Effects of heat treatment of soy protein isolate on the growth performance and immune function of broiler chickens

The effects of heat treatment on the interaction of salt soluble muscle protein and soy protein isolate in model emulsions were studied. Three soy protein isolates (SPI) were used: a commercial one (CSPI) and two pilot plant samples: a native soy protein isolate (NSPI) and an acid treated soy protein isolate (ASPI). Emulsions were prepared with muscle protein (MP), NSPI, ASPI, CSPI and mixtures of MP and the different SPIs, and then treated at 20, 55, 70, 80 and 90°C. Coalescence, soluble protein and electrophoresis of the aqueous phase of the emulsions were evaluated for each temperature. At 20°C the more native soy protein (NSPI) was compatible with MP, producing a stable emulsion that became more stable during heat treatment. CSPI alone could not form a stable interfacial film through the temperature range, however emulsion stabilisation was achieved at 55°C and 70°C when adding MP. Emulsions prepared with MP ASPI were highly unstable at 20°C, while as the emulsion temperature increased, coalescence decreased abruptly and maintained low values at every temperature. MP, NSPI, ASPI and MP NSPI produced stable emulsions both at 20°C and higher temperatures.

Download Full-text

Effect of heat treatment on the nonlinear rheological properties of acid-induced soy protein isolate gels modified by high-pressure homogenization

LWT ◽

10.1016/j.lwt.2022.113094 ◽

2022 ◽

pp. 113094

Author(s):

Zhi-gang Huang ◽

Xue-ying Wang ◽

Jia-yi Zhang ◽

Yi Liu ◽

Tong Zhou ◽

...

Keyword(s):

Heat Treatment ◽

High Pressure ◽

Rheological Properties ◽

Soy Protein ◽

Soy Protein Isolate ◽

Protein Isolate ◽

High Pressure Homogenization

Download Full-text

Rheological and Solubility Properties of Soy Protein Isolate

Molecules ◽

10.3390/molecules26103015 ◽

2021 ◽

Vol 26 (10) ◽

pp. 3015

Author(s):

Timothy D. O′Flynn ◽

Sean A. Hogan ◽

David F. M. Daly ◽

James A. O′Mahony ◽

Noel A. McCarthy

Keyword(s):

Heat Treatment ◽

Soy Protein ◽

Water Solubility ◽

Protein Solubility ◽

Soy Protein Isolate ◽

Protein Isolate ◽

Ph Values ◽

Low Viscosity ◽

Alkaline Conditions ◽

Low Amplitude

Soy protein isolate (SPI) powders often have poor water solubility, particularly at pH values close to neutral, which is an attribute that is an issue for its incorporation into complex nutritional systems. Therefore, the objective of this study was to improve SPI solubility while maintaining low viscosity. Thus, the intention was to examine the solubility and rheological properties of a commercial SPI powder at pH values of 2.0, 6.9, and 9.0, and determine if heat treatment at acidic or alkaline conditions might positively influence protein solubility, once re-adjusted back to pH 6.9. Adjusting the pH of SPI dispersions from pH 6.9 to 2.0 or 9.0 led to an increase in protein solubility with a concomitant increase in viscosity at 20 °C. Meanwhile, heat treatment at 90 °C significantly improved the solubility at all pH values and resulted in a decrease in viscosity in samples heated at pH 9.0. All SPI dispersions measured under low-amplitude rheological conditions showed elastic-like behaviour (i.e., G′ > G″), indicating a weak “gel-like” structure at frequencies less than 10 Hz. In summary, the physical properties of SPI can be manipulated through heat treatment under acidic or alkaline conditions when the protein subunits are dissociated, before re-adjusting to pH 6.9.

Download Full-text