Effect of <scp>pH</scp> on lactic acid fermentation of food waste using different mixed culture inocula

Pau, Simone; Tan, Lea Chua; Lens, Piet N.L.

doi:10.1002/jctb.6982

Cited by 15 publications

(11 citation statements)

References 60 publications

(86 reference statements)

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“…Furthermore, R1 maintained a high stability in terms of LA concentration (3.27-5.83 g COD/L) and production along the experimental run with the pH varying from 2.95 (phase II) to 3.59 (phase IV) showing that LA fermentation occurs even at a pH lower than 3.00. These results are in line with our previous batch screening work [26] where a pH < 4.0 was found to be the most suitable for LA production and accumulation.…”

Section: La Fermentation In Very Acidic Environmentsupporting

confidence: 92%

“…Synthetic FW was used as the substrate for both the screening batch tests and the semicontinuous reactor run. The FW recipe was reported previously [26] and taken from the study of Ariunbataar et al [27] with the aim to mimic the average household FW in Europe. The FW was prepared by reducing ingredients into small pieces, cooked, mixed in the right proportion, and finally milled with the addition of 200 ml of water in order to obtain a homogenous slurry.…”

Section: Substratementioning

confidence: 99%

“…Despite the clear advantages brought by the low pH fermentation listed above, there is currently limited information on the performance of continuous and semicontinuous systems for LA fermentation using FW as the substrate at these acidic conditions. This study is a continuation from the previous work [26] and aims to investigate LA fermentation under uncontrolled acidic systems in two different 1L upflow anerobic sludge bed (UASB) reactors operated in semicontinuous batch mode configuration. The role and effect of the hydraulic retention time (HRT) and organic loading rate (OLR) variations on FW fermentation were also explored.…”

Section: Introductionmentioning

confidence: 99%

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Lactic acid fermentation of food waste at acidic conditions in a semicontinuous system: effect of HRT and OLR changes

Pau

Tan

Arriaga

et al. 2022

Biomass Conv. Bioref.

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Lactic acid production through fermentation is an established technology, however, improvements are necessary to reduce the process costs and to decrease its market price. Lactic acid is used in many industrial sectors and its market has increased in the last decade for its use as the raw material for polylactic acid product. Using food waste as a cheap and renewable substrate, as well as fermentation at uncontrolled pH, helps to make the production cheaper and to simplify the downstream purification process. Lactic acid production at acidic conditions and the role of varying organic loading rate (OLR) and hydraulic retention time (HRT) were tested in two different semicontinuous batch fermentation systems. Reactor performances indicated that lactic acid fermentation was still possible at pH < 3.5 and even up to a pH of 2.95. The highest lactic acid production was recorded at 14-day HRT, 2.14 g VS/L·day OLR, and pH 3.11 with a maximum lactic acid concentration of 8.72 g/L and a relative yield of 0.82 g lactate/g carbohydrates. The fermentation microbial community was dominated by Lactobacillus strains, the organism mainly responsible for lactic acid conversion from carbohydrates. This study shows that low pH fermentation is a key parameter to improve lactic acid production from food waste in a semicontinuous system. Acidic pH favored both the selection of Lactobacillus strains and inhibited VFA producers from utilizing lactic acid as primary substrate, thus promoting the accumulation of lactic acid. Finally, production yields tend to decrease with high OLR and low HRT, while lactic acid production rates showed the opposite trend.

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Section: La Fermentation In Very Acidic Environmentsupporting

confidence: 92%

Section: Substratementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Lactic acid fermentation of food waste at acidic conditions in a semicontinuous system: effect of HRT and OLR changes

Pau

Tan

Arriaga

et al. 2022

Biomass Conv. Bioref.

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“…At ambient temperature, lactic acid was the main product in the early stages of all reactors, probably because the low pH is conducive to lactic acid bacteria and lactic acid synthesis. 25 With the progress of fermentation, butyric acid increased and comprised up to 63% of the maximum product yield (Fig. 2a).…”

Section: Effect Of Different Ph Values and Temperatures On Product Co...mentioning

confidence: 96%

Impact of pH, temperature, and hydraulic residence time on the acidogenic fermentation of fruit and vegetable waste and microbial community analysis

