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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High Versus low Dietary Protein Intake and Bone Health in Older Adults: a Systematic Review and Meta-Analysis
Groenendijk, Inge ; Boeft, L. den; Loon, Luc J.C. van; Groot, Lisette C.P.G.M. de - \ 2019
Computational and Structural Biotechnology Journal 17 (2019). - ISSN 2001-0370 - p. 1101 - 1112.
Bone - Bone density - Fractures - Older adults - Protein

Protein may play a beneficial role in the prevention of bone loss and in slowing down osteoporosis. The effect of dietary protein may be different in older adults compared to younger adults, since this population has a greater need for protein. The aim of this systematic review and meta-analysis was to investigate the impact of a dietary protein intake above the Recommended Dietary Allowance (RDA) of 0.8 g/kg body weight/day from any source on Bone Mineral Density (BMD)/Bone Mineral Content (BMC), bone turnover markers, and fracture risk in older adults compared to a lower dietary protein intake. A systematic search was conducted through October 2018 in 3 databases: CENTRAL, MEDLINE, and EMBASE. We included all prospective cohort studies and Randomized Controlled Trials (RCTs) among adults aged ≥65 years that examined the relation between protein intake on bone health outcomes. Two investigators independently conducted abstract and full-text screenings, data extractions, and risk of bias assessments. Authors were contacted for missing data. After screening of 523 records, twelve cohort studies and one RCT were included. Qualitative evaluation showed a positive trend between higher protein intakes and higher femoral neck and total hip BMD. Meta-analysis of four cohort studies showed that higher protein intakes resulted in a significant decrease in hip fractures (pooled hazard ratio: 0.89; 95% confidence interval: 0.84, 0.94). This systematic review supports that a protein intake above the current RDA may reduce hip fracture risk and may play a beneficial role in BMD maintenance and loss in older adults.

Fatty acids and proteins from marine cold adapted microalgae for biotechnology
Schulze, Peter S.C. ; Hulatt, Christopher J. ; Morales-Sánchez, Daniela ; Wijffels, René H. ; Kiron, Viswanath - \ 2019
Algal Research 42 (2019). - ISSN 2211-9264
Cold water algae - Eicosapentaenoic acid (EPA) - Light - Polyunsaturated fatty acid (PUFA) - Protein - Temperature

Cold-adapted microalgae display unexpectedly high biomass production, pointing to their potential to produce high-value bioproducts under cold and light-limited conditions. From culture collections, we screened eight cold-adapted strains of different genera (Chlamydomonas, Chlorella, Tetraselmis, Pseudopleurochloris, Nannochloropsis and Phaeodactylum) for the production of fatty acids and proteins under low temperature and light regimes (T = 8, 15 °C; I = 50, 100 μmol s−1 m−2). Among the strains, the Arctic isolate Chlamydomonas sp. (RCC 2488) had better growth at 8 °C compared to 15 °C (up to 0.5 gDW L−1 d−1) and highest productivities of protein and polyunsaturated fatty acids (PUFA) (70 and 65 mg L−1 d−1, respectively). Two tested Tetraselmis strains (SAG 1.96, RCC 2604) achieved highest biomass productivities (0.7–1 gDW L−1 d−1), containing up to 50 mg PUFA gDW−1 and 15% proteins. Pseudopleurochloris antarctica (SAG 39.98) grew well at 15 °C (0.4 g L−1 d−1), with 23% proteins in biomass and the highest eicosapentaenoic acid (EPA) productivity (7.6 mg L−1 d−1). Chlorella stigmatophora (RCC 661) achieved productivities of 0.4 gDW L−1 d−1 at 15 °C and produced extracellular polymeric substances (EPS). The major cause for the observed shifts in biochemical profiles was biomass concentration, which is an indicator for the prevailing growth stage. Based on the current experimental design, Chlamydomonas sp. (RCC 2488), T. chuii and P. antarctica can be suggested as the most promising strains for the production of protein and (polyunsaturated-) fatty acids at low temperatures. However, additional strain-specific studies are necessary to statistically validate these findings.

