Grass-clover ley holds an importance role for a sustainable crop production and is mainly used as feed for ruminants. But ley also contains proteins, if extracted, suitable for monogastric animals such as pigs and poultry. If these proteins are extracted, the degree of self-sufficiency of proteins in Sweden can increase and better resource utilization is achieved. In this study we evaluated the utilization of fresh and ensiled grass-clover ley in a straw-based agricultural biorefinery for producing protein concentrate, ethanol, bio-oil and biogas.

Practical lab scale tests of extraction of high value components for food and feed applications from the liquid fraction after ley pressing were carried out. Pretreatments of the solid fraction prior to ethanol fermentation, bio-oil production using HTL (hydrothermal liquefaction) and biogas production were tested. The system for production and supply of the ley was described and the potential for increased ley production in Sweden was quantified. The environmental and economic efficiency of the proposed biorefinery system was evaluated using environmental systems analysis and technoeconomic assessment.

In terms of system profitability, a high protein yield in the extracted protein concentrate it is important. To achieve that, a thorough pre-treatment using mechanical biomass disintegration before fractioning is crucial. This may need to be done in several steps. Screw pressing is a common technique for fractionating ley into a liquid and solid fraction. Double pressing combined with enzymatic treatments or only water addition during the second pressing stage were found to increase the protein yield compared to single pressing. Second pressing had no effect on the amino acid profile of the protein concentrate.

After pressing fresh ley, heat coagulation or isoelectric precipitation can be used to precipitate protein concentrates in one- or two-step processes to produce protein fractions with different functional properties. Tests showed that it is possible to recover chlorophyll and carotenoids from the ley using supercritical carbon dioxide extraction. which is a suitable method for food applications as toxic organic solvents can be avoided. The ensiling process degrades the protein into smaller peptides or free amino acids which makes ensiled grass less suitable for protein recovery by heat coagulation or isoelectric precipitation. Fresh and ensiled timothy and meadow fescue showed a similar amino acid profile as soybeans.

The initial hypothesis that mechanical pressing may disintegrate the lignocellulosic structure of ley sufficiently to produce a sugar stream with a high concentration of sugar for further fermentation by enzymatic hydrolysis was not confirmed. The content of sugars released after the enzymatic hydrolysis was relatively low. The fibre fraction after the mechanical pressing can be suitable for ethanol production if an additional pretreatment method will be incorporated. Fermentation of pressed and steam-exploded ensiled mixed ley showed promising results. The bio-oils produced with the HTL-process were described of high quality, i.e., high carbon content and low ash content. Although, the obtained materials are not directly integrable in today's refineries, the ensiling did not seem to affect the material's potential for biofuel production. The methane potential tests that were carried out in the project of the liquid residual fraction after protein extraction and after the HTL process showed that both can be suitable for methane production, but they showed great behavior differences.

The results from the environmental system analysis showed that extraction of high-quality products from ley, straw and sawdust according to the studied system reduces climate impact (CO2 eq) when the use of ethanol, bio-oil and biogas replaces fossil fuels, protein concentrate replaces soy as feed and carbon dioxide replaces fossil carbon dioxide. At present, the climate impact from extracted protein concentrate is higher than for soybean meal. Grass source for protein extraction followed by ethanol and bio-oil production as an alternative to straw-based ethanol and bio-oil production did not seem to improve the profitability of the studied biorefinery system. Profitability may be improved if protein extraction is performed the whole all year and not seasonal. Higher prices of the extracted protein concentrate may also improve profitability.

The potential for increased grassland cultivation in Sweden for biorefining was estimated at approximately 3.4 million tonnes grass per year. This included incorporating grassland in the crop rotation in grain-dominated areas, intensification of existing grassland cultivation, utilization of fallow and abandoned arable land for grassland cultivation.

Based on the results and the experience acquired from this project, we suggest an extraction plant for grass-clover ley that operates for both fresh and ensiled grassland all year. The plant needs to be supplemented with more advanced technologies such as membrane filtration for the extraction of amino acids from the ensiled ley during the winter season. The protein extraction plants should be located near farms. The extraction plant is also suggested to be located together with a biogas plant to enable co-digesting residual fractions with manure. Thereby, enabling plant nutrients and minerals in digestate to be returned to arable land. Utilizing the solid fiber fraction for biofuel production with fermentation and HTL in large-scale processes remains promising.

