Food Waste Valorization

A topical collection in Fermentation (ISSN 2311-5637). This collection belongs to the section "Industrial Fermentation".

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Editor

Topical Collection Information

Dear Colleagues,

During the industrial processing of agricultural or animal products, large amounts of wastes are produced. All these wastes, generated in large amounts throughout the different seasons of the year, can be considered the most abundant renewable resources on earth.

Due to the large availability and richness in components of these raw materials, a great interest is focused on their reuse, both from an economical and environmental points of view.

The economical interest is based on the fact that many of such wastes could be used as low-cost raw materials for the production of new value-added compounds, with a further production costs reduction. The environmental concern comes from their composition, especially the agro-industrial wastes that can contain potentially toxic compounds, which may cause deterioration of the environment when uncontrolled wastes are either burned or left on the soil to decay naturally or buried under the ground. Moreover, these materials exhibit both high biochemical oxygen demand (BOD) and chemical oxygen demand (COD) values, and give rise to serious pollution problems if not properly disposed of.

Recycling and transformation of food wastes represent a great opportunity in supporting a sustainable development by their conversion into value-added products, through fermentation process.

The Topic Collection will be focused on new food waste fermentation technologies and add value products resulting from food waste fermentation. The main topics include, but are not limited to the following:

- New fermentation process

- New food or feed production

- SCP production

- Biofuel production

- Biomolecules production

- Upstream and downstream optimization

- Fermentation products characterization

This is linked with the collection "Food Waste Valorization" and you can check it from here:

https://www.mdpi.com/journal/fermentation/special_issues/waste_valorization

Dr. Alessia Tropea
Collection Editor

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Published Papers (20 papers)