The influence of protein/phospholipid ratio on the physicochemical and interfacial properties of biomimetic milk fat globules
Chen, Min ; Sagis, Leonard M.C. - \ 2019
Food Hydrocolloids 97 (2019). - ISSN 0268-005X
Emulsion - Milk fat - Oil/water interface - Phospholipids - Protein

The effect of protein/phospholipid ratio on the physicochemical and interfacial properties of biomimetic milk fat globules (BMFGs) was investigated. Butter milk phospholipid (BMP) vesicles prepared with ultrasonication were mixed with whey protein isolate (WPI) at different protein/phospholipid ratios (w/w). After emulsification, the Turbiscan stability index (TSI) was used to quantify the initial stability of BMFGs. At different pH values, visual observation and CLSM were performed to obtain the macro stability and microstructure of BMFGs. In addition, large amplitude oscillatory surface rheology was applied and analysed with Lissajous curves, to explore the oil/water interfacial properties of BMFGs in the nonlinear viscoelastic regime. The TSI indicated a faster creaming rate of BMP stabilized droplets compared to those stabilized by WPI. The macro stability of WPI/BMP co-stabilized BMFGs at different pH was dominated by WPI and BMFGs prepared at the WPI/BMP ratio of 20:80 phase separated from pH 3.0 to 5.0. At acidic pH, the WPI/BMP ratios strongly affected the coalescence and flocculation of BMFGs at the micro level. The surface elasticity indicated that WPI dominated the rheological properties of WPI/BMP co-stabilized oil/water interfaces. Besides, the significant dependence of surface elasticity on deformation amplitudes within the nonlinear regime of WPI stabilized oil/water interfaces indicated a clearly different structure from BMP stabilized interfaces. Conclusively, results of this study showed that the physicochemical and interfacial properties of BMFGs were significantly influenced by the protein/phospholipid ratio in the bulk, which needs to be considered in the design and application of biomimetic milk fat globules.

Investigating the effect of temperature on the formation and stabilization of ovalbumin foams
Delahaije, Roy J.B.M. ; Lech, Frederik J. ; Wierenga, Peter A. - \ 2019
Food Hydrocolloids 91 (2019). - ISSN 0268-005X - p. 263 - 274.
Concentration - Interfacial properties - Protein - Structural characterization - Viscosity

The effect of temperature (below denaturation temperature) on protein foam formation and stabilization is potentially large, but has received little attention. This study aims to identify the effect of temperature (15–60 °C) on ovalbumin-stabilized foams at different concentrations (0.05–50 g L−1), and place this in a theoretical perspective. With increasing temperature the initial adsorption rate (dΠ/dt) increased logarithmically from 0.006 mN m−1 s−1 at 5 °C to 0.084 mN m−1 s−1 at 60 °C. A concentration increase resulted in a linear increase of dΠ/dt. This concentration effect was also observed in the foam ability, although the foam ability increased logarithmically rather than linearly with concentration, as expected based on theory and dΠ/dt. The foam ability was hardly affected by temperature (in contrast to theory and dΠ/dt). This was attributed to the strong decrease of foam stability with increasing temperature, which was expected based on theory. At elevated temperatures, the poor foam stability interferes with the foam ability (i.e. foam stability ≈ timescale of foam formation), a situation also happening at low concentrations. When formation was faster than destabilization, the foam ability relates to the effective adsorption rate. The effective adsorption rate includes the decrease in adsorption probability with increasing surface coverage. The observed balance between the effect of adsorption rate and foam stability on foam ability is not quantitatively predictable based on current theoretical models.

Can interaction specificity in the fungus-farming termite symbiosis be explained by nutritional requirements of the fungal crop?
Costa, Rafael R. da; Vreeburg, Sabine M.E. ; Shik, Jonathan Z. ; Aanen, Duur K. ; Poulsen, Michael - \ 2019
Fungal Ecology 38 (2019). - ISSN 1754-5048 - p. 54 - 61.
Biomass - Carbohydrates - Geometric framework - Interaction specificity - Macrotermes - Nutrition - Odontotermes - Protein - Symbiosis - Termitomyces

Fungus-growing termites are associated with genus-specific fungal symbionts, which they acquire via horizontal transmission. Selection of specific symbionts may be explained by the provisioning of specific, optimal cultivar growth substrates by termite farmers. We tested whether differences in in vitro performance of Termitomyces cultivars from nests of three termite species on various substrates are correlated with the interaction specificity of their hosts. We performed single-factor growth assays (varying carbon sources), and a two-factor geometric framework experiment (simultaneously varying carbohydrate and protein availability). Although we did not find qualitative differences between Termitomyces strains in carbon-source use, there were quantitative differences, which we analysed using principal component analysis. This showed that growth of Termitomyces on different carbon sources was correlated with termite host genus, rather than host species, while growth on different ratios and concentrations of protein and carbohydrate was correlated with termite host species. Our findings corroborate the interaction specificity between fungus-growing termites and Termitomyces cultivars and indicate that specificity between termite hosts and fungi is reflected both nutritionally and physiologically. However, it remains to be demonstrated whether those differences contribute to selection of specific fungal cultivars by termites at the onset of colony foundation.

