scholarly journals The impact of starter culture on the pH and the content of lactic and volatile fatty acids in boiled-smoked sausages

2015 ◽  
Vol 56 (1) ◽  
pp. 34-40
Author(s):  
Dijana Indzhelieva ◽  
Katja-Jorgova Valkova ◽  
Aco Kuzelov ◽  
Darko Andronikov
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Starter Culture ◽  
The Impact

scholarly journals Volatile Fatty Acids Production from Microalgae Biomass: Anaerobic Digester Performance and Population Dynamics during Stable Conditions, Starvation, and Process Recovery

Molecules ◽  
2019 ◽  
Vol 24 (24) ◽  
pp. 4544 ◽  
Author(s):  
Jose Antonio Magdalena ◽  
Elia Tomás-Pejó ◽  
Cristina González-Fernández
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Starvation Period ◽  
Reactor Performance ◽  
Methane Generation ◽  
Microbial Response ◽  
Stable Conditions ◽  
Microbial Analysis ◽  
Process Disturbances ◽  
The Impact

Disturbances in anaerobic digestion (AD) negatively impact the overall reactor performance. These adverse effects have been widely investigated for methane generation. However, AD recently appeared as a potential technology to obtain volatile fatty acids (VFAs) and thus, the impact of process disturbances must be evaluated. In this sense, microbial response towards a starvation period of two weeks was investigated resulting in a conversion of organic matter into VFAs of 0.39 ± 0.03 COD-VFAs/CODin. However, the lack of feeding reduced the yield to 0.30 ± 0.02 COD-VFAs/CODin. Microbial analysis revealed that the starvation period favored the syntrophic acetate-oxidizing bacteria coupled with hydrogenotrophic methanogens. Finally, the system was fed at 9 g COD/Ld resulting in process recovery (0.39 ± 0.04 COD-VFAs/CODin). The different microbiome obtained at the end of the process was proved to be functionally redundant, highlighting the AD robustness for VFAs production.

Toxicity of pH, Ammonia and Volatile Fatty Acids on Hydrogenotrophic Methanogen-Enriched Sludge

2014 ◽  
Vol 955-959 ◽  
pp. 527-531
Author(s):  
Jian Zheng Li ◽  
Yu Peng Zhang ◽  
Chong Liu ◽  
Ze Yu Tang
Keyword(s):  
Fatty Acids ◽  
Acetic Acid ◽  
Anaerobic Digestion ◽  
Propionic Acid ◽  
Butyric Acid ◽  
Volatile Fatty Acids ◽  
Batch Experiments ◽  
Inhibitory Effects ◽  
Hydrogenotrophic Methanogen ◽  
The Impact

The activities of methanogen are easily affected by inhibitory substances and lead to anaerobic digestion failure. To investigate inhibitory effects on methanogenesis of a methanogen-enriched sludge, pH, volatile fatty acids (such as acetic acid, propionic acid and butyric acid), and ammonia were used as inhibitory factors and a L16(45) orthogonal table was employed to design batch experiments. The result of variance analyses shows that pH has the greatest impact on the methanogenesis of the enriched culture. The impact of butyrate, NH3, acetate and propionate was decreased in order. DGGE finger-print shows that there was only one methanogen in the inoculum sludge.

scholarly journals Optimizing the impact of temperature on bio-hydrogen production from food waste and its derivatives under no pH control using statistical modelling

2015 ◽  
Vol 12 (21) ◽  
pp. 6503-6514 ◽  
Author(s):  
C. Arslan ◽  
A. Sattar ◽  
C. Ji ◽  
S. Sattar ◽  
K. Yousaf ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Hydrogen Production ◽  
Food Waste ◽  
Volatile Fatty Acids ◽  
Negative Impact ◽  
Glucose Consumption ◽  
Statistical Modelling ◽  
Effect Of Temperature ◽  
Coefficient Of Determination ◽  
The Impact

Abstract. The effect of temperature on bio-hydrogen production by co-digestion of sewerage sludge with food waste and its two derivatives, i.e. noodle waste and rice waste, was investigated by statistical modelling. Experimental results showed that increasing temperature from mesophilic (37 °C) to thermophilic (55 °C) was an effective mean for increasing bio-hydrogen production from food waste and noodle waste, but it caused a negative impact on bio-hydrogen production from rice waste. The maximum cumulative bio-hydrogen production of 650 mL was obtained from noodle waste under thermophilic temperature condition. Most of the production was observed during the first 48 h of incubation, which continued until 72 h of incubation. The decline in pH during this interval was 4.3 and 4.4 from a starting value of 7 under mesophilic and thermophilic conditions, respectively. Most of the glucose consumption was also observed during 72 h of incubation and the maximum consumption was observed during the first 24 h, which was the same duration where the maximum pH drop occurred. The maximum hydrogen yields of 82.47 mL VS−1, 131.38 mL COD−1, and 44.90 mL glucose−1 were obtained from thermophilic food waste, thermophilic noodle waste and mesophilic rice waste, respectively. The production of volatile fatty acids increased with an increase in time and temperature in food waste and noodle waste reactors whereas they decreased with temperature in rice waste reactors. The statistical modelling returned good results with high values of coefficient of determination (R2) for each waste type and 3-D response surface plots developed by using models developed. These plots developed a better understanding regarding the impact of temperature and incubation time on bio-hydrogen production trend, glucose consumption during incubation and volatile fatty acids production.