2023

Jump to: 2022

14 pages, 1764 KiB  
Article
Thermophilic Dark Fermentation for Simultaneous Mixed Volatile Fatty Acids and Biohydrogen Production from Food Waste
Fermentation 2023, 9(7), 636; https://doi.org/10.3390/fermentation9070636 - 07 Jul 2023
Cited by 2 | Viewed by 1597
Abstract
Food waste is categorized as organic solid waste, which has a negative impact on environmental sustainability. Food waste was simultaneously used for the feasible generation of mixed volatile fatty acids (VFAs) and bio-hydrogen by deploying dark fermentation. Original anaerobic digested sludge was prepared [...] Read more.
Food waste is categorized as organic solid waste, which has a negative impact on environmental sustainability. Food waste was simultaneously used for the feasible generation of mixed volatile fatty acids (VFAs) and bio-hydrogen by deploying dark fermentation. Original anaerobic digested sludge was prepared via the shock technique with 50 g/L glucose under thermophilic temperature (55 °C). The pretreated inoculum was found capable of converting 10 g VS/L food waste to hydrogen with a rather high yield of 135.2 ± 7 mL H2/VSadded. The effect of various concentrations of food waste, including 10.2, 16.3, 20.3, and 26.4 g VS/L, on mixed VFAs production was subsequently carried out in batch dark fermentation. The highest butyric acid concentration (5.26 ± 0.22 g/L) in soluble metabolites was obtained from batch dark fermentation with 26.4 g VS/L of food waste. The dominant Clostridium thermobutyricum, Clostridium sporogenes, and Octadecobacter sp. found in the batch of dark fermentation of food waste could confirm the effectiveness of the load shock pretreatment method for inoculum preparation. The continuous stirred tank reactor (CSTR) inoculated with mixed cultures, also prepared via the load shock pretreatment method and without the addition of external nutrients, was operated by feeding 26.4 g VS/L food waste at the kinetically designed HRT for 4 days, corresponding to an organic loading rate (OLR) of 7.6 g VS/L·d. Under steady state conditions, promising butyric acid (5.65 ± 0.51 g/L)-rich mixed VFAs were achieved along with the hydrogen yield of 104.9 ± 11.0 mL-H2/g VSadded, which is similar to the upper side of the previously reported yields (8.8 ± 0.6–103.6 ± 0.6 mL-H2/g VS). Full article
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14 pages, 1962 KiB  
Article
Bioconversion of Carrot Pomace to Value-Added Products: Rhizopus delemar Fungal Biomass and Cellulose
Fermentation 2023, 9(4), 374; https://doi.org/10.3390/fermentation9040374 - 13 Apr 2023
Cited by 2 | Viewed by 1672
Abstract
Carrot pomace (CP) which is generated in a large volume in the juice production process, is rich in cellulose, hemicellulose, sugars, pectin, and minerals. However, in many previous investigations, only cellulose was purified and utilized while other components of CP were discarded as [...] Read more.
Carrot pomace (CP) which is generated in a large volume in the juice production process, is rich in cellulose, hemicellulose, sugars, pectin, and minerals. However, in many previous investigations, only cellulose was purified and utilized while other components of CP were discarded as waste. Here, CP was valorized into fungal biomass and cellulose with the aim of utilizing all the CP components. Enzymatic pretreatments were applied to solubilize the digestible fraction of CP including hemicellulose, pectin, sucrose, and other sugars for fungal cultivation, while cellulose remained intact in the solid fraction. The dissolved fraction was utilized as a substrate for the cultivation of an edible fungus (Rhizopus delemar). Fungal cultivation was performed in shake flasks and bench-scale bioreactors. The highest fungal biomass concentration was obtained after pretreatment with invertase (5.01 g/L) after 72 h of cultivation (36 and 42% higher than the concentrations obtained after hemicellulase and pectinase treatments, respectively). Invertase pretreatment resulted in the hydrolysis of sucrose, which could then be taken up by the fungus. Carbohydrate analysis showed 28–33% glucan, 4.1–4.9% other polysaccharides, 0.01% lignin, and 2.7–7% ash in the CP residues after enzymatic pretreatment. Fourier transform infrared spectroscopy and thermogravimetric analysis also confirmed the presence of cellulose in this fraction. The obtained fungal biomass has a high potential for food or feed applications, or as a raw material for the development of biomaterials. Cellulose could be purified from the solid fraction and used for applications such as biobased-textiles or membranes for wastewater treatment, where pure cellulose is needed. Full article
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51 pages, 3558 KiB  
Review
Potential and Restrictions of Food-Waste Valorization through Fermentation Processes
Fermentation 2023, 9(3), 274; https://doi.org/10.3390/fermentation9030274 - 10 Mar 2023
Cited by 8 | Viewed by 3198
Abstract
Food losses (FL) and waste (FW) occur throughout the food supply chain. These residues are disposed of on landfills producing environmental issues due to pollutants released into the air, water, and soil. Several research efforts have focused on upgrading FL and FW in [...] Read more.
Food losses (FL) and waste (FW) occur throughout the food supply chain. These residues are disposed of on landfills producing environmental issues due to pollutants released into the air, water, and soil. Several research efforts have focused on upgrading FL and FW in a portfolio of added-value products and energy vectors. Among the most relevant research advances, biotechnological upgrading of these residues via fermentation has been demonstrated to be a potential valorization alternative. Despite the multiple investigations performed on the conversion of FL and FW, a lack of comprehensive and systematic literature reviews evaluating the potential of fermentative processes to upgrade different food residues has been identified. Therefore, this article reviews the use of FL and FW in fermentative processes considering the composition, operating conditions, platforms, fermentation product application, and restrictions. This review provides the framework of food residue fermentation based on reported applications, experimental, and theoretical data. Moreover, this review provides future research ideas based on the analyzed information. Thus, potential applications and restrictions of the FL and FW used for fermentative processes are highlighted. In the end, food residues fermentation must be considered a mandatory step toward waste minimization, a circular economy, and the development of more sustainable production and consumption patterns. Full article
