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

BACKGROUND: Sugar beet is one of the most produced industrial plants in the world, and during manufacturing it produces a large quantity of leaf waste. Because this waste is rich in protein, this study aimed to identify an efficient method for producing large-scale protein concentrate from sugar beet leaves. RESULTS: Results showed that protein extraction from fresh leaves was more effective than from 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 from the extraction process. After extraction, isoelectric precipitation, heat coagulation, and isoelectric-ammonium sulfate precipitation were compared. Although the latter resulted in the highest protein yield, Fourier transform infrared analysis revealed that excessive salt was not removed during dialysis, making it unsuitable for scale-up due to its additional cost and complexity. Therefore, isoelectric precipitation was selected as the appropriate method for protein precipitation from sugar beet leaves. To increase yield, extractions were assisted by ultrasound or enzyme addition. Ultrasound-assisted extraction resulted in an increased protein yield from 20.20% to 28.60%, while Pectinex Ultra SP-L-assisted extraction was the most effective, increasing protein yield from 20.20% to 38.09%. CONCLUSION: Proteins were extracted from fresh sugar beet leaves using optimum conditions (50 °C, 30 min, pH 9) and precipitated at isoelectric point, with enzymatic-assisted extraction yielding the maximum protein recovery. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Optimization of Hoagland solution macro-elements as a culture media, for increasing protein content of duckweeds (Lemna minor).

This study aimed to increase the protein content of duckweed, a promising alternative to animal proteins and a sustainable source of plant protein cultivated via soilless agriculture, by manipulating the culture medium conditions (Hoagland solution). The contribution percentages of KH2PO4 and Ca(NO3)2, pivotal macro-elements in Hoagland solution affecting duckweed protein content, were determined using Plackett-Burman factorial design as 33.06 % and 36.61 %, respectively. Additionally, optimization was conducted employing response surface methodology, incorporating pH alongside KH2PO4 and Ca(NO3)2. Under optimal conditions of 3.92 mM KH2PO4, 7.95 mM Ca(NO3)2, and 7.22 pH, the protein content of duckweed increased significantly, reaching 51.09 % from 39.81 %. The duckweed cultivated in modified Hoagland solution exhibited protein content of 41.74 %, while duckweed grown in commercial Hoagland solution displayed protein content of 33.01 %. This study showed protein content of duckweed could significantly increase according to the growth medium and showcasing its potential as a sustainable source of plant protein.

Optimization of enzyme assisted extraction of protein from the sugar beet (Beta vulgaris L.) leaves for alternative plant protein concentrate production.

This research focused on the effect of temperature (25-75 °C), extraction time (40-120 min) and solvent/solid ratio (15-45 mL/g) and the enzyme assisted extraction on protein extraction efficiency from by-product of sugar beet. 3 different methods were applied in protein isolation and the highest protein yield (34.55%) was obtained by the isoelectric-ammonium sulfate precipitation method. At the optimized condition of temperature 54.25 °C, 81.35 min, and solvent/solid ratio of 27.65 mL/g, the protein yield was found 55.15%. The protein yield has reached 79.01% with an increase of 43.27% with the aid of the enzyme assisted extraction. The physicochemical properties were determined for revealing its potential use in food industry. It is promising that the isolated protein concentrates (SPC-IAP) show high protein content (69.08% d.b) as well as high solubility (98.71% at pH 7.5). SPC-IAP's high brightness (L* = 79.55), low redness (a* = 0.33) and low yellowness (b* = 13.27) values are encouraging for food industry.