Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Aromatic Potential of Diverse Non-Conventional Yeast Species for Winemaking and Brewing
    Gamero, Amparo ; Dijkstra, Annereinou ; Smit, Bart ; Jong, Catrienus de - \ 2020
    Fermentation 6 (2020)2. - ISSN 2311-5637
    Traditionally, Saccharomyces species are those used to conduct industrial alcoholic fermentations. Recently, an increasing interest has arisen with respect to the potential of so-called non-conventional yeasts to improve wine and beer aroma profiles, keeping the particular terroir of each region or for the development of craft beers. In this study, the potential of diverse non-conventional yeasts to improve aroma in winemaking and brewing was investigated, testing several pure and mixed culture combinations. In addition, a comparison between microscale and labscale was carried out in order to assess the value of microwine and microbeer as screening tools. The results indicated that non-Saccharomyces yeasts were good candidates to enhance or diversify aroma profiles in alcoholic beverages, especially regarding acetate ester yield and fruity aromas. However, mixed cultures with Saccharomyces spp. are normally required to achieve a successful fermentation. The adjustment of pithing ratios is crucial for this purpose. Microscale is presented as an effective and efficient screening tool to compare different culture combinations, although scaling-up will always be necessary in order to get results closer to real winemaking or brewing processes
    Functional Validation of Two Fungal Subfamilies in Carbohydrate Esterase Family 1 by Biochemical Characterization of Esterases From Uncharacterized Branches
    Li, Xinxin ; Griffin, Kelli ; Langeveld, Sandra ; Frommhagen, Matthias ; Underlin, Emilie N. ; Kabel, Mirjam A. ; Vries, Ronald P. de; Dilokpimol, Adiphol - \ 2020
    Frontiers in Bioengineering and Biotechnology 8 (2020). - ISSN 2296-4185
    acetyl xylan esterase - carbohydrate esterase - CAZy subfamilies - ferulic acid - feruloyl esterase - fungi - plant biomass degradation

    The fungal members of Carbohydrate Esterase family 1 (CE1) from the CAZy database include both acetyl xylan esterases (AXEs) and feruloyl esterases (FAEs). AXEs and FAEs are essential auxiliary enzymes to unlock the full potential of feedstock. They are being used in many biotechnology applications including food and feed, pulp and paper, and biomass valorization. AXEs catalyze the hydrolysis of acetyl group from xylan, while FAEs release ferulic and other hydroxycinnamic acids from xylan and pectin. Previously, we reported a phylogenetic analysis for the fungal members of CE1, establishing five subfamilies (CE1_SF1–SF5). Currently, the characterized AXEs are in the subfamily CE1_SF1, whereas CE1_SF2 contains mainly characterized FAEs. These two subfamilies are more related to each other than to the other subfamilies and are predicted to have evolved from a common ancestor, but target substrates with a different molecular structure. In this study, four ascomycete enzymes from CE1_SF1 and SF2 were heterologously produced in Pichia pastoris and characterized with respect to their biochemical properties and substrate preference toward different model and plant biomass substrates. The selected enzymes from CE1_SF1 only exhibited AXE activity, whereas the one from CE1_SF2 possessed dual FAE/AXE activity. This dual activity enzyme also showed broad substrate specificity toward model substrates for FAE activity and efficiently released both acetic acid and ferulic acid (∼50%) from wheat arabinoxylan and wheat bran which was pre-treated with a commercial xylanase. These fungal AXEs and FAEs also showed promising biochemical properties, e.g., high stability over a wide pH range and retaining more than 80% of their residual activity at pH 6.0–9.0. These newly characterized fungal AXEs and FAEs from CE1 have high potential for biotechnological applications. In particular as an additional ingredient for enzyme cocktails to remove the ester-linked decorations which enables access for the backbone degrading enzymes. Among these novel enzymes, the dual FAE/AXE activity enzyme also supports the evolutionary relationship of CE1_SF1 and SF2.

    Fasting induces ANGPTL4 and reduces LPL activity in human adipose tissue
    Ruppert, Philip M.M. ; Michielsen, Charlotte C.J.R. ; Hazebroek, Eric J. ; Pirayesh, Ali ; Olivecrona, Gunilla ; Afman, Lydia A. ; Kersten, Sander - \ 2020
    Molecular Metabolism 40 (2020). - ISSN 2212-8778
    Adipose tissue - Fatty acids - Insulin - Lipoprotein lipase - Triglycerides