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15 pages, 3714 KiB  
Article
Effect of Optimized Chitosan Coating Obtained by Lactic Fermentation Chemical Treatment of Shrimp Waste on the Post-Harvest Behavior of Fresh-Cut Papaya (Carica papaya L.)
Fermentation 2023, 9(3), 220; https://doi.org/10.3390/fermentation9030220 - 25 Feb 2023
Cited by 2 | Viewed by 1184
Abstract
Chitosan is a biopolymer obtained from shrimp waste mainly by a polluting chemical method. In this work, a less polluting biological-chemical method to obtain chitosan from this waste has been optimized; this method used a successive lactic fermentation and chemical process. Additionally, in [...] Read more.
Chitosan is a biopolymer obtained from shrimp waste mainly by a polluting chemical method. In this work, a less polluting biological-chemical method to obtain chitosan from this waste has been optimized; this method used a successive lactic fermentation and chemical process. Additionally, in this work, the effect of chitosan coating on the post-harvest behavior of fresh-cut papaya was studied as a practical application. A rotatable central composite design (CCRD) with two variables (fermentation time and total soluble solids of the fermentation medium) was used to optimize the chitosan extraction. The optimized conditions for chitosan extraction were 108 h and 8.74 °Brix. The optimized chitosan showed a high deacetylation degree of 83%, acceptable process yield of 2.03%, a low ash content of 0.23% and a molecular weight of 107.5 kDa. In addition, optimized chitosan decreased the loss of color and acidity, as well as the growth of microorganisms; it also increased the pH of minimally processed papaya slices without a statistically significant difference with that of commercial chitosan. Based on these results, optimized chitosan could be applied to other fruits as a coating to maintain their quality characteristics and inhibit microbial growth during the storage of fresh-cut fruits. Full article
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18 pages, 3538 KiB  
Article
Optimisation of Bioethanol Production in a Potato Processing Industry
Fermentation 2023, 9(2), 103; https://doi.org/10.3390/fermentation9020103 - 23 Jan 2023
Cited by 2 | Viewed by 2392
Abstract
Nowadays, there is a requirement for industries to eliminate carbon from their energy mix and substitute it with greener options. This calls for investment in efforts to facilitate the scaling up of technical advancements. Because of the huge amount of waste, a life [...] Read more.
Nowadays, there is a requirement for industries to eliminate carbon from their energy mix and substitute it with greener options. This calls for investment in efforts to facilitate the scaling up of technical advancements. Because of the huge amount of waste, a life cycle strategy has been used by industries, especially the food industry, to lessen the environmental impact of their products. One of the sectors that burdens the environment with a significant amount of waste is the potato processing industrial sector. The current study focuses on the valorisation of all the potato processing waste streams (potato peels, potato tubers and slices, starch and low-quality chips) towards bioethanol production at a pilot level. After their physico-chemical characterisations, several experimental trials were performed in order to determine the optimum pretreatment and hydrolysis conditions for each waste stream. Acid hydrolysis, alkaline hydrolysis and hydrothermal pretreatment were examined when no pretreatment resulted in low ethanol yields (below 60%). The optimum results that were obtained were applied in a pilot plant of 200L to examine the upscaling factor. It was verified that upscaling by 1000 times generates comparable and, in some cases, greater results. From the integration of the results and the mass balances of a typical potato processing company, a full-scale implementation plan was also set up, where it was calculated that around 2 m3 bioethanol per week could be produced. Full article
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21 pages, 8937 KiB  
Review
Moving towards the Application of Biocatalysis in Food Waste Biorefinery
Fermentation 2023, 9(1), 73; https://doi.org/10.3390/fermentation9010073 - 16 Jan 2023
Cited by 4 | Viewed by 2539
Abstract
Waste valorization is an important strategy to reduce environmental pollution and dependency on petroleum-based fuels. In this regard, utilization of food waste as a versatile and low-cost resource is important. Several advanced catalytic methods for the valorization of food waste have been widely [...] Read more.
Waste valorization is an important strategy to reduce environmental pollution and dependency on petroleum-based fuels. In this regard, utilization of food waste as a versatile and low-cost resource is important. Several advanced catalytic methods for the valorization of food waste have been widely investigated for the production of liquid biofuels. Along this line, chemical catalysts have been explored for the synthesis of liquid biofuels. Chemo-catalysis is mainly metal based, which requires harsh process conditions. Alternatively, biocatalysts are currently being investigated as a result of several advantages such as mild reaction conditions, recyclability, selectivity and biodegradability. In this work, recent biocatalytic technologies for the preparation of liquid biofuels through food waste valorization are discussed thoroughly. Lipases are employed for the synthesis of biodiesel and the upgradation of bio-oil, whereas methane mono-oxygenases could be explored for the production of methanol via the oxidation of methane generated from food wastes. Industrial production of ethanol from food waste using bioconversion technologies is a success story. To date, there has been no specific report on the use of food waste for propanol preparation using enzymes. The ABE process (Acetone–Butanol–Ethanol) (using suitable microorganisms) is used for butanol preparation, where the vacuum stripping system is integrated to remove butanol from the broth and circumvent inhibition. The synthesis of hydrocarbon fuels from fatty acids and triglycerides can be carried out using enzymes, such as carboxylic acid reductase and fatty acid photodecarboxylase (an algal photoenzyme). Both carboxylic acid reductase and fatty acid photodecarboxylase have not yet been applied in the direct valorization of food wastes. Furthermore, limitations of the reported methods, societal and economic aspects and a fresh perspective on the subject, along with important examples, are described. Full article
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2022