Impact of volatile fatty acids to alkalinity ratio and volatile solids on biogas production under thermophilic conditions

2020 ◽  
pp. 0734242X2095739
Author(s):  
Abdul-Aziz Issah ◽  
Telesphore Kabera
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Total Alkalinity ◽  
Stable Range ◽  
Start Up ◽  
Volatile Solids ◽  
Significant Difference ◽  
Thermophilic Conditions ◽  
The Impact

The study assessed the impact of volatile fatty acids (VFA) to total alkalinity (TA) ratio (VFA/TA), and percentage volatile solids (VS) reduction of batch and semi-continuous anaerobic co-digestion of palm nut paste waste (PNPW) and anaerobic-digested rumen waste (ADRW) on digester stability and biogas production under the environmental condition of 50 ± 1°C and hydraulic retention time of 21 days for the batch studies and 14 days for semi-continuous co-digestion. The co-digestion ratios were based on percentage digester volume corresponding to 90%:10%, 75%:25% and 50%:50%. During batch and semi-continuous anaerobic co-digestion, VFA/TA of 0.32–1.0 and VS reduction of 53–67% were observed as the stable range at which biogas production was maximum. In terms of semi-continuous anaerobic digestion (AD), except for the 50%:50% ratio where biogas production progressed steadily from the first to fourteenth days, biogas production initially dropped from 180.1 to 171.3 mL between the first and third days of the 90%:10% reaching a maximum of 184 mL on the fourteenth day. Biogas production declined from 198.8 to 187.5 mL on the second day and then increased to 198.8 ± 0.5 mL in the case of the 75%:25% with a significant difference between the treatment ratios at p < 0.05. Therefore, the study can confirm that the 50%:50% ratio (PNPW:ADRW) is a suitable option for managing crude fat-based waste under thermophilic AD due to its potential for rapid start-up and complete biodegradation of active biomass within a 21-day period. This presupposes that residual methane as greenhouse gas will be void in the effluent if disposed of.

Effects of solids concentration, pH and carbon addition on the production rate and composition of volatile fatty acids in prefermenters using primary sewage sludge

2006 ◽  
Vol 53 (8) ◽  
pp. 263-269 ◽  
Author(s):  
R.J. Zeng ◽  
Z. Yuan ◽  
J. Keller
Keyword(s):  
Fatty Acids ◽  
Production Rate ◽  
Propionic Acid ◽  
Volatile Fatty Acids ◽  
Productivity Loss ◽  
Domestic Wastewater ◽  
Biological Phosphorus Removal ◽  
Operational Conditions ◽  
Solids Concentration ◽  
The Impact

Increasing evidence is emerging that the performance of enhanced biological phosphorus removal (EBPR) systems relies on not only the total amount but also the composition of volatile fatty acids (VFAs). Domestic wastewater often contains limited amounts of VFAs with acetic acid typically being the dominating species. Consequently, prefermenters are often employed to generate additional VFAs to meet the demand for carbon by EBPR and/or denitrification processes. Limited knowledge is currently available on the effects of operational conditions on the production rate and composition of VFAs in prefermenters. In this study, a series of controlled batch experiments were conducted with sludge from a full-scale prefermenter to determine the impact of solids concentration, pH and addition of molasses on prefermentation processes. It was found that an increase in solids concentration enhanced total VFA production with an increased propionic acid fraction. The optimal pH for prefermentation was in the range of 6–7 with significant productivity loss when pH was below 5.5. Molasses addition significantly increased the production of VFAs particularly the propionic acid. However, the fermentation rate was likely limited by the biological activity of the sludge rather than by the amount of molasses added.

