Simultaneous Digestion Research Articles

Glycation reactions of methylglyoxal during digestion in a dynamic, invitro model of the upper gastrointestinal tract (TIM-1).

The 1,2-dicarbonyl compound methylglyoxal (MGO) can react with and thereby impair the function of proteins and DNA, leading to pathophysiological pathways invivo. However, studies on the bioavailability of dietary MGO and its reactions during digestion have diverging results. Therefore, simulated digestion experiments of MGO, protein, and creatine were performed in the dynamic, invitro model of the upper gastrointestinal tract (TIM-1). This multicompartment model continuously adjusts pH values and has realistic gastrointestinal transit times while also removing water and metabolites by dialysis. Samples were analyzed with HPLC-UV for MGO and HPLC-MS/MS for creatine and glycated amino compounds. MGO reacted with creatine during simulated digestion in TIM-1 to form the hydroimidazolone MG-HCr in similar amounts as in a human intervention study. 28%-69% of MGO from the meal were passively absorbed in TIM-1, depending on the addition of creatine and protein. Simultaneous digestion of MGO with ovalbumin led to the formation of the lysine adduct N ε -carboxyethyllysine (CEL) and the methylglyoxal-derived hydroimidazolone of arginine (MG-H1). The formation of both compounds decreased with added creatine. Hence, glycation compounds are formed during digestion and significantly contribute to other ingested dietary glycation compounds, whose physiological consequences are critically discussed.

Optimal aeration area of cathode electrode in the batch type of microbial fuel cells with non-woven interface

Microbial fuel cells (MFCs) are based on the biochemical reaction of microorganisms to decompose organic wastewater for converting chemical energy into power energy. MFCs are considered an environmentally friendly technology that is gaining popularity due to their simultaneous digestion and energy production abilities. To enhance its real application in wastewater treatment, this study proposes to use a non-woven material for replacing the usage of expensive membranes in MFCs. In addition, the study aims to consider a series of different aeration areas of cathode electrodes for finding an optional design. Results have shown that the adoption of non-woven with 0.45 μm can effectively prohibit the diffusion of oxygen into the anode chamber. Moreover, the non-woven material played an important role as an interface between the anode and cathode, enhancing the MFC performance. The usage of suitable non-woven material can replace the role of the membrane when applied in real wastewater applications. The results have shown that the case study where a combination of a 50% aeration area of the cathode electrodes with 25% exposure of the cathode plate in the air yielded relatively better aeration in terms of a higher current density of 250 mA/m2, higher power density of 220 mW/m2, and higher open voltage circuit of 0.4 V, compared to other case studies considered. These results indicate the optimal aeration configuration for MFCs applied in commercial wastewater treatment in the future.

Incorporation of defatted quinoa flour affects in vitro starch digestion, cooking and rheological properties of wheat noodles

Quinoa is a lipid-rich pseudocereal, and lipid oxidation limits the shelf life of quinoa flour. It has been shown that defatting improves the storage properties of quinoa. However, there is a lack of research to support the application of defatted quinoa flour. The rheological properties of dough and in vitro starch digestibility, cooking quality, and texture properties of noodles containing 0%–30% (w/w) defatted quinoa flour (DQF) were investigated. The results showed that the storage modulus (G') of dough substituted with 10% DQF was higher than wheat dough, and the deformation decreased as the DQF content increased. Noodles with DQF (10–20%) had a lower cooking loss and water absorption than noodles with 10% full quinoa flour (FQF), while the noodles with 30% DQF exceeded the satisfactory point of industry standards for cooking loss. On the other hand, the noodles with DQF presented a higher hardness and chewiness than wheat noodles. In vitro digestion results showed two simultaneous digestion fractions for all noodle samples. The noodles' maximum digestion amount and slow digestion fraction content decreased by 5.77% and increased by 9.64%, respectively, with 10% DQF. Considering digestive and cooking characteristics of noodles, we recommend incorporating 10% DQF into noodle formulations. This study will provide scientific support to the industrial product application of quinoa noodles.

