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

<p>Abstract</p> <p><br>BACKGROUND</p> <p>Sugar beet is one of the most produced industrial plants in the world, and during manufacturing, it produces a&nbsp;large quantity of leaf waste. Because this waste is rich in protein, this study aimed to identify an efficient method for producing&nbsp;large-scale protein concentrate from sugar beet leaves.</p> <p><br>RESULTS</p> <p>Results showed that protein extraction from fresh leaves was more effective than dried leaves. Maximum protein extraction was achieved at pH 9, compared with pH 7 or 8. Blanching as a pretreatment reduced protein yield during isoelectric precipitation, with a yield of 2.31% compared to 20.20% without blanching. Consequently, blanching was excluded&nbsp;from the extraction process. After extraction, isoelectric precipitation, heat coagulation, and isoelectric&ndash;ammonium sulfate precipitation were compared. Although the latter resulted in the highest protein yield, Fourier transform infrared analysis revealed&nbsp;that excessive salt was not removed during dialysis, making it unsuitable for scale-up due to its additional cost and complexity.&nbsp;Therefore, isoelectric precipitation was selected as the appropriate method for protein precipitation from sugar beet leaves. To&nbsp;increase yield, extractions were assisted by ultrasound or enzyme addition. Ultrasound-assisted extraction resulted in an&nbsp;increased protein yield from 20.20% to 28.60%, while Pectinex Ultra SP-L-assisted extraction was the most effective, increasing&nbsp;protein yield from 20.20% to 38.09%.</p> <p><br>CONCLUSION</p> <p>Proteins were extracted from fresh sugar beet leaves using optimum conditions (50 &deg;C, 30 min, pH 9) and precipitated at the isoelectric point, with enzymatic-assisted extraction yielding the maximum protein recovery.<br><br></p>