Enrichment of waste yeast with bioactive compounds from grape pomace as an innovative and emerging technology: Kinetics, isotherms and bioaccessibility

Fermentation of American elderberry juice yields functional phytochemicals for spray dried protein-polyphenol ingredients

American elderberry juice (EBJ) and fermented elderberry juice (EBF) were spray dried using two different carriers: S. cerevisiae yeast (SC), used for juice fermentation and as encapsulating agent, and pea protein, to produce protein-polyphenol ingredients. The spray drying (SD) performance (solids recovery, SR; phenolic retention, PR) and quality attributes (physicochemical and functional properties, phytochemical content and bioaccessibility after in vitro digestion) of eight treatments of spray dried elderberry particles were determined. The total phenolic content (TPC) of EBJ (4476 ± 169 mg GAE/L) increased by 27 % after fermentation (EBF: 5706 ± 199 mg GAE/L). The SD performance of EBF (SR > 50 %; PR 55.7-63.9 %) was significantly higher (p < 0.05) compared to EBJ (SR < 50 %; PR 28.6-42.8 %). Stable (aw < 0.3) protein-polyphenol particles, with pH-dependent solubility that increased as pH went from 4 to 10, were produced. The TPC of EBF-derived particles (26.2-28.7 mg GAE/g) was 22-31 % higher than EBJ-derived particles (20.4-21.9 mg GAE/g) and anthocyanins were the major phenolic group detected. An increase in nearly all phenolic metabolite concentrations was observed after fermentation, and an additional increment was observed after spray drying. Phenolic bioaccessibility improved (17-25 % higher) after S. cerevisiae fermentation and when using SC as the drying carrier compared to phenolics source (EBJ or EBF). Overall, here we show a sensible strategy to produce protein-polyphenol particles with better SD performance and enhanced phytochemical content and profile. Our fermentation and spray drying strategy provides practical and efficient means to produce functional fruit ingredients for the emerging clean-label, health-oriented market.

Impact of plasmolysis process on the enrichment of brewer's spent yeast biomass with vitamin D3 by biosorption followed by spray-drying process

Vitamin D3(cholecalciferol)plays a crucial role in various physiological processes. However, vitamin D3 deficiency is a major public health problem affecting millions of people. Therefore, it is important to develop effective strategies that ensure the protection and stability of this important vitamin for food supplementation and fortification. This work aimed to impregnate intact and plasmolyzedSaccharomyces pastorianus brewer's yeast biomass with cholecalciferol using a biosorption process followed by spray drying to characterize the obtained material in terms of morphology, average particle size, zeta potential, moisture, water activity, FT-IR, and the stability of the encapsulated vitamin during the drying and storage process. Plasmolysis proved to be an effective method for improving the biosorption efficiency, retention during spray drying, and stability of vitamin D3. In addition, this process promoted an increase in cell size, which favored the dispersion stability of the system, as evidenced by the zeta potential values. These results contribute to the understanding of a new method for delivering this vitamin that conforms to environmentally conscious practices.

The roles of Saccharomyces cerevisiae on the bioaccessibility of phenolic compounds

Phenolic compounds are a group of non-essential dietary compounds that are widely recognized for their beneficial health effects, primarily due to their bioactive properties. These compounds which found in a variety of plant-based foods, including fruits, vegetables, and grains are known to possess antimicrobial, antioxidant, anti-inflammatory, and anti-carcinogenic properties. However, the health effects of these compounds depend on their bioaccessibility and bioavailability. In recent years, there has been growing interest in the use of probiotics for promoting human health. Saccharomyces cerevisiae is a yeast with potential probiotic properties and beneficial health effects. Biosorption of phenolic compounds on Saccharomyces cerevisiae cell walls improves their bioaccessibility. This characteristic has also allowed the use of this yeast as a biosorbent in the biosorption process due to its low cost, safety, and easy availability. S. cerevisiae enhances the bioaccessibility of phenolic compounds as a delivery system under in vitro digestion conditions. The reason for this phenomenon is the protective effects of yeast on various phenolic compounds under digestion conditions. This article shows the role of S. cerevisiae yeast on the bioaccessibility of various phenolic compounds and contributes to our understanding of the potential impact of yeasts in human health.