Duckweed as human food. The influence of meal context and information on duckweed acceptability of Dutch consumers
Beukelaar, Myrthe F.A. de; Zeinstra, Gertrude G. ; Mes, Jurriaan J. ; Fischer, Arnout R.H. - \ 2019
Food Quality and Preference 71 (2019). - ISSN 0950-3293 - p. 76 - 86.
Consumer attitude - Duckweed - Fit - Information - Meal - Protein

Duckweed is considered a promising source of protein for human food products due to its high protein content and environmentally friendly production properties. In order to achieve successful inclusion in the diet, duckweed should be presented to consumers in an acceptable way. This paper explores Western consumers’ perceptions towards duckweed as human food and investigates in what contexts duckweed could be acceptable to consumers who are not used to eating it. In a first interview study (N = 10), consumers generally responded positively towards duckweed as human food, although associations with turbid ponds also did come up. According to the respondents, duckweed belonged to the food category vegetables. So, duckweed was considered to fit best in meals where vegetables and greens are expected. In a larger online survey (N = 669), it was confirmed that consumers had a more positive deliberate evaluation of duckweed and were more likely to accept a meal with duckweed if duckweed was applied in a fitting meal. It was also shown that providing information about nutritional and sustainability benefits increased deliberate evaluation and acceptability for fitting meals, but decreased it for non-fitting meals. Automatic evaluations positively influenced deliberate evaluation and acceptability, supporting the ‘yuck’ effect, but they did not differ between the meal applications. The current paper shows that if applied in a meal context that fits with consumer expectations, under the assumption that sensory properties like taste are satisfactory, there appear no major objections from consumers against the introduction of duckweed as human food at a larger scale.

The effect of an encapsulated nutrient mixture on food intake and satiety : A double-blind randomized cross-over proof of concept study
Alleleyn, Annick M.E. ; Avesaat, Mark van; Ripken, Dina ; Bleiel, Sinéad B. ; Keszthelyi, Daniel ; Wilms, Ellen ; Troost, Freddy J. ; Hendriks, Henk F.J. ; Masclee, Adrian A.M. - \ 2018
Nutrients 10 (2018)11. - ISSN 2072-6643
Carbohydrate - Distal release - Encapsulated nutrient mixture - Overweight - Protein - Satiety - Weight management

Activation of the intestinal brake by infusing nutrients into the distal small intestine with catheters inhibits food intake and enhances satiety. Encapsulation of macronutrients, which protects against digestion in the proximal gastrointestinal tract, can be a non-invasive alternative to activate this brake. In this study, we investigate the effect of oral ingestion of an encapsulated casein and sucrose mixture (active) targeting the distal small intestine versus a control product designed to be released in the stomach on food intake, satiety, and plasma glucose concentrations. Fifty-nine volunteers received the active and control product on two separate test days. Food intake was determined during an ad libitum meal 90 min after ingestion of the test product. Visual analogue scale scores for satiety and blood samples for glucose analysis were collected at regular intervals. Ingestion of the active product decreased food intake compared to the control product (655 kcal compared with 699 kcal, respectively, p < 0.05). The area under the curve (AUC) for hunger was decreased (p < 0.05) and AUC for satiety was increased (p < 0.01) after ingestion of the active product compared to the control product. Ingestion of an encapsulated protein-carbohydrate mixture resulted in inhibition of food intake compared to a non-encapsulated control product.

Influence of humic acid on transport, deposition and activity of lysozyme in quartz sand
Li, Yan ; Koopal, Luuk K. ; Xiong, Juan ; Wang, Mingxia ; Yang, Chenfeng ; Tan, Wenfeng - \ 2018
Environmental Pollution 242 (2018). - ISSN 0269-7491 - p. 298 - 306.
Deposition - Enzyme activity - Humic acid - Lysozyme - Protein - Transport

Increasing humic acid concentration reduced the mobility of proteins with opposite charges, and the increased activity of effluent proteins could bring potential environmental hazards.

