Novel protein stabilization in white wine: A study on thermally treated zirconia-alumina composites.

A major concern for wineries is haze formation in white wines due to protein instability. Despite its prevalent use, the conventional bentonite method has shortcomings, including potential alteration of color and aroma, slow processing times, and notable wine wastage. Zirconium oxide (ZrO2) effectively removes proteins without affecting wine characteristics. However, producing cost-effective ZrO2 materials with efficient protein removal capabilities poses a significant challenge. This research aims to assess the viability of designing a porous material impregnated with zirconia to remove turbidity-causing proteins effectively. For this purpose, the support material alone (Al2O3) and the zirconia-impregnated support (ZrO2/Al2O3) were subjected to different calcination temperatures. It was observed that high-temperature treatments (750 °C) enhanced wine stability and protein adsorption capacity. The optimal adsorbent achieved a notable reduction in turbidity, decreasing the ΔNTU from 42 to 18, alongside a significant 44 % reduction in the total protein content, particularly affecting proteins in the molecular weight range of 10 to 70 kDa. This result is attributed to modifying the textural properties of ZrO2/Al2O3, characterized by the reduction of acidic sites, augmented pore diameters from 4.81 to 7.74 nm, and the emergence of zirconia clusters across the surface of the porous support. In summary, this study presents the first application of zirconia on the alumina support surface for protein stabilization in white wine. Combining ZrO2/Al2O3 and a high-temperature treatment emerges as a promising, cost-efficient, and environmentally sustainable strategy for protein removal in white wine.

Fermentation of Murta (Ugni molinae) Juice: Effect on Antioxidant Activity and Control of Enzymes Associated with Glucose Assimilation.

Berries are rich in bioactive compounds, including antioxidants and especially polyphenols, known inhibitors of starch metabolism enzymes. Lactic acid fermentation of fruits has received considerable attention due to its ability to enhance bioactivity. This study investigated the effect of fermentation with L. mesenteroides of juice from the Chilean berry murta on antioxidant activity, release of polyphenols, and inhibitory activity against α-amylase and α-glucosidase enzymes. Three types of juices (natural fruit, freeze-dried, and commercial) were fermented. Total polyphenol content (Folin-Ciocalteu), antioxidant activity (DPPH and ORAC), and the ability to inhibit α-amylase and α-glucosidase enzymes were determined. Fermented murta juices exhibited increased antioxidant activity, as evidenced by higher levels of polyphenols released during fermentation. Inhibition of α-glucosidase was observed in the three fermented juices, although no inhibition of α-amylase was observed; the juice from freeze-dried murta stood out. These findings highlight the potential health benefits of fermented murta juice, particularly its antioxidant properties and the ability to modulate sugar assimilation by inhibiting α-glucosidase.

Cochayuyo (Durvillaea incurvata) Extracts: Their Impact on Starch Breakdown and Antioxidant Activity in Pasta during In Vitro Digestion.

Seaweeds, notably cochayuyo (Durvillaea incurvata), are recognized for their rich macro- and micronutrient content, along with their inhibitory effects on the α-glucosidase enzyme. The present study aims to evaluate the effectiveness of this inhibition in actual starchy food products under in vitro gastrointestinal conditions. This study utilized freeze-dried cochayuyo, extracted using hot pressurized liquid extraction with 50% ethanol at 120 °C and 1500 psi. The inhibition mechanism of α-glucosidase was determined, and the polyphenol composition of the extract was analyzed using Ultra-High-Performance Liquid Chromatography. This study further evaluated the extract's impact on starch digestibility, total phenolic content, and antioxidant capacity in pasta (noodles) as representative starchy food under gastrointestinal conditions. The results indicate that the α-glucosidase inhibition mechanism is of mixed type. Phenolic compounds, primarily tetraphloroethol, could contribute to this anti-enzymatic activity. The extract was observed to decrease starch digestibility, indicated by a lower rate constant (0.0158 vs. 0.0261 min-1) and digested starch at an infinite time (77.4 vs. 80.5 g/100 g). A significant increase (~1200 vs. ~390 µmol TROLOX/100 g) in antioxidant activity was also noted during digestion when the extract was used. Thus, this study suggests that the cochayuyo extract can reduce starch digestion and enhance antioxidant capacity under gastrointestinal conditions.

Enhanced Polyphenols Recovery from Grape Pomace: A Comparison of Pressurized and Atmospheric Extractions with Deep Eutectic Solvent Aqueous Mixtures.

