Ha. Alkanhal et al., Changes in protein nutritional quality in fresh and recombined ultra high temperature treated milk during storage, INT J F S N, 52(6), 2001, pp. 509-514
Citations number
27
Categorie Soggetti
Food Science/Nutrition
Journal title
INTERNATIONAL JOURNAL OF FOOD SCIENCES AND NUTRITION
The objective of this study was to determine the changes in nutritional qua
lity of protein in stored UHT milk. Commercial fresh and recombined ultra h
igh temperature (FUHT and RUHT respectively) treated milk samples were used
. Pasteurized milk (P-milk) samples were used for comparison. Milk samples
were freeze-dried for the use in diet formulation. Pasteurized milk samples
were freeze-dried within 24 h of production. FUHT and RUHT milk samples we
re freeze-dried after production (zero time), 3 and 6 months of storage at
37 degreesC. Three nitrogen balance experiments were done at zero time, aft
er 3 and 6 months of storage. The diet used in all experiments were similar
in composition except for protein source. In each experiment egg white (lo
w protein), casein (control), P-milk, and either 0, 3 or 6 months old FUHT
and RUHT milk samples were used as the source of protein in the diets. In e
ach experiment 30 (six for each diet) mate Sprague-Dawley rats were used. A
pparent digestibility (AD), true digestibility (TD), biological value (BV),
and net protein utilization (NPU) were calculated for protein in casein an
d all milk samples. The nutritional quality of protein in FUHT milk before
storage was similar to that of protein in pasteurized milk, but it decrease
d during storage for 3 months and then remained at the same quality up to 6
months of storage. BV and NPU of protein in FUHT milk after storage for 3
and 6 months were lower than that of protein in pasteurized milk by 4% (not
significant) and 5% respectively. On the other hand, the nutritional quali
ty of protein in RUHT milk before storage was lower than that of protein in
pasteurized milk and remained at the same level after storage for 3 months
: however, it decreased significantly after storage for 6 months. AD and TD
, of protein in RUHT milk stored for 6 months were lower than that of prote
in in pasteurized milk by 5% and BV and NPU were lower than that of protein
in pasteurized milk by 9 and 12% respectively. The above reduction in nutr
itional quality of protein in UHT milk may be of significant value in feedi
ng young children who might be dependent on this type of milk in their diet
.