Optimization of High Hydrostatic Pressure Treatments on Soybean Protein Isolate to Improve Its Functionality and Evaluation of Its Application in Yogurt.

Chenxiao Wang,Xuebing Xu,Jin Yue,Hao Yin,Yanyun Zhao,Yan Zheng

doi:10.3390/foods10030667

Abstract

This work aimed to improve the functional properties of soybean protein isolate (SPI) by high hydrostatic pressure (HHP) and develop SPI incorporated yogurt. Response surface methodology (RSM) was used to optimize the HHP treatment parameters, including pressure, holding time, and the ratio of SPI/water. Water holding capacity, emulsifying activity index, solubility, and hardness of SPI gels were evaluated as response variables. The optimized HPP treatment conditions were 281 MPa of pressure, 18.92 min of holding time, and 1:8.33 of SPI/water ratio. Water and oil holding capacity, emulsifying activity, and stability of SPI at different pH were improved. Additionally, relative lipoxygenase (LOX) activity of HHP treated SPI (HHP-SPI) was decreased 67.55 ± 5.73%, but sulphydryl group content of HHP-SPI was increased 12.77%, respectively. When incorporating 8% of SPI and HHP-SPI into yogurt, the water holding capacity and rheological properties of yogurt were improved in comparison with yogurt made of milk powders. Moreover, HHP-SPI incorporated yogurt appeared better color and flavor.

Highlights

Soy is a source of the predominant vegetable proteins
A number of researchers have studied the impact of High hydrostatic pressure (HHP) treatment on Soy protein isolates (SPI) in recent years and found that solubility, water holding capacity, and foaming property could be improved under medium-high pressure for short processing time (5–20 min), while these properties tend to decline under ultra-high pressure [8,9,10]
Other researchers found that protein solubility and in colloidal solubility of SPI are improved, and colloidal-stable calcium added SPI dispersions can be obtained by HHP treatment, since pressure promotes the formation of calcium-protein species that could establish bridges between the droplets [12]

Summary

Introduction

Soy is a source of the predominant vegetable proteins. Soy protein isolates (SPI) are generally produced from soybean by being collected as precipitated curd in the acidic condition [1], and SPI are essential for a wide range of protein-based food formulations [2,3], owing to their outstanding processing ability, high nutritional value, and low cost. High hydrostatic pressure (HHP) technology is a non-thermal food-processing method showing potential for the development of new food products with additional functional and health benefit [5]. Under HHP, proteins are regulated by the Le Chatelier’s principle and shifted to a lower volume conformer, which in turn changes their structure and conformation and influences their functional properties [6,7]. A number of researchers have studied the impact of HHP treatment on SPI in recent years and found that solubility, water holding capacity, and foaming property could be improved under medium-high pressure (up to 400 MPa) for short processing time (5–20 min), while these properties tend to decline under ultra-high pressure (above 400 MPa) [8,9,10]. Other researchers found that protein solubility and in colloidal solubility of SPI are improved, and colloidal-stable calcium added SPI dispersions can be obtained by HHP treatment, since pressure promotes the formation of calcium-protein species that could establish bridges between the droplets [12]

Objectives

Methods

Conclusion