Impact of variation in yield of gas during incubation on simulated gas production and extent of ruminal degradation

1999 ◽  
Vol 1999 ◽  
pp. 38-38
Author(s):  
J. Dijkstra ◽  
J. France ◽  
S. Lopez ◽  
M.S. Dhanoa
Keyword(s):  
Fatty Acids ◽  
Simulation Study ◽  
Degradation Rate ◽  
Volatile Fatty Acids ◽  
Soluble Sugars ◽  
Gas Production ◽  
Production Technique ◽  
Substrate Degradation ◽  
Ruminal Degradation ◽  
The Impact

To calculate the extent of ruminal degradation based on the gas production technique, equations were derived to describe gas production profiles from substrate degradation (France et al. submitted). This derivation demonstrated that if the yield of gas (Y; ml/g degradable OM) produced during the course of incubation varies significantly, then the calculated extent of degradation is not correct. Variation in Y may occur due to variation in the yield of individual volatile fatty acids (VFA) produced. The objective of this simulation study was to examine the impact of variation in individual VFA production and consequently in yield of gas on the extent of ruminal degradation.Gas production profiles were simulated based on a generalized Mitscherlich (GM) equation (see France et al. submitted) for three substrates (soluble sugars, starch, fibre) that differ in degradation rate and VFA production profile (see Table 1).

Influence of Inoculum to Substrate Ratio on Solid Acidogenic Digestion with Pig Manure and Maize Straw

2012 ◽  
Vol 518-523 ◽  
pp. 223-228
Author(s):  
Lei Zhang ◽  
Lian Zhu Du ◽  
Wen Wen Cui ◽  
Ke Qiang Zhang
Keyword(s):  
Fatty Acids ◽  
Acetic Acid ◽  
Volatile Fatty Acids ◽  
Oxygen Demand ◽  
Ammonia Nitrogen ◽  
Threshold Concentration ◽  
Pig Manure ◽  
Fermentation Products ◽  
Substrate Ratio ◽  
The Impact

A laboratory-scale study adopting mixture of manure and straw as substrate was carried out to elucidate the impact of inoculum to substrate ratio(ISR) on hydrolysis and acidification digestion with methanogenic effluent recycling. The chemical oxygen demand(COD), pH, and volatile fatty acids (VFAs) concentration were periodically analyzed in order to completely understand the digestion processing. In addition, ammonia-nitrogen was also monitored. The results showed that acetic acid was dominant in fermentation products of different ISRs and the percentage of acetic acid in total volatile fatty acids (TVFAs) increased with the increase of ISR, and acetic acid accounted to 68.74%, 72.02%, 75.89% and 86.65% of TVFAs when ISR were 15%, 25%, 35% and 50%. Propionic acid accounted for 6.68%, 5.92%, 5.54% and 2.67% of TVFAs produced, and the concentration was less than 0.60 g/L. The possible inhibition by free ammonia was null since the values were far below the threshold concentration reported in other literatures, but the potential inhibition maybe happen after long-term recycling of methanogenic effluent.

Volatile fatty acids production during mixed culture fermentation – The impact of substrate complexity and pH

2017 ◽  
Vol 326 ◽  
pp. 901-910 ◽  
Author(s):  
Ewelina Jankowska ◽  
Joanna Chwialkowska ◽  
Mikolaj Stodolny ◽  
Piotr Oleskowicz-Popiel
Keyword(s):  
Fatty Acids ◽  
Mixed Culture ◽  
Volatile Fatty Acids ◽  
Mixed Culture Fermentation ◽  
The Impact

scholarly journals A Two-Stage Process for Conversion of Brewer’s Spent Grain into Volatile Fatty Acids through Acidogenic Fermentation

2021 ◽  
Vol 11 (7) ◽  
pp. 3222
Author(s):  
Eliana C. Guarda ◽  
Ana Catarina Oliveira ◽  
Sílvia Antunes ◽  
Filomena Freitas ◽  
Paula M. L. Castro ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Organic Acid ◽  
Volatile Fatty Acids ◽  
Operation Mode ◽  
Granular Sludge ◽  
Building Blocks ◽  
Organic Load ◽  
Fermentation Products ◽  
Acidogenic Fermentation ◽  
The Impact

This work is focused on the valorization of brewer’s spent grains (BSG) into volatile fatty acids (VFA) through acidogenic fermentation. VFAs are building blocks for several applications, such as bioplastics’ production. Using acid hydrolysis as pre-treatment, several batch assays were performed and the impact of organic load (OL) and pH on VFA production from BSG hydrolysate was assessed. Regardless of the condition, the produced acids were mainly butyric and acetic acids followed by propionic acid. The OL had a direct impact on the total organic acid concentration with higher concentrations at the highest OL (40 gCOD L−1). pH affected the concentration of individual organic acid, with the highest fermentation products (FP) diversity attained at pH 5.0 and OL of 40 gCOD L−1. To assess the potential application of organic acids for biopolymers (such as polyhydroxyalkanoates) production, the content in hydroxybutyrate (HB) and hydroxyvalerate (HV) monomers was estimated from the respective precursors produced at each pH and OL. The content in HV precursors increased with pH, with a maximum at pH 6.0 (ca. 16% C-mol basis). The acidogenic fermentation of BSG hydrolysate was also assessed in continuous operation, using an expanded granular sludge bed reactor (EGSB). It was shown that the BSG hydrolysate was successfully converted to VFAs without pH control, achieving higher productivities than in the batch operation mode.

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