Researchers from Guru Nanak Dev University in India have reported that protein concentrates, prepared from defatted rice brans, had good water-binding capacity, oil absorption capacity, exhibited good foam stability, and formed "fairly stable" emulsions, giving the ingredient potential for food products ranging from bakery to sausages to salad dressings.
And because rice protein is hypoallergenic, the researchers said that it may act as a suitable ingredient for food formulations targeted at people with food allergies.
"Functional properties of rice bran protein concentrates are comparable with casein and have good potential in food industry," wrote lead author Gurpreet Kaur Chandi in the Journal of Food Engineering .
Rice bran is waste that is normally discarded during rice processing and is naturally rich source of vitamins, minerals, and antioxidants. US company, NutraCea dominates both the human and animal markets, which have a total value of $12 million in the US.
Researchers in India have now proposed that bran protein concentrates from the rice cultivars Basmati 370, Basmati 386 and HBC 19. The protein content of each rice bran protein concentrate (RBPC) was 54, 59 and 52 per cent, respectively, and significantly less than casein (90.6 per cent).
They report that the water-binding capacity, an important measure in bakery, was in the range of 3.875.60 (g/g), which compared favourably with casein (2.48 g/g).
"High water absorption of proteins helps to reduce moisture loss in packed bakery goods. Also it is required to maintain freshness and moist mouth feel of baked foods," said Chandi.
Measures of oil absorption capacity were also better than casein, with RBPC of Basmati 386 and HBC 19 having the highest.
"RBPCs had higher oil absorbing capacity as compared to casein, various leaf protein concentrates and soy protein isolates. High oil absorption is essential in the formulation of food systems like sausages, cake batters, mayonnaise and salad dressings," they said.
The stability of foams formed from the rice bran protein concentrates was also good, said the researchers, with the RBPC of Basmati 370 the best.
The emulsifying capacity of protein concentrates is reported to range from 24 to 74 per cent, and the emulsions were said to be relatively stable under different salt, sugar, and pH values.
"These results showed that RBPCs have good potential to act as a suitable emulsifier under various conditions of pH, salt and especially sugar containing food systems.""Thus, deoiled bran can be effectively used for making protein concentrates and suitably used in various food formulations like weaning foods, dry mixes, baked foods, whipped toppings, salad dressings etc. owing to their high water and oil binding capacities as well as air-water interface stabilizing and emulsifying properties, as demonstrated by the current study," they said.
Source: Journal of Food Engineering Volume 79, Issue 2, Pages 592-597 "Functional properties of rice bran protein concentrates" Authors: G. Kaur Chandi and D.S. Sogi