Physicochemical and Volatile Compounds Analysis of Fruit Wines Fermented with Saccharomyces cerevisiae: FTIR and Microscopy Study with Focus on Anti-Inflammatory Potential

The growing trend in fruit wine production reflects consumers' interest in novel, diverse drinking experiences and the increasing demand for healthier beverage options. Fruit wines made from kiwi, pomegranates, and persimmons fermented using S. bayanus Lalvin strain EC1118 demonstrate the versatility of winemaking techniques. Kiwifruit, persimmon, and pomegranate wines were analyzed using HPLC and GC-TOFMS analyses to determine their concentrations of phenolic acids and volatile compounds. These results were supported by Fourier transform infrared (FTIR) spectroscopy to characterize and compare chemical shifts in the polyphenol regions of these wines. The wines' characterization included an anti-inflammatory assay based on NO, TNF-alpha, and IL-6 production in the RAW 264.7 macrophage model. FTIR spectroscopy predicted the antioxidant and phenolic contents in the wines. In terms of polyphenols, predominantly represented by chlorogenic, caffeic, and gallic acids, pomegranate and kiwifruit wines showed greater benefits. However, kiwifruit wines exhibited a highly diverse profile of volatile compounds. Further analysis is necessary, particularly regarding the use of other microorganisms in the fermentation process and non-Saccharomyces strains methods. These wines exhibit high biological antioxidant potential and health properties, providing valuable insights for future endeavors focused on designing healthy functional food products.

Sonoprocessing enhances the stabilization of fisetin by encapsulation in Saccharomyces cerevisiae cells

The objective of this study was to investigate for the first time the role of S. cerevisiae natural barriers and endogenous cytoplasmatic bodies on the stabilization of fisetin encapsulated via sonoprocessing coupled to freeze-drying (FD) or spray drying (SD). Both protocols of encapsulation improved the resistance of fisetin against thermal treatments (between 60 and 150 °C) and photochemical-induced deterioration (light exposition for 60 days) compared to non-encapsulated fisetin (antioxidant activity retention of approximately 55% and 90%, respectively). When stored under constant relative humidity (from 32.8 to 90%) for 60 days, yeast carriers improved the half-life time of fisetin by up to 4-fold. Spray dried particles were smaller (4.9 μm) and showed higher fisetin release after simulated gastrointestinal digestion (55.7%) when compared to FD. Freeze-dried particles, in turn, tended to agglomerate more than SD (zeta potential -19.7 mV), resulting in reduced loading features (6.3 mg/g) and less efficient protection of fisetin to heat, photo, and moisture-induced deterioration. Overall, spray-dried sonoprocessed fisetin capsules are an efficient way to preserve fisetin against harsh conditions. Altogether, this report shows that sonoprocessing coupled to drying is an efficient, creative, and straightforward route to protect and deliver lipophilic fisetin using yeast capsules for food applications.

Sulfuric acid-assisted ball milling for the preparation of Si-O-enriched straw biochar: removal efficiency of rhodamine B and adsorption mechanism

Traditional pyrolysis biochar has been widely employed to treat dye wastewater. However, there are some problems in the pyrolysis process, such as the generation of harmful gases and the low content of silico-oxygen functional groups to promote adsorption. Straw biochar (Ac-BCbm) was prepared by sulfuric acid co-ball milling method. The adsorption performance and adsorption mechanism of rhodamine B (RhB) under different preparation conditions and factors were investigated. The results showed that the adsorption rate of Ac-BCbm on RhB was up to 94.9%, which was 60.5% and 55.8% higher than that of ball-milling straw (STbm) and biochar prepared by pyrolysis (STBC600), respectively. The Ac-BCbm had better adaptability under different pH and common interfering ions for remove RhB. Characterization and DFT simulation analysis revealed that the sulfuric acid co-ball milling process promoted the formation of Si-OH and Si-O-CH3 oxygen-containing functional groups of Si component in straw, which enhanced the hydrogen bonding interactions and effectively improved the adsorption efficiency. This study investigated a new strategy for biochar preparation by sulfuric acid co-ball milling, which provides an additional development direction for the efficient resource utilization of straw.

