Characterization of high pressure jet–induced fat-protein complexation
ABSTRACT: High-pressure-jet (HPJ) processing of various dairy systems has been shown to disrupt fat droplets and casein micelles and cause a strong association between fat and casein proteins. The present work seeks to better describe this association between fat and casein using a model milk formul...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2022-03-01
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| Series: | Journal of Dairy Science |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0022030221010870 |
| _version_ | 1818247359441666048 |
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| author | G. Lewis J.N. Coupland F.M. Harte |
| author_facet | G. Lewis J.N. Coupland F.M. Harte |
| author_sort | G. Lewis |
| collection | DOAJ |
| description | ABSTRACT: High-pressure-jet (HPJ) processing of various dairy systems has been shown to disrupt fat droplets and casein micelles and cause a strong association between fat and casein proteins. The present work seeks to better describe this association between fat and casein using a model milk formulated from confectionary coating fat (3.6% wt/wt), micellar casein (3.4% wt/wt), and water (93% wt/wt), which was then pasteurized, homogenized, and then either HPJ-treated (400 MPa) or not (non-HPJ-treated, control). Upon ultracentrifugation, fat in the non-HPJ-treated model milk creamed due to its low density. In the HPJ-treated model milk, fat precipitated with protein into a thick bottom layer upon ultracentrifugation, reflecting a strong association between protein and fat. Differential scanning calorimetry (DSC) and time-domain nuclear magnetic resonance of the non-HPJ-treated model milk revealed fat in 2 physical states: (1) fat that is physically similar to the bulk fat and (2) fat that was in smaller droplets (i.e., homogenized) and crystallized at a lower temperature than the bulk fat. In contrast, DSC of HPJ-treated model milks supported the presence of fat in 3 states: (1) fat that is physically similar to the bulk fat, (2) fat in small droplets that required substantial supercooling beyond the non-HPJ-treated model milk to crystallize, and (3) fat in such small domains that it crystallizes in a less stable polymorphic form than the non-HPJ-treated model milk (or does not crystallize at all). The state of fat within the HPJ-treated model milk changed minimally with acidification, indicating that the association is not dependent on the charge on the casein. Cryogenic transmission electron microscopy (Cryo-TEM) of the non-HPJ-treated model milk revealed uniform casein micelles, which likely adsorbed to the surface of fat globules post-homogenization. In contrast, Cryo-TEM of the HPJ-treated model milk revealed a porous protein aggregate that likely had dispersed fat throughout. Together, these results suggest that HPJ treatment causes fat to be entrapped by casein proteins in very small domains. |
| first_indexed | 2024-12-12T15:03:27Z |
| format | Article |
| id | doaj.art-470302b556214cf7b05bb15a957c71aa |
| institution | Directory Open Access Journal |
| issn | 0022-0302 |
| language | English |
| last_indexed | 2024-12-12T15:03:27Z |
| publishDate | 2022-03-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Dairy Science |
| spelling | doaj.art-470302b556214cf7b05bb15a957c71aa2022-12-22T00:20:46ZengElsevierJournal of Dairy Science0022-03022022-03-01105321192131Characterization of high pressure jet–induced fat-protein complexationG. Lewis0J.N. Coupland1F.M. Harte2Department of Food Science, The Pennsylvania State University, University Park 16802Department of Food Science, The Pennsylvania State University, University Park 16802Corresponding author; Department of Food Science, The Pennsylvania State University, University Park 16802ABSTRACT: High-pressure-jet (HPJ) processing of various dairy systems has been shown to disrupt fat droplets and casein micelles and cause a strong association between fat and casein proteins. The present work seeks to better describe this association between fat and casein using a model milk formulated from confectionary coating fat (3.6% wt/wt), micellar casein (3.4% wt/wt), and water (93% wt/wt), which was then pasteurized, homogenized, and then either HPJ-treated (400 MPa) or not (non-HPJ-treated, control). Upon ultracentrifugation, fat in the non-HPJ-treated model milk creamed due to its low density. In the HPJ-treated model milk, fat precipitated with protein into a thick bottom layer upon ultracentrifugation, reflecting a strong association between protein and fat. Differential scanning calorimetry (DSC) and time-domain nuclear magnetic resonance of the non-HPJ-treated model milk revealed fat in 2 physical states: (1) fat that is physically similar to the bulk fat and (2) fat that was in smaller droplets (i.e., homogenized) and crystallized at a lower temperature than the bulk fat. In contrast, DSC of HPJ-treated model milks supported the presence of fat in 3 states: (1) fat that is physically similar to the bulk fat, (2) fat in small droplets that required substantial supercooling beyond the non-HPJ-treated model milk to crystallize, and (3) fat in such small domains that it crystallizes in a less stable polymorphic form than the non-HPJ-treated model milk (or does not crystallize at all). The state of fat within the HPJ-treated model milk changed minimally with acidification, indicating that the association is not dependent on the charge on the casein. Cryogenic transmission electron microscopy (Cryo-TEM) of the non-HPJ-treated model milk revealed uniform casein micelles, which likely adsorbed to the surface of fat globules post-homogenization. In contrast, Cryo-TEM of the HPJ-treated model milk revealed a porous protein aggregate that likely had dispersed fat throughout. Together, these results suggest that HPJ treatment causes fat to be entrapped by casein proteins in very small domains.http://www.sciencedirect.com/science/article/pii/S0022030221010870high pressurelipidscaseincalorimetrynuclear magnetic resonance |
| spellingShingle | G. Lewis J.N. Coupland F.M. Harte Characterization of high pressure jet–induced fat-protein complexation Journal of Dairy Science high pressure lipids casein calorimetry nuclear magnetic resonance |
| title | Characterization of high pressure jet–induced fat-protein complexation |
| title_full | Characterization of high pressure jet–induced fat-protein complexation |
| title_fullStr | Characterization of high pressure jet–induced fat-protein complexation |
| title_full_unstemmed | Characterization of high pressure jet–induced fat-protein complexation |
| title_short | Characterization of high pressure jet–induced fat-protein complexation |
| title_sort | characterization of high pressure jet induced fat protein complexation |
| topic | high pressure lipids casein calorimetry nuclear magnetic resonance |
| url | http://www.sciencedirect.com/science/article/pii/S0022030221010870 |
| work_keys_str_mv | AT glewis characterizationofhighpressurejetinducedfatproteincomplexation AT jncoupland characterizationofhighpressurejetinducedfatproteincomplexation AT fmharte characterizationofhighpressurejetinducedfatproteincomplexation |