Table E.3.
Information extracted from the records retrieved concerning casein micelles, other chemical compounds and changes in physical properties of milk proteins to verify the efficacy of HPP on raw milk or raw colostrum according to the criteria described in Section 2.3.2
| Compound | Effect of HPP | Type of milk/colostrum | Stability after the HPP treatment | Effect compared/validated with target pathogens | Methods available to use | References |
|---|---|---|---|---|---|---|
| Casein micelle (effect on size and composition) | ||||||
| Casein micelle size | Treatments between 400 and 600 MPa resulted in complete disintegration of casein micelles. | Most surveys done with bovine milk, one with buffalo milk and (6) and one with camel (9) milk. Some differences in the primary structure of micelles may explain some differences reported | Changes were generally irreversible on subsequent storage at 5°C, but reassociation is described at 20°C (3, 4) | No data available |
EM (1, 2) PCS (4, 5, 6, 7) MADLS (7, 8, 9, 10) |
(1) Garcia‐Risco et al. (2000); (2) Needs et al. (2000); (3) Huppertz et al. (2004a); (4) Huppertz et al. (2004b); (5) Huppertz et al. (2004c); (6) Huppertz et al. (2005); (7) Leu et al. (2017); (8) Bogahawaththa et al. (2018); (9) Omar et al. (2018); (10) Liu et al. (2020) |
| Solubilisation of casein fractions | Micelle disintegration also implies the solubilisation of casein fractions that follows the course: β → χ → αs1 → αs2‐casein. | Two surveys done with bovine milk. No specific differences reported in goat (1) and buffalo milk (4) | No data available | No data available | Urea‐PAGE | (1) Law et al. (1998); (2) Kiełczewska et al. (2004); (3) Huppertz et al. (2004a); (4) Huppertz et al. (2005) |
| Mineral balance | HPP had no apparent effect on levels of colloidal Ca and P concentrations. | Goats’ milk (1, 2, 3). | Soluble Ca and P concentrations increased during the first day of cooling after HPP (3) | No data available |
MS (1,3) AAS (2) |
(1) Law et al. (1998); (2) De la Fuente et al. (1999); (3) Nassar et al. (2019) |
| Other chemical compounds | ||||||
| Fat globule size | 400–800 MPa treatments increased mean diameter and broadened the size distribution. | Ovine milk (2). | No data available | No data available | Coulter Counter system (1) | (1) Kanno et al. (1998); (2) Gervilla et al. (2001) |
| Fatty acid composition | 250–900 MPa treatments at room temperature did not result in alteration of the composition of neutral and polar lipids, and fatty acids. | Most surveys done with bovine milk, one with ovine (1) and one with caprine (6) milk. | During refrigerated storage the impact of HPP on the attributes of caprine milk fat became apparent only after 14 days (6) | No data available |
GC‐FID (3) HPLC‐LSD (4, 5) |
(1) Gervilla et al. (2001); (2) Delgado et al. (2014); (3) Martinez‐Monteagudo et al. (2014); (4) Rodríguez‐Alcalá et al. (2014); (5) Rodriguez‐Alcala et al. (2015); (6) Kiełczewska et al. (2020) |
| Ribonucleosides | No significant changes reported. | All surveys done with bovine milk. | No data available | No data available | HPLC | (1) Martin et al. (2001); (2) Martin and Meisel (2006) |
| Maillard and volatile compounds | No relevant Maillard reaction (furosine formation), lactulose formation or lactosylation of β‐Lg occur after 100–400 MPa for 10–60 min at room temperature. | Two surveys done with bovine milk and two with human milk (3, 4). | No data available | No data available |
IP RP HPLC (1) GC–MS (3,4) |
(1) López‐Fandiño et al. (1996); (2) Nabhan et al. (2004); (3) Contador et al. (2015); (4); Garrido et al. (2015) |
| Changes in physical properties of milk | ||||||
| Colour | HPP reduces the lightness values (L*) and increases the total colour differences (∆E) and whiteness (WI). Changes were attributable mainly to the disruption of casein micelles. |
Two surveys were done with bovine milk, one with ovine (1), one with Caprine (6) and one with camel (5) milk. |
L* of untreated milk decreased slightly while in milk treated at 300–600 MPa increased slightly during the first 24 h of storage (2) | No data available | Colorimeter | (1) Gervilla et al. (2001); (2) Huppertz et al. (2004c); (3) Huppertz et al. (2005); (4) Omar et al. (2018); (5) Nassar et al. (2019); (6) Kiełczewska et al. (2020) |
| Viscosity | Viscosity increases after HPP. | Caprine | Viscosity continued increasing during storage at 4°C (Nassar et al., 2019). | No data available | Rheometer (2) | Nassar et al. (2019) |
| Turbidity | Turbidity (A320) decreases markedly after treatments up to 300 MPa, but little further decrease was observed at pressures up to 600 MPa. | Bovine | No data available | No data available | Spectrophotometer | Needs et al. (2000) |
AAS: atomic absorption spectrophotometry; ∆E: total colour differences; EM: electron microscopy; FID: Flame‐Ionisation Detection; GC: gas chromatography; HPLC: high‐pressure liquid chromatography; IP RF: ion‐pair reversed‐phase; L*: lightness value; LSD: light scattering detector; MADLS: Multi‐Angle Dynamic Light Scattering; MS: mass spectrometry; PAGE: polyacrylamide gel electrophoresis; PCS: photon correlation spectroscopy; WI: whiteness.