# Brewer's Spent Grains: Possibilities of Vaporization, a Review
## 3 Possible Uses of BSG
### Proteins, Protein Hydrolysates, Bioactive Peptides
Treatment of BSG with sodium dodecyl sulfate (SDS) and disodium phosphate at different temperatures, followed by the addition of ethanol and refrigeration of extracts, resulted in a yield of 49% protein [70]. Bioactive peptides (BAP) are specific amino acid sequences that bring health benefits of interest to the pharmaceutical industry in terms of the discovery of new nutraceuticals or the food industry as ingredients for functional foods [15]. Peptides derived from BSG have potential against cardiovascular diseases and type 2 diabetes [71]. The specific bioactivity of food peptides is given by the length of the amino acid chain and their hydrophobicity and molecular weight. There is a growing interest in the use of bioactive peptides derived from food proteins against chronic diseases and for maintaining health status [72], inhibitory activity on angiotensin conversion enzyme (ACE), and dipeptide peptidase IV (DPP IV), which is being studied in vitro by [PERSON] et al. (2019) [71]. BAPs are encrypted in the primary structure of proteins in the form of inactive amino acids (inactive when part of the source protein) but are activated by fermentation and food processing with the help of enzymes or in the digestive tract after human consumption [72; 73]. According to the BIOPEP-UWM Database of Bioactive Peptides [74], the biological functions of bioactive peptides are ACE inhibitors (angiotensin conversion enzyme I), influence blood pressure regulation, antioxidant activity, antimicrobial activity, opioid activity, and antithrombotic and immunomodulatory activities. Strong bioactivity and high yield are challenges in BAP research [72]. The introduction of bioactive peptides into functional food brings the benefits of the amino acids contained. The techniques used for the synthesis of bioactive peptides are chemical synthesis, enzyme synthesis (as the main technique, microbial fermentation of proteins or protein isolates) [75], and synthesis by recombinant DNA technology [15]. Protein hydrolysis is not only a way to improve nutritional values but also to release bioactive peptides [75]. Obtaining pure peptides involves a laborious process of splitting and isolating individual peptides by chromatographic methods and membrane technologies [75]. Studies in which hydrolyzed proteins in cereals have increased the shelf life of meat have been conducted as the incorporation of antioxidant peptide fractions decreased lipid oxidation from 19% to 15% after one week [75]. Protein hydrolysates can be used in the food industry as texture improvement agents and as food additives or in the pharmaceutical industry. Hydrolysis in BSG has had good rheological results; protein changes by enzymatic or chemical means bring improvements to certain functional properties (water/oil retention capacity, emulsion properties and foam expansion, turbidity) [76]. Hydrolyzed protein isolates with a number of enzymes (Alcalase, Corolase PP, Flavourzyme, and Promod 144 MG) had improvements in heat stability at pH = 6.0, even after 300 min of temperature maintenance at pH between 2.0 and 12.0, which increased solubility, emulsification, and foaming capacity. Nitrogen solubility decreased when pH approaches isoelectric point (pH = 3.8), but the highest solubility was achieved at pH between 6.0 and 12.0. Compared to non-hydrolyzed soy protein, which is more stable at pH = 9.0 than at pH = 3.8, the protein hydrolysates in BSG showed no coagulation at pH = 8.0, but HCT (heat coagulation time) decreased at pH below 6.0 [77]. Protein isolates and protein hydrolysates associated with them can be used as techno-functional ingredients but carefully, as the pH at which they are used influences these properties according to the above-mentioned study.