    Objective: Studies in mice have shown that the decrease in lipoprotein lipase (LPL) activity in adipose tissue upon fasting is mediated by induction of the inhibitor ANGPTL4. Here, we aimed to validate this concept in humans by determining the effect of a prolonged fast on ANGPTL4 and LPL gene and protein expression in human subcutaneous adipose tissue. Methods: Twenty-three volunteers ate a standardized meal at 18.00 h and fasted until 20.00 h the next day. Blood was drawn and periumbilical adipose tissue biopsies were collected 2 h and 26 h after the meal. Results: Consistent with previous mouse data, LPL activity in human adipose tissue was significantly decreased by fasting (−60%), concurrent with increased ANGPTL4 mRNA (+90%) and decreased ANGPTL8 mRNA (−94%). ANGPTL4 protein levels in adipose tissue were also significantly increased by fasting (+46%), whereas LPL mRNA and protein levels remained unchanged. In agreement with the adipose tissue data, plasma ANGPTL4 levels increased upon fasting (+100%), whereas plasma ANGPTL8 decreased (−79%). Insulin, levels of which significantly decreased upon fasting, downregulated ANGPTL4 mRNA and protein in primary human adipocytes. By contrast, cortisol, levels of which significantly increased upon fasting, upregulated ANGPTL4 mRNA and protein in primary human adipocytes as did fatty acids. Conclusion: ANGPTL4 levels in human adipose tissue are increased by fasting, likely via increased plasma cortisol and free fatty acids and decreased plasma insulin, resulting in decreased LPL activity. This clinical trial was registered with identifier NCT03757767.

    Rapid Identification of Mycoplasma bovis Strains from Bovine Bronchoalveolar Lavage Fluid with Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry after Enrichment Procedure
    Bokma, Jade ; Driessche, Laura Van; Deprez, Piet ; Haesebrouck, Freddy ; Vahl, Marianne ; Weesendorp, Eefke ; Deurenberg, Ruud H. ; Pardon, Bart ; Boyen, Filip - \ 2020
    Journal of Clinical Microbiology 58 (2020)6. - ISSN 0095-1137
    Bayesian latent class model - lipase activity - Mycoplasma bovirhinis - Mycoplasma bovis - Mycoplasma dispar

    Mycoplasma bovis is a leading cause of pneumonia in modern calf rearing. Fast identification is essential to ensure appropriate antimicrobial therapy. Therefore, the objective of this study was to develop a protocol to identify M. bovis from bronchoalveolar lavage fluid (BALf) with matrix-assisted laser desorption ionization-time of flight mass spectrometry MALDI-TOF MS and to determine the diagnostic accuracy in comparison with other techniques. BALf was obtained from 104 cattle, and the presence of M. bovis was determined in the following three ways: (i) rapid identification of M. bovis with MALDI-TOF MS (RIMM) (BALf was enriched and after 24, 48, and 72 h of incubation and was analyzed using MALDI-TOF MS), (ii) triplex real-time PCR for M. bovis, Mycoplasma bovirhinis, and Mycoplasma dispar, and (iii) 10-day incubation on selective-indicative agar. The diagnostic accuracy of the three tests was determined with Bayesian latent class modeling (BLCM). After 24 h of enrichment, M. bovis was identified with MALDI-TOF MS in 3 out of 104 BALf samples. After 48 and 72 h of enrichment, 32/104 and 38/100 samples, respectively, were M. bovis positive. Lipase-positive Mycoplasma-like colonies were seen in 28 of 104 samples. Real-time PCR resulted in 28/104 positive and 12/104 doubtful results for M. bovis The BLCM showed a sensitivity (Se) and specificity (Sp) of 86.6% (95% credible interval [CI], 69.4% to 97.6%) and 86.4% (CI, 76.1 to 93.8) for RIMM. For real-time PCR, Se was 94.8% (CI, 89.9 to 97.9) and Sp was 88.9% (CI, 78.0 to 97.4). For selective-indicative agar, Se and Sp were 70.5% (CI, 52.1 to 87.1) and 93.9% (CI, 85.9 to 98.4), respectively. These results suggest that rapid identification of M. bovis with MALDI-TOF MS after an enrichment procedure is a promising test for routine diagnostics in veterinary laboratories.

    Combined bead milling and enzymatic hydrolysis for efficient fractionation of lipids, proteins, and carbohydrates of Chlorella vulgaris microalgae
    Alavijeh, Razieh Shafiei ; Karimi, Keikhosro ; Wijffels, Rene H. ; Berg, Corjan van den; Eppink, Michel - \ 2020
    Bioresource Technology 309 (2020). - ISSN 0960-8524
    Bead milling - Combined treatment - Enzymatic hydrolysis - Fractionation - Microalgae

    A combined bead milling and enzymatic hydrolysis process was developed for fractionation of the major valuable biomass components, i.e., proteins, carbohydrates, and lipids from the microalgae Chlorella vulgaris. The cells were treated by bead milling followed by hydrolysis with different hydrolytic enzymes, including lipase, phospholipase, protease, and cellulase. Without enzymatic hydrolysis, the recovery yield of lipids, carbohydrates, and proteins for bead milled biomass was 75%, 31%, and 40%, respectively, while by applying enzymatic treatments these results were improved significantly. The maximum recovery yield for all components was obtained after enzymatic hydrolysis of bead milled biomass by lipase at 37 °C and pH 7.4 for 24 h, yielding 88% lipids in the solid phase while 74% carbohydrate and 68% protein were separated in the liquid phase. The recovery yield of components after enzymatic hydrolysis of biomass without bead milling was 44% lower than that of the milled biomass.

