Optimizing Household Wastes (Rice, Vegetables, and Fruit) as an Environmentally Friendly Electricity Generator

The high consumption of electricity and issues related to fossil energy have triggered an increase in energy prices and the scarcity of fossil resources.Consequently,many researchers are seeking alternative energy sources.One potential technology,the Microbial Fuel Cell(MFC)based on rice,vegetable,and fruit wastes,can convert chemical energy into electrical energy.This study aims to determine the potency of rice,vegetable,and fruit waste assisted by Cu/Mg electrodes as a generator of electricity.The method used was a laboratory experiment,including the following steps:electrode preparation,waste sample preparation,incubation of the waste samples,construction of a reactor using rice,vegetable,and fruit waste as a source of electricity,and testing.The tests included measuring electrical conductivity,electric current,voltage,current density,and power density.Based on the test results,the maximum current and voltage values for the fruit waste samples were 5.53 V and 11.5 mA,respectively,with a current density of 2.300 mA/cm^(2) and a power density of 12.719 mW/cm^(2).The results indicate the potential for a future development.The next step in development involves determining the optimum conditions for utilizing of rice,vegetable,and fruit waste.The results of the electrical conductivity test on rice,vegetable,and fruit waste samples were 1.51,2.88,and 3.98 mS,respectively,with the highest electrical conductivity value found in the fruit waste sample.

Determination and evaluation of biogas and methane productions of vegetable and fruit wastes with Hohenheim Batch Test method

Nowadays,biogas technology applications are gradually increasing worldwide due to the economic and environmental benefits.Many researches and studies related to the determination of the biogas potential of organic waste materials have been carried out in the recent years.Studies to determine the specific methane potential of organic waste materials have a great importance for both design and economical operation of the biogas plants.Energy potential that will be recovered from organic wastes is substantial in Turkey.Thanks to biogas plants gathering vegetable-fruit wastes and other organic wastes are planned to produce significant amount of renewable energy in Turkish markets.Owing to the use of organic wastes,the disposal of waste as well as energy production,soil,water and air pollution in terms of environmental protection are also minimized.On the other hand,the organic wastes produced from plants can also be utilized as fertilizer in vegetable production.In this study,the cumulative biogas and methane production of vegetable and fruit wastes were experimentally determined with HBT(Hohenheim Batch Test)method.Biogas and methane yields of vegetable and fruit wastes were found as 0.54-0.73 Nm^(3)/(kg ODM)and 0.29-0.37 Nm^(3)/(kg ODM),respectively.The highest value of the cumulative specific methane production was tomato wastes(0.37 Nm^(3)/(kg ODM)),and the lowest value was lettuce wastes(0.29 Nm^(3)/(kg ODM)),as well.The average cumulative specific methane production values of mixed vegetable and fruit wastes are determined as 0.34 Nm^(3)/(kg ODM).

Fruit Waste and Sugarcane Bagasse as Potential Natural Resources of Mineral and Lipophilic Substances

The objectives of this study were to explore alternatives for using fruit waste and sugarcane bagasse as important sources for new products and potential applications in the food industry. Fast foods are part of modern life, as well as sources for producing biofuels based on biomass. The mineral content and compounds of nutritional interest, such as lipophilic substances, were determined in fruit waste （orange peels, passion fruit, bananas, grapes） and sugarcane bagasse. Significant differences were found in the samples tested, where minerals, such as potassium, nitrogen, zinc and iron, were found in fruit residues （bananas, oranges, passion fruit） and sugarcane bagasse. Banana residues were the most important source of minerals, followed by orange peels. Gas chromatography mass spectrography （GC-MS） analyses of the lipophilic fractions obtained from the plant residues revealed the presence of mostly saturated （palmitic, stearic） and unsaturated （oleic and linoleic） fatty acids, as well as other nutritionally valuable compounds, such as antioxidants （flavones in orange residues）. The residues studied here can be used for future research to optimize pretreatment and hydrolysis of biomass for bioethanol production.

