Stabilisation of acidified skimmed milk with HM pectin

TY - JOUR

T1 - Stabilisation of acidified skimmed milk with HM pectin

AU - Jensen, Søren

AU - Rolin, Claus

AU - Ipsen, Richard

PY - 2010/6/1

Y1 - 2010/6/1

N2 - HM pectin was used to stabilise acidified milk drinks (AMD) against flocculation of milk protein. Two temperatures (16 and 27 °C) were used for acidification in order to obtain AMD of different average particle size. Stable samples were diluted with either serum simulating buffer (SSB) or water, and for these samples the adsorption of the pectin onto the casein aggregates was measured using HPLC. The particle diameter, viscosity and sedimentation, as well as the viscoelastic properties, were used to evaluate the amount of pectin needed to stabilise AMD. Additionally, confocal laser scanning microscopy was used with fluorescence recovery after photobleaching (FRAP) to assess protein mobility in samples. Upon diluting with water an increased adsorption of pectin onto the casein aggregates was observed and the stability decreased. In both water and SSB, a certain amount of pectin was firmly-possibly irreversibly-bound to the casein aggregates, and it could be inferred that the adsorbed pectin formed a multilayer on the casein aggregates. Even though the presence of a weak gel network was expected, no gel could be demonstrated in stable AMD by FRAP or the applied rheological measurements. We thus considerer it unlikely that formation of a network is solely responsible for the stability in AMD and propose a stabilising mechanism resembling steric stabilisation combined with secondary adsorption.

AB - HM pectin was used to stabilise acidified milk drinks (AMD) against flocculation of milk protein. Two temperatures (16 and 27 °C) were used for acidification in order to obtain AMD of different average particle size. Stable samples were diluted with either serum simulating buffer (SSB) or water, and for these samples the adsorption of the pectin onto the casein aggregates was measured using HPLC. The particle diameter, viscosity and sedimentation, as well as the viscoelastic properties, were used to evaluate the amount of pectin needed to stabilise AMD. Additionally, confocal laser scanning microscopy was used with fluorescence recovery after photobleaching (FRAP) to assess protein mobility in samples. Upon diluting with water an increased adsorption of pectin onto the casein aggregates was observed and the stability decreased. In both water and SSB, a certain amount of pectin was firmly-possibly irreversibly-bound to the casein aggregates, and it could be inferred that the adsorbed pectin formed a multilayer on the casein aggregates. Even though the presence of a weak gel network was expected, no gel could be demonstrated in stable AMD by FRAP or the applied rheological measurements. We thus considerer it unlikely that formation of a network is solely responsible for the stability in AMD and propose a stabilising mechanism resembling steric stabilisation combined with secondary adsorption.

KW - Acidified milk drinks

KW - Adsorption

KW - Casein

KW - HM pectin

KW - Stability

UR - http://www.scopus.com/inward/record.url?scp=75349100257&partnerID=8YFLogxK

U2 - 10.1016/j.foodhyd.2009.10.004

DO - 10.1016/j.foodhyd.2009.10.004

M3 - Journal article

AN - SCOPUS:75349100257

SN - 0268-005X

VL - 24

SP - 291

EP - 299

JO - Food Hydrocolloids

JF - Food Hydrocolloids

IS - 4

ER -