Feasibility of ultrasound-assisted optimized process of high purity rice bran protein extraction

Abstract

Rice bran is a by-product of the rice milling process, found worldwide in abundance and highlighted due its protein content. This study optimized the conditions for ultrasonic-assisted extraction of protein from defatted rice bran (DRB) and characterized the rice bran protein concentrate (RBPC). A sequential strategy of experimental design was employed; the effect of pH, temperature, ultrasound exposure time, and amplitude were evaluated regarding the percentage of protein extraction by a Full factorial design (FFD) with a fixed frequencies (FFD-A: 37 kHz; FFD-B: 80 kHz). Subsequently, the percentage of protein extracted was optimized employing a Central composite rotatable design (variables: pH and ultrasound exposure time) and RBPC obtained was characterized regarding chemical and functional properties. The pH and ultrasound exposure time had positive effect (P ≤ 0.05) on percentage of protein extraction; moreover, 37 kHz frequency was more effective in protein extraction. The optimized condition (frequency: 37 kHz; temperature: 30 °C; pH: 10; ultrasound exposure time: 30 min; and amplitude: 100%) allowed 15.07% of protein recovery and the RBPC presented 84.76 g 100 g-1 of protein. Magnesium and copper were the main mineral in RBPC (34.4 and 25.5 µg g-1, respectively), while leucine was the limiting amino acid (0.42) and threonine presented the highest chemical score (1.0). The RBPC solubility was minimal at pH 4 and higher at pHs 6-10; the water and oil absorption capacity were higher than bovine serum albumin (BSA) and the emulsifying capacity was comparable to BSA, with a suitable stability. It was possible to obtain a higher purity RBPC than described in the literature, due to the optimization in the extraction process steps, with functional properties suitable for application in food products, especially emulsified ones.

Determination of process parameters and precipitation methods for potential large‐scale production of sugar beet leaf protein concentrate

“…The defatted rice bran protein was extracted by ultrasound‐assisted extraction at two different frequencies: 37 and 80 kHz. The maximum protein yield was recovered at a lower frequency (15.07%) 43 . A similar pattern of results was seen in ultrasound‐assisted extraction of watermelon seed protein.…”

“…The maximum protein yield was recovered at a lower frequency (15.07%). 43 A similar pattern of results was seen in ultrasound-assisted extraction of watermelon seed protein. A higher protein yield of 87% was obtained at ultrasound power of 90 W), frequency 25 kHz, and duty cycle 75%.…”

Ultrasound‐assisted reverse micelle extraction and characterization of tea protein from tea residue

“…The cavitational shear force generated during ultrasonication can destroy the non-covalent bonds (such as hydrogen bonds and hydrophobic bonds) between protein molecules or within the molecules, so that the compact structure of protein aggregates is opened, and the particle size is reduced to improve extraction rate. 24,25 Zhao et al 26 used ultrasonic-assisted extraction of Dolichos lablab L. protein (DLP), and found that the particle size of DLP was significantly smaller and the extraction rate significantly improved compared to traditional extraction methods. Wang et al 27 also found that the particle size of pea protein extracted by ultrasonic-assisted extraction was significantly smaller, and the biological activity of the extracted protein was also significantly enhanced.…”

“…Ultrasound is widely used as a green, safe and reliable technology. The cavitational shear force generated during ultrasonication can destroy the non‐covalent bonds (such as hydrogen bonds and hydrophobic bonds) between protein molecules or within the molecules, so that the compact structure of protein aggregates is opened, and the particle size is reduced to improve extraction rate 24,25 . Zhao et al 26 .…”