Intensification of protein extraction from soybean processing materials using hydrodynamic cavitation

K E Preece,N Hooshyar,P J Fryer,N J Zuidam,A J Krijgsman

doi:10.1016/j.ifset.2017.01.002

Abstract

High pressure homogenisation (HPH) has been investigated for its potential to aid the aqueous extraction of protein and other components from soybeans. HPH treatments (50–125 MPa) were applied to soy slurry and okara, the diluted waste stream from soybase production. Extraction yields of oil, protein and solids were calculated, and the feasibility of the technology was assessed. The most productive HPH treatment investigated improved extraction yields of protein up to 82% with a single pass of soy slurry at 100 MPa. In comparison, a maximal protein extraction yield of 70% has been achieved previously using ultrasound at lab-scale for 15 min (20 kHz, 65 W according to manual, 13 mm probe tip) (Preece et al., in press). Results showed a particle size reduction upon HPH and disruption of intact cells, confirmed via confocal laser scanning microscopy. Multiple HPH passes of soy slurry caused an increase in dynamic viscosity and a small increase in particle size probably due to cell wall swelling, resulting in decreased separation efficiency and consequently a reduced extraction yield. HPH offers extraction assistance, with more promising results reported in comparison to ultrasound-assisted extraction of soybean processing materials. Improvement of current soybean processing is desirable on an industrial level to better use available raw materials and reduce waste production. This study shows the effects of a technology already widely employed in industry for other benefits, such as fine emulsion production and microbial cell disruption. High pressure homogenisation was carried out on a lab-scale on soybean processing materials which were prepared in a pilot plant, with similar feed compositions to those produced at an industrial scale.

Highlights

Protein is an important nutrient to be considered when studying food production for human consumption, with major pressure to provide nourishment for an increasing population
To increase the protein extraction yield, High pressure homogenisation (HPH) was applied to either the slurry or the okara solution at various pressures to determine an appropriate pressure for subsequent treatments
On first observation (Fig. 3), the total protein extraction yield increased with increasing HPH pressure for both samples after a single pass

Summary

Introduction

Protein is an important nutrient to be considered when studying food production for human consumption, with major pressure to provide nourishment for an increasing population. Insoluble materials are removed from the extract typically by decanting, and the fibrous waste stream, termed okara, is utilised as animal feed (Preece et al, in press). This process requires attention as the current yield in factories is relatively low (50–60%); improved production methods may yield a greater mass of protein for human consumption. Oil is located within the cytoplasmic network in oil bodies stabilised by low molecular weight proteins termed oleosins (Rosenthal et al, 1998) These oil bodies are smaller in size than protein bodies with sizes in the range 0.2–0.5 μm. Other limitations include insolubility of materials and entrapment in the continuous phase of the insoluble waste stream (Preece et al, 2015)

Methods

Results

Conclusion