    Consumption of a diet high in dairy leads to higher 15:0 in cholesteryl esters of healthy people when compared to diets high in meat and grain
    Vissers, Linda E.T. ; Soedamah-Muthu, Sabita S. ; Schouw, Yvonne T. van der; Zuithoff, Nicolaas P.A. ; Geleijnse, Johanna M. ; Sluijs, Ivonne - \ 2020
    Nutrition, Metabolism & Cardiovascular Diseases 30 (2020)5. - ISSN 0939-4753 - p. 804 - 809.
    Circulating fatty acids - Dairy products - Margaric acid - Myristic acid - Pentadecanoic acid - Randomized cross-over trial

    Background and aims: A higher dairy product intake has been associated to higher blood concentrations of 15:0 (pentadecanoic acid), 17:0 (margaric acid), and 14:0 (myristic acid). This study investigates whether a diet high in dairy products influences cholesteryl ester fatty acid concentrations of these specific fatty acids (FA). Methods and results: In a randomized multiple cross-over study, 13 men and 17 women aged 22 ± 4 years with a BMI of 21.6 ± 2.2 kg/m2 received 3 isocaloric intervention diets (dairy, meat or grain) in random order. For this post-hoc analysis, FA in plasma cholesteryl esters were measured using gas chromatography. We performed a linear mixed model per centered log-ratio transformed FA, adjusting for period, and the interaction between diet and period. Consumed total fat intake per controlled intervention diet was 31.0 ± 0.9 en%/day (dairy), 31.5 ± 0.6 en%/day (meat), and 28.4 ± 1.2 en%/day (grain), respectively. The dairy diet led to higher relative concentrations of 15:0 when compared to diets high in meat and grain, (β; 0.27, 95%CI: 0.18,0.37; p = 1.2 × 10−5, and β: 0.15; 95%CI: 0.06,0.24; p = 1.2 × 10−2, respectively). The dairy diet also led to higher 14:0 when compared to the meat diet (β: 0.34; 95%CI: 0.21,0.46; p = 6.0 × 10−5), but not when compared to the grain diet. 17:0 did not differ between diets. Conclusion: The plasma cholesteryl ester fraction after a diet high in dairy was characterized by higher 15:0 levels. Concentrations of 14:0 were only higher when comparing the FA profile after a diet high in dairy when compared to a diet high in meat. Clinical trial registration: ClinicalTrials.gov, NCT01314040.

    A lipase fusion feasts on fat
    Ruppert, Philip M.M. ; Kersten, Sander - \ 2020
    Journal of Biological Chemistry 295 (2020)10. - ISSN 0021-9258 - p. 2913 - 2914.

    The enzyme lipoprotein lipase (LPL) is responsible for breaking down triglycerides in the blood. Mutations in LPL cause a rare but debilitating disorder characterized by excessive plasma triglyceride levels for which treatment options are limited. Nimonkar et al. now present a fusion protein between LPL and its physiological transporter GBIHBP1 that is highly active and largely resistant to physiological inhibitors of LPL. Injecting this fusion protein effectively lowers plasma triglycerides in mice and represents a promising new approach for lowering triglycerides in patients with familial chylomicronemia syndrome.

    HILPDA Uncouples Lipid Droplet Accumulation in Adipose Tissue Macrophages from Inflammation and Metabolic Dysregulation
    Dierendonck, Xanthe A.M.H. van; Rosa Rodriguez, Montserrat A. de la; Georgiadi, Anastasia ; Mattijssen, Frits ; Dijk, Wieneke ; Weeghel, Michel van; Singh, Rajat ; Borst, Jan Willem ; Stienstra, Rinke ; Kersten, Sander - \ 2020
    Cell Reports 30 (2020)6. - ISSN 2211-1247 - p. 1811 - 1822.e6.
    ATGL - fatty acid metabolism - Hilpda - inflammation - lipid droplets - macrophages - obesity

    Obesity leads to a state of chronic, low-grade inflammation that features the accumulation of lipid-laden macrophages in adipose tissue. Here, we determined the role of macrophage lipid-droplet accumulation in the development of obesity-induced adipose-tissue inflammation, using mice with myeloid-specific deficiency of the lipid-inducible HILPDA protein. HILPDA deficiency markedly reduced intracellular lipid levels and accumulation of fluorescently labeled fatty acids. Decreased lipid storage in HILPDA-deficient macrophages can be rescued by inhibition of adipose triglyceride lipase (ATGL) and is associated with increased oxidative metabolism. In diet-induced obese mice, HILPDA deficiency does not alter inflammatory and metabolic parameters, despite markedly reducing lipid accumulation in macrophages. Overall, we find that HILPDA is a lipid-inducible, physiological inhibitor of ATGL-mediated lipolysis in macrophages and uncouples lipid storage in adipose tissue macrophages from inflammation and metabolic dysregulation. Our data question the contribution of lipid droplet accumulation in adipose tissue macrophages in obesity-induced inflammation and metabolic dysregulation.

