Search

The recovery efficiency of waste valorization processes depends on an interplay of different conditions that are sometimes overlooked. Process optimization by the means of establishing mathematical relations between the process parameters and outputs is a strong tool to identify optimal operating conditions based on experimental data. In this study, the extraction of anthocyanins from chokeberry (Aronia melancocarpa) juice pomace using homogenization in acidified water was selected as a case study for process optimization using response surface methodology. The parameters studied were the citric acid content in the water, the temperature and the liquid–solid ratio. The optimal conditions to maximize both anthocyanin concentration and total anthocyanin content extracted were 1.5 wt% citric acid, 45 °C and 34 g solvent/g fresh pomace. Furthermore, the model developed predicted satisfactorily the overall anthocyanin content and anthocyanin concentration in the extract, as well as the final pH and total dissolved solids. The process optimization performed in this study sets the ground for further process design targeting the production of high-value products from byproducts or biowaste to be used in food ingredients or supplements. Graphic Abstract Electronic supplementary material The online version of this article (10.1007/s12649-020-01127-w) contains supplementary material, which is available to authorized users.

Manure and digestate liquid fractions are nutrient-rich effluents that can be fractionated and concentrated using membranes. However, these membranes tend to foul due to organic matter, solids, colloids, and inorganic compounds including calcium, ammonium, sodium, sulfur, potassium, phosphorus, and magnesium contained in the feed. This review paper is intended as a theoretical and practical tool for the decision-making process during design of membrane-based systems aiming at processing manure liquid fractions. Firstly, this review paper gives an overview of the main physico-chemical characteristics of manure and digestates. Furthermore, solid-liquid separation technologies are described and the complexity of the physico-chemical variables affecting the separation process is discussed. The main factors influencing membrane fouling mechanisms, morphology and characteristics are described, as well as techniques covering membrane inspection and foulant analysis. Secondly, the effects of the feed characteristics, membrane operating conditions (pressure, cross-flow velocity, temperature), pH, flocculation-coagulation and membrane cleaning on fouling and membrane performance are presented. Finally, a summary of techniques for specific recovery of ammonia-nitrogen, phosphorus and removal of heavy metals for farm effluents is also presented.

This work aimed to investigate the optimum conditions of pressure, temperature, ultrasound intensity, solvent concentration and solvent flowrate of ultrasound-assisted pressurized liquid extraction of anthocyanins from Aronia melanocarpa pomace. The novel setup operates with an aqueous solution of citric acid as extraction solvent. The optimization was performed in order to maximize the total anthocyanins content extracted from the pomace. The optimized conditions of 70 °C, 180 bar, a solvent concentration of 1.5 % wt. citric acid, in a 200 W ultrasound bath were obtained. These conditions resulted in 88.0 % wt. extraction of anthocyanins in 45 min. A kinetic study was performed to study the influence of the temperature on the total anthocyanin yield obtained at the optimal extraction conditions. Moreover, the component stability was assessed to prove that the system could successfully operate at 80 °C. Compared to classical batch extraction using the same solvent concentration and feedstock, the total anthocyanin content of the extract was increased by 19%.

In this chapter a historical and technical background for membrane gas separation is given, together with a review of the basic terms commonly used in the study of membrane separation technology. The mechanism of mass transport through the membrane, how this depends on the chosen membrane material, and how this affects the separation of gas molecules in biogas upgrading is described in detail. The present industrial membrane material of choice for biogas upgrading is polyimide, while carbon molecular sieves and mixed-matrix membranes combining polymers with either zeolites, graphene oxide, or metal-organic frameworks are promising emerging membrane materials. Biogas upgrading requires multistage membrane systems, preferably combined with cryogenic distillation to obtain grid gas and high-purity CO 2. The economic evaluation indicates that production of grid-quality gas and CO 2 from biogas could be economically attractive.

