71A-28 |
|
M. LEWIS, T. Boumpa, A. Tsioulpas, and A. Grandison. School of Food Biosciences, Univ. of Reading, Whiteknights, PO Box 226, Reading, RG6 6AP, United Kingdom Goats' milk is more susceptible to fouling and sediment formation during UHT treatment compared to cows' milk. This is thought to be due to its low alcohol stability compared, arising from its higher level of ionic calcium. The objective was to evaluate different stabilizers to test the hypothesis that reducing ionic calcium will reduce sediment formation in UHT goats' milk. Two batches of goats' milk were UHT-treated at 140 °C for 2 sec. Four different stabilizers were evaluated: sodium hexametaphosphate (SHMP), trisodium citrate (TC), disodium hydrogen orthophosphate (DSHO), and sodium dihydrogen orthophosphate (SD). Ionic calcium was measured using a selective ion electrode, and pH and alcohol stability were also monitored. Sediment was assessed by dry weight measurement of the centrifuged deposit. The wet sediment was also subjected to proximate analysis. Comparisons were made with sediments in some commercial heat-treated milks. For the first batch, the least sediment was obtained using TC (0.2%). The sediment dry weight (sdw) was 0.33 g/100 mL compared to the control with 5.53 g /100 mL. TC addition increased raw milk pH from 6.56 to 6.63 and decreased ionic calcium from 2.80 mM to 0.98 mM. It also increased the alcohol stability from 50% to 98%. For the second batch, TC (0.2%) and SHMP (0.2%) gave the least amount of sediment sdw=0.15 g/100 mL and 0.13g/100 mL, respectively. These samples had a high alcohol stability after heating (74% and 80%, respectively) and low ionic calcium (1.22 mM and 0.85 mM, respectively). Analysis of the wet sediment showed it contained water (~70 to 80%), substantial protein and fat, and some minerals. Small amounts of sediment were found in commercial milks. The results show that reducing ionic calcium increases alcohol stability and reduces its susceptibility to sediment formation.
Session 71A, Dairy Foods: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |