Structured adsorbents for isolation of functional food ingredients

Separation and purification of functional ingredients from raw or waste streams are often done via processes that include a chromatographic step using a packed bed of resin particles that have affinity for the ingredients to be separated. A column packed with these particles presents numerous bottlenecks when dealing with untreated or large streams: a trade-off between mass transfer and hydraulic permeability, a high pressure drop and susceptibility to plugging and fouling. The large equipment (column diameters) and volume of resin needed for a moderate pressure drop and a high capacity, poses problems of elevated costs and complex operation. Other technologies such as radial flow chromatography and polymeric resins membranes may represent an improvement in other applications (e.g. pharma or fine chemicals), but at this point their capacity and costs do not seem to be feasible for the separation of small molecules from larger food streams. The aim of the research discussed in this thesis was to find the principles that determine the suitability of different structured adsorbents, such as monoliths, for the selective adsorption and recovery of high-added value food ingredients of relatively low molecular weight, such as oligosaccharides and bioactive peptides. To ensure a cost-effective process and high capacity for small molecules, we demonstrated the feasibility of using activated carbon, and compared its adsorptive and hydraulic performance in two different structures: porous particles and channeled monoliths (”honeycomb” structures). Furthermore, we assessed the feasibility and window of operation of monoliths in terms of adsorbent and column volume required, compared to packed beds. To demonstrate the isolation of bioactive peptides from crude mixtures with activated carbon, we used activated carbon to recover a lacto-tripeptide IPP from a commercial hydrolyzate (1.5% w/w) in chapter 2. The purity of the initial crude mixture was doubled in the isolate, to up to 35% with a recovery of IPP of about 80% in the first cycles of adsorption. This was repeated over many consecutive adsorption-desorption cycles until the activated carbon packed bed column was exhausted. This exhaustion was found to be caused not only by the occupation of irreversible sites but also by pore blockage. Finally, guidelines were given for the competitive exhaustion of the adsorbent for process optimization in order to obtain higher purity and yield. In chapter 3 we showed the benefits of using channeled monoliths for processing untreated streams. We compared the use of channeled monoliths with a packed bed, both made of the same type of activated carbon, for the adsorption of the lactotripeptide IPP from a crude hydrolyzate. The results showed similar productivity and dynamic adsorptive capacities at comparable linear velocities and residence times, but the packed bed showed a strong pressure drop increase during continuous loading of the column and the same consecutive adsorption-desorption cycles as studied in chapter 2. This indicates the occurrence of pore blockage and plugging of the column. These fouling mechanisms were confirmed with two semi-empirical model analogies: one analogous to membrane fouling and another using an analogy with a set of parallel channels. The strong pressure drop increase was even more noticeable at high velocities (and short residence times). These trends were not observed in the channeled monoliths: no significant pressure drop increase was found here, and high velocities were eminently feasible. In chapter 4 the adsorption of lactose onto a bed of activated carbon particles and activated carbon channeled monoliths was described with a detailed chromatographic model, taking into account the different mass transfer resistances. First, the single component adsorption isotherm parameters were obtained using frontal analysis on both adsorbents. Second, the kinetics of adsorption of lactose on both activated carbon adsorbents were estimated using the shallow bed method, assuming an infinite bath. The uptake curves were fitted to the homogeneous surface diffusion model and the linear driving force approximation. The estimation of the intraparticle diffusion coefficient and the film mass transfer coefficient showed a similar intraparticle mass transfer performance during the uptake adsorptive process. Fitting of the breakthrough data to the general rate model describing the full column operation showed differences in performance during the overall column operation. These differences could be related to higher axial dispersion in the squared channeled monoliths. The difference between the experimentally-derived axial dispersion and he expected assuming tubular coated tubes, suggested that the squared shape was responsible for the inhomogeneity of the flow. In chapter 5, we presented guidelines for the configuration of industrial scale chromatographic separation of small molecules. A window was identified that defines the feasible configurations to use for the highest productivity for a given set of process requirements. The performance of different axial packed beds, channeled monoliths and a continuous monolith assuming silica as base material were compared by means of HETP (height equivalent of theoretical plates) and pressure drop relations. The relations as a function of velocity were used to calculate the resultant velocity and packing length for different conditions (efficiency, pressure drop, affinity constant and throughput). The specific productivity of channeled monoliths was shown to be up to 2.5 orders of magnitude higher than that of a packed bed. Therefore, at large scales (in which the pressure drops need to be limited, and the flow rate is high), channeled monoliths are preferred since they may reduce the equipment size up to 100 times and the required adsorbent volume up to 1000 times. Finally, in chapter 6 we discussed the suitability of activated carbon regarding its re-usability and purification potential in the separation of small food ingredients. The suitability of channeled monoliths for certain applications was also highlighted. Finally, other suitable adsorbents were suggested, and some future prospects in the selection of adsorbents were given.</p

Association of insularity and body condition to cloacal bacteria prevalence in a small shorebird

Do islands harbour less diverse disease communities than mainland? The island biogeography theory predicts more diverse communities on mainland than on islands due to more niches, more diverse habitats and availability of greater range of hosts. We compared bacteria prevalences ofCampylobacter,ChlamydiaandSalmonellain cloacal samples of a small shorebird, the Kentish plover (Charadrius alexandrinus) between two island populations of Macaronesia and two mainland locations in the Iberian Peninsula. Bacteria were found in all populations but, contrary to the expectations, prevalences did not differ between islands and mainland. Females had higher prevalences than males forSalmonellaand when three bacteria genera were pooled together. Bacteria infection was unrelated to bird's body condition but females from mainland were heavier than males and birds from mainland were heavier than those from islands. Abiotic variables consistent throughout breeding sites, like high salinity that is known to inhibit bacteria growth, could explain the lack of differences in the bacteria prevalence between areas. We argue about the possible drivers and implications of sex differences in bacteria prevalence in Kentish plovers

