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.

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Exploring novel food proteins and processing technologies : a case study on quinoa protein and high pressure –high temperature processing
Avila Ruiz, Geraldine - \ 2016
Wageningen University. Promotor(en): Tiny van Boekel, co-promotor(en): Guido Sala; Markus Stieger. - Wageningen : Wageningen University - ISBN 9789462579095 - 152
dietary protein - chenopodium quinoa - whey protein - food process engineering - heat treatment - in vitro digestibility - fractionation - maillard reaction products - ph - viscosity - gelation - aggregation - high pressure technology - sds-page - voedingseiwit - wei-eiwit - levensmiddelenproceskunde - warmtebehandeling - in vitro verteerbaarheid - fractionering - maillard-reactieproducten - viscositeit - gelering - aggregatie - hogedruktechnologie

Foods rich in protein are nowadays high in demand worldwide. To ensure a sustainable supply and a high quality of protein foods, novel food proteins and processing technologies need to be explored to understand whether they can be used for the development of high-quality protein foods. Therefore, the aim of this thesis was to explore the properties of a novel food protein and a novel processing technology for the development of high-quality protein foods. For this, quinoa was chosen as an alternative protein source and high pressure – high temperature (HPHT) processing was chosen as a novel processing technology.

Quinoa protein has been found to have a balanced amino acid profile and to be allergen-free. As this combination is not common among plant proteins, it is worth studying physicochemical and functional protein properties of quinoa further (Chapter 1). Extraction and processing conditions can influence protein properties and thus functionality. Therefore, quinoa protein properties were examined at different extraction and processing conditions (Chapter 2 and 3). For this, the protein was isolated from the seed using alkaline extraction and subsequent acid precipitation. The quinoa protein isolates (QPIs) obtained were examined in terms of protein purity, yield, solubility, denaturation, aggregation and gelation behaviour, and digestibility.

It was found that when extraction pH increased, protein yield and denaturation increased, which was explained by a higher protein charge, leading to increased unfolding and solubilisation (Chapter 2). Protein purity decreased with increasing extraction pH, which was associated with a possible co-extraction of other seed components. QPIs obtained at extraction pH 8 (E8) and 9 (E9) had a higher solubility in the pH range of 3-4.5 (E9 solubility was highest at pH 7) compared to the isolates obtained at extraction pH 10 (E10) and 11 (E11). It was hypothesised that at a higher extraction pH, the larger extent of protein denaturation led to the exposure of hydrophobic groups, thus decreasing surface polarity and solubility. When suspensions of E8 and E9 were heated, protein aggregation increased and semi-solid gels with a dense microstructure were formed. In contrast, suspensions of E10 and E11 aggregated to a lower degree and did not form self-supporting gels upon heating. The gels obtained with E10 and E11 had furthermore a microstructure showing loose particles. Increased protein aggregation and improved gel formation at lower extraction pH were hypothesised to be due to a higher degree of hydration and swelling of protein particles during heating, leading to increased protein-protein interactions. These findings show that QPI obtained at an extraction pH below 9 might be used to prepare semi-solid gelled foods, while QPI obtained at pH values higher than 10 might be more suitable to be applied in liquid foods.

Heat treatments of QPI suspensions lead to an increased protein denaturation and aggregation but to a decreased in vitro gastric protein digestibility, especially at a high temperature (120°C) and extraction pH (11) (Chapter 3). It was hypothesised that QPIs obtained at a higher extraction pH and treated at higher temperature were denatured to a greater extent and contained stronger protein crosslinks. Therefore, enzyme action was impaired to a higher degree compared to lower temperatures and extraction pH values. This means that by controlling extraction pH and treatment temperature the digestibility of quinoa protein can be optimised.

The disadvantage of the conventional fractionation method used in Chapter 2 and 3 is that it requires high amounts of energy and water and the solvents used can denature the protein, possibly leading to a loss in functionality. Therefore, recently, a new method has been developed, hybrid dry and aqueous fractionation, which uses less energy and water and has proved successful for obtaining protein-rich fractions from pea. It was not known whether hybrid dry and aqueous fractionation can be used to obtain protein-rich fractions of quinoa (Chapter 4). Quinoa seeds were carefully milled to disentangle the protein-rich embryo from the starch-rich perisperm. Using subsequent air-classification, the embryo and perisperm were separated based on size into a protein-rich fraction and a starch-rich fraction, respectively (dry fractionation). The protein-rich fraction was further milled to a smaller particle size and suspended in water. This step was to solubilise the protein (aqueous fractionation), whereby a smaller particle size and adding NaCl optimised the solubilisation efficiency. The addition of salt helped to extract more salt-soluble proteins from quinoa, next to the water-soluble proteins. After centrifugation, the protein-enriched top aqueous phase was decanted and ultrafiltered for further protein concentration. The process generated a quinoa protein-rich fraction with a protein purity of 59.4 w/dw% and a protein yield of 62.0%. Having used 98% less water compared to conventional protein extraction, this new method is promising for industry to obtain quinoa protein concentrates in a more economic, sustainable and milder way.

