Biofloc technology has been developed as a sustainable system in aquaculture, which uses microbial processes to remove nutrients from the water and convert them into microbial biomass. For optimal performance, the addition of carbohydrates is essential, while their type can regulate microbial activity and composition. Specifically, we hypothesize that dietary supplementation of wheat bran, containing indigestible carbohydrates such as non-starch polysaccharides, can provide complex substrates supporting diverse microbial communities within the biofloc. In this study, we investigated how higher dietary wheat bran input affected the biofloc prokaryotic and eukaryotic microbial communities in Pacific white shrimp (Litopenaeus vannamei) culture. Two pelleted diets were made: a control diet (CONdiet) with a composition similar to a commercial shrimp diet, and a diet rich in non-starch polysaccharides (WBdiet), which was created by adding wheat bran to the control diet ingredient mix, before pelleting. These two diets were fed isonitrogenous to the shrimp for 42 days, and sampling of the biofloc was performed every three weeks. The results showed shifts in both the alpha and beta diversity in biofloc during the experiment. Diet had a significant effect on the prokaryotic community composition in the biofloc at the end of the culture period, with several genera being enriched in biofloc tanks fed the WBdiet such as Muricauda, Pirellula, and Cyanobacteriaceae. Regarding the eukaryotic communities, overall, only a few taxa were significantly affected within the WBdiet, belonging to the Trebouxiophyceae and Suillus groups. Interestingly, when feeding the WBdiet, the biofloc microbial communities exhibited predicted functionalities that were more abundant in carbohydrate metabolism, and specifically related to pentose, fructose, mannose and galactose metabolism. These results provide a basis for the control of biofloc microbial communities by using ingredients rich in plant-derived non-starch polysaccharides which shrimp cannot digest but are good energy source for the microbiota in the biofloc.

Background: Eating rate is a modifiable risk factor for obesity and efficient methods to objectively characterise an individual's oral processing behaviours could help better identify people at risk of increased energy consumption. Many previous approaches to characterise oral processing and eating rate have relied on specialised equipment or wearable devices that are time consuming, expensive or require expertise to administer. The current trial used video-coding of the consumption of a standardised test food (the ‘carrot test’) to measure oral processing. Objective: We sought (i) to test whether self-reported eating rate (SRER) is predictive of food oral processing derived from coded eating behaviours captured in the laboratory with a standardised test food, and (ii) to test whether differences in SRER are predictive of oral processing behaviours, eating rate and intake of a test meal. Methods: Two hundred and fifty-three volunteers (86 male and 167 female, mean age 39.5 ± 13.6 years, mean BMI 22.2 ± 3.4 kg/m2) provided their SRER and anthropometric measurements of height, weight and dual-energy X-ray absorptiometry (DEXA) percentage fat mass. Participants were also video recorded eating a fixed 50 g portion of carrot and an ad libitum lunch meal of fried rice. Average eating rate (g/min), bite size (g) and number of chews per bite for the carrot and lunch were derived through behavioural coding of the videos. Energy intake (kcal) was recorded at lunch and a later afternoon snack. Results: Faster SRER significantly predicted faster eating rate, larger bite size and more chews per bite observed during intake of the carrot (ß = −0.26–0.21, p ≤ 0.001) and the lunch (ß = −0.26–0.35, p ≤ 0.014). SRER did not significantly predict intake at lunch or during the afternoon snack (ß = 0.05–0.07, p ≥ 0.265). Participants’ oral processing of the carrot significantly predicted oral processing of the lunch (ß = −0.25–0.40, p ≤ 0.047) and faster eating rate of the carrot significantly predicted increased lunch intake (ß = 0.119, p = 0.045). None of the oral processing behaviours predicted afternoon snack intake (ß = −0.01–0.05, p ≥ 0.496). None of these associations were moderated by BMI or body composition. Conclusion: We confirm that SRER is a valid measure of group level differences in individual oral processing behaviours, but did not predict an individual's energy intake at a lunch-time meal. With this approach, it is possible to characterise differences in eating rate by coding eating behaviours for a standardized test food (in this case, a fixed portion of raw carrot). This approach could be used to provide an objective measure of a person's habitual oral processing behaviour, and was shown to be a significant predictor of eating rate and energy intake for a later test meal.

Hypothesis. Multi-walled tubular aggregates formed by hierarchical self-assembly of beta-cyclodextrin (β-CD) and sodium dodecylsulfate (SDS) hold a great potential as microcarriers. However, the underlying mechanism for this self-assembly is not well understood. To advance the application of these structures, it is essential to fine-tune the cavity size and comprehensively elucidate the energetic balance driving their formation: the bending modulus versus the microscopic line tension. Experiments. We investigated temperature-induced changes in the hierarchical tubular aggregates using synchrotron small-angle X-ray scattering across a broad concentration range. Detailed analysis of the scattering patterns enabled us to determine the structural parameters of the microtubes and to construct a phase diagram of the system. Findings. The microtubes grow from the outside in and melt from the inside out. We relate derived structural parameters to enthalpic changes driving the self-assembly process on the molecular level in terms of their bending modulus and microscopic line tension. We find that the conformation of the crystalline bilayer affects the saturation concentration, providing an example of a phenomenon we call conformational freezing point depression. Inspired by the colligative phenomenon of freezing point depression, well known from undergraduate physics, we model this system by including the membrane conformation, which can describe the energetics of this hierarchical system and give access to microscopic properties without free parameters.

Scientific committee member

Walnuts are renowned for their rich oil content and nutritional value, imparting significant health benefits. Walnut oleosomes, naturally present in a pre-emulsified state, can be effectively extracted through aqueous methods. Mechanical processes, such as twin-crew pressing or blending, are commonly employed to disrupt cell walls and extract oleosomes. Our study focused on investigating these two methods under varying soaking pH for walnut oleosomes extraction to develop an efficient extraction process for large-scale production or specific applications. Results showed that the oil content of extracted oleosomes ranged from 84.5% to 89.5%, with no substantial differences noted. Twin-screw pressing significantly achieved higher extraction yields (53.3–57.8%) compared to blending (35.7–36.4%), while blending produced walnut oleosomes with higher zeta potential, viscosity, storage modulus, and smaller particle size, improving physical stability compared to blended samples. The soaking pH levels minimally impacted extraction efficiency and physicochemical attributes of the oleosomes. Overall, blending offered oleosomes with relatively better physical stability, while twin-screw pressing was more advantageous for higher yields, making it more commercially viable for large-scale production. This study underscored the efficiency of sustainable approach in harnessing walnut oleosomes for various industrial applications.

Lupin protein isolate (LPI) has high nutritional value and good foaming properties around neutral pH; however, its functionality becomes poor at acidic pH, due to reduced protein solubility. The addition of pectin to LPI can increase its solubility at acidic pH and hence improve protein functionality. Here, we investigated the air-water interfacial and foaming properties of LPI-pectin (1:1) mixtures at pH 3.5–7.0. We used interfacial shear and dilatational rheology, characterized the air-water interfacial microstructure with AFM of Langmuir-Blodgett films, and linked the results to the foaming properties of the LPI-pectin mixtures. Based on the phase diagram, LPI and pectin formed co-soluble mixtures at pH 6.0 and 7.0, while LPI-pectin electrostatic complexes were formed at pH 3.5 and 4.0. In the co-soluble mixtures, proteins diffused faster towards the air-water interface than the electrostatic complexes, due to smaller particle sizes of the proteins. Their air-water interfaces showed distinct differences with respect to microstructure and mechanical properties. The interfaces stabilized by co-soluble mixtures were dominated by protein aggregates, leading to weaker interfaces in response to shear and dilatational deformation, while the complexes formed thicker and denser polymeric air-water interfaces that were stiffer and more solid-like. As a result, the complex-stabilized foams were more stable than those stabilized with co-soluble mixtures. Findings from this study indicate that soluble LPI-pectin complexes formed at pH 3.5 and 4.0 were more efficient in improving interfacial and foaming properties of LPI than the co-soluble mixtures at pH 6.0 and 7.0, which can be used to tailor the properties of acid aerated products stabilized by LPI.

The availability of conventional linear mineral phosphorus (P) fertilization will become lower as phosphate rock stocks are limited and strongly concentrated in a few locations. Therefore, we need to increase agronomic P use efficiency and find alternative, recycled, sources of P. Two possible solutions mentioned in the literature are (i) using struvite, a mineral circular P fertilizer; and (ii) making use of earthworm activity, which has been shown to increase P availability. Here, we study the interaction between these two approaches, with the hypothesis that earthworms could increase the P availability from the poorly soluble struvite. We set up a field-based mesocosm experiment in a sandy soil with a low agronomic P status with 13 different treatments combining three earthworms species (Lumbricus rubellus Hoffmeister, Aporrectodea caliginosa Savigny and A. longa Ude alone or in a threes species mixture), different P fertilizers (no P, Triple Super Phosphate (TSP) and struvite). The experiment lasted 13 months (five fertilisation-harvest cycles). We found that, in field conditions, the yield and P uptake of Lolium perenne did not differ between fertilization with struvite or TSP. Earthworms only played a minor role in explaining ryegrass P uptake compared to fertilisation. We did not see either positive nor negative interactions between earthworms and struvite, meaning that earthworms did not further increase the P availability from struvite. The equal performances of struvite and TSP are explained by an enhanced effort from plants to actively take up P through a modification of root traits. This includes increased arbuscular mycorrhizal fungi colonisation and the production of finer and longer roots. Our results show that struvite performs comparably to TSP under realistic field conditions, making it a viable alternative to phosphate rock-based fertilizers.

The way food is presented can significantly influence liking, satiation, and emotional responses to food. This study explored these effects across two separate experiments by examining the impact of plate size (small vs. large) and plating style (high-stacked vs. spread) on participants’ liking, satisfaction, fullness, and food-evoked emotions when consuming chicken salad. In the first experiment, conducted online (n = 192), we used interactive 360-degree videos to simulate real-life experiences of chicken salads under the different conditions. The second experiment expanded this research into a real-life cafeteria setting (n = 176) where participants actually consumed the chicken salads. In this setting, salads served on a large plate with high-stacked plating received the highest ratings for liking, compared to the other conditions: small plate-high-stacked, small plate-spread, and large plate-spread. This condition also evoked the most positive food-related emotions, such as happiness, satisfaction, and relaxation, and was perceived as closest to the “ideal portion size.” Notably, the real-life experiment provided a better discrimination between the experimental conditions, with more intense and higher ratings on food-evoked emotions, liking, and willingness to pay compared to the online context. Real-life eating encompasses social interactions, sensory stimulation and post-ingestive effects, offering a richer and more accurate representation of actual eating experiences. These findings highlight the importance of real-life multi-modal measurement environments for obtaining accurate measures of food perception, acceptance and eating behaviours.

Waste management has emerged as a critical issue in aquaculture. In this study, we examined the impact of dietary starch and non-starch polysaccharides (NSP) content on nutrient digestibility, faecal waste production, faecal removal efficiency and the faecal characteristics in three salmonid species, namely rainbow trout (Oncorhynchus mykiss), Atlantic salmon (Salmo salar) and Arctic charr (Salvelinus alpinus). Four diets were formulated according to a 2 × 2 factorial design. The first factor, starch, was tested by including 0% gelatinised wheat flour (low starch) or 20% gelatinised wheat flour (high starch) in a plant-based basal diet. The second factor, NSP, was tested by adding 0% NSP source (low NSP) or 10% NSP source (high NSP). High NSP level was achieved by adding an equal mixture of soya hull (5%) and wheat bran (5%). Diets were tested in triplicates for each species and feeding was done restrictively. Experimental duration was 42 days for rainbow trout and Atlantic salmon and 49 days for Arctic charr. Among the three species investigated, Arctic charr had the lowest digestibility values for most nutrients, whereas rainbow trout and Atlantic salmon values were comparable. High starch level in the diet reduced the macronutrient (protein, fat and ash) digestibility in all three species. High starch and high NSP levels in the diet increased faecal waste production, with the effect being more pronounced for the NSP content of the diet. High dietary starch levels increased the proportion of smaller-sized particles, while high NSP content increased the ability of faecal particles to withstand mechanical stress. The high starch level in the diet lowered faecal removal efficiency but increased by high NSP content. The highest and lowest faecal removal efficiency was recorded for Atlantic salmon and Arctic charr, respectively. The amount of non-removed faeces accumulating in the system was increased by the high starch levels in rainbow trout and Atlantic salmon but remained unaffected by the NSP content of the diet across the species. No interaction effect between starch and NSP content of diets was observed for faecal removal efficiency and non-removed faeces. Among the three species investigated, Arctic charr had the maximum amount of non-removed faeces per kilogram of dry matter feed.