Jump to: 2023

8 pages, 1622 KiB  
Article
Green Methane as a Future Fuel for Light-Duty Vehicles
Fermentation 2022, 8(12), 680; https://doi.org/10.3390/fermentation8120680 - 27 Nov 2022
Cited by 1 | Viewed by 1545
Abstract
Food waste (FW) has traditionally been disposed by incineration or landfilling; however, it can be converted to green methane (GM) via anaerobic digestion, and GM can be used as fuel for light-duty natural gas vehicles (LDNGVs). A lifecycle assessment (LCA) of FW-based GM [...] Read more.
Food waste (FW) has traditionally been disposed by incineration or landfilling; however, it can be converted to green methane (GM) via anaerobic digestion, and GM can be used as fuel for light-duty natural gas vehicles (LDNGVs). A lifecycle assessment (LCA) of FW-based GM production and LDNGV operation in China, a new scenario, was performed. The LCA results were compared with those for the conventional FW treatment, where a “well-to-wheel” system boundary including FW collection, GM production from FW, and vehicle manufacturing, operation, and disposal was defined. The LCA results showed that the global warming impacts of the new FW scenario are 44.3% lower than those of the conventional option. The fine particulate matter formation impact of the new FW scenario was dominated by the displacement effect of electricity supply to anaerobic digestion, followed by CO2 adsorption by the primary source. The sensitivity analysis showed that hydroelectric power as the best primary source for electricity supply could substantially reduce both global warming and FRS in the new scenario. In the short term, the proposed FW scenario could be a feasible option for achieving sustainable society by minimizing environmental impacts of FW treatment. Full article
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17 pages, 3287 KiB  
Article
Multi-Objective Optimization of Beverage Based on Lactic Fermentation of Goat’s Milk Whey and Fruit Juice Mixes by Kefir Granules
Fermentation 2022, 8(10), 500; https://doi.org/10.3390/fermentation8100500 - 30 Sep 2022
Cited by 4 | Viewed by 1711
Abstract
Numerous fruits are produced in Ecuador, of which about 40% are never eaten. In addition, fresh goat cheeses are in high demand. However, goat cheese generates goat milk whey with high contamination loads, and, therefore, it must be adequately treated before being discharged [...] Read more.
Numerous fruits are produced in Ecuador, of which about 40% are never eaten. In addition, fresh goat cheeses are in high demand. However, goat cheese generates goat milk whey with high contamination loads, and, therefore, it must be adequately treated before being discharged into ecosystems. This research aims to use a mixture of tree tomato, common strawberry juices, and goat’s milk whey, to be statically fermented by milk and water kefir grains (WKG) for 48 h. For this, a dual mixture design of L-optimal response surface methodology was carried out to find the conditions that maximized all the responses evaluated (lactic-acid bacteria and yeasts concentrations and the overall acceptability assessed on a 7-point scale). Experiments were carried out in San Gabriel, Ecuador. Temperatures during the day and night were 20.2 ± 0.3 °C and 18.7 ± 0.3 °C, respectively. Three conditions were selected, where the highest response values were reached. Complementary experiments demonstrated the validity of the models. When comparing the results of the present study with similar ones carried out previously, higher values were observed in the concentration of yeasts, which seems related to the presence of the WKG. It is concluded that they could be suitable functional beverage candidates. Full article
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15 pages, 1253 KiB  
Article
Microbial Astaxanthin Production from Agro-Industrial Wastes—Raw Materials, Processes, and Quality
Fermentation 2022, 8(10), 484; https://doi.org/10.3390/fermentation8100484 - 26 Sep 2022
Cited by 7 | Viewed by 2859
Abstract
The antioxidant and food pigment astaxanthin (AX) can be produced by several microorganisms, in auto- or heterotrophic conditions. Regardless of the organism, AX concentrations in culture media are low, typically about 10–40 mg/L. Therefore, large amounts of nutrients and water are necessary to [...] Read more.
The antioxidant and food pigment astaxanthin (AX) can be produced by several microorganisms, in auto- or heterotrophic conditions. Regardless of the organism, AX concentrations in culture media are low, typically about 10–40 mg/L. Therefore, large amounts of nutrients and water are necessary to prepare culture media. Using low-cost substrates such as agro-industrial solid and liquid wastes is desirable for cost reduction. This opens up the opportunity of coupling AX production to other existing processes, taking advantage of available residues or co-products in a biorefinery approach. Indeed, the scientific literature shows that many attempts are being made to produce AX from residues. However, this brings challenges regarding raw material variability, process conditions, product titers, and downstream processing. This text overviews nutritional requirements and suitable culture media for producing AX-rich biomass: production and productivity ranges, residue pretreatment, and how the selected microorganism and culture media combinations affect further biomass production and quality. State-of-the-art technology indicates that, while H. pluvialis will remain an important source of AX, X. dendrorhous may be used in novel processes using residues. Full article
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11 pages, 603 KiB  
Article
Changes in Bioactive Compounds, Antioxidant Activities and Chemical Properties of Pickled Tea By-Product Fermentation: Promising Waste Management and Value-Added Product
Fermentation 2022, 8(10), 472; https://doi.org/10.3390/fermentation8100472 - 21 Sep 2022
Cited by 1 | Viewed by 3248
Abstract