Next to exploring novel food proteins for the development of high-quality protein foods, novel processing technologies are also important to study. This is because traditional thermal processing can deteriorate the quality of protein-rich foods and beverages by causing undesired browning or too high viscosities. Therefore, for sterilisation purposes, HPHT processing was investigated for the treatment of protein foods (Chapter 5). Model systems, whey protein isolate – sugar solutions, were used to study the effect of pressure at high temperature on Maillard reactions, browning, pH, protein aggregation and viscosity at different pH. It was found that pressure retarded early and advanced Maillard reactions and browning at pH 6, 7 and 9, while it inhibited protein aggregation and, thereby, a high viscosity at pH 7. The mechanism behind this might be that pressure induces a pH drop, possibly via dissociation of ionisable compounds, and thus slows down Maillard reactions. Differences in protein conformation, protein-protein interactions and sensitivity of whey proteins, depending on pH, pressure and heat, might be at the base of the reduced protein aggregation and viscosity observed at pH 7. The results show that HPHT processing can potentially improve the quality of protein-sugar containing foods, for which browning and high viscosities are undesired, such as high-protein beverages.

Finally, the properties of quinoa protein and HPHT processing were discussed in a broader context (Chapter 6). It was concluded that QPI obtained at pH 9 is a promising alternative to pea and soy protein isolate from a technical perspective and that QPI protein yields can be optimised. Also, quinoa protein-rich fractions obtained with the hybrid dry and aqueous fractionation method were predicted to have comparable properties to QPI, soy and pea protein isolates. However, from a marketing perspective, the protein-rich fraction was considered more advantageous to be up-scaled compared to QPI. High pressure at ambient or high temperature was found to have an added value compared to heat, which can be used for the development of high-quality protein food. Lastly, quinoa protein and HPHT processing might become more attractive for industry in the light of current trends, if present predictions can be confirmed and remaining issues can be resolved.

Bacillus cereus spore damage recovery and diversity in spore germination and carbohydrate utilisation
Warda, Alicja K. - \ 2016
Wageningen University. Promotor(en): Tjakko Abee, co-promotor(en): Masja Nierop Groot. - Wageningen : Wageningen University - ISBN 9789462579262 - 157
bacterial spores - bacillus cereus - heat treatment - damage - microbiological techniques - bacteriële sporen - warmtebehandeling - schade - microbiologische technieken

Bacterial spores are extremely robust survival vehicles that are highly resistant towards environmental stress conditions including heat, UV radiation and other stresses commonly applied during food production and preservation. Spores, including those of the toxin-producing food-borne human pathogen Bacillus cereus, are ubiquitously present in a wide range of environmental niches such as soil, plant rhizosphere, intestinal tract of insects and animals, and it is virtually impossible to prevent contamination at the primary production level. Heat treatments are conventionally applied in food processing to reduce the microbial load of food products, however, to comply with consumer desire for products with higher sensory and nutritional values, the treatment intensity may become milder. Consequently, subpopulations of spores may emerge that are sublethally damaged rather than inactivated conceivably causing quality and safety issues following repair and outgrowth. In this thesis, a functional genomics approach was used in combination with subpopulation and single spore analysis to identify factors involved in recovery of heat damaged spores, and to link B. cereus genotypes to nutrient-induced germination capacity and carbohydrate utilisation capacity.

Using comparative analysis of B. cereus ATCC 14579 wild type and targeted mutants, putative damage repair factors were identified such as putative transcriptional regulator CdnL, that supported recovery of spores in a range of conditions including model foods. The majority of identified genes encoding putative damage repair factors appeared to be unique for B. cereus group members. This novel information on spore recovery adds to further insights in versatility of survival strategies of B. cereus.