Rheological Characterization of a Mixed Fruit/Vegetable Puree Feedstock for Hydrogen Production by Dark Fermentation

Bio-hydrogen (Bio-H2) production from the organic fraction of solid waste, as fruit and vegetable wastes, constitutes an interesting and feasible technology to obtain clean energy. In spite of the feasibility to produce Bio-H2 from fruit/vegetable wastes (FVW), data about its rheological characterization are scarce. This information is useful to establish the hydrodynamic behavior, which controls the overall mixing process when the feedstock for Bio-H2 production process is a mixture of FVW. In this work, the rheological behavior of a vegetable/fruit waste mixture was characterized. The effect of the solids content (%, w/w), temperature, time (tyxotropy effects) and shear rate over the apparent viscosity of the mixture was evaluated. Most of the mixtures showed non-Newtonian behavior. The curves are typical rheofluidizing fluids. The rheological curves were different at increasing solids contents (80%, 60%, 40% and 30%), independent from the temperature. Rheological data were fitted to the power law model. Correlation factors R2 for the different mixtures were 0.991-0.995 for 80%, 0.961 -0.986 for 60%, 0.890 -0.925 for 40%. In the case of 30% of solids, the R2 value was not acceptable, and it was also found that this mixture was very near to the Newtonian behavior. Calculated activation energies (Ea) values were 15.98, 14.89 and 20.96 kJ/mol for the 80%, 60%, 40% mixtures, respectively. FVW purees rheological behavior was well characterized by Carbopol solutions at given concentrations and pH values. This fluid can be used as a model for other studies, e.g. LDA (Laser Doppler Anemometry) and PIV (Particle Image Velocimetry).

Microbial community structures in an integrated two-phase anaerobic bioreactor fed by fruit vegetable wastes and wheat straw

The microbial community structures in an integrated two-phase anaerobic reactor（ITPAR）were investigated by 16 S r DNA clone library technology. The 75 L reactor was designed with a 25 L rotating acidogenic unit at the top and a 50 L conventional upflow methanogenic unit at the bottom, with a recirculation connected to the two units. The reactor had been operated for 21 stages to co-digest fruit/vegetable wastes and wheat straw, which showed a very good biogas production and decomposition of cellulosic materials. The results showed that many kinds of cellulose and glycan decomposition bacteria related with Bacteroidales,Clostridiales and Syntrophobacterales were dominated in the reactor, with more bacteria community diversities in the acidogenic unit. The methanogens were mostly related with Methanosaeta, Methanosarcina, Methanoculleus, Methanospirillum and Methanobacterium; the predominating genus Methanosaeta, accounting for 40.5%, 54.2%, 73.6% and 78.7% in four samples from top to bottom, indicated a major methanogenesis pathway by acetoclastic methanogenesis in the methanogenic unit. The beta diversity indexes illustrated a more similar distribution of bacterial communities than that of methanogens between acidogenic unit and methanogenic unit. The differentiation of methanogenic community composition in two phases, as well as pH values and volatile fatty acid（VFA） concentrations confirmed the phase separation of the ITPAR. Overall, the results of this study demonstrated that the special designing of ITPAR maintained a sufficient number of methanogens, more diverse communities and stronger syntrophic associations among microorganisms, which made two phase anaerobic digestion of cellulosic materials more efficient.

Determination of the Antioxidant Potentials of Two Different Varieties of Banana Peels in Two Different Solvents

Fruit wastes which are perishable pose a big problem to pollution monitoring agencies;however these problems can be reduced by utilizing the high value compounds present in the food waste. Banana peels contain a reasonable number of antioxidant compounds such as gallocatechin and dopamine. This paper investigates the anti-oxidant potential of two different varieties of Banana peels (Dwarf cavandish and Musa omini). The peels were extracted with two different solvents (Methanol and Ethanol) using the soxhlet extractor. The results show that ethanolic extracts have higher phenolics and flavonoid contents (336.83 - 383.83 mgGAE/100g, 242.83 - 252.82 mgRutin/100g) compared to the methanolic extracts of the same banana varieties (299.42 - 344 mgGAE/100g, 240.77 - 241.23 mgRutin/100g). However methanolic extracts exhibit higher DPPH Antioxidants Activity (30.82% - 51.66%) compared to ethanolic extracts (25.44% - 30.27%). This implies that antioxidative compounds other than phenolics and flavonoids were also involved in inhibiting the DPPH Radicals. It was also observed that at any concentration between 0.5 - 2.5 mg, ethanol extracts of both dwarf cavandish and musa omini had higher reducing power than the other two varieties.