Pickled tea is an ethnic fermented product produced using Assam tea (Camellia sinensis var. assamica) leaves. It is produced in large quantities every year and the liquid waste from its production is estimated to be up to 2500 mL per every [...] Read more.
Pickled tea is an ethnic fermented product produced using Assam tea (Camellia sinensis var. assamica) leaves. It is produced in large quantities every year and the liquid waste from its production is estimated to be up to 2500 mL per every kilogram of pickled tea production. To reduce the waste, pickled tea juice remaining from the process was developed into (1) pineapple kombucha and (2) formulated functional drinks as “value added” products. The juice used for making kombucha was collected at 15 days of pickled tea fermentation due to its high value in antioxidant activity (previous study, 2250 µmol TE per g DW). After fermenting the juice with starter culture, the properties of pineapple kombucha were assessed at 0, 1, 3, 5, 7, 9, 11 days. Results showed that the total phenolic of pineapple kombucha was reduced, while antioxidant assay (FRAP and ORAC) slightly increased. The most suitable fermentation period of pineapple kombucha was at day 3. The formulated drink was made from mixing pineapple kombucha with ginger and lemon juice at various ratios including 100:0:0, 80:10:10 and 80:15:5. The ratio 80:10:10 gave the highest TP and antioxidant activity for the functional drink. In addition, for sensory analysis, liking attribute of 80:15:5 fermented juice kombucha pineapple favor was significantly higher compared to other formulations. The study demonstrates the promising second fermentation process of by-product juice from pickled tea production for the conversion to value-added functional drink with reasonable antioxidant properties. Full article
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16 pages, 1853 KiB  
Article
Bioconversion of Some Agro-Residues into Organic Acids by Cellulolytic Rock-Phosphate-Solubilizing Aspergillus japonicus
Fermentation 2022, 8(9), 437; https://doi.org/10.3390/fermentation8090437 - 03 Sep 2022
Cited by 3 | Viewed by 1996
Abstract
Biological-based conversion of agricultural residues into bioactive compounds may be considered to be the basis for various vital industries. However, finding a suitable microorganism is a challenge in the bioconversion process. Therefore, this study was conducted to find local fungal isolates able to [...] Read more.
Biological-based conversion of agricultural residues into bioactive compounds may be considered to be the basis for various vital industries. However, finding a suitable microorganism is a challenge in the bioconversion process. Therefore, this study was conducted to find local fungal isolates able to convert a combination of plant biomass residues into organic acids (OAs). Based on their cellulase and phytase activities and rock phosphate (RP) solubilization potential, an efficient 15 fungal isolates (named F1 to F15) were selected and identified by both morphological and molecular methods using the 18S rRNA sequencing technique. The best fungal isolate (F15) was identified as Aspergillus japonicus. After 4 weeks of incubation below solid-state fermentation (SSF) with a mix of sugarcane bagasse and faba bean straw (3:7), with 7.5% (v/w) fungal inoculum to the growth medium, the biodegradation process by the fungus reached its peak, i.e., maximum cellulolytic activity and RP solubilization ability. Under such fermentation conditions, seven organic acids were detected using HPLC, in the following order: ascorbic acid > oxalic acid > formic acid > malic acid > succinic acid > lactic acid > citric acid. Based on the results, Aspergillus japonicus (F15) could produce OAs and cellulose enzymes, and could be considered a new single-step bio-converter of sugarcane bagasse and faba bean straw residues into OAs. Furthermore, this fungus could be a new source of fungal cellulose, and could present a practical approach to reducing environmental contamination. Additional work is encouraged for more optimization of fermentation conditions. Full article
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13 pages, 289 KiB  
Article
Effect of Cyanide-Utilizing Bacteria and Sulfur Supplementation on Reducing Cyanide Concentration and In Vitro Degradability Using In Vitro Gas Production Technique
Fermentation 2022, 8(9), 436; https://doi.org/10.3390/fermentation8090436 - 03 Sep 2022
Cited by 3 | Viewed by 1743
Abstract
The objective of this research was to supplement the cyanide-utilizing bacteria and sulfur in the HCN-rich diet, affecting the gas production and fermentation of rumen in vitro, and lowering the HCN content and the digestion of nutrients. A 2 × 2 × 3 [...] Read more.
The objective of this research was to supplement the cyanide-utilizing bacteria and sulfur in the HCN-rich diet, affecting the gas production and fermentation of rumen in vitro, and lowering the HCN content and the digestion of nutrients. A 2 × 2 × 3 factorial experiment in a completely randomized design was applied during the test. In the experiments, three factors were used. Factor A was the level of CUB at 0 and 108 CFU/mL. Factor B was the level of sulfur in the diet at 0% and 3% of dry matter (DM). Factor C was the three levels of potassium cyanide (KCN) at 0, 300, and 600 ppm. The interaction of CUB × sulfur × KCN affected gas production from the immediately soluble fraction (a) (p < 0.05). However, the greatest ruminal cyanide concentration was found when CUB (with and without), sulfur (3%), and KCN (600 ppm) were introduced at 0 h (p < 0.05). It revealed that the addition of CUB and sulfur had a significant impact on gas accumulation at 96 h (p < 0.05). The addition of CUB with sulfur had an effect on pH at 2 h and ruminal cyanide levels at 6 h (p < 0.05). At 2 h, sulfur supplementation with KCN had an effect on NH3-N (p < 0.01). The addition of sulfur (3%) and KCN (300 ppm) produced the highest ammonia nitrogen. However, the combination of sulfur (3%) and KCN (600 ppm) produced the lowest level of ammonia nitrogen (p < 0.01). CUB supplementation increased the in vitro dry matter digestibility (IVDMD) by 11.16% compared to the without-CUB supplemented group (p < 0.05). Supplementation with 3% sulfur increased the in vitro neutral detergent fiber (IVNDFD) by 16.87% but had no effect on IVDMD or in vitro acid detergent fiber (IVADFD) (p < 0.05). The volatile fatty acid (VFA) such as acetate, propionate, and butyrate were not different when CUB, sulfur, and KCN were added. Doses above 600 ppm had the lowest concentrations of TVFA and propionate (p < 0.01). Based on the results of this investigation, supplementing with CUB and sulfur (3%) may improve cumulative gas, digestibility, and TVAF. Supplementing with CUB, on the other hand, reduced HCN the most, by 54.6%. Full article