Interpreting the B-cell receptor repertoire with single-cell gene expression using Benisse

B-cell receptors (BCRs) are a crucial player in the development and activation of B cells, and their mature forms are secreted as antibodies, which execute functions such as the neutralization of invading pathogens. All current analytical approaches for BCRs solely investigate the BCR sequences and ignore their correlations with the transcriptomics of the B cells, yielding conclusions of unknown functional relevance regarding the roles of BCRs and B cells, and could generate biased interpretation. Many single-cell RNA-sequencing (scRNA-seq) techniques can now capture both the gene expression and BCR of each B cell, which could potentially address this issue. Here, we investigated 43,938 B cells from 13 scRNA-seq datasets with matched scBCR sequencing, and we observed an association between the BCRs and the B cells’ transcriptomics. Motivated by this, we developed the Benisse model (BCR embedding graphical network informed by scRNA-seq) to provide refined analyses of BCRs guided by single-cell gene expression. Benisse revealed a gradient of B-cell activation along BCR trajectories. We discovered a stronger coupling between BCRs and B-cell gene expression during COVID-19 infections. We found that BCRs form a directed pattern of continuous and linear evolution to achieve the highest antigen targeting efficiency, compared with the convergent evolution pattern of T-cell receptors. Overall, a simultaneous digestion of the BCR and gene expression of B cells, viewed through the lens of Benisse, will lead to a more insightful interpretation of the functional relevance of the BCR repertoire in different biological contexts.

Experimentally observed Campylobacter jejuni survival kinetics in chicken meat products during model gastric digestion tended to be lower than model predictions

Campylobacter jejuni-related foodborne diseases are mainly attributed to the consumption of undercooked chicken meat and cross-contaminated produce. This study aimed to develop a survival kinetics model, based on the Weibull model, for predicting foodborne C. jejuni survival during gastric digestion in a model stomach. We previously confirmed that C. jejuni can survive temperatures up to 62 °C; therefore, certain types of grilled chicken skewers (yakitori) were examined for C. jejuni survival during simulated gastric digestion. C. jejuni survival on a chicken thigh following grilling was examined to confirm the foods for digestion experiments. Further, C. jejuni survival during model digestion was investigated through simultaneous digestion of raw chicken and cross-contaminated iceberg lettuce. The model stomach pH increased from 1.5 to 6.0 immediately after yakitori ingestion and did not decrease below 4.0 within 3 h of digestion. Gastric digestion did not significantly contribute to C. jejuni inactivation (<1.5 log reduction after 3 h digestion). Our model could predict C. jejuni survival kinetics in simulated gastric fluid under varying pH during model digestion. This approach can be used to predict C. jejuni survival rates following digestion to improve food safety and reduce Campylobacter-related disease outbreaks.

Protein content correlates with the in vitro starch digestibility of raw barley flour

Protein content is one of the most important criteria used to evaluate the nutritional and functional qualities of raw barley, yet, its relation with starch digestibility remain elusive. The in vitro starch digestion kinetics of six barley varieties were characterized and correlated with the total protein content, starch chain-length distribution and the particle size distributions (PSD) of raw barley flour. Both the logarithm of slope plot and sequential first-order kinetics model were applied to fit the digestion curves. Results showed that only a single digestible starch fraction was observed for all flour samples under the simultaneous digestion of pancreatic amylase and amyloglucosidase. The barley protein content significantly and negatively correlated with the digestion rate constant k (r = 0.93, p = 0.007), whereas it significantly and positively correlated with the C∞ (r = 0.89, p = 0.017) corresponding to the amount of starch digested at infinite digestion time. No significant correlations between PSD and kinetic parameters were found, whereas of barley containing higher protein content, it contained a relatively higher amount of medium amylopectin chains with degree of polymerization (DP) raging from 34 to 67, and a smaller averaged DP of amylose molecules. This could rationalize its slower starch digestion rate. The current study provides important information for barley breeders and manufacturers to develop barley products with preferred starch functional properties except for only according to the barley protein content.

