Mediterranean agri-food processing wastes pyrolysis after pre-treatment and recovery of precursor materials: A TGA-based kinetic modeling study

Preliminary Experimental Results and Modelling Study of Olive Kernel Gasification in a 2 MWth BFB Gasifier

Gasification is a promising and attractive thermochemical method for biomass-to-energy conversion, with fluidized bed reactors being one of the best options for large-scale operations. Olive residues in particular are potentially excellent candidate biomass fuels in the Mediterranean area, due to the region’s increased capacity in olive oil production. Herein, the gasification experiments of olive kernels in a 2 MWth air-blown, bubbling fluidized bed reactor located at CENER’s facilities (BIO2C) in Navarra, Spain are presented. Even though technical issues were demonstrated due to the operation of the plant with a high-density biomass fuel and given the scale of the process, a quasi-steady-state and isothermal 12 h operation at an equivalence ratio of 0.25 ± 0.03 was attained. Given the satisfactory experimental results, an Aspen Plus simulation model of the process was also attempted. Notably, the proposed methodology agrees well with the experimental results and can be regarded as a starting point in future studies examining the gasification of relevant biomass in a MW-scale unit. Next, the effect of equivalence ratio and residual biomass moisture content were also evaluated, with the scope of designing future experiments that require minor modifications in the already existing apparatus. Finally, a syngas utilization route through the provision of energy for district heating purposes in the nearby village of Aoiz was proposed.

Agri-Food Contexts in Mediterranean Regions: Contributions to Better Resources Management

The agri-food frameworks have specific characteristics (production units with small dimensions and in great number with implications in the respective markets) that call for adjusted approaches, even more so when they are considered in Mediterranean contexts (where global warming will have relevant impacts). In fact, the Mediterranean regions and countries have particular specificities (due to their climate conditions) that distinguish them from their neighbours. This is particularly true in Europe, for example, where the southern countries present socioeconomic dynamics (associated with the respective public debt) that are different from those identified in the northern regions. From this perspective, it seems pertinent to analyse the several dimensions of the agri-food systems in the Mediterranean area. To achieve these objectives, a search was carried out on 26 December 2020 on the scientific databases Web of Science Core Collection (WoS) and Scopus for the topics “agr*-food” and “Mediterranean”. These keywords were selected after a previous literature survey and to capture the agri-food contexts in Mediterranean regions. The keyword “agr*-food” was considered in this way to allow for a wider search (including “agri-food”, “agro-food”, etc.). Considering only articles (excluding proceeding papers, book chapters, and books, because in some cases it is difficult to access the entire content of the document), 100 and 117 documents were obtained from the WoS and Scopus, respectively. After removing the duplicated studies and taking into account the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) approach, 137 documents were surveyed through a literature review. As main insights, several dimensions embedded in the concept of agri-food were highlighted, from those related to heritage subjects to natural assets. On the other hand, the following subtopics were identified: agri-food dynamics and sustainability, agriculture and agri-food systems, agri-chains and food consumption, and food production and composition impact on agri-chains. Stressing the gaps in the scientific literature, related to the topics here addressed, there are possibilities to better explore the several dimensions and solutions offered by the new developments associated with smart agriculture and agriculture 4.0, specifically for the Mediterranean contexts and their challenges. Finally, to complement the PRISMA methodologies, an MB2MBA2 (Methodology Based on Benchmarking of Metadata, from scientific databases, and Bibliometric Assessment and Analysis) approach is suggested to carry out systematic literature reviews, based on bibliometric analysis.

Combined Experimental and Multivariate Model Approaches for Glycoalkaloid Quantification in Tomatoes

The intake of tomato glycoalkaloids can exert beneficial effects on human health. For this reason, methods for a rapid quantification of these compounds are required. Most of the methods for α-tomatine and dehydrotomatine quantification are based on chromatographic techniques. However, these techniques require complex and time-consuming sample pre-treatments. In this work, HPLC-ESI-QqQ-MS/MS was used as reference method. Subsequently, multiple linear regression (MLR) and partial least squares regression (PLSR) were employed to create two calibration models for the prediction of the tomatine content from thermogravimetric (TGA) and attenuated total reflectance (ATR) infrared spectroscopy (IR) analyses. These two fast techniques were proven to be suitable and effective in alkaloid quantification (R² = 0.998 and 0.840, respectively), achieving low errors (0.11 and 0.27%, respectively) with the reference technique.

