Abstract
The effects of heating 5% (w/v) Na caseinate solutions in the temperature range 120-140°C for 30 or 60 min at pH 7.0 on the nutritional properties of the protein were investigated. Protein efficiency ratio (PER) was slightly but significantly (P < 0.05) reduced by both heat treatments from 2.8 for the control (unheated Na caseinate) to 2.6 (120°C treatment) and 2.4 (132°C treatment). The digestibility in vivo in rats of the sample heated at 132°C (94.0%) was slightly lower than that of the control (95.3%), but there was no significant difference between the control and the sample heated at 120°C (94.7%). Digestibility in vitro by trypsin plus chymotrypsin was lower for both heated samples than for the control. Available lysine and methionine contents were reduced slightly in the heated samples. The results suggest that the decrease in PER of Na caseinate on heating may be due mainly to loss of available methionine. The reactivity of caseinate to TNBS was increased on heating, which indicates that some proteolysis occurred. SDS-polyacrylamide gel electrophoretograms of treated samples showed that several peptides were formed due to the heat-induced proteolysis.
| Original language | English |
|---|---|
| Pages (from-to) | 243-247 |
| Number of pages | 5 |
| Journal | International Dairy Journal |
| Volume | 9 |
| Issue number | 3-6 |
| DOIs | |
| Publication status | Published - Mar 1999 |
Keywords
- Amino acids
- Nitrogen digestibility
- Protein efficiency ratio
- Sodium caseinate