Optimization and Analysis of Liquid Anaerobic Co-Digestion of Agro-Industrial Wastes via Mixture Design

Anaerobic co-digestion (AcoD) is a widely employed technique to produce biogas from simultaneous digestion of various biomasses. However, the selection of the optimal proportions of the substrates in the mixtures presents a challenge. This research used a mixture design to investigate the interactions between the liquid fraction of piglet manure (PM), cow manure (CWM), and starch wastewater (SWW). A modified Gompertz model was used to identify the statistically significant parameters of the methane production curves. The optimal compositions of the mixtures were identified based on multi-objective optimization of the maximal methane yield (YCH4) and maximal methane specific production rate (rCH4) parameters. The study was validated using a double mixture of PM and CWM and a triple mixture. The estimated degradation rates for both mixtures were faster than the predicted ones. The absolute relative errors of rCH4 were 27.41% for the double mixture and 5.59% for the triple mixture, while the relative errors of YCH4 were 4.64% for the double mixture and 10.05% for the triple mixture. These relative errors are within the normal limits of a process with high variability like AD. Thus, mixture design supported by the tested models is suitable for the definition of practically advisable mixtures of substrates.

Determination of the dewatered digestate amounts and methane yields from the co-digestion of biowaste as a basis for a cost-benefit analysis

Co-digestion is the simultaneous digestion of two or more substrates and a common practice at wastewater treatment plants (WWTPs). The amounts of methane and digested sludge produced are key parameters for evaluating the economic efficiency of co-digestion. However, the share of dewatered digestate produced from co-substrates is not known. Synergistic effects in co-digestion, i.e. a better biodegradability compared to the mono-digestion of each substrate, might reduce the amounts of digested sludge and increase methane yields. However, these effects might also influence the calculation of methane and digestate quantities from co-substrates. The main objective of this work was to provide a basis for the cost-benefit analysis of biowaste (BW) co-digestion at WWTPs for this data. Therefore, continuous and batch experiments with sewage sludge (SS) and BW co-digestion were conducted and evaluated for methane and digestate production, and possible synergistic effects. BW co-digestion led to an additional production of 0.35 t total solids (TS) of dewatered sludge per ton TSadded in continuous and 0.23 t TS of dewatered sludge per ton of TSadded in batch experiments. The methane yield from BW was 441 L/kg TSadded in continuous experiments and 482 L/kg TSadded batch test. No synergistic effects were observed in both batch and continuous co-digestion experiments. Batch tests were found to be suitable for a rough estimation of the co-digestion economic efficiency key parameters. Continuous experiments are recommended to obtain more robust data. A cost-benefit analysis found that electricity production from co-digestion can generate savings of 88-170 €/t TSadded compared to grid purchase.

A novel pretreatment biotechnology for increasing methane yield from lipid-rich wastewater based on combination of hydrolytic enzymes with Candida rugosa fungus

Lipid-rich wastewater from the local dairy industry (cheese whey) in the Galilee, Israel was hydrolyzed by using two different sources of lipase as hydrolytic enzymes: fungal (Candida rogusa lipase-AY) and animal porcine pancreatic lipase(PPL). Pretreatment efficiency was verified by comparative biodegradability tests of raw and treated wastewater samples. Simultaneous hydrolysis and anaerobic digestion in the same reactors were also tested. Enzymatic pretreatment of these samples at a concentration of 0.05 w v−1 showed organic matter removal of 90% and methane formation increases of 140% for the fungal source enzyme (i.e., AY), while for the animal source enzyme (i.e., PPL) was 86 and 130%, respectively. Enzymatic pretreatment led to significant methane formation which was obtained only for moderate substrate concentration (initial chemical oxygen demand of 15 gL−1); While in high concentrated lipid-rich wastewater led to methane yield inhibition. The main finding was that the combination of AY enzyme with Candida rugosa fungus (i.e., enzyme mixture) led to a high efficiency in methane production (+152%) and organic materials removal (more than 90%). In summary, the use of fungal hydrolytic lipase mixed with Candida rugosa fungus is a promising method for enhancing methane production during the biodegradation of fat and grease-rich wastewaters.