Environmental assessment of viticulture waste valorisation through composting as a biofertilisation strategy for cereal and fruit crops

Composting is a solid waste management alternative that avoids the emission of methane associated with its disposal in landfill and reduces or eliminates the need for chemical fertilisers if compost is applied. The main objective of this study was to analyse the environmental burdens of composting as a way to achieve a more circular valorisation of wine waste. To do so, with the purpose of identifying optimal operational conditions and determining the "hotspots" of the process, the life cycle assessment (LCA) methodology was used. The consumption of diesel fuel in machinery was determined to be the main critical point in the environmental effects of the system, followed by the transport and distribution of the compost. After the application of compost instead of mineral fertilisers, corn, tomato and strawberry crops would have a better environmental performance in most impact categories. In this sense, a maximum improvement of 65% in terrestrial ecotoxicity is achieved in strawberry cultivation. In light of the results obtained, it is demonstrated that composting is a suitable way of organic waste valorisation according to Circular Economy principles.

Alternatives for Chemical and Biochemical Lignin Valorization: Hot Topics from a Bibliometric Analysis of the Research Published During the 2000–2016 Period

A complete bibliometric analysis of the Scopus database was performed to identify the research trends related to lignin valorization from 2000 to 2016. The results from this analysis revealed an exponentially increasing number of publications and a high relevance of interdisciplinary collaboration. The simultaneous valorization of the three main components of lignocellulosic biomass (cellulose, hemicellulose, and lignin) has been revealed as a key aspect and optimal pretreatment is required for the subsequent lignin valorization. Research covers the determination of the lignin structure, isolation, and characterization; depolymerization by thermal and thermochemical methods; chemical, biochemical and biological conversion of depolymerized lignin; and lignin applications. Most methods for lignin depolymerization are focused on the selective cleavage of the β-O-4 linkage. Although many depolymerization methods have been developed, depolymerization with sodium hydroxide is the dominant process at industrial scale. Oxidative conversion of lignin is the most used method for the chemical lignin upgrading. Lignin uses can be classified according to its structure into lignin-derived aromatic compounds, lignin-derived carbon materials and lignin-derived polymeric materials. There are many advances in all approaches, but lignin-derived polymeric materials appear as a promising option.

Thermal analysis methods for the rapid identification and authentication of swiftlet (Aerodramus fuciphagus) edible bird's nest - A mucin glycoprotein

Edible bird's nest of the swiftlet Aerodramus fuciphagus, is an unusual dried mucin glycoprotein, which has been used, particularly by Asians, as a premium food and wide spectrum health supplement for centuries. For the first time, thermogravimetry, differential thermogravimetry, and differential scanning calorimetry methods are used for the rapid identification and authentication of edible bird's nest. It is shown that edible bird's nest has a total moisture content of 12.6% which is removed below 200°C, followed by two major decomposition steps on heating under nitrogen gas. The first decomposition step (200-735°C) has a mass loss of 68.0% with maximum rate of mass loss at about 294°C, and the second decomposition step (735-1000°C) has a mass loss of 15.4% with maximum rate of mass loss at about 842°C, leaving a ceramic residue of about 4.0%. Differential scanning calorimetry shows that there are two kinds of bound water in edible bird's nest: (a) loosely bound water (about 7.5%) that dehydrates from edible bird's nest first, largely below 110°C, which can also be removed by lyophilization, and (b) tightly bound water (about 5.0%), still present in the edible bird's nest after lyophilization, that dehydrates from edible bird's nest between 100 and 200°C. The unique thermogravimetry and differential thermogravimetry curves of edible bird's nest serve as analytical standards and offer a simple, fast technique that requires only a small sample size (5-10mg) without the need for sample pretreatment to authenticate and check for edible adulterants which may be introduced into edible bird's nest with a profit motive.