Editorial

4 pages, 159 KiB

Open AccessEditorial

Chemicals from Food Supply Chain By-Products and Waste Streams

by Marta Coma and Afroditi Chatzifragkou

Molecules 2019, 24(5), 978; https://doi.org/10.3390/molecules24050978 - 11 Mar 2019

Cited by 6 | Viewed by 2609

Circular economy and bioeconomy concepts have been introduced within an EU framework to sustainably overcome the dominant development model of “take, make, and dispose”, which has contributed to current economic, environmental, and societal burdens [...] Full article

(This article belongs to the Special Issue Chemicals from Food Supply Chain By-Products and Waste Streams)

Research

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15 pages, 299 KiB

Open AccessArticle

Supercritical Fluid Extraction of Carotenoids from Vegetable Waste Matrices

by Micael de Andrade Lima, Ioannis Kestekoglou, Dimitris Charalampopoulos and Afroditi Chatzifragkou

Molecules 2019, 24(3), 466; https://doi.org/10.3390/molecules24030466 - 28 Jan 2019

Cited by 89 | Viewed by 6790

Abstract

The aim of this work was to evaluate a previously-developed model on supercritical fluid extraction (SFE) for carotenoid recovery from carrot peels on various carotenoid-rich fruit and vegetable wastes. To this end, 15 matrices, including flesh and peels of sweet potato, tomato, apricot, [...] Read more.

The aim of this work was to evaluate a previously-developed model on supercritical fluid extraction (SFE) for carotenoid recovery from carrot peels on various carotenoid-rich fruit and vegetable wastes. To this end, 15 matrices, including flesh and peels of sweet potato, tomato, apricot, pumpkin and peach, as well as flesh and wastes of green, yellow and red peppers, were submitted to SFE under optimised conditions (59 °C, 350 bar, 15 g/min CO₂, 15.5% (v/v) ethanol as co-solvent, 30 min of extraction time). The obtained extracts were characterised for their total carotenoid content, antioxidant activity and total carotenoid recovery (TCR). TCR values were greater than 90% w/w for most samples, with β-carotene being the most successfully extracted compound (TCRs 88–100% w/w). More polar carotenoids, such as lutein and lycopene, exhibited lower TCRs. A comparison with literature data suggested that carotenoid extraction is partially dependent on the composition of vegetable matrices, specifically on polysaccharide and moisture content. The results indicated that the optimised SFE conditions can be used as a general model for carotenoid extraction from various fruit and vegetable matrices and as a viable method for adding value to these waste streams by generating carotenoid-rich extracts. Full article

(This article belongs to the Special Issue Chemicals from Food Supply Chain By-Products and Waste Streams)

26 pages, 1561 KiB

Open AccessFeature PaperArticle

Production of Added-Value Chemical Compounds through Bioconversions of Olive-Mill Wastewaters Blended with Crude Glycerol by a Yarrowia lipolytica Strain

by Dimitris Sarris, Anna Rapti, Nikolaos Papafotis, Apostolis A. Koutinas and Seraphim Papanikolaou

Molecules 2019, 24(2), 222; https://doi.org/10.3390/molecules24020222 - 09 Jan 2019

Cited by 56 | Viewed by 3986

Abstract

Olive mill wastewaters (OMW) are the major effluent deriving from olive oil production and are considered as one of the most challenging agro-industrial wastes to treat. Crude glycerol is the main by-product of alcoholic beverage and oleochemical production activities including biodiesel production. The [...] Read more.

Olive mill wastewaters (OMW) are the major effluent deriving from olive oil production and are considered as one of the most challenging agro-industrial wastes to treat. Crude glycerol is the main by-product of alcoholic beverage and oleochemical production activities including biodiesel production. The tremendous quantities of glycerol produced worldwide represent a serious environmental challenge. The aim of this study was to assess the ability of Yarrowia lipolytica strain ACA-DC 5029 to grow on nitrogen-limited submerged shake-flask cultures, in crude glycerol and OMW blends as well as in media with high initial glycerol concentration and produce biomass, cellular lipids, citric acid and polyols. The rationale of using such blends was the dilution of concentrated glycerol by OMW to (partially or fully) replace process tap water with a wastewater stream. The strain presented satisfactory growth in blends; citric acid production was not affected by OMW addition (Cit_max~37.0 g/L, Y_Cit/Glol~0.55 g/g) and microbial oil accumulation raised proportionally to OMW addition (L_max~2.0 g/L, Y_L/X~20% w/w). Partial removal of color (~30%) and phenolic compounds (~10% w/w) of the blended media occurred. In media with high glycerol concentration, a shift towards erythritol production was noted (Ery_max~66.0 g/L, Y_Ery/Glol~0.39 g/g) simultaneously with high amounts of produced citric acid (Cit_max~79.0 g/L, Y_Cit/Glol~0.46 g/g). Fatty acid analysis of microbial lipids demonstrated that OMW addition in blended media and in excess carbon media with high glycerol concentration favored oleic acid production. Full article