Yeast cells-xanthan gum coacervation for hydrosoluble bioactive encapsulation

This study assessed the technological feasibility of microencapsulating vitamin C (VC) via coacervation between yeast cells (YC) and xanthan gum (XG). The interaction efficiency between YC and XG was examined across various pHs and ratios, while characterizing the microcapsules in terms of encapsulation efficiency, particle size, and thermal and chemical stability. Additionally, in vitro digestion experiments were conducted to determine the digestion efficiency and bioavailability of the bioactive compound. The optimally produced microcapsules exhibited favorable functional attributes, including low water activity (≤ 0.3) and particle size (≤ 33.52 μm), coupled with a high encapsulation efficiency (∼ 86.12 %). The microcapsules were able to increase the stability of VC at high temperatures and during storage when compared to the control. The in vitro experiment revealed that the microcapsules effectively retained approximately 50 % of the VC in simulated gastric fluid, with up to 80 % released in simulated intestinal fluid. However, due to prior degradation in the simulated gastric fluid, the achieved bioavailability was around 68 %. These results are promising, underscoring the potential of these microcapsules as a viable technology for encapsulating, protect, and releasing water-soluble bioactives in the GI tract.

Bioinspired yeast-based β-glucan system for oral drug delivery

Oral drug delivery is the preferred route of drug administration for patients, especially those who need long-term medication. Recently, bioinspired drug delivery systems have emerged for the oral delivery of various therapeutics. Among them, the yeast-based β-glucan system is a novel and promising platform, for oral administration that can overcome the biological barriers of the harsh gastrointestinal environment. Remarkably, the yeast-based β-glucan system not only protects the drug through the harsh gastrointestinal environment but also achieves targeted therapeutic effects by specifically recognizing immune cells, especially macrophages. Otherwise, it exhibits immunomodulatory properties. Based on the pleasant characteristics of the yeast-based β-glucan system, they are widely used in various macrophage-related diseases for oral administration. In this review, we introduced the structure and function of yeast-based β-glucan. Subsequently, we further summarized the current preparation methods of yeast-based β-glucan carriers and the strategies for preparing yeast-based β-glucan drug delivery systems. In addition, we focus on discussing the applications of β-glucan drug delivery systems in various diseases. Finally, the current challenges and future perspectives of the β-glucan drug delivery system are introduced.

Biosorption of bioactive compounds in bacterial nanocellulose: Mechanisms and physical-chemical properties

Bacterial cellulose (BC) is a biomaterial produced by Gluconacetobacter xylinus, with wide applicability in different areas, such as biomedical, pharmaceutical, and food. BC production is usually carried out in a medium containing phenolic compounds (PC), such as teas, however, the purification process leads to the loss of such bioactive. Thus, the innovation of this research consists of the reincorporation of PC after the purification of the BC matrices through the biosorption process. In this context, the effects of the biosorption process in BC were evaluated to maximize the incorporation of phenolic compounds from a ternary mixture of hibiscus (Hibiscus sabdariffa), white tea (Camellia sinensis), and grape pomace (Vitis labrusca). The biosorbed membrane (BC-Bio) showed a great concentration of total phenolic compounds (TPC = 64.89 mg L^-1) and high antioxidant capacity through different assays (FRAP: 130.7 mg L^-1, DPPH: 83.4 mg L^-1, ABTS: 158.6 mg L^-1, TBARS: 234.2 mg L^-1). The physical tests also indicated that the biosorbed membrane presented high water absorption capacity, thermal stability, low permeability to water vapor and improved mechanical properties compared to BC-control. These results index that the biosorption of phenolic compounds in BC efficiently increases bioactive content and improves physical membrane characteristics. Also, PC release in a buffered solution suggests that BC-Bio can be used as a polyphenol delivery system. Therefore, BC-Bio is a polymer with wide application in different industrial segments.