Kaempferol and its derivatives:Biological activities and therapeutic potential

Kaempferol,a natural plant-origin flavonoid,exhibits therapeutic anti-inflammatory,antioxidant,anticancer,antidiabetic,and neuroprotective properties.Kaempferol acts within several distinct mechanisms like apoptotic induction in cancer cells,enzymatic inhibition,signalling pathway inhibition,and downregulation in cell viability during the G2/M phase of cell division.This review summarizes the therapeutic effects of kaempferol against several health ailments.The recent progress on kaempferol obtained from fruits and vegetables as an antioxidant,anti-inflammatory,anticancer,antidiabetic,and neuroprotective agent and its mechanisms of action are also discussed.In addition,kaempferol has been reported to be present in wastes and byproducts from post-fruit and vegetable processing.Thus,a paradigm shift towards valorizing fruits and vegetable industrial wastes/byproducts to obtain bioactive kaempferol can support the circular economy pillar for generating wealth from waste and for finding a sustainable alternative source.

Influence of Substrate Proximate Properties on Voltage Production in Microbial Fuel Cells

In the current study, we investigate the influence of proximate properties of five different fruits on voltage and current generated from a double chamber microbial fuel cell. Fruits comprising of avocado, tomato, banana, watermelon and mango were analyzed for proximate properties using standard methods. Rumen fluid was used as the inoculum in fabricated H-shaped double chamber fuel cells with graphite rods electrodes at room temperature. The voltage and current generated were monitored daily for 30 days using a DT9205A digital multi-meter. The average moisture content for the fruits samples ranged from 82.86% - 95.16% while the crude fat was in the range of 0.12% - 0.33% with avocado having fat levels at 9.03%. Carbohydrates level was the highest in banana at 19.24% and the lowest in tomato waste at 2.93%. Tomato waste produced the highest voltage of 0.702 V on day 20 while lower voltage was noted in watermelon fruit wastes at 0.019 V. The voltage and current increased linearly with time for all the fruit wastes. These results indicate that substrate proximate properties influence the voltage and current generated in microbial fuel cell. In addition, moisture content and carbohydrates level were the major factors that influence microbial fuel cells performance.

Effects of mixture ratio on anaerobic co-digestion with fruit and vegetable waste and food waste of China

The biochemical methane potentials for typical fruit and vegetable waste （FVW） and food waste （FW） from a northern China city were investigated, which were 0.30, 0.56 m3 CH4/kgVS （volatile solids） with biodegradabilities of 59.3% and 83.6%, respectively. Individual anaerobic digestion testes of FVW and FW were conducted at the organic loading rate （OLR） of 3 kg VS/（m3-day） using a lab-scale continuous stirred-tank reactor at 35°C. FVW could be digested stably with the biogas production rate of 2.17 ma/（m3-day） and methane production yield of 0.42 m3 CH4/kg VS. However, anaerobic digestion process for FW was failed due to acids accumulation. The effects of FVW： FW ratio on co-digestion stability and performance were further investigated at the same OLR. At FVW and FW mixing ratios of 2：1 and 1：1, the performance and operation of the digester were maintained stable, with no accumulation of volatile fatty acids （VFA） and ammonia. Changing the feed to a higher FW content in a ratio of FVW to FW 1：2, resulted in an increase in VFAs concentration to 1100-1200 rag/L, and the methanogenesis was slightly inhibited. At the optimum mixture ratio 1：1 for co-digestion of FVW with FW, the methane production yield was 0.49 m3 CH4/kg VS, and the volatile solids and soluble chemical oxygen demand （sCOD） removal efficiencies were 74.9% and 96.1%, respectively.

Chemical characterisation, insecticidal and antioxidant activities of essential oils from four Citrus spp. fruit peel waste

Citrus peel is a major fruit waste generated during the processing of citrus fruits. We extracted and chemically characterised essential oil from four different species of citrus peel waste and evaluated its insecticidal, antioxidant and phytotoxic activities. GC-MS/MS characterisation revealed D-limonene as the major constituent of citrus peel waste essential oil. The essential oils from the four citrus peel wastes showed significant contact, fumigant and repellent activities against two key stored grain pests Tribolium castaneum (Herbst) and Callosobruchus chinensis (L.). DPPH, ABTS, and FRAP assays revealed the antioxidant potential of the citrus peel waste essential oil. The essential oil did not affect the germination of wheat seeds and revealed the safety of essential oil to germinating seeds. Hence, the essential oil extracted from citrus peel waste can be valorised and utilised as a botanical insecticide against T. castaneum and C. chinensis .

