Table 3.
Batch‐to‐batch analysis of the NF produced under neutral conditions
| Parameter | Batch number | Method of analysis | ||||
|---|---|---|---|---|---|---|
| #1‐N | #2‐N | #3‐N | #4‐N | #5‐N | ||
| Physico‐chemical parameters | ||||||
| Insolubility index (mL) | 0.09 | 0.09 | 0.09 | 0.09 | 0.09 | ISO 8156:2005/IDF 129:2005 |
| pH (10% solution) | 7.1 | 7.1 | 7.1 | 7.1 | 7.1 | ISO 5546:2010/IDF 115:2010 |
| Composition | ||||||
| Protein ‘as is’ (N × 6.38) (%) | 94.39 | 93.67 | 93.87 | 92.24 | 93.83 | Kjeldahl; ISO 8968‐3:2004/IDF 20‐3:2004 |
| Protein in DM (N × 6.38) (%) | 98.30 | 97.73 | 97.54 | 95.90 | 97.41 | Calculation (1) |
| BLG (2) (% of protein) | 97.33 | 98.50 | 100.04 | 102.48 | 97.58 | RP‐HPLC/UV (validated internal method) |
| Lactose (%) | 0.09 | 0.09 | 0.09 | 0.09 | 0.09 | Enzymatic; ISO 5765‐2/IDF 79‐2:2002 |
| Fat (%) | 0.09 | 0.09 | 0.04 | 0.04 | 0.04 | Gravimetry; ISO 1736/IDF 9:2008 |
| Ash (%) | 1.86 | 1.87 | 1.80 | 1.76 | 1.82 | Gravimetry; NMKL 173:2005 |
| Moisture (%) | 3.98 | 4.16 | 3.76 | 3.82 | 3.68 | Gravimetry; ISO 6731:2010/IDF 21:2010 |
| Minerals | ||||||
| Aluminium (mg/kg) | < 0.5 | < 0.5 | < 0.5 | < 0.5 | < 0.5 | EN ISO 17294‐2‐E29 (DE Food)/ICP‐MS |
| Chromium (mg/kg) | 0.38 | 0.32 | 0.34 | 0.33 | 0.36 | DS/EN 13805m:2014, DS/EN ISO 17294m:2016/ICP‐MS |
| Chloride (%) | 0.04 | 0.04 | 0.04 | 0.04 | 0.04 | Potentiometric titration; ISO 5943:2006/IDF 88:2006 |
| Calcium (%) | 0.01 | 0.01 | 0.01 | 0.01 | 0.01 | ICP (internal method) |
| Magnesium (%) | 0.003 | 0.003 | 0.003 | 0.003 | 0.003 | ICP (internal method) |
| Phosphorus (%) | 0.03 | 0.03 | 0.03 | 0.03 | 0.03 | ICP (internal method) |
| Potassium (%) | 0.67 | 0.68 | 0.68 | 0.66 | 0.68 | ICP (internal method) |
| Sodium (%) | 0.27 | 0.28 | 0.28 | 0.27 | 0.28 | ICP (internal method) |
| Contaminants | ||||||
| Arsenic (mg/kg) | < 0.01 | < 0.01 | < 0.01 | < 0.01 | < 0.01 | DS/EN 13805m:2014, DS/EN ISO 17294m:2016/ICP‐MS |
| Cadmium (mg/kg) | < 0.01 | < 0.01 | < 0.01 | < 0.01 | < 0.01 | ICP‐MS ISO 17294‐2:2016 |
| Lead (mg/kg) | 0.004 | 0.008 | 0.004 | < 0.003 | < 0.003 | ICP‐MS ISO 17294‐2:2016 |
| Mercury (mg/kg) | < 0.005 | < 0.005 | < 0.005 | < 0.005 | < 0.005 | ICP‐MS ISO 17294‐2:2016 |
| Aflatoxin M1 (µg/kg) | < 0.01 | < 0.01 | < 0.01 | < 0.01 | < 0.01 | HPLC‐FLD (internal method) |
| Microbial parameters | ||||||
| Total plate count (CFU/g) | < 10 | 70 | < 10 | < 10 | < 10 | ISO 4833‐1:2013 |
| Yeast and mould (CFU/g) | < 10 | < 10 | < 10 | < 10 | < 10 | ISO 6611:2004/IDF 94:2004 |
| Enterobacteriaceae (CFU/g) | < 10 | < 10 | < 10 | < 10 | < 10 | ISO 21528‐2:2017 |
| Salmonella (in 25 g) | ND | ND | ND | ND | ND | ISO 6579 |
| B. cereus (CFU/g) | < 10 | < 10 | < 10 | < 10 | < 10 | ISO 7932:2004 |
| L. monocytogenes (in 25 g) | ND | ND | ND | ND | ND | ISO 11290 |
| S. aureus (CFU/g) | < 10 | < 10 | < 10 | < 10 | < 10 | ISO 6888‐1:1999/Amd.1:2003 |
| Sulfite‐reducing clostridia (CFU/g) | < 10 | < 10 | < 10 | < 10 | < 10 | ISO 15213:2003 |
ADPI: American Dairy Products Institute; Amd.: Amendment; CFU: Colony forming unit; DE Food: German Food and Feed Code; DM: Dry matter; DS: Danish standard; EN: European norm; ICP: Inductively coupled plasma; IDF: International Dairy Federation; ISO: International Organisation for Standardisation; HPLC/FLD: High‐performance liquid chromatography with fluorescence detection; MS: Mass spectrometry; ND: Not detected; ‘N’: NF produced under neutral conditions; NMKL: Nordic Committee on Food Analysis; RP‐HPLC/UV: Reversed phase high‐performance liquid chromatography with UV detection.
Protein in DM = (Protein ‘as is’/DM) × 100%.
The levels of BLG, expressed as % of the total protein, exceed 100% in some batches, which can be attributed to the uncertainty of the method (RP‐HPLC/UV) used for the quantification of BLG using a commercial standard with 90% purity.