11 pages, 1238 KiB  
Communication
Potential of New Bacterial Strains for a Multiproduct Bioprocess Application: A Case Study Using Isolates of Lactic Acid Bacteria from Pineapple Silage of Costa Rican Agro-Industrial Residues
Fermentation 2022, 8(8), 361; https://doi.org/10.3390/fermentation8080361 - 29 Jul 2022
Cited by 1 | Viewed by 2331
Abstract
Lactic acid bacteria (LAB) with potential for the development of multi-product processes are necessary for the valorization of side streams obtained during the biotechnological production of lactic acid (LA). In this study, 14 LAB strains isolated from pineapple agro-industrial residues in Costa Rica [...] Read more.
Lactic acid bacteria (LAB) with potential for the development of multi-product processes are necessary for the valorization of side streams obtained during the biotechnological production of lactic acid (LA). In this study, 14 LAB strains isolated from pineapple agro-industrial residues in Costa Rica were cultivated in microplates, and the six strains with the highest growth were selected for fermentation in microbioreactors to evaluate the production of LA and acetic acid, and the consumption of glucose. Lacticaseibacillus paracasei 6710 and L. paracasei 6714 presented the highest OD600 values (1.600 and 1.602, respectively); however, the highest LA (in g/L) production was observed in L. paracasei 6714 (14.50 ± 0.20) and 6712 (14.67 ± 0.42). L. paracasei 6714 was selected for bioreactor fermentation and reached a maximum OD600 of 6.3062 ± 0.141, with a LA yield of 84.9% and a productivity of 1.06 g L−1 h−1 after 21 h of fermentation. Finally, lipoteichoic acid (LTA) detection from biomass was performed and the antimicrobial activity of the compounds present in the supernatant was studied. LTA was detected from L. paracasei 6714 biomass, and its supernatant caused significant inhibition of foodborne surrogate microorganisms. LAB isolated from pineapple silage have biotechnological potential for multiproduct processes. Full article
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10 pages, 1998 KiB  
Communication
Increase in Electrical Parameters Using Sucrose in Tomato Waste
Fermentation 2022, 8(7), 335; https://doi.org/10.3390/fermentation8070335 - 16 Jul 2022
Cited by 15 | Viewed by 3004
Abstract
The use of organic waste as fuel for energy generation will reduce the great environmental problems currently caused by the consumption of fossil sources, giving agribusiness companies a profitable way to use their waste. In this research, tomato waste with different percentages of [...] Read more.
The use of organic waste as fuel for energy generation will reduce the great environmental problems currently caused by the consumption of fossil sources, giving agribusiness companies a profitable way to use their waste. In this research, tomato waste with different percentages of sucrose (0-target, 5, 10, and 20%) was used in microbial fuel cells manufactured on a laboratory scale with zinc and copper electrodes, managing to generate maximum peaks of voltage and a current of 1.08 V and 6.67 mA in the cell with 20% sucrose, in which it was observed that the optimum operating pH was 5.29, while the MFC with 0% (target) sucrose generated 0.91 V and 3.12 A on day 13 with a similar pH, even though all the cells worked in an acidic pH. Likewise, the cell with 20% sucrose had the lowest internal resistance (0.148541 ± 0.012361 KΩ) and the highest power density (224.77 mW/cm2) at a current density of 4.43 mA/cm2, while the MFC with 0% sucrose generated 160.52 mW/cm2 and 4.38 mA/cm2 of power density and current density, respectively, with an internal resistance of 0.34116 ± 0.2914 KΩ. In this sense, the FTIR (Fourier-transform infrared spectroscopy) of all the substrates used showed a high content of phenolic compounds and carboxylate acids. Finally, the MFCs were connected in a series and managed to generate a voltage of 3.43 V, enough to light an LED (green). These results give great hope to companies and society that, in the near future, this technology can be taken to a larger scale. Full article
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14 pages, 1077 KiB  
Article
Kefir Enriched with Carob (Ceratonia siliqua L.) Leaves Extract as a New Ingredient during a Gluten-Free Bread-Making Process
Fermentation 2022, 8(7), 305; https://doi.org/10.3390/fermentation8070305 - 28 Jun 2022
Cited by 11 | Viewed by 2667
Abstract
This work is focused on the preparation of an innovative gluten-free (GF) bread with remarkable softness and antioxidant features over time. To overcome the technological inconveniences related to the removal of gluten from bread, the kefir beverage fortified with antioxidant vegetable extracts is [...] Read more.