(This article belongs to the Special Issue Chemicals from Food Supply Chain By-Products and Waste Streams)

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13 pages, 2062 KiB

Open AccessArticle

Use of Confectionery Waste in Biogas Production by the Anaerobic Digestion Process

by Agnieszka A. Pilarska, Krzysztof Pilarski, Agnieszka Wolna-Maruwka, Piotr Boniecki and Maciej Zaborowicz

Molecules 2019, 24(1), 37; https://doi.org/10.3390/molecules24010037 - 21 Dec 2018

Cited by 24 | Viewed by 3740

Abstract

It was the objective of this study to verify the efficiency and stability of anaerobic digestion (AD) for selected confectionery waste, including chocolate bars (CB), wafers (W), and filled wafers (FW), by inoculation with digested cattle slurry and maize silage pulp. Information in [...] Read more.

It was the objective of this study to verify the efficiency and stability of anaerobic digestion (AD) for selected confectionery waste, including chocolate bars (CB), wafers (W), and filled wafers (FW), by inoculation with digested cattle slurry and maize silage pulp. Information in the literature on biogas yield for these materials and on their usefulness as substrate in biogas plants remains to be scarce. Owing to its chemical structure, including the significant content of carbon-rich carbohydrates and fat, the confectionery waste has a high biomethane potential. An analysis of the AD process indicates differences in the fluctuations of the pH values of three test samples. In comparison with W and FW, CB tended to show slightly more reduced pH values in the first step of the process; moreover an increase in the content of volatile fatty acids (VFA) was recorded. In the case of FW, the biogas production process showed the highest stability. Differences in the decomposition dynamics for the three types of test waste were accounted for by their different carbohydrate contents and also different biodegradabilities of specific compounds. The highest efficiency of the AD process was obtained for the filled wafers, where the biogas volumes, including methane, were 684.79 m³ Mg⁻¹ VS and 506.32 m³ Mg⁻¹ VS, respectively. A comparable volume of biogas (673.48 m³ Mg⁻¹ VS) and a lower volume of methane (407.46 m³ Mg⁻¹ VS) were obtained for chocolate bars. The lowest volumes among the three test material types, i.e., 496.78 m³ Mg⁻¹ VS (biogas) and 317.42 m³ Mg⁻¹ VS (methane), were obtained for wafers. This article also proposes a method of estimation of the biochemical methane potential (theoretical BMP) based on the chemical equations of degradation of sugar, fats, and proteins and known biochemical composition (expressed in grams). Full article

(This article belongs to the Special Issue Chemicals from Food Supply Chain By-Products and Waste Streams)

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11 pages, 1070 KiB

Open AccessArticle

Effect of Effluent Recirculation on Biogas Production Using Two-Stage Anaerobic Digestion of Citrus Waste

by Lukitawesa, Rachma Wikandari, Ria Millati, Mohammad J. Taherzadeh and Claes Niklasson

Molecules 2018, 23(12), 3380; https://doi.org/10.3390/molecules23123380 - 19 Dec 2018

Cited by 35 | Viewed by 5642

Abstract

Citrus waste is a promising potential feedstock for anaerobic digestion, yet the presence of inhibitors such as d-limonene is known to limit the process. Effluent recirculation has been proven to increase methane yield in a semi-continuous process for recalcitrant material, but it [...] Read more.

Citrus waste is a promising potential feedstock for anaerobic digestion, yet the presence of inhibitors such as d-limonene is known to limit the process. Effluent recirculation has been proven to increase methane yield in a semi-continuous process for recalcitrant material, but it has never been applied to toxic materials. This study was aimed to investigate the effect of recirculation on biogas production from citrus waste as toxic feedstock in two-stage anaerobic digestion. The first digestion was carried out in a stirred tank reactor (STR). The effluent from the first-stage was filtered using a rotary drum filter to separate the solid and the liquid phase. The solid phase, rich in hydrophobic D-limonene, was discarded, and the liquid phase containing less D-limonene was fed into the second digester in an up-flow anaerobic sludge bed (UASB) reactor. A high organic loading rate (OLR 5 g VS/(L·day)) of citrus waste was fed into the first-stage reactor every day. The effluent of the first-stage was then fed into the second-stage reactor. This experiment was run for 120 days. A reactor configuration without recirculation was used as control. The result shows that the reactor with effluent recirculation produced a higher methane yield (160–203 NmL/g·VS) compared to that without recirculation (66–113 NmL/g·VS). More stable performance was also observed in the reactor with recirculation as shown by the pH of 5–6, while without recirculation the pH dropped to the range of 3.7–4.7. The VS reduction for the reactor with recirculation was 33–35% higher than that of the control without recirculation. Recirculation might affect the hydrolysis-acidogenesis process by regulating pH in the first-stage and removing most of the D-limonene content from the substrate through filtration. Full article