Different types of foods may contain different types and levels of nutrients including amino acids and carbohydrates, that can affect spore germination capacity and subsequent outgrowth performance of vegetative B. cereus cells. Nutrient germinants present in food products can trigger specific germinant receptors (GRs) located in the spore inner membrane leading to spore germination, a critical step before growth resumes. Combined analysis of genotypes and nutrient-induced germination phenotypes using high throughput flow cytometry analysis at the level of individual spores, revealed substantial diversity in germination capacity with a subset of strains showing a very weak germination response even in nutrient-rich media containing high levels of amino acids. Phylogenetically, these B. cereus strains grouped in subgroup IIIA encompassing strains containing pseudogenes or variants of some of the Ger clusters and two strains containing the recently identified SpoVA2mob transposon, that induced heat resistance with concomitant reduced germination response in Bacillus subtilis spores. The same B. cereus isolates were also used to link genotypes with carbohydrate utilisation clusters present on the genomes, and this revealed representatives of subgroup IIIA to lack specific carbohydrate utilisation clusters (starch, glycogen, aryl beta-glucosides; salicin, arbutin and esculin) suggesting a reduced capacity to utilise plant-associated carbohydrates for growth. Since these B. cereus subgroup IIIA representatives contain host-associated carbohydrate utilisation gene clusters and a subset of unique Ger clusters, their qualification as poor germinators may require revision following assessment of spore germination efficacy using host-derived compounds as germinants.

The research described in this thesis has added novel insights in B. cereus capacity to cope with spore damage and provided novel overviews of the distribution and putative functionality of (sub)clusters of GRs and carbohydrate utilisation clusters. Knowledge on spore damage repair, germination and metabolism capacity adds to further understanding of B. cereus ecology including niche occupation and transmission capacity.

Warmtebehandeling kastanjebloedingsziekte : hoe werkt het?
Kuik, A.J. van; Lammeren, A.A.M. van - \ 2015
Wageningen : Wageningen UR - 12 p.
straatbomen - openbaar groen - aesculus - gewasbescherming - ziektebestrijdende teeltmaatregelen - warmtebehandeling - bacterieziekten - pseudomonas syringae - street trees - public green areas - plant protection - cultural control - heat treatment - bacterial diseases
Kastanjebloedingsziekte is de meest bedreigende ziekte van paardenkastanjebomen. De ziekte wordt veroorzaakt door een bacterie en is dus besmettelijk. De meeste bomen bezwijken aan deze ziekte. Warmtebehandeling is op dit moment de enige methode die de ziekte kan stoppen. De boom wordt ingepakt met een ‘warmtedeken’. De warmtebehandeling maakt de boom zo goed mogelijk vrij van de ziekteverwekkende bacterie. Hierdoor krijgt de boom de gelegenheid om de aantasting te overgroeien en dus te herstellen.
Water retention in mushroom during sustainable processing
Paudel, E. - \ 2015
Wageningen University. Promotor(en): Remko Boom, co-promotor(en): Ruud van der Sman. - Wageningen : Wageningen University - ISBN 9789462575967 - 148
mushrooms - water holding capacity - physical properties - hydration - chemical composition - heat treatment - canning - process optimization - sustainability - paddestoelen - waterbergend vermogen - fysische eigenschappen - hydratatie - chemische samenstelling - warmtebehandeling - inblikken - procesoptimalisatie - duurzaamheid (sustainability)

This thesis deals with the understanding of the water holding capacity of mushroom, in the context of a redesign of their industrial processing. For designing food process the retention of food quality is of the utmost importance. Water holding capacity is an important quality aspect of mushrooms. A convenient process design methodology which accounts also for product quality is Conceptual Process Design (CPD). An approach to follow CPD methodology is first to explore, the material properties of the products to find optimal processing conditions. In this stage the constraints of (existing) processing equipment are not considered. Later in the second stage, suboptimal processing conditions are determined considering the constrains of equipment.

In mushroom canning, temperature induced loss of water holding capacity (WHC) of tissue manifests as a lower product yield. This loss of water is accompanied with the loss of nutrients, dissolved in the water. In addition to the loss of product quality like water holding capacity, mushroom canning (with alternating heating and cooling steps) also induces losses of useful resources as (potable) water. In terms of water use, water is added at several steps, and is discarded at other places. This shows that there is opportunity to improve the sustainability of the production system, but with the constraint that product quality is not impaired, or evenly improved.