    Facile enzymatic Cγ-acylation of lignin model compounds
    Hilgers, Roelant ; Vincken, Jean Paul ; Kabel, Mirjam A. - \ 2020
    Catalysis Communications 136 (2020). - ISSN 1566-7367
    CALB - Esterification - Lipase - p-coumaric acid - p-hydroxybenzoic acid - Synthesis

    Simple β-O-4’ linked dimeric model compounds are often targeted as substrate to mimic the reactivity of lignin in enzymatic or chemical treatments. These models mimic the structure and reactivity of regular β-O-4′ linkages in lignin, but are less suitable to predict the reactivity of acylated β-O-4′ substructures, which are abundant in various types of lignin. Here, we present a one-step lipase-catalyzed acylation of a commercially available lignin model compound with p-coumaric acid, p-hydroxybenzoic acid, cinnamic acid and acetic acid as acyl donors. This facile procedure allows to obtain new and relevant lignin model compounds at milligram scale, with simple purification of products and unreacted substrate.

    Decompounding discrete distributions: A nonparametric Bayesian approach
    Gugushvili, Shota ; Mariucci, Ester ; Meulen, Frank van der - \ 2020
    Scandinavian journal of statistics 47 (2020)2. - ISSN 0303-6898 - p. 464 - 492.
    compound Poisson process - data augmentation - diophantine equation - Gibbs sampler - Metropolis-Hastings algorithm - Nonparametric Bayesian estimation

    Suppose that a compound Poisson process is observed discretely in time and assume that its jump distribution is supported on the set of natural numbers. In this paper we propose a nonparametric Bayesian approach to estimate the intensity of the underlying Poisson process and the distribution of the jumps. We provide a Markov chain Monte Carlo scheme for obtaining samples from the posterior. We apply our method on both simulated and real data examples, and compare its performance with the frequentist plug-in estimator proposed by Buchmann and Grübel. On a theoretical side, we study the posterior from the frequentist point of view and prove that as the sample size n→∞, it contracts around the “true,” data-generating parameters at rate 1/√n, up to a n factor.

    Evaluation of food-grade vegetable oils using ultrasonic velocity measurement and fatty acid composition
    Yan, Jing ; Wright, William M.D. ; Roos, Yrjo ; Ruth, Saskia M. Van - \ 2019
    In: 2019 IEEE International Ultrasonics Symposium, IUS 2019. - IEEE computer society (IEEE International Ultrasonics Symposium, IUS ) - ISBN 9781728145969 - p. 2435 - 2438.
    density - extra virgin olive oil - fatty acid methyl ester (FAME) test - oil viscosity - ultrasonic velocity

    Extra virgin olive oil (EVOO) is a high-value food commodity and is often a target for food fraud, in which the EVOO is adulterated with lower grade oils such as refined olive oil (ROO), pomace olive oil (POO) and other vegetable oils of nut or seed origin such as rapeseed or canola oil (RSO), peanut oil (PNO) and sunflower oil (SFO). The objective of this study is to investigate ultrasonic techniques to distinguish between different food-grade oils based on their fatty acid (FA) composition. An ultrasonic pulse-echo system was used to measure the propagation delay and hence the velocity of ultrasonic waves at 5 MHz in three different types of olive oil (EVOO, POO and ROO) and three other vegetable oils of nut or seed origin (PNO, RSO and SFO). The ultrasonic system was temperature controlled in a heated water bath at 23.5°C±0.05°C. The ultrasonic velocity was determined using the differential propagation delay from four 2.00 mm increments in the propagation path, determined using a micrometer to ±0.005 mm to eliminate any uncertainty in the initial propagation path. The FA content of each oil was determined using an ISO 12966-2 (2017) automatic BF3 transmethylation procedure followed by gas chromatography according to ISO 12966-4 (2015) using an Agilent HP7890A Gas Chromatograph. 80 different samples were tested, using extra virgin olive oil (n=30), refined olive oil (n=15), pomace olive oil (n=15), rapeseed/canola oil (n=10), sunflower oil (n=5), and peanut oil (n=5). The FA composition and ultrasonic velocity of each sample were measured. A statistically significant correlation between polyunsaturated fatty acid (PUFA) content and ultrasonic velocity, and a statistically significant negative correlation between monounsaturated and saturated fatty acid (MUFA and SFA) content and ultrasonic velocity, were noted. The ultrasonic velocity may thus be used to help distinguish between different food-grade vegetable oils that have a high PUFA content, such as sunflower oil and rapeseed/canola oil, and those with a high MUFA content such as olive oil and peanut oil. The FA composition appears to influence the density and compressibility of the oil, which determine the ultrasound velocity.