In vitro digestion rate of fully gelatinized rice starches is driven by molecular size and amylopectin medium-long chains

In current study, the effects of starch fine molecular structures on its in vitro digestibility at fully gelatinized stage were investigated. The digestion kinetics of 15 fully gelatinized rice starches were obtained and correlated with starch chain-length distributions and molecular size distributions. Both logarithm of slopes and parallel first-order kinetic model were applied to fit the digestion curves to a few kinetics-based parameters. Result showed there were two simultaneous digestion fractions (fast versus slow) for fully gelatinized rice starches. The rate constants of slowly-digestible fraction significantly correlated with starch molecular sizes, especially with that of amylopectin molecules. Hydrodynamically larger amylopectin molecules tend to contain more shorter branches but less long chains. This slows down the starch hydrolysis by α-amylase while the action of AMG is less antagonistically hindered, increasing overall digestion rate. This study provides important information for rice breeders and manufacturers to develop rice products with reduced starch digestibility.

Direct and Indirect Effects of Increased CO2 Partial Pressure on the Bioenergetics of Syntrophic Propionate and Butyrate Conversion.

Simultaneous digestion and in situ biogas upgrading in high-pressure bioreactors will result in elevated CO2 partial pressure (pCO2). With the concomitant increase in dissolved CO2, microbial conversion processes may be affected beyond the impact of increased acidity. Elevated pCO2 was reported to affect the kinetics and thermodynamics of biochemical conversions because CO2 is an intermediate and end-product of the digestion process and modifies the carbonate equilibrium. Our results showed that increasing pCO2 from 0.3 to 8 bar in lab-scale batch reactors decreased the maximum substrate utilization rate (rsmax) for both syntrophic propionate and butyrate oxidation. These kinetic limitations are linked to an increased overall Gibbs free energy change (ΔGOverall) and a potential biochemical energy redistribution among syntrophic partners, which showed interdependence with hydrogen partial pressure (pH2). The bioenergetics analysis identified a moderate, direct impact of elevated pCO2 on propionate oxidation and a pH-mediated effect on butyrate oxidation. These constraints, combined with physiological limitations on growth exerted by increased acidity and inhibition due to higher concentrations of undissociated volatile fatty acids, help to explain the observed phenomena. Overall, this investigation sheds light on the role of elevated pCO2 in delicate biochemical syntrophic conversions by connecting kinetic, bioenergetic, and physiological effects.

Simulation of Human Small Intestinal Digestion of Starch Using an In Vitro System Based on a Dialysis Membrane Process.

This work deepens our understanding of starch digestion and the consequent absorption of hydrolytic products generated in the human small intestine. Gelatinized starch dispersions were digested with α-amylase in an in vitro intestinal digestion system (i-IDS) based on a dialysis membrane process. This study innovates with respect to the existing literature, because it considers the impact of simultaneous digestion and absorption processes occurring during the intestinal digestion of starchy foods and adopts phenomenological models that deal in a more realistic manner with the behavior found in the small intestine. Operating the i-IDS at different flow/dialysate flow ratios resulted in distinct generation and transfer curves of reducing sugars mass. This indicates that the operating conditions affected the mass transfer by diffusion and convection. However, the transfer process was also affected by membrane fouling, a dynamic phenomenon that occurred in the i-IDS. The experimental results were extrapolated to the human small intestine, where the times reached to transfer the hydrolytic products ranged between 30 and 64 min, according to the flow ratio used. We consider that the i-IDS is a versatile system that can be used for assessing and/or comparing digestion and absorption behaviors of different starch-based food matrices as found in the human small intestine, but the formation and interpretation of membrane fouling requires further studies for a better understanding at physiological level. In addition, further studies with the i-IDS are required if food matrices based on fat, proteins or more complex carbohydrates are of interest for testing. Moreover, a next improvement step of the i-IDS must include the simulation of some physiological events (e.g., electrolytes addition, enzyme activities, bile, dilution and pH) occurring in the human small intestine, in order to improve the comparison with in vivo data.