The WHC is an important property that determines several aspects of foods. For example, it determines the juiciness of fruits, vegetables and meat products; the freshness (firmness, or crispiness) of green-leafy vegetables; and the calorie intake per serving for high calorie containing foods such as cheese. Despite being a widely used term in food science, there is no clear definition of water holding capacity and its thermodynamic nature is not fully acknowledged. The understanding of the WHC is even poorer in structured cellular foods such as mushroom, where different water fractions are present in various compartments. In a cellular system water is present as 1) a solution in the vacuoles, 2) water osmotically bound to the cytoplasmic and the cell wall materials and 3) capillary water in pores, which might be filled during processing. Because they have a distinct capillary phase, the mushroom is a good system to study the contributions of various water fraction on the total water retention.

The main aim of the current work is to provide insight for the development of canned mushroom processing where: 1) the resources of energy and water are efficiently used, and 2) the quality of mushroom is maintained. These two aims are related to the efficient use of raw materials and maintenance of full weight of mushroom during processing. The WHC is an important quality indicator of mushrooms. The analysis related to water retention of mushroom has been carried out at microscale where molecular and structural interactions in relation to water retention are studied. The micro scale analysis is discussed in chapter 2, chapter 3 and chapter 4. The sustainability analysis is carried out at mesoscale where analysis is carried out at the unit operation level which is described in chapter 5.

In chapter 2, the heat-induced change in water holding capacity of particular the gel phase of the mushroom is interpreted with the Flory-Rehner theory, commonly applied to polymer gels. As done earlier for meat, we have first assumed that WHC loss in mushroom can also be attributed to the protein denaturation. This assumption is based on the experimental observation that, like meat, mushroom also follows a typical sigmoid relation with change in temperature. In the theory, we have regarded mushroom as a homogeneous biopolymer hydrogel, in which salt and sugar are dissolved. The water holding capacity is then understood as the swelling capacity of the biopolymer gel. The thermodynamic state of this simplified system is characterized by the so-called swelling pressure, which is decomposed into three independent contributions: 1) the mixing pressure induced by sugars and polymers, 2) the ionic pressure induced by the salt, and 3) the elastic pressure induced by the polymers. An assumption was made that the heat treatment denatures mushroom protein, which is reflected in the change of the Flory Huggins interaction for protein. It follows the same temperature dependency as the WHC loss by mushroom under zero mechanical load. The assumption of the temperature dependency of the interaction parameter is tested with an independent sorption measurement. With the assumption, the sorption curve for mushroom sample which were preheated previously at 30, 60 and 90 °C could accurately be predicted. Curve fitting of WHC under various mechanical loads has shown that model parameters that are associated with the elastic pressure, the crosslink density and fraction of the polymer in the relaxed state, are temperature dependant. The values of increased in contrast to the decrease of upon heating of mushroom tissue up to temperature of 70°C. The result indicates that heat treatment increases the polymer chain length between the cross links as original conformation of mushroom is lost. At the same time, more crosslinks are formed by a polymer because of aggregation of polymers. However, in our fitting procedure, we have excluded WHC data at low external pressure values, as water is present in both gel phase as in in the capillaries. This is done as the pores in this range are not fully collapsed and the Flory Rehner theory is valid only for the gel phase

In chapter 2 mushroom is simplified in the sense that only compositional contribution is considered in WHC but not the structural contributions. In subsequent chapters we have acknowledged that mushroom has a cellular structure with a distinct pore phase. The pores are intentionally filled during processing via vacuum impregnation. The contribution of water present in the capillaries due to vacuum impregnation of mushroom has been discussed in chapter 3. Both the temperature of heat treatment and the initial porosity of mushroom contribute independently to water holding capacity of heat treated mushroom. The hydration of heat treated mushroom increases linearly with the initial porosity of mushroom for all the temperatures from 30 to 90 °C. The porosity of mushroom can also largely explain the increase in hydration of heat treated mushroom with storage as both porosity and the hydration increase simultaneously with the storage days. The fluid that filled in the capillaries acts against collapse of the hyphae which have inherent elastic force that works in the other direction. The initial porosity of mushroom is an important aspect that determines the hydration of the heat treated mushroom and therefore, cannot be ignored. In addition, the Flory-Rehner theory alone cannot capture the contribution of the capillary water. Hence an addition is needed in the theory to capture this effect.