    Geography and ethnicity related variation in the Chinese human milk serum proteome
    Zhang, Lina ; Ma, Ying ; Yang, Zhenyu ; Jiang, Shan ; Liu, Jun ; Hettinga, Kasper A. ; Lai, Jianqiang ; Zhou, Peng - \ 2019
    Food & Function 10 (2019)12. - ISSN 2042-6496 - p. 7818 - 7827.

    Human milk provides a range of nutrients and bioactive components, which can support the growth and development of infants. However, human milk composition may change due to geographic and ethnic variation. This study investigated the variation of the Chinese human milk serum proteome based on mothers with different ethnicities living in different parts of China, using TMT labeling combined with Nano-LC Q Exactive HF MS/MS proteomics. In total, 693 proteins were identified and quantified in human milk serum from Yunnan (Han and Bai ethnicity), Gansu (Han and Tibetan ethnicity), Xinjiang (Uygur ethnicity), and Inner Mongolia (Mongolian ethnicity). The biological function distribution of identified proteins and the summed intensity of proteins belonging to each biological function were similar among groups. The five relatively highly abundant milk serum proteins, lactoferrin, serum albumin, polymeric immunoglobulin receptor, macrophage mannose receptor 1, and bile salt-activated lipase were not significantly different among different geographies and ethnicities. On the other hand, we found 34 proteins that did significantly differ with geography and ethnicity. Those significantly different proteins have known strong interaction in inflammation response and regulation of multi-organism processes. Taken together, biological function distribution was similar on both the qualitative and quantitative levels, and proteins with similar abundance are important in providing basic nutrition and protection for infants, whereas the significantly different proteins may be important for the healthy development of infants from different locations and ethnicities.

    Batch stripping of flavour active compounds from beer: Effect of dry matter and ethanol on equilibrium and mass transfer in a packed column
    Ammari, Ali ; Schroën, Karin - \ 2019
    Food and Bioproducts Processing 118 (2019). - ISSN 0960-3085 - p. 306 - 317.
    Alcohol - CO - Equilibrium - Ester - Henry's law constant - Mass transfer coefficient

    Physiochemical similarities of volatile compounds and their interactions with the beer matrix are the main challenging factors in selective separation of ethanol for the production of non-alcoholic beer and removal of excess (off-)flavours produced during fermentation, such as isoamyl acetate. In this paper, we are especially interested in the effect of beer dry matter, a complex mixture of carbohydrates and proteins, and of ethanol on flavour behaviour during treatment with a packed bed column using CO2 as a stripping agent. By analysing the gas phase at different dry matter concentrations, we observed that its’ presence is a facilitating factor for ethyl acetate and isoamyl acetate release, whereas isoamyl alcohol is retained in the liquid phase. These effects are a result of combined mass transfer effects and affinity for carbon dioxide, which are both affected by the presence of ethanol in the feed stream. Mass transfer analysis of isoamyl alcohol and ethanol revealed that the resistance is not controlled by their solubility in water but the affinity to CO2.

    Using poly(β-hydroxybutyrate-β-hydroxyvalerate) as carbon source in biofloc-systems : Nitrogen dynamics and shift of Oreochromis niloticus gut microbiota
    Liu, Gang ; Deng, Yale ; Verdegem, Marc ; Ye, Zhangying ; Zhu, Songming - \ 2019
    Science of the Total Environment 694 (2019). - ISSN 0048-9697
    Biodegradable polymers (BDPs) - Biofloc system - Carbohydrate - Gut microbiota - Nitrogen dynamic