Combination of parallel and sequential digestion kinetics reveals the nature of digestive characteristics of short-term retrograded rice starches

Cooked rice is commonly consumed after a short period of cooling, which results in the short-term starch retrogradation. Starch fine molecular structures that are important for its in vitro digestibility after short-term retrogradation were thus investigated in this study. A modified first-order kinetics model was developed in order to consider both the sequential and simultaneous digestion phases in the system. Correlation analysis between the resulted digestion parameters with starch fine molecular structures, i.e. chain-length distribution and molecular size distribution, showed that the number of digestion phases was determined by the amount of amylose short to medium chains and starch molecular size; relatively lower amount of these chains and larger starch molecules could result in two digestible fractions (fast versus slow) that possess a combination of sequential and parallel digestion pattern. Among the starches with two digestible fractions, a relatively larger amylose molecules, higher amount of amylose short to medium chains, shorter amylose medium chains, as well as longer amylopectin medium chains would result in a slower digestion rate for both the fast- and slow-digestible starch fraction. The initiation time of the digestion of slow-digestible starch fraction was positively correlated with the amount of amylose short to medium chains, while negatively correlated with the amylose molecular size. These results could enable rice breeders to develop rice varieties with slower starch digestibility by introducing desirable starch fine molecular structures.

Synergistic effect of anaerobic co-digestion of South African food waste with cow manure: Role of low density-polyethylene in process modulation

The simultaneous digestion of two or more organic substrate in anoxic conditions is a proven strategy for optimizing anaerobic digestion (AD) efficiency, likewise, the maintenance of process temperature within the biocatalytic range of AD processes is critical for process stabilization. However, challenges with yield and process stability yet presents major bottlenecks for bio-digester designs specifically for low-income households due to characteristic limitations in feed profile and constant exposure to natural elements and fluctuations in weather conditions. In this study, knowledge of common advantages of co-digestion of kitchen wastes and animal manure; nutrient balancing for improved microbial growth and activity, augmentation of substrate characteristics, was combined with household digester design modification (with low-density polyethylene (LDPE) cover) for an improved, yet techno-feasible process. Low-cost, durable LDPE commonly used for its greenhouse heating function was explored here for sustaining bio-methane production from organic feeds in and at household digester conditions. Food wastes (KW) was co-digested with cow manure (CW) in a modular anaerobic digester with and without LDPE cover. Findings showed the optimum feed blend: KW to CW, 3:1 produced the highest amount of biogas over a hydraulic retention time of 30 days and organic loading rate of 4.41 kgVS/L/day. The co-digestion runs suggested significant synergy across runs while mono-digestion of KW failed due to acidification. Fed-batch codigestion of the substrates in the LDPE modified digester resulted in a significant increase in methane content of produced biogas with proof of slurry temperature within the mesophilic range (29–44 °C) across the 3-month study time.

Biogas production from anaerobic co-digestion of waste activated sludge: co-substrates and influencing parameters

Anaerobic digestion is a versatile biotechnology to treat waste activated sludge (WAS), the main by-products of biological wastewater treatment, because it can achieve simultaneously energy recovery (biogas) and pollutant reduction (organic matter, pathogens). However, the potential of biogas production from mono-digestion of WAS is usually limited by the imbalance carbon to nitrogen (C/N) ratio of WAS and ammonia accumulation. Anaerobic co-digestion, simultaneous digestion of two or more substrates, should be a feasible option to resolve these disadvantages. The abundant organic wastes from municipal, industrial, and agricultural field have been the ideal co-substrates because they not only can balance the substrate nutrient to obtain the optimal C/N ratio, but also can adjust pH and dilute the toxic materials to mitigate the inhibition to methanogens, consequently improving the yield of biogas, especially methane. This paper classified the main organic co-substrates according to their source and reviewed their application in anaerobic co-digestion of WAS. Then the influence of temperature, pH, organic loading rate, hydraulic retention time, C/N ratio, digester type and pretreatment method on biogas production was extensively discussed. Finally, this review brought forward the challenges and outlooks of anaerobic co-digestion in the future.