Genetic variation and correlation studies between micronutrient (Fe and Zn), protein content and yield attributing traits in mungbean (Vigna. radiata L.)
Singh, Renu ; Heusden, Adriaan W. Van; Kumar, Ram ; Visser, Richard G.F. - \ 2018
Legume Research 41 (2018)2. - ISSN 0250-5371 - p. 167 - 174.
Correlation - Iron - Mungbean - Protein - Quality traits - Quantitative traits
Mungbean can effectively contribute in alleviation of iron, zinc and protein malnutrition as it is a source of micronutrients and protein. To improve this cultivars have to be developed which are rich in micronutrients and protein. But in general more focus is given to quantitative traits such as yield. Breeding mungbean for enhanced grain nutrients is still in its startup phase. The present study was carried out to access genetic variation for both quantitative as qualitative traits. The correlation between important traits such as yield and Fe, Zn, protein content was calculated. A positive correlation was found between iron and zinc content (r = 0.47) whereas no significant correlation with grain yield was observed indicating no compromise of yield for improving quality. Breeding a cultivar which is nutritionally improved along with high yield is therefore possible. A few promising cultivars with high micronutrients, protein and yield were identified. These cultivars can be used in specific breeding programs aiming at nutrient-rich high yielding cultivars.
Biorefinery of the macroalgae Ulva lactuca : extraction of proteins and carbohydrates by mild disintegration
Postma, P.R. ; Cerezo-Chinarro, O. ; Akkerman, R.J. ; Olivieri, G. ; Wijffels, R.H. ; Brandenburg, W.A. ; Eppink, M.H.M. - \ 2018
Journal of Applied Phycology 30 (2018)2. - ISSN 0921-8971 - p. 1281 - 1293.
Enzymes - High shear homogenization - Macroalgae - Osmotic shock - Protein - Pulsed electric field

The effect of osmotic shock, enzymatic incubation, pulsed electric field, and high shear homogenization on the release of water-soluble proteins and carbohydrates from the green alga Ulva lactuca was investigated in this screening study. For osmotic shock, both temperature and incubation time had a significant influence on the release with an optimum at 30 °C for 24 h of incubation. For enzymatic incubation, pectinase demonstrated being the most promising enzyme for both protein and carbohydrate release. Pulsed electric field treatment was most optimal at an electric field strength of 7.5 kV cm−1 with 0.05 ms pulses and a specific energy input relative to the released protein as low as 6.6 kWh kgprot −1. Regarding literature, this study reported the highest protein (~ 39%) and carbohydrate (~ 51%) yields of the four technologies using high shear homogenization. Additionally, an energy reduction up to 86% was achieved by applying a novel two-phase (macrostructure size reduction and cell disintegration) technique.

Supplemental protein from dairy products increases body weight and vitamin D improves physical performance in older adults : a systematic review and meta-analysis
Dewansingh, Priya ; Melse-Boonstra, Alida ; Krijnen, Wim P. ; Schans, Cees P. van der; Jager-Wittenaar, Harriët ; Heuvel, Ellen G.H.M. van den - \ 2018
Nutrition Research 49 (2018). - ISSN 0271-5317 - p. 1 - 22.
Aged - Nutritional status - Physical fitness - Protein - Vitamin D
The purpose of these systematic review and meta-analysis was to assess the effectiveness of dairy components on nutritional status and physical fitness in older adults, as evidence for efficacy of the supplementation of these components is inconclusive. Scopus and MEDLINE were searched. Main inclusion criteria for articles were as follows: double-blind, randomized, placebo-controlled trials including participants aged ≥55 years who received dairy components or a placebo. Outcome measures were nutrient status (body weight and body mass index) and physical fitness (body composition, muscle strength, and physical performance). Thirty-six trials with 4947participants were included. Most trials investigated protein and vitamin D supplementation and showed no effect on the outcomes. Meta-analysis on the effect of protein on body weight showed a significant increase in mean difference of 1.13 kg (95% confidence interval, 0.59-1.67). This effect increased by selecting trials with study a duration of 6 months in which less nourished and physically fit participants were included. Trials where the participants were (pre-)frail, inactive older adults or when supplementing ≥20 g of protein per day tended to increase lean body mass. Only small significant effects of vitamin D supplementation on Timed Up and Go (mean difference –0.75 seconds; 95% confidence interval –1.44 to −0.07) were determined. This effect increased when vitamin D doses ranged between 400 and 1000 IU. Additional large randomized controlled trials of ≥6 months are needed regarding the effect of dairy components containing an adequate amount of vitamin D (400-1000 IU) and/or protein (≥20 g) on nutritional status and physical fitness in malnourished or frail older adults.
Agronomic performance and seed quality attributes of Camelina (Camelina sativa L. crantz) in multi-environment trials across Europe and Canada
Zanetti, Federica ; Eynck, Christina ; Christou, Myrsini ; Krzyzaniak, Michal ; Righini, Daria ; Alexopoulou, Efthimia ; Stolarski, Mariusz J. ; Loo, Eibertus N. van; Puttick, Debbie ; Monti, Andrea - \ 2017
Industrial Crops and Products 107 (2017). - ISSN 0926-6690 - p. 602 - 608.
Eicosenoic acid - Oil - Oil yield - Oilseed - Protein - TKW - α-linolenic acid