    Inorganic‑nitrogen removal is essential for the sustainable operation of aquaculture industry and also influences the health of aquatic animals, which may be accomplished by utilizing biofloc technology. In this paper, we studied the use of three different carbon sources 1) longan seed powder (LP), 2) Poly(β-hydroxybutyrate-β-hydroxyvalerate) (PHBV) and 3) synthesized PHBV and LP (PHBVL) in biofloc systems for 90 days to investigate the nitrogen dynamics and gut microbiota of Nile tilapia (Oreochromis niloticus). The PHBVL and PHBV groups had higher total inorganic‑nitrogen removal efficiencies (70.99 ± 19.45% and 63.54 ± 19.44%) than the LP group (35.02 ± 11.21%), which had an accumulation of nitrate. Meanwhile, the biofloc in PHBVL and PHBV group generally had a higher amino acid composition, particularly for methionine and lysine, but was not reflected in the tilapia muscle. High-throughput sequencing indicated that the different carbohydrates shaped different bacterial community compositions in the fish gut after exposure in the three environments for 90-day. These differences, which resulted in different gut digestive enzyme activities (amylase, lipase and trypsin), and growth performance, which the food conversion ratio in the PHBVL group was lower than LP and PHBV group, the final body weight in PHBVL group was average 4.33% and 3.65% bigger than in LP and PHBV group. Network analysis revealed that the keystone taxa (90.33%) were Proteobacteria, Chloroflexi, Actinobacteria, Planctomycetes, Verrucomicrobia and Bacteroidetes, which relative abundance varied in the fish gut in the three groups. The experiment verified the feasibility and advantage to use biodegradable polymers (BDPs) as carbohydrates for biofloc systems.

    Impact of food odors signaling specific taste qualities and macronutrient content on saliva secretion and composition
    Morquecho-Campos, Paulina ; Bikker, Floris J. ; Nazmi, Kamran ; Graaf, Kees de; Laine, Marja L. ; Boesveldt, S. - \ 2019
    Appetite 143 (2019). - ISSN 0195-6663
    Cephalic phase response - Olfaction - Salivary protein - Salivation - Smell

    Olfactory food cues can induce appetite for similar food products in humans. Odors may thus signal essential information about a foods’ composition such as taste or even macronutrient content and may stimulate specific physiological responses in anticipation of food intake. Several studies have shown that sensory food cues could stimulate saliva secretion. However, potential differences between food odors in their effect on saliva secretion, or the effects of olfactory stimulation on changes in saliva composition remain to be elucidated. To gain more insight, we conducted two studies to determine the influence of various odors, representing different taste qualities (study 1) and macronutrients (study 2), on salivary biomarkers. In study 1, 36 participants were randomly exposed to no-odor, non-food, and odors signaling sweet, savory, and sour taste. In study 2, 60 participants were randomly exposed to no-odor, non-food, and odors signaling carbohydrates, protein, fat, and low-calorie food. For each condition, whole-mouth saliva was collected and saliva secretion rate determined. Furthermore, we determined mouth-watering perception (subjective salivation), visco-elasticity (study 1 only), mucin concentration, α-amylase and lingual lipase activity (study 2 only). For both studies, linear mixed model analyses showed that saliva secretion rate significantly increased by food odor exposure compared to no-odor and non-food conditions. However, no changes in salivary composition were observed. These findings indicate that food odors play a crucial role in anticipatory saliva responses and can thereby affect subsequent eating behavior.

    Development of a low-alcoholic fermented beverage employing cashew apple juice and non-conventional yeasts
    Gamero, Amparo ; Ren, Xiao ; Lamboni, Yendouban ; Jong, Catrienus de; Smid, Eddy J. ; Linnemann, Anita R. - \ 2019
    Fermentation 5 (2019)3. - ISSN 2311-5637
    Alcoholic beverages - Aroma profile - Cashew apple juice - Hanseniaspora guilliermondii - Non‐conventional yeasts - Saccharomyces cerevisiae - Torulaspora microellipsoides

    Cashew apples are by‐products in the production of cashew nuts, which are mostly left to rot in the fields. Cashew apple juice (CAJ), a highly nutritious beverage, can be produced from them. It is rich in sugars and ascorbic acid, but its high polyphenol content makes it bitter and astringent, and therefore difficult to commercialize. The kingdom of fungi contains more than 2000 yeast species, of which only a few species have been studied in relation to their potential to produce aroma compounds. The aim of this research was to develop a new low‐alcoholic fermented beverage to valorize cashew apples. For this purpose, a screening was carried out employing non‐conventional yeast species and some species of the genus Saccharomyces for comparison, followed by a more detailed study with four selected strains cultured at different conditions. The production of volatile aroma compounds as a function of the presence of oxygen, temperature, and yeast species was investigated. The results showed that the more diverse aroma profiles appeared at 25 °C under anaerobic cultivation conditions, where Saccharomyces cerevisiae WUR 102 and Hanseniaspora guilliermondii CBS 2567 excelled in the synthesis of certain aroma compounds, such as β-phenylethanol and its acetate ester (rose aroma). Further studies are needed to test consumer acceptance of these new products.