The mycelium of mushroom-forming fungi represents an underappreciated protein source that can be cultivated on agricultural rest-streams and industrially prepared substrates. Consumer food options include unprocessed fresh mycelium or products derived from purified mycelium protein. Both the use of rest streams and the association of fresh mycelia with moulds can create a tension between potentially disgusting and naturalness cues. The current paper investigates this tension in a 3 (substrate: manure, wood, glucose) by 3 (level of processing: unprocessed mycelium cake, purified mycelium protein powder, burger from mycelium protein) experimental survey (N = 449). Results show that substrate source has limited impact on disgust but a slightly greater influence on perceived naturalness. Level of processing has a significant effect on both disgust and naturalness. As expected, social value and attitude based on benefit-risk trade-off inform acceptance. While effects of disgust and naturalness on benefit-risk attitude and social value balance each other, a direct effect of disgust on acceptance remains, underscoring the pivotal role of disgust in shaping consumer acceptance. This suggests for mycelium producers there is freedom of choice of substrate as it has limited effect on consumer acceptance.

The management of biofloc quality and quantity is critical in biofloc-based aquaculture systems. This research explores the effects of the selective removal of settleable and unsettled bioflocs on biofloc quality, fish growth, nitrogen transformation and bacterial community dynamics in these systems. Nile tilapia (Oreochromis niloticus) was reared at a density of 2.7 kg/m3 in nine 250-L conical breeding tanks over a 47-day period. Systems where unsettled bioflocs were removed outperformed others, achieving a 26 % higher weight gain in tilapia and maintaining more stable and lower levels of total ammonia (0.45 mg-N/L) and nitrite (0.35 mg-N/L). Additionally, these systems maintained a healthier bacterial environment, evidenced by a 27 % increase in beneficial bacterial populations and a 30 % reduction in harmful bacteria. Conversely, tanks removing settleable bioflocs showed a 19 % higher microbial diversity but experienced fluctuations in nitrogen levels. Notably, the intestinal bacterial community in tilapia from the unsettled biofloc group closely mirrored (87 % similarity) that of their corresponding bioflocs, with significant pathogenic symptoms observed (p < 0.05). These findings suggest the importance of implementing precise biofloc management strategies, highlighting that the selective removal of unsettled bioflocs enhances fish growth and improves overall system health. Future research should explore the mechanistic relationships between settleable and unsettled bioflocs to refine management strategies that bolster sustainability and economic benefits.

Deforestation is one of the major threats to the climate and vital habitats for humans and animals. Forest Foresight, the new intelligent system developed by the World Wildlife Fund (WWF), can predict illegal logging. Wageningen University & Research is working on making the system even smarter, and the initial results in Gabon (Africa) are promising.

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Namens het hele Nature Today-team wensen we u heel veel natuur toe in 2024. We staan klaar om net als in 2023 heel veel interessante natuurberichten van de tientallen partners over actuele ontwikkelingen in de natuur te publiceren. We zijn net als jullie benieuwd naar welke nieuwe soorten ontdekt gaan worden, waarom er van sommige soorten weinig of juist opeens heel veel zijn en ga zo maar door.