Camelina (Camelina sativa L. Crantz) is considered a relatively new oilseed Brassicacea in both Europe and North America, even though its history as a crop dates back to the Bronze Age. Camelina has recently received renewed interest from both the scientific community and bio-based industries around the world. The main attractive features of this species are: drought and frost tolerance, disease and pest resistance, a unique seed oil composition with high levels of n-3 fatty acids, a considerably high seed oil content, and satisfactory seed yields, in particular under low-input management and in limiting environments. Aiming at evaluating the feasible introduction of recently released camelina breeding lines under different environmental conditions and their productive potential a multi-location trial was set up. The agronomic performance of nine improved genotypes of camelina was evaluated in a wide range of environments in Europe (Greece, Italy, Poland) and in five locations across Canada, in two consecutive growing seasons (2015 and 2016). Sowing time was optimized for each location according to the different climatic conditions. Camelina proved to be a highly adaptable species, reaching seed yields of about 1MgDMha-1 under the most limiting conditions (i.e., low precipitation, poor soil quality, extremely high temperature at flowering). Growing environments characterized by mild temperatures and adequate rainfall (>170mm, during the growing season) resulted in higher average seed yields. The length of the growing cycle varied greatly between different locations (80-110d), but the cumulative thermal time was quite stable (∼1200 GDD, growing degree days). The advanced breeding line 787-08, which possesses up to 30% larger seed compared to the mean seed size of all other test entries, proved to be the most promising genotype across all locations in Europe and Canada, combining high seed yields (1.1-2.7MgDMha-1) with improved yield stability. To the best of our knowledge, for the first time, camelina lines with improved oil composition (i.e., increased oleic and α-linolenic and lower linoleic acid contents) for feed, food and industrial applications were identified (789-02 and 887).

Moving from molecules, to structure, to texture perception
Foegeding, E.A. ; Stieger, Markus ; Velde, Fred van de - \ 2017
Food Hydrocolloids 68 (2017). - ISSN 0268-005X - p. 31 - 42.
Emulsion - Oral processing - Polysaccharide - Protein - Structure - Texture

The two main food biopolymers, proteins and polysaccharides, are used in many foods to form structures that are the basis of product identity and quality. One of the main factors determining food quality is texture. A simplistic view of food is that molecules are assembled into structures, and the breakdown of structures during oral processing determines texture. There have been great advancements in understanding mechanisms for how proteins and polysaccharides assemble into structures, and factors determining the mechanical properties of the structures. In contrast, the understanding of how breakdown of structures during oral processing produces specific textural properties is still incomplete. Structuring processes based on protein-polysaccharide mixtures and emulsion gels are evaluated regarding structure formation and texture perception. It is shown that these systems can be designed to modulate specific textural properties. Finally, future trends in this area are discussed.