This paper investigated the effects of heat treatment (75 °C × 18 s and 100 °C × 18 s) and wet-mix total solids level (TS: 50 and 60%, w/w) on the physicochemical and techno-functional properties of model infant milk formula (IMF) powders. IMF produced from wet-mixes with 50% TS preheated at 75 °C (50%-75°C) exhibited the longest wettability time (55 ± 2 s) and the poorest flowability, explained by the small particle size (D [4;3]= 16.5 ± 2.29 μm) and low poured bulk density (0.27 ± 0.02 g/cm3). Larger particles were obtained by increasing both pasteurization temperature and TS. Further, powders from 60% TS wet-mixes showed less particle size uniformity, leading to better packing and higher bulk densities. 50%-75°C powders also showed the lowest onset glass transition temperature, which may affect its storage stability. Wettability time was reduced by increasing TS from 50 to 60% or by increasing pre-heating temperature from 75 to 100 °C. However, as observed by low-field nuclear magnetic resonance, the increase in the pasteurization temperature slowed down the global rehydration process. The flowing properties of the powders improved by increasing TS level of the wet-mix. In conclusion, the pre-spray drying wet-mix processing variables, pasteurization temperature and TS level, had a major effect on the physicochemical and functional properties of the IMF powders. It is crucial to understand how variations in the process parameters affect these powder characteristics, due to their functional, technological and economic importance.

Within the context of circular economy, there is an increasing interest to utilise agrifood by-products. However, extensive extraction and purification steps make the valorisation of side streams not always cost effective. Therefore, an increased knowledge of the functionality of unrefined side streams could increase their utilisation in food products. We investigated the thermal gelation of mixed legume systems containing a commercial pea protein isolate (Pisum sativum) and the unrefined fraction remaining after protein extraction from lentils (Lens culinaris). The unrefined lentil fraction contained mainly starch (~45 g/100 g) and insoluble cell wall polysaccharides (~50 g/100 g) with minor amounts of soluble protein (4 g/100 g) and polyphenols (<1 mg GAE/g). The addition of the unrefined lentil fraction increased the strength and Young's modulus of pea protein gels in the pH range 3–4.2, and also increased the gels’ elastic modulus G'. The microstructure could be described as a mixed network of swollen protein particles of different sizes (5–50 μm), gelatinised starch and cell wall fragments. The results demonstrate that unrefined side streams from lentils could be used for textural modification of plant protein gels, with implications for the design of novel plant-based foods.

The present study aimed to characterize wastewater fractions obtained after the wet extraction of proteins from legumes. In addition, the suitability of wastewater fractions for the potential recovery of high value-added compounds was also examined, and consequently, the prevention of the environmental impact of these wastes was explored. Similar to the industrial production of proteins, wet alkaline and acidic extractions of proteins from faba bean and pea flours were performed in two stages of extraction. The different wastewater fractions were characterized by measuring their organic matter content, total solids (TS), total dissolved solids (TDS), electrical conductivity (EC), pH, and turbidity. The value-added compounds from these wastewater fractions were quantified, which included the protein content, carbohydrate content, phenolic content, and antioxidant activity. In addition, the phenolic compounds in these factions were identified and quantified. It was observed that the fractions obtained in the first extraction stage had 60%–90% higher organic matter content, measured as the chemical oxygen demand (COD), compared to the second fractions, indicating a higher environmental impact of the former in case of disposal. The results obtained for COD, TS, TDS, EC, pH, and turbidity demonstrated that microfiltration reduced only the turbidity (85%), and consequently, a decrease was observed in the particulate matter, while there was a practically negligible reduction in the soluble matter. Wastewater from faba exhibited the highest polyphenol content and antioxidant activity, and was, therefore, considered the most valuable fraction for potential valorization.

Although Arctic charr side streams contain limited amounts of fish flesh, they are a rich fish oil source (46.3 ± 0.6%). The aim of the study was to investigate the potential for valorization of Arctic charr filleting side streams through the extraction of oil by supercritical CO2 technology. The effect of temperature (40 °C and 80 °C) and pressure (20, 35 and 45 MPa) on the final extract after supercritical fluid extraction (SFE) was evaluated. Temperature increase enhanced the yield but decreased the antioxidant activity at 45 MPa, did not affect the yield and the antioxidant activity at 35 MPa, whereas yield was limited at 20 MPa and 80 °C. Extracts were rich in monounsaturated fatty acids (56.7–58.3%, especially oleic acid 37.2–38.0%), and polyunsaturated fatty acids (20.2–26.1%, especially DHA 7.3–11.4%). The presence of astaxanthin significantly preserved the extracts from oxidation. Industrial relevance: Supercritical carbon dioxide extraction is a green technology appropriate for the recovery of non-polar and heat sensitive compounds. The extracted Arctic charr oils were rich in polyunsaturated fatty acids and astaxanthin which inhibited oxidation in combination with the absence of oxygen and light during the process. This technology could be an excellent alternative for more sustainable valorization of fish processing side streams. © 2021 The Author(s)

Preparation of a bolus is a complex process with both food comminution and degree of lubrication with saliva playing an important role in a safe swallow. Swallowing disorders i.e. dysphagia, are especially present among the elderly population and often lead to choking and further health complications. The aim of this research was to investigate the relationship between the perception of ease of swallowing in the elderly and the rheological parameters of particulated foods, using broccoli purees as a model system. Particulated foods can be described as a concentrated dispersion of plant particles in a fluid phase. The effect of the fluid phase (Newtonian vs. shear thinning) and dispersed phase (plant particles with different size distribution and morphology) on the rheological properties of simulated boli was studied by characterising shear viscosity, viscoelasticity, yield stress, extensional viscosity and cohesiveness. Ease of swallowing and mouthfeel were evaluated by a semi trained healthy elderly panel (n = 19, aged 61 to 81). Ease of swallowing was correlated with the presence of yield stress and extensional viscosity in the bolus, characteristic of boli with xanthan gum as the fluid phase. Although the properties of the fluid phase played a dominant role in the ease of swallowing, compared to the dispersed phase, both components played a role in the rheological properties of the bolus and the perception of ease of swallowing by the elderly panel. These results provide insights into the design of personalised foods for populations with specific needs such as those suffering from swallowing disorders.