Preserving archives in countries like India, Indonesia, Sri-Lanka, Brazil, and Suriname is challenging because of tropical climate conditions (high relative humidity (RH) and high temperature (T)), especially in combination with often non-reliable climate control systems. Variable (and fast changing) climate conditions in combination with high RH pose a serious threat to archival records. The National Archives of the Netherlands (NAN) cooperates with local archive institutions to preserve the archives originating from the Dutch presence in these countries. The aim of this project is to investigate the packaging concept of archive boxes and to come with possible solutions to protect archived documents better against (fast changing) variable climate conditions and insect intrusion, thereby taking into account also other requirements such as economy (low price), possibility for local production (less transportation), sustainability, and lifetime. For good preservation it is important that the RH (or water activity) inside the box and of the archived material is below about 60%. Starting point of this project was the wish to create a packaging (archive box) that protects its content against varying climatic environmental conditions. A hypothesis was that this could be obtained by a suitable packaging material and coating with optimal moisture permeability in combination with an absorber. This could result in a lower RH and lower RH variability inside the packaging upon changes in environmental conditions. Wageningen Food and Biobased Research (WFBR) performed a study to possible solutions, including an investigation to the state of the art knowledge on the moisture migration phenomena relevant for the archive box. Based on these results, WFBR developed a quantitative physical model describing moisture transport through and inside an archive box, to get insight in the key factors that control water migration and moisture content of the archived materials and to test the starting hypotheses. With this model the effects of different packaging options, including coating and usage of moisture absorbers, were evaluated in relation to (changes in) environmental RH and T. WFBR found that application of polymer coatings on cardboard archival boxes will indeed decrease the water vapor flux between the inside and outside environment of the box, but that it will only be effective on a time scale of hours to days and not on longer desired time scale of months. For boxes that need to withstand moisture migration on a time scale of months, other materials are needed, like metals or plastics, that do not comply with additional requirements like cost effectiveness and/or the possibility of local production. Furthermore, in case of relatively high humidity inside the box due to e.g. adding a relative wet paper to the box or due to a mal functioning of the climate control system for a period longer than about a few days, the outflux of water from the box is also decreased when a coating is applied. This results in the counter effective result that when the coating on an archival box is improved to decrease water vapour permeability, the archival content (upon a temporarily increase of the humidity in the storage room) will be subjected for a longer duration to high humidity inside the box. Concerning the role of absorbers, it is concluded that the effect of common absorbers is very limited. This because they are already saturated at RH’s around 50%, which are common RH’s in tropical archival storage rooms. Therefore their buffering capacity when the environmental RH increase above 50% is very limiting. Ideally, a special absorber is needed that does not absorb at storage room humidities (below about 55%) but absorbs at higher RH’s that may occur either during transport or during defects in the climate control of a storage room. However these are specific and expensive and do not match the boundary conditions set in this project. In general, the archives of the NAN experience different types of problems due to the tropical climate, which require different types of solutions. There is no archive box or material that can solve all of these problems at the same time. This because the effect of a certain adaptation, like application of a coating or absorber, on the moisture exposure of the archived documents, depends on the details and timescale of the experienced problem. So, because tropical archives experience different types of problems of different durations, no general advice for the construction of an archive box can be given to minimize the exposure of the archived materials to high humidities. However, recommendations depending on the situation and duration can be and are given. These include changing the currently used corrugated cardboard to solid board and closing gaps in the box to minimize insect intrusion as well as stabilize the storage conditions and improve handling protocols.

Groene waterstof maken uit zeewater en tegelijkertijd schoon drinkwater en elektriciteit. En uit datzelfde zeewater bovendien waardevolle mineralen als lithium en tafelzout filteren. Onderzoekers van de Wageningen University & Research (WUR) laten met de Zeewaterstof-methode (SeaHydrogen) zien dat het kan. “Op deze manier houden we de waterstofeconomie milieuvriendelijk en haalbaar.”