Method for extracting antibacterial peptides and albumin from pea whey wastewater

Abstract

The disclosure provides a method for extracting antibacterial peptides and albumin from pea whey wastewater, which includes following steps: in extracting the albumin, centrifuging with the pea whey wastewater generated during pea protein processing as raw material; controlling temperature and exchanging heat to adjust temperature of the raw material; sequentially performing a microfiltrating, nanofiltration, ultrafiltration and secondary nanofiltration to obtain an albumin slurry; performing a multi-effect concentration on the albumin slurry; adding an alkaline substances to adjust pH; sterilizing and drying to finally obtain the albumin, which realizes a targeted extraction of the albumin with small molecular weight in the pea whey wastewater and avoids resource waste. The albumin with small molecular weight and the antibacterial peptides in the pea whey water are effectively recycled, thus avoiding environmental pollution caused by improper treatment of the pea whey water and realizing resource reuse.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]The present application claims the benefit of Chinese Patent Application No. 202010154908.3 filed on Mar. 9, 2020, the contents of which are incorporated herein by reference in their entirety.TECHNICAL FIELD[0002]The disclosure belongs to the technical field of protein extraction, and particularly relates to a method for extracting antibacterial peptides and albumin from pea whey wastewater.BACKGROUND ART[0003]Pea, as a crop with high starch content, is commonly used as a raw material for vermicelli and glass noodles. Pea whey wastewater is the one from a production of pea isolated proteins. To get every ton of the isolated protein, 25 to 35 cubic meters of the pea whey wastewater may be discharged, and domestic pea isolated protein production enterprises produce more than 13 million tons of the pea whey every year, which is of great amount.[0004]The pea whey wastewater contains large amount of ammonia nitrogen and COD, with ammonia nitro...

AI Technical Summary

Benefits of technology

[0038]1. According to the disclosure, by setting the whole process flow, a targeted extraction of the albumin with small molecular weight is carried out in the pea whey water. The pea whey water is centrifuged followed by temperature controlling and heat exchanging so that macromolecular proteins in the pea whey water can be separated, which ensures that the albumin and pea oligosaccharides enter a next process without blocking devices, thus laying a foundation for providing a relatively averaged albumin molecular weight subsequently.

[0039]2. In the ultrafiltration, a pore size of the ultrafiltration membrane is configured to provide a molecular weight cut-off of 1000 to 5000 Daltons so as to ensure that the molecular weight of the separated albumin is concentrated in a range of 1000 to 5000 Daltons, in which the albumin with a molecular weight within the range of 1000-5000 Daltons accounts for 85%, and the molecular weight is relatively average and small, and the albumin is easy to be absorbed and utilized by human body.

[0040]3. The temperature controlling and heat exchanging were carried out before the microfiltration to keep the temperature of the whey water stable and make it reach an optimum operating temperature before the microfiltration, thus laying a foundation for subsequent effective separation. In the microfiltration, macromolecular proteins that were not separated by centrifuging in the pea whey water were further separated, laying a foundation for the subsequent nanofiltration. In the nanofiltration, the nanofiltration module is used to further separate the albumin and remove 93% to 95% of water at the same time, and after the nanofiltration, the albumin still contains a small amount of oligosaccharides; at this time, the ultrafiltration is carried out to separate the albumin from the oligosaccharides. However, at this time, the albumin still contains excess salt, which leads to a lower albumin purity. Then, the secondary nanofiltration is carried out, in which the sanitary anti-pollution nanofiltration membrane is adopted, and the clean water separated during the nanofiltration is added for washing to elute the excess salt, and after washing is complete, the clean water is separated and recycled. With a series of steps described above, the albumin with small molecular weight in the pea whey water can be effectively recycled with a higher purity, thus avoiding environmental pollution caused by improper treatment of the pea whey water and realizing resource reuse.

[0041]4. In the present disclosure, the conventional enzymolysis process is not adopted, and the albumin is guaranteed with a good mouthfeel to a maximum extent, with a high product recycling rate and without bitterness or off-flavors, thus presenting high product quality. According to the disclosure, a physical extraction mode is adopted with no chemical reaction involved, so that amino acids in the albumin are maintained relatively complete, and the albumin contains various amino acids, has similar amino acid content with pure albumin, and thus presents good product performance and high nutritional value.

[0042]5. In this scheme, the macromolecular proteins in bean whey water is removed with various separation and water washing processes, which effectively reduces interference of the macromolecular proteins on subsequent albumin separation process and ensures the purity of the albumin. In this process, a desalination process is adopted, in which the salt in the albumin is washed with the water and separated by the nanofiltration membrane to remove sour taste of the whey proteins.

[0043]6. In the present disclosure, the nanofiltration module is used to further separate the albumin and remove 93% to 95% of water at the same time, and this water can be recycled and used in the secondary nanofiltration, which removes a sewage treatment process and saves energy and water resources.

Problems solved by technology

However, the above-described treatment process presents low technical added value, and economic benefits brought by products of the process are low, resulting in resource waste; at the same time, due to an addition of a large number of flocculants, there are safety risks and potential safety hazards.

However, after recovering pea isolated protein, the residual pea whey wastewater still contains protein components with small molecular weight, which cannot be effectively extracted and utilized.

If the protein cannot be extracted effectively, not only the protein in the pea whey is wasted, but also an albumin loss, and thus environmental pollution, is caused.

However, it is still difficult to effectively recycle the albumin with small molecular weight due to physical properties of pea whey proteins.

For these technologies, firstly, target products are different; secondly, if the enzymatic hydrolysis technologies are applied to extract the albumin from the pea whey, a bitter taste occurs in the protein and mouthfeel is affected; furthermore, the extracted protein or polypeptides are not conducive to human absorption and utilization.

In addition, in other methods of separating and purifying whey proteins, the whey proteins are often extracted from wastewater in soybean production, and because these methods are applied to different initial raw material from the pea whey, these methods cannot be directly converted and used in the pea whey, and thus recycling rate and purity of the pea albumin cannot be guaranteed for these methods.

Antibacterial peptide is a kind of polypeptide with antibacterial activity, which acts on bacterial cell membrane, destroys its integrity, produces perforation, enters the cell and destroys its organelles, and causes metabolic disorder.

Moreover, the produced antibacterial peptide has low activity, poor heat resistance and thermal stability.

Currently, in treating the pea whey water, there are no other treating methods except separating various proteins, which also causes loss of the antibacterial peptide.

However, at this time, the albumin still contains excess salt, which leads to a lower albumin purity.