Ultrasound-assisted encapsulation of curcumin and fisetin into Saccharomyces cerevisiae cells: a multistage batch process protocol

Some of the challenges of yeast encapsulation protocols are low phytochemical internalization rates and limited intracellular compartment of yeasts. This study uses an ultrasound-assisted batch encapsulation (UABE) protocol to optimize the encapsulation of curcumin and fisetin by recovering non-encapsulated biomaterial and further incorporating it into non-loaded yeasts in three encapsulation stages (1ES, 2ES, and 3ES). The effect of selected acoustic energies (166.7 and 333.3 W L^-1 ) on the encapsulation efficiency (EE), yield (EY), and antioxidant activity retention were evaluated, and then, compared with a control process (without ultrasound treatment). Compared to the control, enhanced EEs were achieved for both curcumin (10.9% control to 58.5% UABE) and fisetin (18.6% control to 76.6% UABE) after 3ES and the use of 333.3 W L^-1 . Similarly, the yeast maximum loading capacity was improved from 6.6 to 13.4 mg g^-1 for curcumin; and from 11.1 to 26.4 mg g^-1 for fisetin after UABE protocol. The antioxidant activity of produced biocapsules was positively correlated with the bioactive loaded content of yeasts when ultrasound treatment was applied. Overall, results from this study provide valuable information regarding UABE processes, and moreover, bring new and creative perspectives for the ultrasound technology in the food industry.

Efficient encapsulation of curcumin into spent brewer's yeast using a pH-driven method

Curcumin (CUR) was encapsulated into yeast cells (YCs) through a pH-driven method with a 5.04-fold increase in loading capacity and a 43.63-fold reduction in incubation time compared to the conventional diffusion method. Optimal encapsulation was obtained when the mass ratio of CUR to YCs was 0.1, and the loading capacity and encapsulation efficiency were 8.07% and 80.66%, respectively. Encapsulation of CUR into YCs was confirmed by fluorescence microscopy, differential scanning calorimetry, and thermogravimetric analysis. Fourier transform infrared spectroscopy and X-ray diffraction further demonstrated that the encapsulated CUR was interacted with mannoprotein and β-glucan of the cell wall network through hydrophobic interaction and hydrogen bond in amorphous state. The in vitro bioaccessibility of YCs-loaded CUR was significantly increased by 6.05-fold. The enhanced encapsulation efficiency and rapid encapsulation process proposed in this study could facilitate YCs-based microcarriers to encapsulate bioactive substances with higher bioaccessibility.

Investigation of brewer’s spent yeast as a bio-vehicle for encapsulation of natural colorants from pumpkin (Cucurbita moschata) peels

Brewer’s spent yeast (BSY) Saccharomyces cerevisiae has been currently explored as a bio-vehicle for encapsulation of bioactive compounds and as a delivery system. The main objectives of this work were...

Processing, chemical signature and food industry applications of Camellia sinensis teas: An overview

The plant Camellia sinensis is the source of different teas (white, green, yellow, oolong, black, and pu-ehr) consumed worldwide, which are classified by the oxidation degree of their bioactive compounds. The sensory (taste, aroma, and body of the drink) and functional properties of teas are affected by the amount of methylxanthines (caffeine and theobromine), amino acids (l-theanine) and reducing sugars in their composition. Additionally, flavan-3-ols, mainly characterized by epicatechins, catechins, and their derivatives, represent on average, 60% of the bioactive compounds in teas. These secondary metabolites from teas are widely recognized for their antioxidant, anti-cancer, and anti-inflammatory properties. Thus, Camellia sinensis extracts and their isolated compounds have been increasingly used by the food industry. However, bioactive compounds are very susceptible to the oxidation caused by processing and degradation under physiological conditions of gastrointestinal digestion. In this context, new approaches/technologies have been developed for the preservation of these compounds. This review presents the main stages involved in production of Camellia sinensis teas following a description of their main bioactive compounds, biological properties, stability and bioaccessibility. Besides, and updated view of Camellia sinensis teas in the field of food science and technology was provided by focusing on novel findings and innovations published in scientific literature over the last five years.

