The term ‘protein co-precipitates’ was first used to describe a product produced by the acidification and heating of a combination of casein and whey proteins.
However, the notion was broadened to include mixtures of milk proteins with proteins from other sources and mixtures of proteins with polysaccharides.
New approaches
The paper asserts that it may be possible to find new approaches to obtain high protein yields from protein co-precipitates in order to deliver commercially viable solutions.
“Co-precipitated products can be directly used for supplementing and enrichment of low quantity and poor quality food sources,” the authors conclude.
They also claim protein co-precipitates may have positive effects on the allergenicity of food proteins and suggest more needs to be done to look into this area.
Further investigation
They call for further investigation into several aspects of protein co-precipitates, including the use of protein-based by-products from sectors such as brewing, dairy and oilseed processing.
More work needs to be done on combining more than two sources of protein co-precipitate and the evaluation of the effects of protein co-precipitate fortification on various diseases, they state.
The researchers from Jordan, Canada and Australia claim that protein co-precipitates improve the appearance, texture, stability and nutritional characteristics of many food products.
Research into protein blends
Increasing world population, the increasing demand for, and cost of, protein-rich foods and the need to improve the nutritional and functional properties of protein ingredients has driven research into protein blends, they state.
Milk proteins are expensive and are currently not available in large quantities. Plant proteins are cheaper, but lack some essential amino acids, limiting their nutritional content.
Protein co-precipitate blends offer a range of biological, physical, chemical, functional, sensory and nutritional properties for the food industry to use, the scientists assert.
Amino acid deficiencies
They can also overcome amino acid deficiencies exhibited by single-source proteins, they add. But they claim there is relatively little published information available on the subject.
Milk protein co-precipitates are produced by the precipitation of casein and whey proteins using a combination of heat treatments and addition of acid with or without addition calcium salts.
Plant protein co-precipitates have shown higher nutritional value, and superior functional properties, lower level of anti-nutritional factors, higher in vitro protein digestibility and higher levels of essential amino acids, than individual protein isolates.
Whey–plant protein co-precipitate formed by acid and heat precipitation has used different combinations of raw materials, including defatted soy flour and cottage cheese whey, soybean–whey and cottonseed–whey.
Source: Food and Bioproducts Processing, 2012, available online from December 5; doi: http://dx.doi.org/10.1016/j.fbp.2012.11.011; 'Protein co-precipitates: a review of their preparation and functional properties'.
Authors: Muhammad H Alu'datt; Ghaid J Al-Rabadi; Inteaz Alli; Khalil Ereifej; Taha Rababah; Mohammad N Alhamad; Peter J Torley