    Clustering of oil droplets in o/w emulsions enhances perception of oil-related sensory attributes
    Fuhrmann, P.L. ; Kalisvaart, Laura ; Sala, G. ; Scholten, E. ; Stieger, M.A. - \ 2019
    Food Hydrocolloids 97 (2019). - ISSN 0268-005X
    o/w emulsions - Sensory perception - Oil droplet clustering - creaminess - Saliva - Lubrication
    The sensory perception of o/w emulsions is determined by their structure and physicochemical properties. The aims of this study were (a) to determine the influence of oil droplet clustering in o/w emulsions on sensory perception and (b) to link their sensory attributes to rheological, tribological and structural properties. Clustered emulsions were prepared by combining o/w emulsions stabilised by different sets of emulsifiers: (a) positively-charged gelatine and negatively-charged whey protein (WPI), and (b) positively-charged gelatine and negatively-charged diacetyl tartaric acid ester of mono- and diglycerides (DATEM). Oil droplet clusters ranging in diameter from 1 to 50 μm were obtained. The difference in charge density between gelatine- and DATEM-stabilised oil droplets was higher than that between gelatine- and WPI-stabilised droplets. This difference allowed to alter the interaction strength within oil droplet clusters. The sensory perception of clustered emulsions was quantified using the Rate-All-That-Apply (RATA) methodology with untrained subjects (n = 83). Participants assessed o/w emulsions varying in cluster size (1 μm–50 μm), cluster strength (tuned by changing the emulsifier-pairs), and single droplet emulsions with and without adjusted viscosity, as well as a reference emulsion with large single droplets (comparable in size to emulsions with large clusters). Creaminess and thickness intensities were significantly higher for clustered o/w emulsions compared to that of single droplet o/w emulsions with the same oil content and similar oil droplet/cluster size. With increasing cluster size, creaminess and thickness intensities increased significantly for hetero-aggregated clusters with weak interactions (gelatine-whey protein). When cluster interactions were stronger (gelatine-DATEM), creaminess intensity increased to a lesser extent and grittiness intensity increased considerably. Thickness and creaminess were strongly correlated to the rheological (e.g. consistency) and tribological properties (e.g. fiction coefficient at 10 mm/s) of o/w emulsions with clustered oil droplets. Grittiness and fattiness were strongly correlated to the tribological properties (slope of mixed regime) of o/w emulsions and their interactions with saliva. We conclude that clustering of oil droplets in o/w emulsions by hetero-aggregation allows to enhance the sensory perception of fat-related attributes by tuning rheological and tribological properties, and provides an effective method to structure liquid foods to obtain specific sensory properties.
    Microbial production of short and medium chain esters: Enzymes, pathways, and applications
    Kruis, Aleksander J. ; Bohnenkamp, Anna C. ; Patinios, Constantinos ; Nuland, Youri M. van; Levisson, Mark ; Mars, Astrid E. ; Berg, Corjan van den; Kengen, Servé W.M. ; Weusthuis, Ruud A. - \ 2019
    Biotechnology Advances 37 (2019)7. - ISSN 0734-9750
    Alcohol - Alcohol acyltransferase - Bulk chemical - Carboxylic acid - Ester - Metabolic engineering - Microbial synthesis

    Sustainable production of bulk chemicals is one of the major challenges in the chemical industry, particularly due to their low market prices. This includes short and medium chain esters, which are used in a wide range of applications, for example fragrance compounds, solvents, lubricants or biofuels. However, these esters are produced mainly through unsustainable, energy intensive processes. Microbial conversion of biomass-derived sugars into esters may provide a sustainable alternative. This review provides a broad overview of natural ester production by microorganisms. The underlying ester-forming enzymatic mechanisms are discussed and compared, with particular focus on alcohol acyltransferases (AATs). This large and versatile group of enzymes condense an alcohol and an acyl-CoA to form esters. Natural production of esters typically cannot compete with existing petrochemical processes. Much effort has therefore been invested in improving in vivo ester production through metabolic engineering. Identification of suitable AATs and efficient alcohol and acyl-CoA supply are critical to the success of such strategies and are reviewed in detail. The review also focusses on the physical properties of short and medium chain esters, which may simplify downstream processing, while limiting the effects of product toxicity. Furthermore, the esters could serve as intermediates for the synthesis of other compounds, such as alcohols, acids or diols. Finally, the perspectives and major challenges of microorganism-derived ester synthesis are presented.

    Probing the regulation of cellular lipid metabolism by trans fatty acids and the lipid-sensitive ANGPTL4 protein
    Oteng, Antwi-Boasiako - \ 2019
    Wageningen University. Promotor(en): S. Kersten. - Wageningen : Wageningen University - ISBN 9789463439084 - 232

    A coordinated regulation of lipid metabolism is important in maintaining cardiometabolic health, since a dysregulation in lipid metabolism is implicated in hyperlipidaemia, insulin resistance, type 2 diabetes, non-alcoholic fatty liver disease (NAFLD), atherosclerosis and coronary artery disease. This thesis has investigated the pre-clinical effects of dietary trans fatty acids, lipid-sensitive angiopoietin-like 4 (ANGPTL4) and muscle inflammation on cardiometabolic health. The aim is to further understand the metabolic and molecular mechanisms by which trans fatty acids, ANGPTL4 and muscle-specific inflammation impact cardiometabolic health in order to devise therapeutic strategies.