Phycocyanins from cyanobacteria are possible sources for new natural blue colourants. Their chromophore, phycocyanobilin (PCB), was cleaved from the apoprotein by solvolysis in alcohols and alcoholic aqueous solutions. In all cases two PCB isomers were obtained, while different solvent adducts were formed upon the use of different reagents. The reaction is believed to take place via two competing pathways, a concerted E2 elimination and a S N2 nucleophilic substitution. Three cleavage methods were compared in terms of yield and purity: conventional reflux, sealed vessel heated in an oil bath, and microwave assisted reaction. The sealed vessel method is a new approach for fast cleavage of PCB from phycocyanin and gave at 120 °C the same yield within 30 min compared to 16 h by the conventional reflux method (P

In a circular economy, products are made from renewable resources and the waste streams generated during production are either reused, recycled or recovered. The Biocascade methodology considers bio-waste as a resource that can be exploited to produce high-value products such as pharmaceuticals, food ingredients and nutrients; and low-value products such as feed, energy or soil conditioners. The Biocascade principle ensures optimal biomass exploitation by following a hierarchy from high-to-low value, where the waste from one process is the starting material for the next. Biowaste from plant origin is a very suitable resource for applying the Biocascade methodology, both in terms of worldwide production and of variety of components. In this review, the biowaste from sour cherry wine, ornamental kalanchoe plants and red clover feed production, have been examined for processing using a Biocascade approach. Starting from the biowaste characterization, the most relevant components have been identified highlighting their potential uses. The extraction methodology is then discussed in terms of solvent used, operating conditions and yield. Based on the information retrieved from literature, different process flowsheets have been proposed to maximize the use of the biowaste following the Biocascade perspective and targeting zero-waste generation. Graphic Abstract: [Figure not available: see fulltext.].

The production of sour cherry wine results in large amounts of biowaste known as press cake or pomace. This pomace contains among others the fruit skin and flesh that have been previously reported to be a rich source of anthocyanins and phenolic acids. These components can be extracted and formulated to be used as natural pigments, nutraceuticals or cosmeceuticals. In the present work, sour cherry wine pomace has been extracted in aqueous buffers and ultrafiltered using ceramic membranes. Two enzyme formulations based on pectinases and cellulases have been added to the extraction media, and their influence on the extraction yield in batch mode, ultrafiltration performance and product degradation has been assessed. Sour cherry wine pomace has been found to contain relatively low amounts of anthocyanins (48.6 ± 0.9 mg kg-1) and phenolic acids (82.1 ± 2.9 mg kg-1) as compared to biowaste from other sour cherry food products. The use of enzyme formulations based on cellulase and pectinase was not shown to improve the total amount of anthocyanin and phenolic acids extracted. However, an increase in ultrafiltration permeate flux was observed when the enzymes were used.

Chokeberries (genus Aronia) are known to be one of the richest sources of anthocyanins among fruits and berries (Kähkönen et al. 2001). In juice production, a large amount of the anthocyanins remains in the pomace, which is typically discarded as waste. This makes chokeberry pomace a valuable source of anthocyanins, that can be extracted and purified to be used in food and pharmaceutical applications (Borowska and Brzóska, 2016). However, other water-soluble compounds such as sugars and phenolic acids are also extracted along anthocyanins, and need to be removed from the solution to achieve an anthocyanin product of higher purity.In the present work, extracts from chokeberry pomace have been subjected to ultrafiltration and reverse osmosis with the aim of removing sugars and increasing the concentration of anthocyanins.

Phycocyanins are pigment-protein complexes with potential application as natural food colourants. The perceived colour of phycocyanins varies with pH, and a method to stabilise the colour over a broad range of pH values is requested by the food industry. In this work, the stabilising effect of sodium dodecyl sulphate (SDS) micelles on pH-induced colour variations of phycocyanin was examined. SDS was shown to stabilise the blue conformation of phycocyanin, preventing formation of the green conformation, which is prevalent at low pH. The studies indicated that the stabilising effect occurred through interaction or entrapment of the non-protonated, circular helical (blue) structure of phycocyanin and the anionic SDS micelles. The interaction prevented conversion into protonated, partially unfolded (green) phycocyanin species. This information opens for new possibilities to stabilise the blue conformation of phycocyanin and to apply the stabilised form in food products as a natural blue food colourant.