Abstract
α-Lactalbumin (α-La) and β-lactoglobulin (β-Lg) fractions were obtained from Portuguese native breeds of ewes and goats by preparative gel filtration and further purified by ion exchange; their genetic variants were characterized by isolectric focusing, and β-Lg isolated was further characterized by differential scanning calorimetry. Separation of β-Lg and α-La by molecular exclusion from native whey was relatively easy, whereas β-Lg from both breeds accounted for a single peak via ion exchange under various gradients of NaCl. Isoelectric focusing has indicated that α-La from ovine and caprine wheys appears as a single variant in each case, as well as β-Lg from caprine whey; however, β-Lg from ovine whey appears as two peaks, tentatively denoted as β-Lg A and B. Further comparison with bovine whey made it possible to rank whey proteins by increasing value of pi as follows: bovine β-Lg A, bovine α-La, bovine β-Lg B, ovine and caprine α-La, ovine β-Lg A, and finally ovine β-Lg B and caprine β-Lg. β-Lg from goat's whey showed the highest onset temperature of denaturation in the presence (78-97 °C) or absence (90-100 °C) of NaCl for every pH tested; when NaCl was present, a good correlation between pI and onset temperature of denaturation was obtained for pH values in the range 3.5-7.0.
Original language | English |
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Pages (from-to) | 245-252 |
Number of pages | 8 |
Journal | International Journal of Food Science and Technology |
Volume | 34 |
Issue number | 3 |
DOIs | |
Publication status | Published - 1999 |
Keywords
- Dairy
- Electrophoresis
- Ewe
- Goat
- Proteins
- Whey