Liu

Wang

et al. 2022

J of Chemical Tech & Biotech

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BACKGROUND: The carboxylic acids produced through acidogenic fermentation of fruit and vegetable waste present wide application and high added value. By performing batch experiments, the influence of pH and temperature on the acidogenic fermentation performance was investigated, and the effects of hydraulic retention time (HRT) on performance and microbial community in semi-continuous fermentation were also studied.RESULTS: A maximum product yield of 0.66 ± 0.01 g g −1 VS fed (volatile solids of feed substrate) was found at mesophilic temperature and pH 9.0; acetic acid, propionic acid, and butyric acid comprised 59%, 20%, and 21% of the product, respectively. During semi-continuous fermentation, a maximum product yield of 0.69 ± 0.03 g g −1 VS fed was found at pH 9.0 and an HRT of 5 days. Lactic acid and acetic acid were regarded as the main products, with respective percentages of 85% and 12%. Reducing the HRT to 3 days increased the daily production from 11.33 ± 0.46 to 15.89 ± 0.67 g d −1 . Microbial community analysis revealed that Lactobacillus was predominant in the semi-continuous alkaline fermentation system. CONCLUSION: Alkaline fermentation was more favorable for obtaining higher product yield both in batch and semi-continuous fermentation. Within semi-continuous alkaline fermentation, the maximum yield was observed at an HRT of 5 days, but a higher daily production was found at an HRT of 3 days. Additionally, reducing the HRT did not change the dominant bacteria but could change the composition of the products. This work provides a theoretical basis and guidance for enhancing product yield and optimizing formation of product.

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“…The maximum LA productivity ranged from 1.12±0.05 to 1.55 ± 0.08 g/L.h giving the maximum value at 8.5 of pH value. pH plays a key role in the fermentation process, as it determines the final metabolites produced (that is, LA or the organic acid composition) and thus affects the final LA titer and yield based on consumed sugars [47].…”

Section: Effect Of Ph Values On La Production By E Faecium Wh51-1mentioning

confidence: 99%

Statistical optimization of the fermentation factors for increased biorefinery of corn-steep water effluent to lactic acid by Enterococcus faecium strain WH51-1

Selim

Fouda

Salem

et al. 2022

Biomass Conv. Bioref.

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Organic waste bioprocessing for production of useful products are increasing due to fossil fuel depletion, problems with waste management, and the requirement for biodegradable plastics. Lactic acid (LA) is important in foods, polymer beverages, cosmetics, and medicine applications. However, the main challenge in the large-scale processing of LA is the enhanced production and productivity using low-cost resources. In this study, Enterococcus faecium WH51-1, a newly obtained thermo-alkali tolerant LA bacterium, was used for LA production from corn-steep water (CSW) as raw material. The optimal culture conditions and medium components were established. Different concentrations of yeast extract (YE) and pH values were investigated with highest LA production of 48.2 ± 2.7 g/L at a yield of 0.89 ± 0.04 g/g-consumed sugars and a productivity of 0.50 ± 0.03 g/L.h at pH 8.5 without YE supplementation. A central composite design (CCD) was utilized to determine the high LA concentrations at optimal values for the process variables (sugar concentrations, temperature, inocula sizes, pH value, and YE concentration). The model was realized with an acceptable fit. The optimization of the factors was carried out by normal probability plots, interaction-plots, incorporating effect plots, analysis of variance (ANOVA), surface plots, Pareto charts, and contour plots. All the parameters were influenced at a 5% significance level. Additionally, some of the possible interactions between these parameters also influenced the production process. A regression model was suggested and fitted the experimental data very well. The results of this work investigated that LA synthesized of the optimized-fermentation conditions was 10% greater than classical optimization methods. This study presented a green “free nutrient” and cost-effective utilization of corn steep effluent as a cheap alternative substrate for biorefinery to lactic acid. Graphical Abstract

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Effect of pH on lactic acid fermentation of food waste using different mixed culture inocula

Cited by 15 publications

References 60 publications

Lactic acid fermentation of food waste at acidic conditions in a semicontinuous system: effect of HRT and OLR changes

Lactic acid fermentation of food waste at acidic conditions in a semicontinuous system: effect of HRT and OLR changes

Impact of pH, temperature, and hydraulic residence time on the acidogenic fermentation of fruit and vegetable waste and microbial community analysis

Statistical optimization of the fermentation factors for increased biorefinery of corn-steep water effluent to lactic acid by Enterococcus faecium strain WH51-1

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