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Investigation of relationship between surface tension of feed solution containing various proteins and surface composition and morphology of powder particles

- Xu, Yun, Howes, Tony, Adhikari, Benu, Bhandari, Bhesh

  • Authors: Xu, Yun , Howes, Tony , Adhikari, Benu , Bhandari, Bhesh
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Drying Technology Vol. 30, no. 14 (2012), p. 1548-1562
  • Full Text: false
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  • Description: The surface tension of freshly created food protein powder isolates was measured in aqueous solutions as a function of concentration, hydrolysis, and temperature. The surface tension of the solutions was measured immediately to best predict their surface-active behavior in a spray-drying scenario, where instantaneous values are more relevant than equilibrium surface tension measurements. Whole whey protein, hydrolyzed whey proteins (degrees of hydrolysis of 4, 9.5, 12, 17, and 20.2%), soy protein, pea protein isolates, and gelatin powders were diluted in a range of concentrations (0.04-2 g/L) and their surface tension values were reported at 23 +/- 1 degrees C. It was found that at higher concentrations hydrolyzed whey proteins at degrees of hydrolysis of 9.5 and 12%, and soy protein isolates in particular, showed excellent surface activity (shown through a decrease in surface tension) compared to nonhydrolyzed whey protein and gelatin. When comparing the influence of the degree of hydrolysis of whey proteins, the reverse was observed at lower concentrations (0.04-0.1 g/L), with the nonhydrolyzed whey protein reducing surface tension values more effectively than their hydrolyzed counterparts. Additionally, the protein solutions (2 g/L) were maintained at higher temperatures of 40, 50, and 60 degrees C and the surface tension values were measured. There was a general improvement of surface activity of proteins indicated by the reduced surface tension of solutions at these temperatures compared with the pure water values. The protein solutions were also spray dried with maltodextrin (MD30) and the powder particle surface composition and structures were analyzed via X-ray photoelectron spectroscopy and scanning electron micrography. There was a trend of correlation between the surface activities of protein in solution with that of the surface composition of protein found on the powder particles. However, there were morphological indicators that corresponded well to the amount of protein present on the surface.

Improving the foaming properties of soy protein isolate through partial enzymatic hydrolysis

- Zeng, Maomao, Adhikari, Benu, He, Zhiyong, Qin, Fan., Huang, Xuang, Chen, Jie

  • Authors: Zeng, Maomao , Adhikari, Benu , He, Zhiyong , Qin, Fan. , Huang, Xuang , Chen, Jie
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Drying Technology Vol. 31, no. 13-14 (2013), p. 1545-1552
  • Full Text: false
  • Reviewed:
  • Description: The effect of partial enzymatic hydrolysis of soy protein isolate (SPI) on its foaming properties is investigated in this study. Enzymes of different origin, including papain, alcalase, and pancreatin, were used. Foaming properties (foaming capacity and foam stability) were measured and their relationships with physicochemical characteristics such as degree of hydrolysis, molecular weight of hydrolysates, and surface tension were investigated. Papain hydrolyzed SPI hydrolysates were found to be the best in terms of improved foaming capacity and foam stability. Molecular weights of SPI hydrolysates obtained by papain and alcalase hydrolysis were mainly in the range of 5 kDa to 30 kDa, while those hydrolyzed by pancreatin had molecular weight above 50 kDa. Foaming capacity was found to correlate well with the relative abundance of hydrolysate in the molecular weight range of 5 kDa to 10 kDa (r = 0.84, p < 0.05). Surface hydrophobicity was found to correlate negatively (r = - 0.89, p < 0.05) with foaming capacity of SPI hydrolysates. Surface tension values of SPI hydrolysates produced by all enzymes were significantly lower than (p < 0.05) compared to that of SPI. The surface tension of pancreatin hydrolyzed SPI hydrolysates was lower than the surface tension of those hydrolyzed by papain and alcalase. The surface tension of pancreatin hydrolyzed SPI hydrolysates decreased more rapidly with time compared to the rest. These findings will provide better understanding of how best to carry out the partial hydrolysis of SPI using various enzymes in order to improve its foaming properties. © 2013 Copyright Taylor and Francis Group, LLC.
  • Description: C1
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