This work is focused on the preparation of an innovative gluten-free (GF) bread with remarkable softness and antioxidant features over time. To overcome the technological inconveniences related to the removal of gluten from bread, the kefir beverage fortified with antioxidant vegetable extracts is employed as a functional ingredient in the bread-making process. In this context, carob (Ceratonia siliqua L.) leaves represent an outstanding source of active molecules and are proposed to enrich milk-based beverages. Different extraction strategies were evaluated, and the process was improved to select a solvent (water, ethanol, or hydroalcoholic solution) and methodology (Soxhlet or ultrasound-assisted extraction) able to guarantee the best performances in terms of yield and antioxidant capacity. For kefir addition, two varieties of carob leaves (Selvatica and Amele) are employed. Functional GF bread, obtained by partially replacing the water with the enriched kefir, is prepared, and the final product is characterized in terms of its antioxidant and rheological properties. The final product shows improved compositional and technological parameters over time. Full article
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11 pages, 2240 KiB  
Article
Golden Berry Waste for Electricity Generation
Fermentation 2022, 8(6), 256; https://doi.org/10.3390/fermentation8060256 - 27 May 2022
Cited by 14 | Viewed by 2202
Abstract
The environmental problems caused by the excessive use of fossil fuels for electricity generation have led to the development of new technologies. Microbial fuel cells constitute a technology that uses organic sources for electricity generation. This research gives a novel means of using [...] Read more.
The environmental problems caused by the excessive use of fossil fuels for electricity generation have led to the development of new technologies. Microbial fuel cells constitute a technology that uses organic sources for electricity generation. This research gives a novel means of using Golden Berry waste as fuel for electricity generation through microbial fuel cells made at low cost, achieving current and voltage peaks of 4.945 ± 0.150 mA and 1.03 ± 0.02 V, respectively. Conductivity values increased up to 148 ± 1 mS/cm and pH increased up to 8.04 ± 0.12 on the last day. The internal resistance of cells was 194.04 ± 0.0471 Ω, while power density was 62.5 ± 2 mW/cm2 at a current density of 0.049 A/cm2. Transmittance peaks of the Fourier-transform infrared (FTIR) spectrum showed a decrease when comparing the initial and final spectra, while the bacterium Stenotrophomonas maltophilia was molecularly identified with an identity percentage of 99.93%. The three cells connected in series managed to generate 2.90 V, enough to turn on a TV remote control. This research has great potential to be scalable if it is possible to increase the electrical parameters, generating great benefits for companies, farmers, and the population involved in the production and marketing of this fruit. Full article
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14 pages, 1258 KiB  
Article
Designing a Waste-Based Culture Medium for the Production of Plant Growth Promoting Microorganisms Based on Cladodes Juice from Opuntia ficus-indica Pruning
Fermentation 2022, 8(5), 225; https://doi.org/10.3390/fermentation8050225 - 14 May 2022
Cited by 6 | Viewed by 3350
Abstract
The production of beneficial microorganisms is the first step to obtain a commercial-based product for application in agriculture. In this study, prickly pear (Opuntia ficus-indica) pruning waste was evaluated as a raw material for the production of large amounts of Plant [...] Read more.
The production of beneficial microorganisms is the first step to obtain a commercial-based product for application in agriculture. In this study, prickly pear (Opuntia ficus-indica) pruning waste was evaluated as a raw material for the production of large amounts of Plant Growth Promoting Microorganisms (PGPMs) reducing the number of generated wastes. Specifically, five PGPMs constituting a synthetic microbial consortium with complementing plant growth-promoting traits were grown on a laboratory scale and, subsequently, on a pilot scale using a 21-L bioreactor. Primarily, the physical-chemical characterization of the culture medium obtained from the juice of Opuntia cladodes was carried out, revealing the presence of sugars and organic acids with different molar ratios. Compared to conventional media, the waste medium did not show significant differences in bacterial growth efficiency. Instead, the survival rates of the bacteria grown in cladodes juice media, after air-drying on zeolite or freeze-drying, were significantly higher than those observed when they were grown in conventional media. The present work is the first conducted on a pilot-scale that maximizes the production of PGPMs in submerged fermentation using cladodes juice from Opuntia, reducing both economic and environmental impacts associated with the generation of wastes. Full article
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20 pages, 2932 KiB  
Article
Improvement of the Nutritional Quality of Psophocarpus tetragonolobus Tubers by Fermentation with Ruminal Crabtree-Negative Yeasts on the In Vitro Digestibility and Fermentation in Rumen Fluid
Fermentation 2022, 8(5), 209; https://doi.org/10.3390/fermentation8050209 - 04 May 2022
Cited by 5 | Viewed by 2559
Abstract
The purpose of this study was to determine how ruminal Crabtree-negative yeast affects the nutritional characteristics of winged bean (Psophocarpus tetragonolobus) tubers (WBT), in vitro gas and digestibility, and rumen fermentation. The experiment was carried out in a randomized complete design [...] Read more.
