Bioactive peptides from brewer\'s spent grain (BSG) and brewer\'s spent yeast (BSY), two by-products of the brewing industry, have great potential as functional food ingredients, dietary supplements or nutraceuticals to reduce the risk of numerous pathological conditions. Nevertheless, the oral administration of these peptides poses great challenges since peptides must undergo gastrointestinal digestion, intestinal absorption and hepatic metabolism, which can affect their bioavailability and, therefore, the expected outcomes. This review provides a comprehensive and critical analysis of the potential impact of the oral route on the bioactivity of BSG/BSY peptides as assessed by in vitro assays and identifies research gaps that require novel approaches/methodologies. The data collected indicate that in addition to the significant influence of gastrointestinal digestion, intestinal absorption and hepatic metabolism also have a major impact on the bioactivity of brewing peptides. The major gap identified was the insufficient evidence regarding hepatic metabolism, which points for the need of employing in vitro assays in this research field to provide such clarification. Thus, to reach the market, the impact of the oral route on the bioactivities of BSG/BSY peptides must be properly studied in vitro to allow adequate/effective administration (dosage/frequency) with a beneficial impact on the population health.

Yeast, crucial in beer production, holds great potential owing to its ability to transform into a valuable by-product resource, known as brewer\'s spent yeast (BSY), with potentially beneficial physiological effects. This study aimed to compare the composition and soluble polysaccharide content of Brewer\'s spent yeast with those of cultured yeast strains, namely Saccharomyces cerevisiae (SC) and S. boulardii (SB), to facilitate the utilization of BSY as an alternative source of functional polysaccharides. BSY exhibited significantly higher carbohydrate content and lower crude protein content than SC and SB cells. The residues recovered through autolysis were 53.11%, 43.83%, and 44.99% for BSY, SC, and SB, respectively. Notably, the polysaccharide content of the BSY residue (641.90 μg/mg) was higher than that of SC (553.52 μg/mg) and SB (591.56 μg/mg). The yields of alkali-extracted water-soluble polysaccharides were 33.62%, 40.76%, and 42.97% for BSY, SC, and SB, respectively, with BSY comprising a comparable proportion of water-soluble saccharides made with SC and SB, including 49.31% mannan and 20.18% β-glucan. Furthermore, BSY demonstrated antioxidant activities, including superoxide dismutase (SOD), ABTS, and DPPH scavenging potential, suggesting its ability to mitigate oxidative stress. BSY also exhibited a significantly higher total phenolic compound content, indicating its potential to act as an effective functional food material.

The treatment of hypertension is of major importance to reduce the risk of cardiovascular disease, the leading cause of death worldwide. Angiotensin-converting enzyme (ACE) inhibitors are anti-hypertensive drugs associated with several side effects. Natural products, namely bioactive peptides from brewing by-products, brewers\' spent grain (BSG), and yeast (BSY), are promising alternatives since they can inhibit ACE in vitro. However, the oral intake of these peptides may modify their expected inhibitory effect owing to possible changes in active peptides\' bioavailability, which have not been assessed so far. The goal of this study was to simulate oral administration to evaluate BSG/BSY peptides\' effectiveness by submitting protein hydrolysates sequentially to simulated gastrointestinal digestion, intestinal absorption (Caco-2 cells), and liver metabolism (HepG2 cells). MTT assay was used to assess BSG/BSY protein hydrolysates safeness. The ACE-inhibitory potential of initial and final protein hydrolysates (BSY, BSG, and a new product, MIX) were tested using a fluorometric assay and compared with captopril (1 µM, an ACE-inhibitory drug). Simulation of oral administration greatly increased BSY and MIX protein hydrolysates\' ACE-inhibitory capacity, though final MIX and BSG revealed greater ACE-inhibitory potential than captopril. Notwithstanding, all final protein hydrolysates presented ACE-inhibitory capacity, thus being promising compounds to manage hypertension.

Brewer\'s spent yeast (BSY) is among the most voluminous by-products generated in brewery industry that adds to the waste; however, smart utilization of BSY could lead to edible biomass production besides waste management. To utilize it for biomass production, it is being used in fish feeds; however, its effect on the fish physiology has been scantily studied. The present study investigated the proteomic changes in muscle tissues of carp Labeo rohita fed with BSY-based diet, to understand its impact on muscle physiology and biomass. Six feeds were prepared with different grades of BSY (0, 20, 30, 40, 50, 100% replacement of fishmeal with BSY) and fishes were fed for 90 days. Highest weight gain%, feed conversion efficiency, specific growth rate% were observed in 30% BSY-replaced group and this group was considered for the proteomic study. Comparative shotgun proteomic analysis was carried out by LC-MS/MS and data generated have been deposited in ProteomeXchange Consortium with dataset identifier PXD020093. A total of 62 proteins showed differential abundance; 29 increased and 33 decreased in the 30% BSY-replaced group. Pathway analysis using IPA and Panther tools revealed that the proteins tyrosine protein kinase, PDGFα, PKRCB and Collagen promote muscle growth by inducing the PI3K-AKT pathway. Conversely, the proteins Serine/threonine-protein phosphatase, Phosphatidylinositol 3,4,5-trisphosphate5-phosphatase 2A and Ras-specific guanine- nucleotide-releasing factor inhibit muscle growth indicating that 30% BSY-replaced feed promote muscle growth in a highly controlled manner. Findings suggest that BSY could be recycled for carp feed production in large scale thereby leading to resource conservation, reducing environmental effects.