(This article belongs to the Special Issue Chemicals from Food Supply Chain By-Products and Waste Streams)

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12 pages, 1202 KiB

Open AccessArticle

Thermophilic Co-Digestion of the Organic Fraction of Municipal Solid Wastes—The Influence of Food Industry Wastes Addition on Biogas Production in Full-Scale Operation

by Przemysław Seruga, Małgorzata Krzywonos and Marta Wilk

Molecules 2018, 23(12), 3146; https://doi.org/10.3390/molecules23123146 - 30 Nov 2018

Cited by 12 | Viewed by 2919

Abstract

Anaerobic digestion (AD) has been used widely as a form of energy recovery by biogas production from the organic fraction of municipal solid wastes (OFMSW). The aim of this study was to evaluate the effect of the introduction of co-substrates (restaurant wastes, corn [...] Read more.

Anaerobic digestion (AD) has been used widely as a form of energy recovery by biogas production from the organic fraction of municipal solid wastes (OFMSW). The aim of this study was to evaluate the effect of the introduction of co-substrates (restaurant wastes, corn whole stillage, effluents from the cleaning of chocolate transportation tanks) on the thermophilic anaerobic digestion process of the mechanically separated organic fraction of municipal solid wastes in a full-scale mechanical-biological treatment (MBT) plant. Based on the results, it can be seen that co-digestion might bring benefits and process efficiency improvement, compared to mono-substrate digestion. The 15% addition of effluents from the cleaning of chocolate transportation tanks resulted in an increase in biogas yield by 31.6%, followed by a 68.5 kWh electricity production possibility. The introduction of 10% corn stillage as the feedstock resulted in a biogas yield increase by 27.0%. The 5% addition of restaurant wastes contributed to a biogas yield increase by 21.8%. The introduction of additional raw materials, in fixed proportions in relation to the basic substrate, increases biogas yield compared to substrates with a lower content of organic matter. In regard to substrates with high organic loads, such as restaurant waste, it allows them to be digested. Therefore, determining the proportion of different feedstocks to achieve the highest efficiency with stability is necessary. Full article

(This article belongs to the Special Issue Chemicals from Food Supply Chain By-Products and Waste Streams)

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16 pages, 2182 KiB

Open AccessArticle

Valorization of Brewers’ Spent Grain for the Production of Lipids by Oleaginous Yeast

by Alok Patel, Fabio Mikes, Saskja Bühler and Leonidas Matsakas

Molecules 2018, 23(12), 3052; https://doi.org/10.3390/molecules23123052 - 22 Nov 2018

Cited by 42 | Viewed by 5208

Abstract

Brewers’ spent grain (BSG) accounts for 85% of the total amount of by-products generated by the brewing industries. BSG is a lignocellulosic biomass that is rich in proteins, lipids, minerals, and vitamins. In the present study, BSG was subjected to pretreatment by two [...] Read more.

Brewers’ spent grain (BSG) accounts for 85% of the total amount of by-products generated by the brewing industries. BSG is a lignocellulosic biomass that is rich in proteins, lipids, minerals, and vitamins. In the present study, BSG was subjected to pretreatment by two different methods (microwave assisted alkaline pretreatment and organosolv) and was evaluated for the liberation of glucose and xylose during enzymatic saccharification trials. The highest amount of glucose (46.45 ± 1.43 g/L) and xylose (25.15 ± 1.36 g/L) were observed after enzymatic saccharification of the organosolv pretreated BSG. The glucose and xylose yield for the microwave assisted alkaline pretreated BSG were 34.86 ± 1.27 g/L and 16.54 ± 2.1 g/L, respectively. The hydrolysates from the organosolv pretreated BSG were used as substrate for the cultivation of the oleaginous yeast Rhodosporidium toruloides, aiming to produce microbial lipids. The yeast synthesized as high as 18.44 ± 0.96 g/L of cell dry weight and 10.41 ± 0.34 g/L lipids (lipid content of 56.45 ± 0.76%) when cultivated on BSG hydrolysate with a C/N ratio of 500. The cell dry weight, total lipid concentration and lipid content were higher compared to the results obtained when grown on synthetic media containing glucose, xylose or mixture of glucose and xylose. To the best of our knowledge, this is the first report using hydrolysates of organosolv pretreated BSG for the growth and lipid production of oleaginous yeast in literature. The lipid profile of this oleaginous yeast showed similar fatty acid contents to vegetable oils, which can result in good biodiesel properties of the produced biodiesel. Full article