A comparative study on fibrinolytic enzymes extracted from six Bacillus spp.isolated from fruit-vegetable waste biomass

Fibrinolytic enzymes are considered as a significant therapeutic agent for thrombosis.Keeping the quest for identification of effective fibrinolytic enzyme(s)from microbial source,a comparative study was done on six Bacillus spp.isolated from fruit and vegetable waste.The fibrinolytic activities of the isolates were confirmed by a fibrin plate assay.Six potential isolates were identified by 16s rRNA sequencing as Bacillus altitudinus HEM05,Bacillus halotolerance ARKH1,Bacillus safensis CO05,Bacillus subtilis subsp.inaquorum BE1,Bacillus tequilensis SAS23 and Bacillus siamensis BHO27.Extracellular fibrinolytic enzymes were purified to homogeneity from all six isolates by acetone precipitation,anion exchange chromatography and gel filtration chromatography.Purified fibrinolytic enzymes showed fibrinolytic specific activity ranging from 60.92 U mg-1 to 220.19 U mg-1.Molecular weight(SDS PAGE)of purified enzymes ranged from 30,200 kDa to 69,500 kDa.Enzymes were effective over wide range of pH from 5 to 10,with optimum pH between 7 and 10.The enzymes were active between 37°C to 60°C.Effect of inhibitory activity of metal ions,protease inhibitors and amidolytic activity on purified enzymes indicated fibrinolytic enzymes from Bacillus altitudinus HEM05,Bacillus halotolerance ARKH1,Bacillus safensis CO05 as plasmin serine protease,from Bacillus subtilis subsp.inaquorum BE1,Bacillus tequilensis SAS23 as subtilin chymotrypsin like metalloprotease and from Bacillus siamensis BHO27 as subtilin chymotrypsin.In vitro assays for the purified enzyme preparations from all six isolates confirmed enzymes could activate plasminogen and significantly degraded the fibrin net of blood clot.

Supercritical fluid extraction of bioactives from fruit waste and its therapeutic potential

Fruits are a rich source of bioactive compounds and form a major component of the total horticultural produce.Unfortunately,fruit wastes that contains a wide range of bioactive compounds such as phenolics,minerals,dietary fibre,vitamins,oils,and enzymes,to name a few,are discarded.The post-processing by-products of fruit processing industries include the peel,pomace,and seeds.Owing to the presence substantial contents of bioactive compounds,these fruit by-products have been explored for the recovery of bioactives using several extraction techniques.Amongst the various techniques studied for the extraction of bioactives,supercritical fluid extraction(SCFE)has captured the interest of researchers,mainly because it overcomes the limitations posed by conventional extraction methods.This review discusses SCFE as a green technique for the extraction of bioactives(polyphenols,vitamins,pigments and fatty acids)from fruit wastes,and factors that affect SCFE therefrom.Furthermore,the bioactivities of these components such as anti-diabetic,anti-oxidants,anti-inflammatory,anti-microbial,anti-cancer,cardioprotective,and neuroprotective agents have been highlighted.Lastly,future prospects of using SCFE for ensuring optimal extraction of bioactives and their potential biological and food applications have been discussed.

Valorization of malaysian tropical fruit seeds: A review of their nutrition, bioactivity, processing and food application

Malaysia produces varieties of tropical fruits such as durian, rambutan, jackfruit, mango, papaya, and mangosteen but the seeds are considered waste. The seeds contain beneficial nutrients such as protein, carbohydrates, fat, and minerals, and have high bioactive properties. Various processing methods have been applied to extract the seeds and apply them to the food system. The information is scattered and incomprehensive, therefore, this paper aims to review the chemical properties and biological activities of the selected tropical fruit seeds, and their processing and functional properties to the food. Most seeds are rich in carbohydrates but also contain various minerals and fatty acids. The antioxidant, antidiabetic, anti-bacterial/anti-fungal, anti-inflammatory, anti-hyper cholesterol and anti-proliferative properties were also reported with rambutan and papaya seeds having the most bioactive properties. Novel and conventional extraction methods of the seeds, the functionality of the seeds to improve the food such as pasting and emulsifying properties, and their effect on the colour, texture, sensory and storage stability were also highlighted. In summary, all the selected seeds have the potential to be upcycled as food ingredients as they contain various nutrients while providing therapeutic and functional properties, however, further research can be considered to optimize the seeds' usability.