The purpose of this study was to determine how ruminal Crabtree-negative yeast affects the nutritional characteristics of winged bean (Psophocarpus tetragonolobus) tubers (WBT), in vitro gas and digestibility, and rumen fermentation. The experiment was carried out in a randomized complete design with a 5 × 2 (+1) factorial arrangement. Factor A determined the WBT products (a1 = dry WBT, a2 = fermented WBT without yeast in media solution, a3 = fermented WBT with Pichia kudriavzevii KKU20, a4 = fermented WBT with Candida tropicalis KKU20, and a5 = fermented WBT with Saccharomyces cerevisiae), whereas factor B determined the level of fermented WBT replacing cassava chips (b1 = WBT at 50% and b2 = 100% levels). The results of the experiment showed that the fermentation approach could increase the crude protein (CP) content of WBT by around 7% (p < 0.01). The WBT fermented with yeast lowered the number of aerobic bacteria during the fermentation process (p < 0.01). P. kudriazevii KKU20 yeast strain had a 17.3% higher final asymptotic gas volume (Vf) than the C. tropicalis KKU20. Crabtree-negative yeast had a higher in vitro dry matter digestibility (IVDMD) than Crabtree-positive yeast after 12 h of incubation (p < 0.01). Fermented WBT with yeast had a higher IVDMD after 24 h of incubation than fermented WBT without yeast in the media solution (p < 0.05). The fermented WBT with C. tropicalis KKU20 enhanced propionic acid (C3) concentrations when cassava chips were replaced for half of all of the diet (C3 ranged from 26.0 to 26.4 mol/100 mol; p < 0.01). Furthermore, Crabtree-negative yeast isolated from the rumen stimulates rumen bacteria more effectively than Crabtree-positive yeast (p < 0.01). According to our findings, nutritional enrichment with yeast might increase the in vitro gas production and digestibility of WBT. The study also demonstrated that Crabtree-negative yeast has a promising lead in terms of improving rumen fermentation quality. However, further research is required before deciding on an effective approach for optimizing the potential of WBT as a feed source. Full article
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14 pages, 1955 KiB  
Article
Biotransformation of Agricultural By-Products into Biovanillin through Solid-State Fermentation (SSF) and Optimization of Different Parameters Using Response Surface Methodology (RSM)
Fermentation 2022, 8(5), 206; https://doi.org/10.3390/fermentation8050206 - 02 May 2022
Cited by 5 | Viewed by 3315
Abstract
Vanillin is a flavorful and aromatic secondary metabolite found in vanilla plants. Natural vanillin, produced through processed vanilla beans accounts for scarcely 0.2% of industrial requirements. Vanillin produced via chemical methods and microbial fermentation fills the remaining gap. Among naturally available precursors for [...] Read more.
Vanillin is a flavorful and aromatic secondary metabolite found in vanilla plants. Natural vanillin, produced through processed vanilla beans accounts for scarcely 0.2% of industrial requirements. Vanillin produced via chemical methods and microbial fermentation fills the remaining gap. Among naturally available precursors for biovanillin synthesis, ferulic acid is widely used because of its structural similarity and abundant availability. Herein, various agricultural lignocellulosic by-products (sugarcane bagasse, wheat straw, rice straw, rice bran, and corn cob) were scrutinized for their ferulic acid content, and their biotransformation into biovanillin was examined by solid-state fermentation (SSF). Then, different physicochemical parameters, i.e., moisture content, pH, temperature, inoculum size, and incubation days, were optimized to achieve a high yield of biovanillin using central composite design (CCD) of response surface methodology (RSM). Among agricultural by-products tested, sugarcane bagasse produced 0.029 g/100 g of biovanillin using Enterobacter hormaechei through SSF. After optimization, the highest concentration of biovanillin (0.476 g/100 g) was achieved at a moisture content of 70%, temperature of 37.5 °C, pH 7.5, inoculum size of 4 mL and incubation time of 48 h. The F-value of 6.10 and p-value of 0.002 evidenced the ultimate significance of the model. The significance of the constructed model was supported by the 91.73% coefficient of determination (R2), indicating that the effects of moisture, pH, and temperature were significant. HPLC and FTIR confirmed the sample identification and purity (was reported to be 98.3% pure). In conclusion, sugarcane bagasse appears to be a cost-effective substrate choice for large-scale biovanillin production. Full article
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11 pages, 912 KiB  
Article
Single Cell Protein Production through Multi Food-Waste Substrate Fermentation
Fermentation 2022, 8(3), 91; https://doi.org/10.3390/fermentation8030091 - 23 Feb 2022
Cited by 26 | Viewed by 8248
Abstract
Today, food valorization represents an important challenge to environmental sustainability. Food waste can be used as a substrate for single cell protein production suitable for animal feed. In this study, animal and agricultural food waste, represented by fish, pineapple, banana, apple, and citrus [...] Read more.
Today, food valorization represents an important challenge to environmental sustainability. Food waste can be used as a substrate for single cell protein production suitable for animal feed. In this study, animal and agricultural food waste, represented by fish, pineapple, banana, apple, and citrus peels, have been used simultaneously as a fermentation substrate for single cell protein production by Saccharomyces cerevisiae, to evaluate the possibility of using a multi complex substrate for a simultaneous biovalorization of different food waste. The fermentation process was implemented by the supplementation of a hydrolytic enzyme and nutrient to allow the best yeast growing conditions. At the end of the process, the final substrate was enriched in protein, reaching up to 40.19% of protein, making the multisubstrate useful for animal feed. The substrate was also investigated for crude lipid, ash, lignin, soluble and insoluble sugar. The substrate composition at the end of the fermentation process was represented by 14.46% of crude lipid, 1.08% ash, 6.29% lignin. Conversely, the soluble and insoluble sugars dropped down from 20.5% to 6.10% and 19.15% to 2.14%, respectively, at the end of the process. Full article
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