Valorisation of Proteins from Rubber Tree
Widyarani, ; Coulen, Stef C.W. ; Sanders, Johan P.M. ; Bruins, Marieke E. - \ 2017
Waste and Biomass Valorization 8 (2017)4. - ISSN 1877-2641 - p. 1027 - 1041.
Biorefinery - Indonesia - Protein - Rubber latex - Rubber leaves - Rubber seeds
Purpose: The objective of this study was to identify the availability, possible applications, and economic potential of proteins that are present in different parts of the rubber tree. Proteins from non-food sources can be used in e.g. animal feed or biochemicals production with no or little competition with food production, rendering them important biobased feedstock. Rubber tree is primarily grown for its latex that is used in rubber production. Indonesia has the largest rubber plantation area that is mostly owned and run by smallholder farmers. Using non-latex fractions from the rubber tree may generate additional income, and increase the economics of rubber plantations in general. Methods: Several biomass streams from the rubber tree and subsequent latex processing were considered. Data were compiled from literature, a case study, and interviews with researchers, smallholder farmers, and managers at rubber processing plant and plantation. Results: Latex waste streams, seeds, and leaves were considered to have the highest potential based on the amount of available proteins, and processes to isolate proteins from these streams were proposed. Isolation of specific functional properties from natural sources requires complex (and expensive) separation processes and therefore only economically feasible when specific use of the protein(s) for high value applications can be identified. Purification of many interesting proteins from latex fractions has already been described. Processing of seeds and leaves may also yield useful proteins for food, other purposes, and also still unknown high value applications. Conclusions: A biorefinery concept can be applied to obtain multiple products from the seeds and leaves, and protein extraction can be performed with available knowledge and technology. Small scale processing can be more beneficial for the farmers, especially if the products are used locally for feed.
Intraileal casein infusion increases plasma concentrations of amino acids in humans : A randomized cross over trial
Ripken, Dina ; Avesaat, Mark van; Troost, F.J. ; Masclee, A.A. ; Witkamp, R.F. ; Hendriks, Henk F. - \ 2017
Clinical Nutrition 36 (2017)1. - ISSN 0261-5614 - p. 143 - 149.
Amino acid absorption - Ileal brake - Protein

Background: Activation of the ileal brake by casein induces satiety signals and reduces energy intake. However, adverse effects of intraileal casein administration have not been studied before. These adverse effects may include impaired amino acid digestion, absorption and immune activation. Objective: To investigate the effects of intraileal infusion of native casein on plasma amino acid appearance, immune activation and gastrointestinal (GI) symptoms. Design: A randomized single-blind cross over study was performed in 13 healthy subjects (6 male; mean age 26 ± 2.9 years; mean body mass index 22.8 ± 0.4 kg/m-2), who were intubated with a naso-ileal feeding catheter. Thirty minutes after intake of a standardized breakfast, participants received an ileal infusion, containing either control (C) consisting of saline, a low-dose (17.2 kcal) casein (LP) or a high-dose (51.7 kcal) of casein (HP) over a period of 90 min. Blood samples were collected for analysis of amino acids (AAs), C-reactive protein (CRP), pro-inflammatory cytokines and oxylipins at regular intervals. Furthermore, GI symptom questionnaires were collected before, during and after ileal infusion. Results: None of the subjects reported any GI symptoms before, during or after ileal infusion of C, LP and HP. Plasma concentrations of all AAs analyzed were significantly increased after infusion of HP as compared to C (p <0.001), and most AAs were increased after infusion of LP (p <0.001). In total, 12.49 ± 1.73 and 3.18 ± 0.87 g AAs were found in plasma after intraileal infusion of HP and LP, corresponding to 93 ± 13% (HP) and 72 ± 20% (LP) of AAs infused as casein, respectively. Ileal casein infusion did not affect plasma concentrations of CRP, IL-6, IL-8, IL-1β and TNF-α. Infusion of HP resulted in a decreased concentration of 11,12-dihydroxyeicosatrienoic acid whereas none of the other oxylipins analyzed were affected. Conclusions: A single intraileal infusion of native casein results in a concentration and time dependent increase of AAs in plasma, suggesting an effective digestion and absorption of AAs present in casein. Also, ileal infusion did not result in immune activation nor in GI symptoms. Clinicaltrials.gov: NCT01509469.

Performance of pigs kept under different sanitary conditions affected by protein intake and amino acid supplementation
Meer, Y. van der; Lammers, A. ; Jansman, A.J.M. ; Rijnen, M.M.J.A. ; Hendriks, W.H. ; Gerrits, W.J.J. - \ 2016
Journal of Animal Science 94 (2016)11. - ISSN 0021-8812 - p. 4704 - 4719.
Amino acid - Immune system - Performance - Pig - Protein - Sanitary conditions