Valorisation of fruit waste for enhanced exopolysaccharide production by Xanthomonas campestries using statistical optimisation of medium and process

The aim of this research work was to enhance the fermentative production of exopolysaccharide(EPS)with mixed fruit waste as a key substrate.Xanothomonas campestries was isolated from spoiled orange and its EPS production efficiency was determined using EPS medium.Prior to optimisation,the production was 3.4 g/L,upon optimizing the medium the production improved to 9.2 g/L.The medium formulation was studied by sequential addition of medium components and replacement of sugar with mixed fruit waste.In formulated medium,the production enhanced to 11.1 g/L.For further optimisation,the response surface methodology was used,which resulted in the enhancement of production to 14.5 g/L.The scale-up study was undertaken in a 10 L shake flask and fermenter.In 10 L flask EPS,production was 14.45 g/L in 100 h,whereas in 10 L fermenter it was 21.10 g/L in 60h only.The optimisation studies gave nearly 500%(6.2fold)enhanced EPS production and dwindle in fermentation time.Replacement of sucrose with fruit waste extract made the process environment-friendly;omission of L-cystine and use of 50%reduced amount of sodium acetate in the medium lowered the production cost of EPS.The developed process resulted in the utilization of fruit waste and was also useful in solving the fruit waste disposal problem.

Sustainable food industrial waste management through single cell protein production and characterization of protein enriched bread

Production of single cell protein(SCP)from food waste is one of the promising approaches for excellent waste management.In the present study,SCP was produced through submerged fermentation using selected food wastes(banana peel,citrus peel,carrot pomace and potato peel).During process optimization,combinations of various temperature and nitrogen sources were studied for optimum SCP yield(g/100g).The results indicated that maximum SCP yield was obtained at 30℃ for 7 days on potato peels,whereas citrus and banana peels exhibited the lowest SCP yield at the same process conditions.The SCP compositional analysis indicated that the amount of non-essential amino acids was significantly higher than wheat flour.Furthermore,SCP enriched bread was prepared by adding SCP at different concentrations(0,4,8,and 12%).The organoleptic properties indicated that SCP addition up to 4%was acceptable to prepare protein enriched bread.Thus,SCP may be effectively used for food waste management and food security.

Utilization of plant-based natural coagulants as future alternatives towards sustainable water clarification

Rapid industrial developments coupled with surging population growth have complicated issues dealing with water scarcity as the quest for clean and sanitized water intensifies globally. Existing flesh water supplies could be contaminated with organic, inorganic and biological matters that have potential harm to the society. Turbidity in general is a measure of water cloudiness induced by such colloidal and suspended matters and is also one of the major criteria in raw water monitoring to meet the stipulated water quality guidelines. Turbidity reduction is often accomplished using chemical coagulants such as alum. The use of alum is widely associated with potential development of health issues and generation of voluminous sludge. Natural coagulants that are available in abundance can certainly be considered in addressing the drawbacks associated with the use of chemical coagulants. Twenty one types of plant-based natural coagulants categorized as fruit waste and others are identified and presented collectively with their research summary in this review. The barriers and prospects of commercialization of natural coagulants in near future are also discussed.