Comparison of structured adsorbents for the adsorptive isolation of food ingredients from large streams

We present guidelines for the configuration of industrial scale chromatographic separation of small molecules. We compared the performance of different axial packed beds, channeled monoliths and a continuous monolith assuming silica as base material. The calculated mass transfer rates were used to calculate the height of a theoretical plate (HETP). The HETP and pressure drop relations as a function of velocity were used to calculate the resultant velocity and packing length for different conditions (efficiency, pressure drop, affinity constant and throughput). The specific productivity of channeled monoliths can be up to 2.5 orders of magnitude higher than that of a packed bed. This implies that at large scales (in which the pressure drops need to be limited, and the flow rate is high), channeled monoliths are preferred since they may reduce the equipment size up to 100 times and the required resin volume up to 1000 times. Accordingly, we demonstrate the potential of channeled monoliths in chromatographic processes but also draw a window pointing out the feasible configurations to use with the highest productivity for a given set of process requirements

Mapping the potential of the food loss and waste flows for circularity applications in the Amsterdam Metropolitan Area

Food losses and waste (FLW) is a significant issue that affects food security, climate change, and resource efficiency. To address this, FLW reduction can be achieved through prevention and valorization strategies, which require quantification of FLW streams. While FLW quantification is a new field with several challenges, there is a growing interest in quantifying FLW at the city or metropolis level, e.g., as seen in Amsterdam's efforts to become a circular city.This paper presents an initial study that quantifies food losses and waste (FLW) along the food supply chains in Amsterdam Metropolitan Areas, identifying hotspots for FLW, the associated nutrients, and its contribution to climate change (i.e. greenhouse gas emissions associated with the FLW). The study provides valuable insights for city managers to improve FLW prevention and valorization, and the methodology developed can be applied to other metropolises. Overall, this research makes an important contribution to FLW quantification and management

Recovery of a bioactive tripeptide from a crude hydrolysate using activated carbon

Separation and purification processes of neutraceuticals, such as bioactive peptides, are usually done in a multistep process that sometimes requires a final chromatographic step using expensive resins. Activated carbon is a promising economic alternative for the resins. We report here on the application of a hydrophobic interaction on a chromatographic column packed with particles of activated carbon to isolate a lactotripeptide from a crude hydrolysate. Consecutive adsorptive–desorptive cycles were used until exhaustion of the column. Liquid chromatography–mass spectrometry results showed an enrichment of the lactotripeptide isoleucine–proline–proline with a yield of up to 80% in the third cycle and a twofold increase in purity to up to 35%. Some guidelines are given for the competitive exhaustion of the adsorbent for process optimization in order to obtain higher purity and yield

Exergy efficiency from staple food ingredients to body metabolism : The case of carbohydrates

One of the methods to evaluate the efficiency in the production of foods is using exergy, the share of useful energy, and exergy analysis. In this paper, we propose a link between exergy analysis and nutrition to account for the exergy efficiency (exergy of output per exergy of input) in the metabolism of nutrients from foods in the human body. For this, we analyzed the exergy efficiency of four different chains of carbohydrate-rich products based on semi-industrial preparation processes and we included nutrient bioavailability through the use of several bioavailability indicators, including the glycemic index and protein digestibility. The least exergy efficient chain changed when not only looking at the exergy losses of the food processing chains, but also including the bioavailability and conversion of nutrients into adenosine triphosphate (ATP), the main molecule for energy storage in the body. When including only the processing chain, white bread presented the highest exergy loss, whereas the lowest values pointed to the spaghetti chain when also including metabolism both because of its preprocessing chain and its low bioavailability. In contrast, cooked potatoes were found to be an efficient source of ATP due to both a high metabolic efficiency and low process exergy losses. The carbohydrate bioavailability had a strong influence on the overall exergy efficiency of the studied cases, which shows the importance of including bioavailability aspects in the sustainability assessment of industrial food processing chains

Genetic, morphological, and acoustic evidence reveals lack of diversification in the colonization process in an island bird

International audienceSongbirds with recently (i.e., early Holocene) founded populations are suitable models for studying incipient differentiation in oceanic islands. On such systems each colonization event represents a different evolutionary episode that can be studied by addressing sets of diverging phenotypic and genetic traits. We investigate the process of early differentiation in the spectacled warbler (Sylvia conspicillata) in 14 populations separated by sea barriers from three Atlantic archipelagos and from continental regions spanning from tropical to temperate latitudes. Our approach involved the study of sexual acoustic signals, morphology, and genetic data. Mitochondrial DNA did not provide clear population structure. However, microsatellites analyses consistently identified two genetic groups, albeit without correspondence to subspecies classification and little correspondence to geography. Coalescent analyses showed significant evidence for gene flow between the two genetic groups. Discriminant analyses could not correctly assign morphological or acoustic traits to source populations. Therefore, although theory predicting that in isolated populations genetic, morphological, or acoustic traits can lead to radiation, we have strikingly failed to document differentiation on these attributes in a resident passerine throughout three oceanic archipelagos