There is growing evidence that requirements for particular AA increase when pigs are kept under low sanitary conditions. The extent towhich reduction in growth performance is related to these increased requirements is unclear. To evaluate this relationship, an experiment (2 × 2 × 2 factorial arrangement) was performed with 612 male pigs (9 per pen) kept under low sanitary conditions (LSC) or high sanitary conditions (HSC) and offered ad libitum access to either a normal CP concentration diet (NP; 17, 15, and 15% CP for the starter, grower, and finisher phase, respectively) or a low CP concentration diet (LP; 20% CP reduced relative to NP for each phase), each of which containing a basal AA profile (AA-B) or a supplemented AA profile (AA-S). The supplemented diet type contained 20% more Met, Thr, and Trp relative to Lys on an apparent ileal digestible basis compared with the basal diet type. Pigs were followed for a complete fattening period and slaughtered at a targeted pen weight of 110 kg. Haptoglobin concentrations in serum (0.92 g/L for LSC and 0.78 g/L for HSC) and IgG antibody titers against keyhole limpet hemocyanin (3.53 for LSC and 3.08 for HSC) collected in the starter, grower, and finisher phases and pleuritis scores at slaughter (0.51 for LSC and 0.20 for HSC) were greater for LSC pigs compared with HSC pigs (P ≤ 0.01), illustrating that sanitary conditions affected health conditions. The ADG and G:F were greater for HSC pigs compared with LSC pigs (P ≤ 0.01). The number of white blood cells (WBC) was higher in (AA-S)–fed pigs compared with (AA-B)–fed pigs when kept at LSC but not at HSC [SS (sanitary conditions) × AA interaction, P = 0.04]. Pigs fed NP had a lower number of WBC compared with pigs fed LP (P = 0.02). The number of platelets in pigs fed AA-S diets was higher compared with pigs fed AA-B diets (P ≤ 0.01). A 20% reduction in dietary supplementation of Met, Thr, and Trp relative to Lys decreased G:F more in LSC pigs than in HSC pigs (interaction, P = 0.03), illustrating that dietary requirements for these AA differ depending on sanitary conditions. This study, performed under practical conditions, shows that AA requirements are dependent on sanitary conditions. Furthermore, supplementation of diets with particular AA may improve performance, especially under poor hygienic conditions. Dietary protein concentration as well as Met, Thr, and Trp supplementation can modify immune status, which may influence resistance to sub-clinical and clinical diseases.

Insights on older adults' perception of at-home sensory-hedonic methods : A case of Ideal Profile Method and CATA with ideal
Ruark, Angelica ; Vingerhoeds, Monique H. ; Kremer, Stefanie ; Nijenhuis, Mariska ; Piqueras-Fiszman, Betina - \ 2016
Food Quality and Preference 53 (2016). - ISSN 0950-3293 - p. 29 - 38.
Aging - CATA - IPM - Older consumers - Protein - Sensory-hedonic methods

The increasing average life expectancy and overall percentage of the older population is leading to a growing interest in healthy aging. Thus, there is a demand for flavourful, and pleasant foods, rich in certain nutrients, targeted at older consumers. In order to be able to tailor foods to older consumers wants and needs, it is necessary to investigate and - if necessary - to further improve sensory and consumer science testing methodologies when working with healthy and frail/malnourished older adults.This study aims to investigate older consumers' perception and performance of two sensory-hedonic methods conducted at home based on their ease of use, preference, duration to complete the task, and discrimination ability. Insights about their understanding of the tasks were also collected. Additionally, the study compares the older adults' performance and perception to those of young consumers. The two methods selected for comparison were Yes/No forced-choice Check-All-That-Apply with ideal (CATA-I) and Ideal Profile Method (IPM).Due to the interest in older consumers increasing their protein intake, seven protein-enriched dairy drinks were selected. The dairy drinks were sampled one per day, using one method one week and the other method two weeks later by 67 older (M = 67.96 y.o., SD = 5.09) and 83 young subjects (M = 22.95 y.o., SD = 2.31). Although the IPM method was reported to be more difficult for the older group than CATA-I, there was no preference between the two methods. In addition, they seemed to struggle with the limited options in CATA-I. The data of the older consumers revealed a similar number of discriminating attributes to characterise the products using both methods; the results were also similar to those of the young participants. This study provides novel consumer-centric insights on the use and understanding of two relatively new sensory-hedonic methods by older adults.

Effect of increased protein intake on renal acid load and renal hemodynamic responses
Teunissen-Beekman, Karianna F.M. ; Dopheide, Janneke ; Geleijnse, Marianne ; Bakker, Stephan J.L. ; Brink, Elizabeth J. ; Leeuw, Peter W. de; Baak, Marleen A. van - \ 2016
Physiological Reports 4 (2016)5. - ISSN 2051-817X - 10 p.
Acid load - Carbohydrate - Glomerular filtration rate - Kidney - Protein

