O'Chiu Emily, Vardhanabhuti Bongkosh
Food Science Program, Division of Food Systems and Bioengineering, University of Missouri, Columbia 65211; International Food Products, Fenton, MO 63026.
Food Science Program, Division of Food Systems and Bioengineering, University of Missouri, Columbia 65211.
J Dairy Sci. 2017 May;100(5):3404-3412. doi: 10.3168/jds.2016-12053. Epub 2017 Mar 9.
Heated soluble complexes of whey protein isolate (WPI) with polysaccharides may be used to modify the properties of aerated dairy gels, which could be formulated into novel-textured high-protein desserts. The objective of this study was to determine the effect of polysaccharide charge density and concentration within a WPI-polysaccharide complex on the physical properties of aerated gels. Three polysaccharides having different degrees of charge density were chosen: low-methoxyl pectin, high-methoxyl type D pectin, and guar gum. Heated complexes were prepared by heating the mixed dispersions (8% protein, 0 to 1% polysaccharide) at pH 7. To form aerated gels, 2% glucono-δ-lactone was added to the dispersions of skim milk powder and heated complex and foam was generated by whipping with a handheld frother. The foam set into a gel as the glucono-δ-lactone acidified to a final pH of 4.5. The aerated gels were evaluated for overrun, drainage, gel strength, and viscoelastic properties. Without heated complexes, stable aerated gels could not be formed. Overrun of aerated gel decreased (up to 73%) as polysaccharide concentration increased from 0.105 to 0.315% due to increased viscosity, which limited air incorporation. A negative relationship was found between percent drainage and dispersion viscosity. However, plotting of drainage against dispersion viscosity separated by polysaccharide type revealed that drainage decreased most in samples with high-charge-density, low-methoxyl pectin followed by those with low-charge-density, high-methoxyl type D pectin. Aerated gels with guar gum (no charge) did not show improvement to stability. Rheological results showed no significant difference in gelation time among samples; therefore, stronger interactions between WPI and high-charge-density polysaccharide were likely responsible for increased stability. Stable dairy aerated gels can be created from WPI-polysaccharide complexes. High-charge-density polysaccharides, at concentrations that provide adequate viscosity, are needed to achieve stability while also maintaining dispersion overrun capabilities.
乳清分离蛋白（WPI）与多糖的热溶性复合物可用于改变充气乳制品凝胶的特性，这些凝胶可被制成具有新颖质地的高蛋白甜点。本研究的目的是确定WPI-多糖复合物中多糖的电荷密度和浓度对充气凝胶物理性质的影响。选择了三种具有不同电荷密度程度的多糖：低甲氧基果胶、高甲氧基D型果胶和瓜尔豆胶。通过在pH 7下加热混合分散液（8%蛋白质，0至1%多糖）制备热复合物。为了形成充气凝胶，向脱脂奶粉和热复合物的分散液中加入2%葡萄糖酸-δ-内酯，并通过手持打蛋器搅拌产生泡沫。随着葡萄糖酸-δ-内酯酸化至最终pH值4.5，泡沫凝固成凝胶。对充气凝胶的膨胀率、排水率、凝胶强度和粘弹性进行了评估。没有热复合物时，无法形成稳定的充气凝胶。由于粘度增加限制了空气的掺入，当多糖浓度从0.105%增加到0.315%时，充气凝胶的膨胀率降低（高达73%）。发现排水率百分比与分散液粘度之间呈负相关。然而，按多糖类型分开绘制排水率与分散液粘度的关系图显示，电荷密度高的低甲氧基果胶样品中的排水率下降最多，其次是电荷密度低的高甲氧基D型果胶样品。含有瓜尔豆胶（无电荷）的充气凝胶在稳定性方面没有改善。流变学结果表明样品之间的凝胶化时间没有显著差异；因此，WPI与高电荷密度多糖之间更强的相互作用可能是稳定性提高的原因。可以由WPI-多糖复合物制备稳定的乳制品充气凝胶。需要高电荷密度的多糖，其浓度要能提供足够的粘度，以实现稳定性，同时还要保持分散液的膨胀能力。