    Trans fatty acids are unsaturated fatty acids that contain at least one double bond in the trans configuration. In humans, the consumption of certain trans fatty acids is implicated in the onset and progression of cardiovascular diseases due in part to the ability of such trans fatty acids to raise the plasma levels of total and LDL-cholesterol, and decrease the levels of HDL-cholesterol. However, the underlying mechanisms for the deleterious effects of trans fatty acids are not fully understood. We show in C57Bl/6 mice that a diet enriched in industrial trans fatty acids from partially hydrogenated soybean oil promotes non-alcoholic fatty liver disease (NAFLD) compared to cis-unsaturated and saturated fatty acid diets. At the cellular level, we demonstrate in murine hepatocyte and adipocyte cell lines that the industrial fatty acid elaidate induces cholesterogenesis through enhanced expression and activity of sterol regulatory element binding protein 2 (SREBP2).

    ANGPTL4 is an inhibitor of lipoprotein lipase (LPL). LPL hydrolyses circulating triglycerides to generate fatty acids for uptake into tissues. Therefore, as an inhibitor of LPL, ANGPTL4 indirectly raises the levels of circulating triglycerides leading to an associated increased risk for cardiovascular diseases. However, the potential of inhibiting ANGPTL4 to lower the risk of cardiovascular diseases is hampered by lethal side-effects in ANGPTL4-deficient mice fed diets rich in saturated fatty acids. In this thesis, we demonstrate that ANGPTL4-deficient mice respond favourably to a trans fat diet than a saturated fat diet. Furthermore, we show that saturated fatty acids but not trans fatty acids induce inflammation and endoplasmic reticulum (ER) stress in murine macrophages. This thesis also characterised a novel ANGPTL4-hypomorphic mice model with only a partial expression of the N-terminal domain of ANGPTL4. Following a chronic high saturated fat diet challenge, the hypomorphs showed reduced levels of plasma triglycerides as the complete ANGPTL4-deficient mice. Interestingly, the hypomorphs showed attenuated and milder forms of the side-effects that occur in the complete ANGPTL4-deficient mice.

    Finally, this thesis has also examined the role of muscle specific inflammation on systemic glucose homeostasis. We found that skeletal muscle-specific inflammation via over-expression of monocyte chemoattractant protein-1 (MCP-1) does not affect systemic glucose and insulin sensitivity in mice.

    Taken together, this thesis has provided insight into the molecular mechanisms of trans fatty acids and highlighted the prospect of harnessing the therapeutic potential of ANGPTL4 inactivation for correcting cardiometabolic abnormalities.

    New insights into angiopoietin-like proteins in lipid metabolism and cardiovascular disease risk
    Kersten, Sander - \ 2019
    Current Opinion in Lipidology 30 (2019)3. - ISSN 0957-9672 - p. 205 - 211.

    PURPOSE OF REVIEW: The angiopoietin-like proteins (ANGPTLs), consisting of ANGPTL3, ANGPTL4, and ANGPTL8, have gained significant interest for their role as inhibitors of lipoprotein lipase (LPL) and for their potential as therapeutic targets for correcting dyslipidemia. This review provides an overview of the most relevant new insights on the connection between ANGPTLs, plasma lipids, and coronary artery disease. RECENT FINDINGS: Carriers of loss-of-function variants in ANGPTL3 have a reduced risk of coronary artery disease and reduced plasma levels of triglycerides and LDL-C, while carriers of loss-of-function variants in ANGPTL4 have a reduced risk of coronary artery disease and reduced plasma levels of triglycerides and increased HDL-C. There is evidence that carrier status of ANGPTL4 loss-of-function variants may also influence risk of type 2 diabetes. ANGPTL3 is produced in liver and is released as a complex with ANGPTL8 to suppress LPL activity in fat and muscle tissue. ANGPTL4 is produced by numerous tissues and likely mainly functions as a locally released LPL inhibitor. Both proteins inactivate LPL by catalyzing the unfolding of the hydrolase domain in LPL and by promoting the cleavage of LPL. Antisense oligonucleotide and monoclonal antibody-based inactivation of ANGPTL3 reduce plasma triglyceride and LDL-C levels in human volunteers and suppress atherosclerosis in mouse models. SUMMARY: ANGPTL3/ANGPTL8 and ANGPTL4 together assure the appropriate distribution of plasma triglycerides across tissues during different physiological conditions. Large-scale genetic studies provide strong rationale for continued research efforts to pharmacologically inactivate ANGPTL3 and possibly ANGPTL4 to reduce plasma lipids and coronary artery disease risk.

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