washing samples were
drained and gently blotted with adsorbent paper and weighed. Moisture and dry matter
content of the samples were determined by vacuum oven drying for 24 h at 70 o C. All
experiments were done in triplicate and the average value was taken for further calculations.
Calculations
Water loss (WL) was expressed as the net loss of water from the fresh cossettes after
osmotic treatment based on initial sample weight and solids gain (SG) was calculated as net
uptake of solids by osmosed sample based on initial sample weight (Le Marguer, 1988):
M
M
WL
(%)
0
i
100
W
0
(1)
S
S
i
0
SG
(%)
100
W
(2)
0
where: M 0 is moisture content of fresh sample (g); M i is moisture content of osmosed sample;
S 0 is solids content of fresh sample (g); S i is solids content of osmotically treated sample (g)
and W 0 is total weight of fresh sample (g).
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