Deep eutectic solvents (DES) are emerging as potent polyphenol extractors under normal atmospheric conditions. Yet, their effectiveness in hot pressurized liquid extraction (HPLE) must be studied more. We explored the ability of various water/DES and water/hydrogen bond donors (HBDs) mixtures in both atmospheric solid liquid extraction (ASLE) and HPLE (50%, 90 °C) for isolating specific polyphenol families from Carménère grape pomace. We assessed extraction yields based on total polyphenols, antioxidant capacity, and recovery of targeted polyphenols. The HBDs ethylene glycol and glycerol outperformed DES in atmospheric and pressurized extractions. Ethylene glycol exhibited a higher affinity for phenolic acids and flavonols, while flavanols preferred glycerol. Quantum chemical computations indicated that a high-water content in DES mixtures led to the formation of new hydrogen bonds, thereby reducing polyphenol-solvent interactions. HPLE was found to be superior to ASLE across all tested solvents. The elevated pressure in HPLE has caused significant improvement in the recovery of flavanols (17-89%), phenolic acids (17-1000%), and flavonols (81-258%). Scanning electron microscopy analysis of post-extraction residues suggested that high pressures collapse the plant matrix, thus easing polyphenol release.

Advances in White Wine Protein Stabilization Technologies.

The unstable proteins in white wine cause haze in bottles of white wine, degrading its quality. Thaumatins and chitinases are grape pathogenesis-related (PR) proteins that remain stable during vinification but can precipitate at high temperatures after bottling. The white wine protein stabilization process can prevent haze by removing these unstable proteins. Traditionally, bentonite is used to remove these proteins; however, it is labor-intensive, generates wine losses, affects wine quality, and harms the environment. More efficient protein stabilization technologies should be based on a better understanding of the main factors and mechanisms underlying protein precipitation. This review focuses on recent developments regarding the instability and removal of white wine proteins, which could be helpful to design more economical and environmentally friendly protein stabilization methods that better preserve the products´ quality.

Aroma profile design of wine spirits: Multi-objective optimization using response surface methodology.

Developing new distillation strategies can help the spirits industry to improve quality, safety and process efficiency. Batch stills equipped with a packed column and an internal partial condenser are an innovative experimental system, allowing a fast and flexible management of the rectification. In this study, the impact of four factors (heart-cut volume, head-cut volume, pH and cooling flow rate of the internal partial condenser during the head-cut fraction) on 18 major volatile compounds of Muscat spirits was optimized using response surface methodology and desirability function approaches. Results have shown that high rectification at the beginning of the heart-cut enhances the overall positive aroma compounds of the product, reducing off-flavor compounds. In contrast, optimum levels of heart-cut volume, head-cut volume and pH factors varied depending on the process goal. Finally, three optimal operational conditions (head off-flavors reduction, flowery terpenic enhancement and fruity ester enhancement) were evaluated by chemical and sensory analysis.

Modeling Metabolic Interactions in a Consortium of the Infant Gut Microbiome.

The gut microbiome is a complex microbial community that has a significant influence on the host. Microbial interactions in the gut are mediated by dietary substrates, especially complex polysaccharides. In this environment, breakdown products from larger carbohydrates and short chain fatty acids are commonly shared among gut microbes. Understanding the forces that guide microbiome development and composition is important to determine its role in health and in the intervention of the gut microbiome as a therapeutic tool. Recently, modeling approaches such as genome-scale models and time-series analyses have been useful to predict microbial interactions. In this study, a bottom-up approach was followed to develop a mathematical model based on microbial growth equations that incorporate metabolic sharing and inhibition. The model was developed using experimental in vitro data from a system comprising four microorganisms of the infant gut microbiome (Bifidobacterium longum subsp. infantis, Lactobacillus acidophilus, Escherichia coli, and Bacteroides vulgatus), one substrate (fructooligosaccharides, FOS), and evaluating two metabolic products (acetate and lactate). After parameter optimization, the model accurately predicted bacterial abundance in co-cultures from mono-culture data. In addition, a good correlation was observed between the experimental data with predicted FOS consumption and acid production. B. infantis and L. acidophilus were dominant under these conditions. Further model validation included cultures with the four-species in a bioreactor using FOS. The model was able to predict the predominance of the two aforementioned species, as well as depletion of acetate and lactate. Finally, the model was tested for parameter identifiability and sensitivity. These results suggest that variations in microbial abundance and activities in the infant gut were mainly explained by metabolic interactions, and could be properly modeled using Monod kinetics with metabolic interactions. The model could be scaled to include data from larger consortia, or be applied to microbial communities where sharing metabolic resources is important in shaping bacterial abundance. Moreover, the model could be useful in designing microbial consortia with desired properties such as higher acid production.

The impact of cooking and delivery modes of thymol and carvacrol on retention and bioaccessibility in starchy foods.