Insight on açaí seed biomass economy and waste cooking oil: Eco-sorbent castor oil-based

The reuse of açaí seeds is an organic approach for valorizing biomass, encouraging the public policies of circular economy, which reduces the human impact on the production chain processes. This research proposes an alternative for açaí seed as a filler in castor oil-based polyurethane, obtaining eco-sorbent to evaluate the sorption capacity for another impactful food industry by-product: waste cooking oil (WCO). Eco-sorbents were obtained with castor oil based-polyol and isocyanate (MDI) by mass mixing equal to 1:1 (OH:NCO), reinforced with açaí seed residue (5-20 wt%). The samples were characterized by techniques scanning electron microscopy (SEM), optical microscopy (OM), apparent density, contact angle, infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Sorption capacity and efficiency were evaluated as a function of the fiber content, with tests performed in times of 30-180 s in two systems: oil and oil/water. The results showed that the eco-sorbents had a hydrophobic nature (θ > 98.3°) and macroporous morphology (pore size from 152 to 119 μm), which allowed the adsorption of residual cooking oil by the porous structure. The kinetics study showed that the sample with greater fiber content (15% wt.) reached the equilibrium in a short time compared to the neat PU for the oil system, with a sorption capacity of 9.50 g g^-1 in the first 30 s. For the oil/water system, an opposite behavior could be observed, with a sorption capacity of 9.98 g g^-1 in the 150 s equilibrium time. The Langmuir isotherm model presented a maximum adsorption capacity of 10.42 g g^-1. However, the Freundlich isotherm model had a better fit to the experimental data with R² (0.97) and lower chi-square (0.159), showing favorable adsorption (n = 1.496). Thus, it was proved that the weak interactions (connection H) and the binding energy of the predominant physisorption for the oil/water system. Thus, developed eco-sorbents are an excellent option for the sorption of WCO.

Development of natural pigments microencapsulated in waste yeast Saccharomyces cerevisiae using spray drying technology and their application in yogurt

Although Saccharomyces cerevisiae has shown potential utilization as a bio-vehicle for encapsulation, there are no reports about the functionality of natural colorants encapsulated using yeast cells. The main objectives of this study were to produce natural food coloring by encapsulating extracts from grape pomace (GP) and jabuticaba byproducts (JB) in brewery waste yeast and evaluate the functionality of the pigments by their incorporation into yogurts. Particles produced by the encapsulation of extracts from GP and JB in S. cerevisiae using 5% of yeast had the highest encapsulation efficiencies for both anthocyanins (11.1 and 47.3%) and phenolic compounds (67.5 and 63.6%), the highest concentration of both bioactives during storage and stable luminosity. Yogurts showed a pseudoplastic behavior and were considered weak gels. Colored yogurts had acceptance indexes between 73.9 and 81.4%. This work evidenced the utilization of enriched yeasts as coloring agents and interesting additives for the production of functional foods.

Weak Binding of Epigallocatechin to α-Lactalbumin Greatly Improves Its Stability and Uptake by Caco-2 Cells

Improving the stability and bioavailability of catechins is of great importance. Epigallocatechin (EGC), the major catechin in green tea, is a potent antioxidant with numerous attributed health benefits. However, the low permeability and stability limit its enrichment in the diet for preventive medicine. In this study, we explored the interaction of EGC and α-lactalbumin by spectroscopic, thermodynamic, and crystallographic methods. The isothermal titration calorimetry experiments elucidated that α-lactalbumin binds to EGC at a ratio of 1:1 with a low affinity of (4.01 ± 0.11) × 10⁵ M^-1. A crystal structure solved at a high resolution (1.2 Å) provided direct evidence for the weak interaction between EGC and α-lactalbumin at an atomic level. The novel binding site was discovered at the exterior surface of α-lactalbumin for the first time, supporting a new binding behavior. Consequently, our results demonstrated that the binding of α-lactalbumin to EGC could protect EGC against light-induced, thermal-induced, and pH-induced damage. More importantly, the formed complex has better bioaccessibility than unbound EGC, which was approved by a cell absorption experiment. Such research is beneficial for designing protein-based nanocarriers for polyphenols.