Increased protein intake versus maltodextrin intake for 4 weeks lowers blood pressure. Concerns exist that high-protein diets reduce renal function. Effects of acute and 4-week protein intake versus maltodextrin intake on renal acid load, glomerular filtration rate and related parameters were compared in this study. Seventy-nine overweight individuals with untreated elevated blood pressure and normal kidney function were randomized to consume a mix of protein isolates (60 g/day) or maltodextrin (60 g/day) for 4 weeks in energy balance. Twenty-four-hour urinary potential renal acid load (uPRAL) was compared between groups. A subgroup (maltodextrin N = 27, protein mix N = 25) participated in extra test days investigating fasting levels and postprandial effects of meals supplemented with a moderate protein- or maltodextrin-load on glomerular filtration rate, effective renal plasma flow, plasma renin, aldosterone, pH, and bicarbonate. uPRAL was significantly higher in the protein group after 4 weeks (P ≤ 0.001). Postprandial filtration fraction decreased further after the protein-supplemented breakfast than after the maltodextrin-supplemented breakfast after 4 weeks of supplementation (P ≤ 0.001). Fasting and postprandial levels of glomerular filtration rate, effective renal plasma flow, renin, aldosterone, angiotensin-converting enzyme, pH and bicarbonate did not differ between groups. In conclusion, 4 weeks on an increased protein diet (25% of energy intake) increased renal acid load, but did not affect renal function. Postprandial changes, except for filtration fraction, also did not differ between groups. These data suggest that a moderate increase in protein intake by consumption of a protein mix for 4 weeks causes no (undesirable) effects on kidney function in overweight and obese individuals with normal kidney function.

Effect of extraction pH on heat-induced aggregation, gelation and microstructure of protein isolate from quinoa (Chenopodium quinoa Willd)
Ruiz, Geraldine Avila ; Xiao, Wukai ; Boekel, Tiny van; Minor, Marcel ; Stieger, Markus - \ 2016
Food Chemistry 209 (2016). - ISSN 0308-8146 - p. 203 - 210.
Aggregation - Denaturation - Extraction - Gelation - Protein - Quinoa - Solubility

The aim of this study was to determine the influence of extraction pH on heat-induced aggregation, gelation and microstructure of suspensions of protein isolates extracted from quinoa (Chenopodium quinoa Willd). Quinoa seed protein was extracted by alkaline treatment at various pH values (pH 8 (E8), 9 (E9), 10 (E10) and 11 (E11)), followed by acid precipitation. The obtained protein isolates were freeze dried. The protein isolates E8 and E9 resulted in a lower protein yield as well as less protein denaturation. These isolates also had a higher protein purity, more protein bands at higher molecular weights, and a higher protein solubility in the pH range of 3-4.5, compared to the isolates E10 and E11. Heating the 10% w/w protein isolate suspensions E8 and E9 led to increased aggregation, and semi-solid gels with a dense microstructure were formed. The isolate suspensions E10 and E11, on the other hand, aggregated less, did not form self-supporting gels and had loose particle arrangements. We conclude that extraction pH plays an important role in determining the functionality of quinoa protein isolates.

Denaturation and in Vitro Gastric Digestion of Heat-Treated Quinoa Protein Isolates Obtained at Various Extraction pH
Ruiz, Geraldine Avila ; Opazo-Navarrete, Mauricio ; Meurs, Marlon ; Minor, Marcel ; Sala, Guido ; Boekel, Tiny van; Stieger, Markus ; Janssen, Anja E.M. - \ 2016
Food Biophysics 11 (2016)2. - ISSN 1557-1858 - p. 184 - 197.
Denaturation - Digestibility - Extraction pH - Heat processing - Protein - Quinoa

The aim of this study was to determine the influence of heat processing on denaturation and digestibility properties of protein isolates obtained from sweet quinoa (Chenopodium quinoa Willd) at various extraction pH values (8, 9, 10 and 11). Pretreatment of suspensions of protein isolates at 60, 90 and 120 °C for 30 min led to protein denaturation and aggregation, which was enhanced at higher treatment temperatures. The in vitro gastric digestibility measured during 6 h was lower for protein extracts pre-treated at 90 and 120 °C compared to 60 °C. The digestibility decreased with increasing extraction pH, which could be ascribed to protein aggregation. Protein digestibility of the quinoa protein isolates was higher compared to wholemeal quinoa flour. We conclude that an interactive effect of processing temperature and extraction pH on in vitro gastric digestibility of quinoa protein isolates obtained at various extraction pH is observed. This gives a first indication of how the nutritional value of quinoa protein could be influenced by heat processing, protein extraction conditions and other grain components.

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