Equine F(ab')2-based antivenom preparation by simultaneous caprylic acid fractionation and pepsin digestion

Equine F(ab')2-based antivenom preparation by simultaneous caprylic acid fractionation and pepsin digestion

On-slide tissue digestion for mass spectrometry based glycomic and proteomic profiling

We describe a protocol for glycomic and proteomic profiling that uses serial enzyme digestions from the surface of fresh frozen or fixed tissue slides. The abundances of the extracted glycans and peptides are determined using liquid chromatography-mass spectrometry. In a typical experiment, our method quantifies 14 heparan sulfate disaccharides, 11 chondroitin sulfate disaccharides, 50 N-glycan compositions and approximately 1200 proteins from a 1.8 mm circle, on the surface of a fresh frozen tissue slide from rat brain. Each enzymatic digestion is incubated overnight with direct application of enzyme on the tissue surface. Overall, the sample preparation process for multiple tissue slides takes a day per biomolecule class. This protocol saves time by simultaneous digestion of large N-glycans and small HS disaccharides and subsequent separation using size exclusion chromatography. Compared to wet tissue analysis, this method requires less time by a factor of two. By comparison, MALDI-imaging provides higher spatial resolution of glycans and proteins but lower depth of coverage. MALDI dissociates fragile glycan substituents including sulfates and is not recommended for analysis of glycosaminoglycans (GAGs).

Renewable Biochemical Methane Potential through Anaerobic Co-digestion from Selective Feed Stocks

Biochemical Methane Potential (BMP) analysis provides a measure of the anaerobic biodegradability of a given substrate. BMP test is also used to evaluate the potential biogas (methane) production between various Co-digestion substrates. This test is also used to determine the amount of organic carbon in a given material that can be an aerobically converted to methane-Biogas. Studies were carried out for the production of biogas from the leather solid waste. Co-digestion (simultaneous digestion of two or more substrates) studies were carried out in batch reactor using the fleshing (a solid waste generated during the processing of raw hides or skins into finished leather) along with the fruit and vegetable waste at mesophilic condition 35° C). The anaerobic methanogenic seed sludge prepared separately followed by standard BMP test, which was used as the seed inoculums. Recent research on this topic is reviewed in this current paper.

Anaerobic co-digestion of sewage sludge and molasses

The efficiency of simultaneous digestion of sewage sludge and by-product of refining sugar beets (molasses) was investigated. The study was conducted for 28 days under mesophilic conditions. 0.5%, 1%, 1.5%, 2% and 3% (m/m) of molasses was added to the mixture of sludge. The result of the study showed that addition of molasses had positive effect the biogas production. The biggest biogas yield was achieved in sample with 0.5% of molasses (95.69 mL/g VS). In this sample biogas production increased by 21% in comparison with reference sample (without molasses). The biggest methane content (73%) was also observed in the sample with 0.5% of molasses. For comparison in reference sample was produced biogas with 70% content of methane. The dose over 0.5% of molasses caused inhibition of fermentation process. The minimal degree (38%) of degradation of organic matter was achieved in reference sample (38.53%) and in sample with 0.5% of molasses (39.71%) but in other samples was in the range of 35.61-36.76 % (from 3% to 1%, respectively). Digestion process have adverse effect on dewatering properties of sludge. Before co-digestion capillary suction time was from 31 s to 55 s, and after process increased from 36 s to 556 s (from 0% to 3% of molasses, respectively).

Effect of lime loading on the performance of simultaneous lime treatment and dry anaerobic digestion of smooth cordgrass

ABSTRACTThe effects of lime loading on simultaneous lime treatment and dry digestion (SLTDD) of smooth cordgrass (SC) were evaluated at 35°C by batch reactors and leaching bed reactors (LBRs). Biogas yields of 1.5%, 3%, and 5% (w/w) lime loadings decreased by 7.1%, 20%, and 75.7%, respectively, compared with no-lime treatment with 198.0 mL/g total solids (TS) by batch reactors. The LBRs with liquid recycling and pH adjustment enhanced biogas production with 148.1–236.1 mL/g TS. The inhibition occurred SLTDD may be ascribed to be high pH and temperature from lime hydration at the initial stage. The activity for methanogenic bacteria was more inhibited than other anaerobic bacteria.