Oregano and thyme possess beneficial properties for human health, mainly attributable to monoterpenes such as thymol and carvacrol. The main objective of this research was to assess, on starchy food, the impact of cooking (boiling and baking) and delivery (ground leaves and essential oil) modes on retention and bioaccessibility of thymol and carvacrol. Retention was assessed after cooking, while bioaccessibility was estimated in cooked samples using an in vitro digestion model. Our results indicate that bioaccessibility was weakly dependent on cooking and delivery modes (27-33%). Boil cooking presented 20% more retention than baking for both compounds. When essential oil was added to the food matrix, thymol was retained almost 25% more when compared with ground leaves' addition. Conversely, carvacrol was retained 39% more when ground leaves were added.

Construction of robust dynamic genome-scale metabolic model structures of Saccharomyces cerevisiae through iterative re-parameterization.

Dynamic flux balance analysis (dFBA) has been widely employed in metabolic engineering to predict the effect of genetic modifications and environmental conditions in the cell׳s metabolism during dynamic cultures. However, the importance of the model parameters used in these methodologies has not been properly addressed. Here, we present a novel and simple procedure to identify dFBA parameters that are relevant for model calibration. The procedure uses metaheuristic optimization and pre/post-regression diagnostics, fixing iteratively the model parameters that do not have a significant role. We evaluated this protocol in a Saccharomyces cerevisiae dFBA framework calibrated for aerobic fed-batch and anaerobic batch cultivations. The model structures achieved have only significant, sensitive and uncorrelated parameters and are able to calibrate different experimental data. We show that consumption, suboptimal growth and production rates are more useful for calibrating dynamic S. cerevisiae metabolic models than Boolean gene expression rules, biomass requirements and ATP maintenance.

Effect of pressurized hot water extraction on antioxidants from grape pomace before and after enological fermentation.

Grape pomace was extracted with pressurized hot water at laboratory scale before and after fermentation to explore the effects of fermentation and extraction temperature (50-200 °C) and time (5 and 30 min) on total extracted antioxidant levels and activity and to determine the content and recovery efficiency of main grape polyphenols, anthocyanins, and tannins. Fermented pomace yielded more total antioxidants (TAs), antioxidant activity, and tannins, than unfermented pomace but fewer anthocyanins. Elevating the extraction temperature increased TA extraction and antioxidant activity. Maximum anthocyanin extraction yields were achieved at 100 °C and at 150 °C for tannins and tannin-anthocyanin adducts. Using higher temperatures and longer extraction times resulted in a sharp decrease of polyphenol extraction yield. Relevant proanthocyanidin amounts were extracted only at 50 and 100 °C. Finally, TA recovery and activity were not directly related to the main polyphenol content when performing pressurized hot water grape pomace extraction.

The enhancement of antioxidant compounds extracted from Thymus vulgaris using enzymes and the effect of extracting solvent.

We evaluate the total phenolic compounds (TPC) content and the antioxidant activity (AA) of extracts obtained from ground fresh thyme (FT) and depleted thyme (DT), a by-product of the process of essential oil extraction. In addition, enzymatic treatments were evaluated to improve the extraction yields of polyphenolic compounds from thyme. Extractions were performed using several solvents as methanol, ethanol, and water. Enzymes were applied prior to extraction or during the extraction process. The best results were obtained using a mixture of methanol and water, resulting in 2790 and 220 mg Gallic acid equivalent (GAE)/L of TPC for FT and DT, respectively. A similar result was observed for AA. With regard to enzymatic treatment, application of Grindamyl CA 150 enzyme as a pre-treatment resulted in the production of an extract from DT with 614 mg TE (trolox equivalent)/L of AA, 70% more than the control, and an AA of 621 mg TE/L (74% more than the control sample) was obtained using Grindamyl CA 150 during the extraction process. These results suggest that enzymatic treatment is an interesting alternative for producing antioxidant extracts from DT.

Effects of temperature and time on polyphenolic content and antioxidant activity in the pressurized hot water extraction of deodorized thyme (Thymus vulgaris).

The effects of temperature (50-200 °C) and contact time (5-30 min) on the pressurized hot water extraction of deodorized thyme were explored for antioxidant activity, polyphenol profiles, and total antioxidants. Six not previously reported polyphenolic compounds were identified in thyme. An inverse correlation was found between the antioxidant activity and total antioxidants with the amount and diversity of polyphenols. The highest total extract yield and antioxidant activity were obtained at 200 °C, although maximum polyphenol extraction yields of hydroxycinnamic acids, flavones, flavonols/flavanones, and total polyphenols were detected at 100 °C and 5 min. Higher temperatures and longer exposure times reduced extract polyphenol diversity. Dihydroxyphenyllactic acid was the only phenolic compound for which extraction yield increased with temperature, probably as a product of the thermal degradation of rosmarinic acid. Consequently, for extracting phenolics from thyme, 100 °C and 5 min would be appropriate operating conditions, whereas antioxidant-active nonphenolic compounds were favored at higher temperatures and exposure times.