Agro-waste reduction and reuse are among the current main social challenges. In this perspective, the present research was aimed at the complete valorisation of Garganega grape pomace by recovering bioactive phenol extracts and by testing the solid fibre extract residues in composite formulation for packaging applications. The pomace was derived from white wine production, therefore, respect to red pomace, it was promptly removed from must after pressing, and its exploitation can be particularly interesting and valuable as still rich in active compounds. Phenol extracts were obtained both via solvent-based and pressurised liquid extractions and their phytochemical compositions were compared in terms of total amount of phenols, flavonoids, flavanols, anthocyanins, hydroxycinnamic acids, and reducing sugars. Antioxidant activity and detailed phenol profiles were also achieved. The highest phenol yield was obtained via solvent-based extraction with 75% acetone (v/v), solid/liquid ratio 1:5, 2h incubation at 50°C (77.9 gGAeq/kgDW). The fibrous solid residue of the extraction was characterized via thermogravimetric analysis and used for composite preparation by melt mixing with the renewable and biodegradable PHBV polymer through a green approach (solvent-less process). The composites resulted thermally stable at high temperatures, showing initial degradation processes only at temperatures higher than 250°C. Differential scanning calorimetry analyses were carried out to study melting and crystallization phenomena, while mechanical properties were investigated by tensile tests. The materials finally showed properties similar to those of the matrix. The bio-composites can be considered as an alternative to plain PHBV, since they are less expensive and eco-friendlier thanks to a reduced polymeric content, and they could represent a suitable way for full agro-waste exploitation.

This study considered the effect of low energy microwave assisted freezing (MAF) on freezing time and quality attributes (microstructure, texture, drip loss and colour) of apple and potato. MAF of apples and potatoes was performed by applying constant microwave (MW) power (167 W/kg) and pulsed MW power (500 and 667 W/kg with 10 s pulse width and 20 s pulse interval resulting in an average power of 167 and 222 W/kg) during the freezing process. The temperature profile was monitored during the freezing process, and the microstructure was examined using X-ray micro-tomography and cryo-SEM. Other quality parameters such as texture, drip loss and colour were evaluated with thawed samples. It appeared that the freezing time was not affected by the MAF process. It is the first time that a MAF process is used for freezing plant-based products and showed that the application of microwaves during freezing process caused less freeze damage than the control condition.

The paper aims at optimising and validating possible routes toward the full valorisation of grape agrowaste to produce bioactive molecules and new materials. Starting from Merlot red pomace, phenol complex mixtures were successfully extracted by using two different approaches. Extracts obtained by solvent-based (SE) technique contained up to 46.9 gGAeq/kgDW of total phenols. Depending on the used solvent, the prevalence of compounds belonging to different phenol families was achieved. Pressurized liquid extraction (PLE) gave higher total phenol yields (up to 79 gGAeq/kgDW) but a lower range of extracted compounds. All liquid extracts exerted strong antioxidant properties. Moreover, both SE and PLE extraction solid residues were directly exploited (between 5 and 20% w/w) to prepare biocomposite materials by direct mixing via an eco-friendly approach with PHBV polymer. The final composites showed mechanical characteristics similar to PHVB matrix. The use of pomace residues in biocomposites could therefore bring both to the reduction of the cost of the final material, as a lower amount of costly PHBV is used. The present research demonstrated the full valorisation of grape pomace, an agrowaste produced every year in large amounts and having a significant environmental impact.

Final quality of frozen foods is determined by the shape and size of the formed ice crystals, as they might cause irreversible damage to the cellular structure -crystals larger than cells will break them appart, impairing quality. Recent studies using microwave assisted freezing (MAF) - a novel alternative freezing technology - have shown that microwave radiation can influence the ice crystal formation leading to crystal size reduction. Two concepts have been proposed regarding the mechanism of action such as”NITOM” concept (Nucleation Induced by Temperature Oscillation caused by MWs) and the”NIMIW” (Nucleation Induced by constant or pulsed MIcroWaves power). The present study aimed to enlighten the influence of different microwave assisted freezing parameters on the ice crystal growth. A Response Surface Method (RSM) has been used to evaluate the effect of three process parameters (i.e. MW pulse width, power and cooling rate) on final crystal size, correlating processing conditions to final crystal sizes and setting the basis for further analysis.