Sequential ultrasound-assisted extraction of pectin and phenolic compounds for the valorisation of ‘Granny Smith’ apple peel

This study aims to evaluate the impact of the sequential extraction system for phenolic compounds and pectin from waste ‘Granny Smith’ apple peel using ultrasound. The effects of solvent, formic acid concentration (CFA), and the number of extraction steps on the content of individual and total phenolic compounds (TPC), total flavonoids, and antioxidant capacity, were determined. Then, pectin was obtained from apple peel before (BE) and after (AE) phenolic compounds extraction, using conventional (TR) or ultrasound-assisted procedures (US). The two-steps 80% Acetone (0% CFA) extraction system had the highest TPC (3.47 g GAE/Kg). Procyanidin B2 (0.03-0.77 g/kg) was the major phenolic compound extracted from ‘Granny Smith’ apple peel. AE pectin extraction yield (6.38% for US and 4.92% for TR) was higher than BE. Pectin obtained had 57-60% DE, 9.3-10.3% Methoxyl content, and 436-460 equivalent weight. Wasted apple peel is a great low-cost source of phenolic compounds and pectin. Furthermore, it is possible to achieve the highest yields of both compounds through appropriate extraction sequences (AE: phenolic compound extraction followed by pectin extraction) and alternative technologies like ultrasound-assisted extraction.

Effect of solvent mixtures on the ultrasound-assisted extraction of compounds from pineapple by-product

Extraction of compounds from pineapple by-products can be affected by operational conditions and solvents.This study aimed to(i)carry out the ultrasound-assisted extraction of phenolic compounds from pineapple peels using different types of solvents and operating conditions and(ii)characterize the extracts obtained.The solvents with the highest efficiency in extracting total phenolic compounds(TPC),namely water,ethanol,and acid solution(1 mol L−1 HCl),were tested in different proportions using a simplex-centroid mixture design.The effects of time(5–45 min),temperature(30–60°C),and ultrasonic power(0–100 W)were also evaluated.Extracts were assessed for antioxidant potential,phenolic profile,and sugar composition.TPC contents ranged from 219.75 to 405.06 mg GAE 100 g−1,with the highest value obtained in the mixture of ethanol(0.50)and acid solution(0.50).The extract with the highest TPC content and antioxidant activity was obtained at 60°C,50 W of ultrasonic power and 30 min.The extract obtained under these conditions contained fructose(7.17 g 100 g−1)and glucose(8.29 g 100 g−1)as major soluble sugars and caffeic acid(217.65 mg 100 g−1)as the major phenolic acid.Therefore,the extraction of compounds under the conditions studied is an alternative to the valorization of pineapple waste.

Clean label extraction of bioactive compounds from food waste through microwave-assisted extraction technique-A review

Clean label and green extraction have attained popularity due to elimination of solvent use and reduction in energy consumption.In this regard,microwave assisted extraction have emerged as a novel process for extraction of bioactive compounds.This process observed to consume less time and energy but have higher extraction efficiency.Additionally,the functionality of bioactive compounds has not degraded in this process.Therefore,this article explores the potential of microwave-based extraction as a green and ecofriendly technique.Moreover,it has been coupled with conventional technique(e.g.steam distillation,steam diffusion,hydrodistillation,air hydrodistillation,and hydro-diffusion and gravity)to ease the process and increase the efficiency.Available data highlights the importance of various hybrid techniques(microwave+conventional ones)for the extraction of bioactive compounds from fruit&vegetable waste.

Anaerobic digestion in mesophilic and room temperature conditions: Digestion performance and soil-borne pathogen survival

Tomato plant waste（TPW） was used as the feedstock of a batch anaerobic reactor to evaluate the effect of anaerobic digestion on Ralstonia solanacearum and Phytophthora capsici survival. Batch experiments were carried out for TS（total solid） concentrations of 2%, 4% and 6% respectively, at mesophilic（37 ± 1°C） and room（20–25°C） temperatures. Results showed that higher digestion performance was achieved under mesophilic digestion temperature and lower TS concentration conditions. The biogas production ranged from 71 to 416 L/kg VS（volatile solids）. The inactivation of anaerobic digestion tended to increase as digestion performance improved. The maximum log copies reduction of R. solanacearum and P. capsici detected by quantitative PCR（polymerase chain reaction） were 3.80 and 4.08 respectively in reactors with 4% TS concentration at mesophilic temperatures. However, both in mesophilic and room temperature conditions, the lowest reduction of R. solanacearum was found in the reactors with 6% TS concentration, which possessed the highest VFA（volatile fatty acid） concentration. These findings indicated that simple accumulation of VFAs failed to restrain R. solanacearum effectively, although the VFAs were considered poisonous. P. capsici was nearly completely dead under all conditions. Based on the digestion performance and the pathogen survival rate, a model was established to evaluate the digestate biosafety.