(This article belongs to the Special Issue Chemicals from Food Supply Chain By-Products and Waste Streams)

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18 pages, 11675 KiB

Open AccessArticle

Comparative Phytonutrient Analysis of Broccoli By-Products: The Potentials for Broccoli By-Product Utilization

by Mengpei Liu, Lihua Zhang, Suk Lan Ser, Jonathan R. Cumming and Kang-Mo Ku

Molecules 2018, 23(4), 900; https://doi.org/10.3390/molecules23040900 - 13 Apr 2018

Cited by 86 | Viewed by 12867

Abstract

The phytonutrient concentrations of broccoli (Brassica oleracea var. italica) florets, stems, and leaves were compared to evaluate the value of stem and leaf by-products as a source of valuable nutrients. Primary metabolites, including amino acids, organic acids, and sugars, as well as [...] Read more.

The phytonutrient concentrations of broccoli (Brassica oleracea var. italica) florets, stems, and leaves were compared to evaluate the value of stem and leaf by-products as a source of valuable nutrients. Primary metabolites, including amino acids, organic acids, and sugars, as well as glucosinolates, carotenoids, chlorophylls, vitamins E and K, essential mineral elements, total phenolic content, antioxidant activity, and expression of glucosinolate biosynthesis and hydrolysis genes were quantified from the different broccoli tissues. Broccoli florets had higher concentrations of amino acids, glucoraphanin, and neoglucobrassicin compared to other tissues, whereas leaves were higher in carotenoids, chlorophylls, vitamins E and K, total phenolic content, and antioxidant activity. Leaves were also good sources of calcium and manganese compared to other tissues. Stems had the lowest nitrile formation from glucosinolate. Each tissue exhibited specific core gene expression profiles supporting glucosinolate metabolism, with different gene homologs expressed in florets, stems, and leaves, which suggests that tissue-specific pathways function to support primary and secondary metabolic pathways in broccoli. This comprehensive nutrient and bioactive compound profile represents a useful resource for the evaluation of broccoli by-product utilization in the human diet, and as feedstocks for bioactive compounds for industry. Full article

(This article belongs to the Special Issue Chemicals from Food Supply Chain By-Products and Waste Streams)

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Review

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32 pages, 1839 KiB

Open AccessFeature PaperReview

Medium Chain Carboxylic Acids from Complex Organic Feedstocks by Mixed Culture Fermentation

by Vicky De Groof, Marta Coma, Tom Arnot, David J Leak and Ana B Lanham

Molecules 2019, 24(3), 398; https://doi.org/10.3390/molecules24030398 - 22 Jan 2019

Cited by 99 | Viewed by 10412

Abstract

Environmental pressures caused by population growth and consumerism require the development of resource recovery from waste, hence a circular economy approach. The production of chemicals and fuels from organic waste using mixed microbial cultures (MMC) has become promising. MMC use the synergy of [...] Read more.

Environmental pressures caused by population growth and consumerism require the development of resource recovery from waste, hence a circular economy approach. The production of chemicals and fuels from organic waste using mixed microbial cultures (MMC) has become promising. MMC use the synergy of bio-catalytic activities from different microorganisms to transform complex organic feedstock, such as by-products from food production and food waste. In the absence of oxygen, the feedstock can be converted into biogas through the established anaerobic digestion (AD) approach. The potential of MMC has shifted to production of intermediate AD compounds as precursors for renewable chemicals. A particular set of anaerobic pathways in MMC fermentation, known as chain elongation, can occur under specific conditions producing medium chain carboxylic acids (MCCAs) with higher value than biogas and broader applicability. This review introduces the chain elongation pathway and other bio-reactions occurring during MMC fermentation. We present an overview of the complex feedstocks used, and pinpoint the main operational parameters for MCCAs production such as temperature, pH, loading rates, inoculum, head space composition, and reactor design. The review evaluates the key findings of MCCA production using MMC, and concludes by identifying critical research targets to drive forward this promising technology as a valorisation method for complex organic waste. Full article

(This article belongs to the Special Issue Chemicals from Food Supply Chain By-Products and Waste Streams)

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