Ultrasound-assisted adsorption/desorption for the enrichment and purification of flavonoids from baobab (Adansonia digitata) fruit pulp

This work described the purification and enrichment of flavonoids from baobab (Adansonia digitata) fruit pulp (BFP) by ultrasound-assisted adsorption/desorption procedure using macroporous resins. Four resins were tested and HPD-500 polar resin exhibited the best adsorption/desorption properties. Based on preliminary experiments and literature reports, the effects of various ultrasonic conditions including high power short time (HPST, 540 W for 5 min), medium power medium time (MPMT, 270 W for 15 min) and low power long time (LPLT, 45 W for 30 min) as well as different temperatures (T = 25-45 °C) on the adsorption of Total Flavonoids Content (TFC) were investigated in comparison with orbital shaking/no sonication (NS). Also, the effect of ultrasound on the desorption capacity and recovery of TFC was determined at different concentrations of ethanol (30-100%). Remarkably, ultrasonic treatment significantly increased the adsorption/desorption capacity and recovery and shortened the equilibrium time. The pseudo-second-order kinetic and Freundlich isotherm models better delineated the adsorption process under ultrasound. Moreover, the adsorption process was both spontaneous and thermodynamically favourable with physical adsorption and multilinear intraparticle diffusion being the predominant mechanisms of the whole process. HPST treatment at 25 °C with 80% ethanol as the desorption solvent most noticeably enhanced the adsorption/desorption of flavonoids and contributed to the highest recovery of TFC, Total Phenolic Content (TPC), and antioxidant capacity in addition to a 5-8-fold reduction in total sugar and acid contents when compared with NS treatment. Moreover, HPLC analysis revealed that the content of nine out of thirteen phenolic compounds from the HPST treatment was the highest, and the individual flavonoids content increased by 2-3-fold compared with the other treatments. Our analyses suggested that ultrasound can be employed as a practical approach to intensify the adsorption and desorption of functional compounds in BFP.

Utilization of grape pomaces and brewery waste Saccharomyces cerevisiae for the production of bio-based microencapsulated pigments

This research approaches the utilization of brewery waste yeast Saccharomyces cerevisiae as a vehicle for the encapsulation and protection of phenolic compounds from Cabernet Sauvignon and Bordeaux grape pomace extracts. The main purpose of this research was to enrich the biomass of yeast to investigate its potential as a novel vehicle for further application as pigment or functional ingredient. The obtained powders presented characteristics appropriated for storage, such as low water activity (<0.289), hygroscopicity (<13.71 g/100 g) and moisture (<7.10%) and particle sizes lower than the sensory perceptible (<11.45 µm). This work proved that yeasts were loaded after spray-drying, thus, they might be considered as biocapsules. Furthermore, the bioaccessibility of encapsulated phenolic compounds from Bordeaux and Cabernet Sauvignon extracts was 34.96% and 14.25% higher compared to their respective free extracts, proving that yeasts are not only biocapsules of easy application, but also a biological material capable of protecting and delivering the compounds during gastrointestinal digestion.

Antiproliferative activity of green, black tea and olive leaves polyphenols subjected to biosorption and in vitro gastrointestinal digestion in Caco-2 cells

Olive (Olea europaea L.) leaves and tea (Camellia sinensis) are rich sources of bioactive compounds, especially polyphenols. Our previous studies have evidenced the potential use of Saccharomyces cerevisiae as a natural delivery system for these antioxidants and a means to improve their bioaccessibility in the human gut. In the present work, the antiproliferative effect of green tea (GT), black tea (BT) and olive leaves (OL) infusions and suspensions of S. cerevisiae were evaluated, for the first time, in human colon cancer cells (Caco-2) after biosorption and in vitro gastrointestinal digestion. The bioaccessible fractions (BF) were not overtly cytotoxic, not affecting cell viability. ROS and mitochondrial membrane potential changes (Δψm) values were reduced compared with control cells. Moreover, all the BF after biosorption induced a significant (p < 0.05) increase in cell proportions in S-phase. The arrest of the cell cycle was reversible without induction of apoptosis, suggesting that the biosorbed phenolics in both infusions and suspensions act as cytostatic agents.