The impact of bread fortification with β-glucans and with proteins/proteolytic enzymes from brewers\' spent yeast on physical characteristics was evaluated. β-Glucans extraction from spent yeast cell wall was optimized and the extract was incorporated on bread to obtain 2.02 g β-glucans/100 g flour, in order to comply with the European Food Safety Authority guidelines. Protein/proteolytic enzymes extract from spent yeast was added to bread at 60 U proteolytic activity/100 g flour. Both β-glucans rich and proteins/proteolytic enzymes extracts favoured browning of bread crust. However, breads with proteins/proteolytic enzymes addition presented lower specific volume, whereas the incorporation of β-glucans in bread lead to uniform pores that was also noticeble in terms of higher specific volume. Overall, the improvement of nutritional/health promoting properties is highlighted with β-glucan rich extract, not only due to bread β-glucan content but also for total dietary fibre content (39% increase). The improvement was less noticeable for proteins/proteolytic enzymes extract. Only a 6% increase in bread protein content was noted with the addition of this extract and higher protein content would most likely accentuate the negative impact on bread specific volume that in turn could impair consumer acceptance. Therefore, only β-glucan rich extract is a promising bread ingredient.

OBJECTIVE: The anti-inflammatory activity of sardine protein hydrolysates (SPH) obtained by hydrolysis with proteases from brewing yeast surplus was ascertained.
METHODS: For this purpose, a digested and desalted SPH fraction with molecular weight lower than 10 kDa was investigated using an endothelial cell line (EA.hy926) as such and in a co-culture model with an intestinal cell line (Caco-2). Effects of SPH <10 kDa on nitric oxide (NO) production, reactive oxygen species (ROS) inhibition and secretion of monocyte chemoattractant protein 1 (MCP-1), vascular endothelial growth factor (VEGF), chemokine IL-8 (IL-8) and intercellular adhesion molecule-1 (ICAM-1) were evaluated in TNF-α-treated and untreated cells.
RESULTS: Upon TNF-α treatment, levels of NO, MCP-1, VEGF, IL-8, ICAM-1 and endothelial ROS were significantly increased in both mono- and co-culture models. Treatment with SPH <10 kDa (2.0 mg peptides/mL) significantly decreased all the inflammation markers when compared to TNF-α-treated control. This protective effect was more pronounced in the co-culture model, suggesting that SPH <10 kDa Caco-2 cells metabolites produced in the course of intestinal absorption may provide a more relevant protective effect against endothelial dysfunction. Additionally, indirect cross-talk between two cell types was established, suggesting that SPH <10 kDa may also bind to receptors on the Caco-2 cells, thereby triggering a pathway to secrete the pro-inflammatory compounds.
CONCLUSIONS: Overall, these in vitro screening results, in which intestinal digestion, absorption and endothelial bioactivity are simulated, show the potential of SPH to be used as a functional food with anti-inflammatory properties.

Brewer\'s spent yeast (BSY) autolysates may have potential applications as food ingredients or nutraceuticals due to their antioxidant and ACE-inhibitory activities. The impact of simulated gastrointestinal (GI) digestion, the interaction with intracellular sources of oxidative stress, the intestinal cell permeability of BSY peptides, and the antioxidant and ACE-inhibitory activities of BSY permeates were assayed. Gastrointestinal digestion of BSY autolysates enhanced antioxidant and ACE-inhibitory activities as measured in vitro. No cytotoxic effects were observed on Caco-2 cells after exposure to the digested BSY autolysates within a concentration range of 0.5 to 3.0 mg of peptides/mL. A protective role to induced oxidative stress was observed. The transepithelial transport assays indicate high apparent permeability coefficient (Papp) values for BSY peptides across Caco-2/HT29-MTX cell monolayer (14.5-26.1 × 10-6 cm/s) and for Caco-2 cell monolayer model (12.4-20.8 × 10-6 cm/s), while the antioxidant and ACE-inhibitory activities found in flux material from the basolateral side suggest transepithelial absorption of bioactive compounds.

Anaerobic digestion treatment of brewer\'s spent yeast (SY) is a viable option for bioenergy capture. The biochemical methane potential (BMP) assay was performed with three different samples (SY1, SY2, and SY3) and SY1 dilutions (75, 50, and 25 % on a v/v basis). Gompertz-equation parameters denoted slow degradability of SY1 with methane production rates of 14.59-4.63 mL/day and lag phases of 10.72-19.7 days. Performance and kinetic parameters were obtained with the Gompertz equation and the first-order hydrolysis model with SY2 and SY3 diluted 25 % and SY1 50 %. A SY2 25 % gave a 17 % of TCOD conversion to methane as well as shorter lag phase (<1 day). Average estimated hydrolysis constant for SY was 0.0141 (±0.003) day(-1), and SY2 25 % was more appropriate for faster methane production. Methane capture and biogas composition were dependent upon the SY source, and co-digestion (or dilution) can be advantageous.