The Emulsifier Dependent Effect of Homogenization Pressure and Temperature
A comparison of samples produced under the same conditions but with different emulsifiers (LgCAS vs WP) showed that emulsions with LgCAS had significantly higher PV than WP emulsions already at day 0, except emulsions prepared under high pressure/room temperature, which were not significantly different (Fig. 3a vs b). At day 14, all emulsions with LgCAS had significantly higher PV than all emulsions with WP. Confirming results from PV data, LgCAS emulsions in general had higher concentrations of the volatiles quantified than the similar emulsions prepared with WP (for five of the seven volatiles). Despite more or less similar conclusions from the effect of pressure and temperature on protein compositions in the aqueous phase and droplet size distributions for WP and LgCAS emulsions, their oxidative stability differed significantly. Hence, LgCAS emulsions oxidized more than WP emulsions under the conditions applied in the present study. The better oxidative stability of WP emulsions was surprising, since emulsions prepared with casein in previous studies have been shown to have increased oxidative stability compared to emulsions prepared with whey proteins [31, 37–40]. However, these emulsions were prepared with casein only and did not contain any b-lactoglobulin and this may have influenced the results. In addition, the opposite effect on the oxidative stability of emulsions with different emulsifier combinations was observed when increasing the homogenization pressure. Hence, this indicates that when CAS is present (as in LgCAS) it is most beneficial to have this protein in the aqueous phase and b-lactoglobulin at the interface, whereas when CAS is not present (as in WP), it is more beneficial to have b-lactoglobulin in the aqueous phase and a-lactalbumin at the interface. An antioxidative effect of b-lactoglobulin in the aqueous phase of Brij-stabilized emulsions has been shown by Elias et al. [8], and was suggested to mainly depend on a radical scavenging effect of cysteine and tryptophan residues. The same authors later reported that b-lactoglobulin may possess both radical scavenging activity and have
metal chelating properties when present in the aqueous phase of Brij-stabilized emulsions [33]. These observations support the observations in the present study on the importance of b-lactoglobulin in the aqueous phase.
Emulsifier ขึ้นอยู่กับผลของอุณหภูมิและความดัน HomogenizationA comparison of samples produced under the same conditions but with different emulsifiers (LgCAS vs WP) showed that emulsions with LgCAS had significantly higher PV than WP emulsions already at day 0, except emulsions prepared under high pressure/room temperature, which were not significantly different (Fig. 3a vs b). At day 14, all emulsions with LgCAS had significantly higher PV than all emulsions with WP. Confirming results from PV data, LgCAS emulsions in general had higher concentrations of the volatiles quantified than the similar emulsions prepared with WP (for five of the seven volatiles). Despite more or less similar conclusions from the effect of pressure and temperature on protein compositions in the aqueous phase and droplet size distributions for WP and LgCAS emulsions, their oxidative stability differed significantly. Hence, LgCAS emulsions oxidized more than WP emulsions under the conditions applied in the present study. The better oxidative stability of WP emulsions was surprising, since emulsions prepared with casein in previous studies have been shown to have increased oxidative stability compared to emulsions prepared with whey proteins [31, 37–40]. However, these emulsions were prepared with casein only and did not contain any b-lactoglobulin and this may have influenced the results. In addition, the opposite effect on the oxidative stability of emulsions with different emulsifier combinations was observed when increasing the homogenization pressure. Hence, this indicates that when CAS is present (as in LgCAS) it is most beneficial to have this protein in the aqueous phase and b-lactoglobulin at the interface, whereas when CAS is not present (as in WP), it is more beneficial to have b-lactoglobulin in the aqueous phase and a-lactalbumin at the interface. An antioxidative effect of b-lactoglobulin in the aqueous phase of Brij-stabilized emulsions has been shown by Elias et al. [8], and was suggested to mainly depend on a radical scavenging effect of cysteine and tryptophan residues. The same authors later reported that b-lactoglobulin may possess both radical scavenging activity and haveเหล็กคีเลตพักเมื่ออยู่ในขั้นตอนการละลายของ Brij-เสถียร emulsions [33] ข้อสังเกตเหล่านี้สนับสนุนข้อสังเกตในการศึกษาเกี่ยวกับความสำคัญของ b-lactoglobulin ในเฟสอ
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