Ultrasonic-assisted enzymatic extraction and identification of anthocyanin components from mulberry wine residues

Mulberry wine residues produced during the wine-brewing process contain several anthocyanins and other bioactive compounds. Therefore this study optimized the conditions for ultrasound-assisted enzymatic extraction of anthocyanins from mulberry wine residues. A three-level, four-factor Box-Behnken design was used to optimize the extraction conditions. Moreover, anthocyanins were determined using an ultra-performance liquid chromatograph coupled to a mass spectrometer (UPLC-MS). The mathematical model suggested a high coefficient of determination (R2 = 0.9475) for the optimum conditions, namely 52 °C, 315 W, 0.22% enzyme and 94 min incubation. The yield (5.98 mg/g) was close to the predicted value (5.87 mg/g). The two anthocyanins (cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside) identified are consistent with those present in mulberry. The optimized conditions increased anthocyanin yield, through improved utilization of mulberry wine residues. The findings will potentially lead to a reduction in the environmental burden of this waste and improve the efficiency and productivity of the mulberry fruit processing industry.

Improvement of phenolic compound bioaccessibility from yerba mate (Ilex paraguariensis) extracts after biosorption on Saccharomyces cerevisiae

Great efforts have been made to increase the bioaccessibility of bioactive compounds from plant sources. This can be achieved by the innovative and effective method of biosorption of these compounds in Saccharomyces cerevisiae obtained from the industrial fermentative process (waste yeast). In this context, this research evaluated if chemical modifications of depleted yeast can improve the capacity to biosorb the phenolic compounds and if through in vitro digestion tests, this approach can increase bioaccessibility of the secondary metabolites from yerba mate. The results showed that the chemical modification of the yeast promoted an increase in the biosorption efficiency of the bioactive compounds. Mass spectrometry peaks for the phenolic compounds reduced after biosorption as observed for the caffeic and dicaffeoylquinic acids and for kaempferol and rutin. In addition, a 10% reduction of caffeine was verified after biosorption, quantified by mass spectrometry chromatography. This showing that the compounds were retained in the cells, which was also observed by an increase of cell turgidity with scanning electron microscopy (SEM). Mid-infrared spectroscopy showed that the major bands related to the components of the compounds increased proportionally after biosorption. Furthermore, an increase of bioaccessibility of the yerba mate bioactive compounds adsorbed in S. cerevisiae was verified when compared with the crude extract.

Parametric and phenomenological studies about ultrasound-enhanced biosorption of phenolics from fruit pomace extract by waste yeast

In this work, sonication (20-kHz) was conducted to assist the biosorption of phenolics from blueberry pomace extracts by brewery waste yeast biomass. The adsorption capacity of yeast increased markedly under ultrasonic fields. After sonication at 394.2 W/L and 40 °C for 120 min, the adsorption capacity was increased by 62.7% compared with that under reciprocating shaking. An artificial neural network was used to model and visualize the effects of different parameters on yeast biosorption capacity. Both biosorption time and acoustic energy density had positive influences on yeast biosorption capacity, whereas no clear influence of temperature on biosorption process was observed. Regarding the mechanism of ultrasound-enhanced biosorption process, the amino and carboxyl groups in yeast were considered to be associated with the yeast biosorption property. Meanwhile, ultrasound promoted the decline of the structure order of yeast cells induced by phenolic uptake. The interactions between yeast cells and phenolics were also affected by the structures of phenolics. Moreover, the mass transfer process was simulated by a surface diffusional model considering the ultrasound-induced yeast cell disruption. The modeling results showed that the external mass transfer coefficient in liquid phase and the surface diffusion coefficient under sonication at 394.2 W/L and 40 °C were 128.5% and 74.3% higher than that under reciprocating shaking, respectively.