Table 3.
Moisture concentrations (%) in whey permeate, whey powder, and lactose determined by various oven methods and the Karl Fischer (KF) method (Exp. 2)1
| Ingredient | Oven-drying method | KF method3 | |||||
|---|---|---|---|---|---|---|---|
|
| |||||||
| Drying time (h) | Drying temperature (°C) | ||||||
|
| |||||||
| 1352 | 95 | 105 | 115 | 125 | |||
| Whey permeate5,6 | 1 | 7.5±0.1 | 1.3±0.01 | 1.6±0.02 | 3.3±0.15 | 5.5±0.13 | 3.0±0.09 |
| 2 | 1.4±0.03 | 2.3±0.03 | 3.4±0.05 | 6.1±0.05 | |||
| 3 | 1.5±0.13 | 2.74±0.03 | 3.8±0.03 | 6.3±0.03 | |||
| 4 | 1.5±0.00 | 2.6±0.05 | 4.8±0.13 | 7.0±0.02 | |||
| 5 | 1.5±0.01 | 3.7±0.11 | 5.2±0.05 | 6.7±0.04 | |||
| 6 | 1.5±0.01 | 2.8*±0.03 | 5.8±0.03 | 7.4±0.05 | |||
| 9 | 1.6±0.01 | 3.5±0.02 | 6.3±0.01 | 8.0±0.03 | |||
| 15 | 1.6±0.01 | 4.4±0.01 | 6.4±0.01 | 9.7±0.13 | |||
| 24 | 1.7±0.00 | 4.8±0.03 | 6.8±0.01 | 12.9±0.17 | |||
| Whey powder5,6 | 1 | 7.7±0.06 | 1.7±0.01 | 2.0±0.00 | 2.9±0.06 | 5.8±0.14 | 3.8±0.08 |
| 2 | 1.8±0.01 | 2.3±0.02 | 2.8±0.04 | 6.2±0.04 | |||
| 3 | 1.8±0.01 | 2.64±0.02 | 3.1±0.03 | 5.9±0.04 | |||
| 4 | 1.9±0.03 | 2.6±0.02 | 4.2±0.08 | 7.2±0.02 | |||
| 5 | 2.0±0.03 | 3.2±0.07 | 4.5±0.04 | 7.0±0.04 | |||
| 6 | 1.9±0.00 | 2.7±0.02 | 5.5±0.04 | 7.4±0.07 | |||
| 9 | 2.1±0.01 | 3.1±0.02 | 5.9±0.01 | 7.8±0.02 | |||
| 15 | 2.2±0.03 | 3.5*±0.03 | 6.8±0.03 | 8.4±0.02 | |||
| 24 | 2.2±0.01 | 4.3±0.04 | 7.0±0.01 | 9.2±0.01 | |||
| Lactose5,6 | 1 | 5.1±0.01 | 0.3±0.16 | 0.3±0.03 | 1.8±0.08 | 3.8±0.11 | 4.5±0.05 |
| 2 | 0.2±0.00 | 0.9±0.01 | 2.0±0.04 | 4.4*±0.05 | |||
| 3 | 0.1±0.01 | 1.24±0.02 | 2.5±0.02 | 4.9±0.02 | |||
| 4 | 0.2±0.00 | 1.3±0.00 | 3.5±0.06 | 5.1±0.00 | |||
| 5 | 0.2±0.00 | 1.8±0.06 | 4.0±0.01 | 5.1±0.00 | |||
| 6 | 0.1±0.01 | 1.5±0.03 | 4.5±0.03 | 5.1±0.01 | |||
| 9 | 0.2±0.01 | 2.0±0.01 | 5.0±0.01 | 5.1±0.00 | |||
| 15 | 0.2±0.00 | 2.6±0.01 | 5.0±0.01 | 5.1±0.01 | |||
| 24 | 0.2±0.00 | 3.2±0.03 | 5.1±0.01 | 5.1±0.01 | |||
n = 2 for KF and n = 3 for all oven methods.
An oven method drying at 135°C for 2 h (AOAC, 2005; method 930.15).
The Karl Fischer method (AOAC, 2005; method 2001.12).
An oven method drying at 105°C for 3 h (Shreve et al., 2006; NFTA 2.2.2.5).
The weight loss-on-drying measured by an oven method drying at 135°C for 2 h (AOAC, 2005; method 930.15) differed from the moisture measured by the KF method (p<0.05).
The weight loss-on-drying measured by an oven method drying at 105°C for 3 h (Shreve et al., 2006; NFTA 2.2.2.5) differed from the moisture measured by the KF method (p<0.05).
This method had the least deviation (%) from the KF method.