The cellular phase in mushroom tissue is even more complicated because water is present in this phase in two other forms, as gel water and the intracellular water. Chapter 4 takes into account the role of structure in the WHC. The role of cell membrane integrity and the cell-wall structural components is investigated for retention of the water fraction. The cell membrane integrity is calculated from the conductivity measurement of the fluid that leaches out from the vacuole that has salts in it. The loss of the cell membrane integrity largely explains the water loss from heat treated mushroom sample. The loss of cell membrane integrity is also related with the water loss from frozen mushroom, but additional losses occur during freezing due to novel crosslinks formed during the growth of ice crystals compressing the unfrozen cell wall material. The enzymatic hydrolysis of mushroom cellular components shows that chitin and mushroom protein both contribute to the water holding capacity either via osmotic binding or by their role to provide the mechanical strength to the mushroom hyphae. In addition, proteins have additional contributions to water retention by mushroom because of their electrostatic interaction as polyelectrolyte. This is evident as the hydration of the mushroom increases with pH of mushroom.

In chapter 5, the efficiency of the use of the resources (raw materials, energy water) is investigated. The mass and exergy flow in the current production system is visualized with the Sankey diagrams. The sustainability of unit operations involved in the current production system of canned are analysed with the second law efficiency using exergy. Using ideas from Process Intensification three alternative routes are proposed for the production of canned mushrooms namely: 1). Slicing before vacuum hydration, and 2) Using hot water for vacuum hydration and 3) Using blanch water for vacuum hydration. Using hot water for vacuum hydration is not seen as a feasible option, since it consumed more resources. Slicing mushroom before their vacuum hydration and using blanch water for hydration of mushroom lowers the resources requirement for production. In addition, using blanch water for hydration also increases the final product yield.

Finally, the main findings of this thesis are summarized in the general discussion in chapter 6. The findings from previous chapters are combined to an overall description of water loss from heat treated mushroom. The overall description of water holding capacity in mushrooms is given in terms of the thermodynamic conditions for equilibrium between the different compartments holding water. The two dimensions of the thesis, the higher water retention of processed mushroom and more sustainable operation are discussed in the light of conceptual process design, using a micro/mesoscale approach. At the microscale material properties of mushroom are discussed. The biggest effect comes from cell membrane integrity loss. The porosity of fresh mushroom and the ionic interactions of polymers are the other effects that influence the WHC. Mesoscale analysis shows that shifting the sequence of unit operations and reusing the blanch water that is discarded in the current production process can improve the sustainability. Finally based on outcome of current work, future perspective of current work is discussed briefly.

Overall, this thesis demonstrated that there is substantial scope in improving the efficiency in the use of resources in producing preserved mushroom. Also scope in retention of water in the mushroom tissue is demonstrated. Thus this thesis shows that both aspects, product and process efficiency, can be improved at the same time.

Zieke bomen krijgen een jas aan (onderzoek van André van Lammeren en Fons van Kuik)
Lammeren, Andre van - \ 2015
arboriculture - street trees - chestnuts - aesculus - plant protection - plant pathogenic bacteria - pseudomonas - tree surgery - heat treatment - cultural control - educational resources
Correlating composition and functionality of soy protein hydrolysates used in animal cell cultures
Gupta, A.J. - \ 2015
Wageningen University. Promotor(en): Harry Gruppen, co-promotor(en): Peter Wierenga; J.W. Boots. - Wageningen : Wageningen University - ISBN 9789462573208 - 127
sojaeiwit - eiwithydrolysaten - functionele eigenschappen - warmtebehandeling - celculturen - chemische samenstelling - metabolomica - soya protein - protein hydrolysates - functional properties - heat treatment - cell cultures - chemical composition - metabolomics


Soy protein hydrolysates are often supplemented to chemically defined (CD) media in cell cultures, but there is little understanding of the effect of their composition on their functionality (viable cell density, total immunoglobulin (IgG), and specific IgG production). To identify the key parameters (e.g. compound classes) that determine their functionality, hydrolysates were prepared from different starting materials (meal, concentrates, and isolate) and from soybean meal that was heated for different time periods. The functionality of these hydrolysates were compared to those of industrial hydrolysates. From the comparison, it was shown that the variation in industrial and experimental processes of hydrolysate production induced larger variation in the functionality than the variation in starting materials. Moreover, it was observed that the correlations between the functionality and compositional parameters observed in one experiment were absent in the other experiments. During the study, it became apparent that the variations in other factors, like CD media and temperature during culturing also resulted in variation in functionality. The extent of variations in the functionality due to variation in CD media and temperature during culturing was equivalent to the variation caused by varying the hydrolysate composition. The functionality data of the different experiments were fitted with a model that described the relation between specific IgG production and viable cell density. Using the model, the maximum achievable total IgG production could be calculated for a culture condition. This information can provide directions for further optimization of hydrolysates to maximize total IgG production.

Models of the fate of glucosinolates in Brassicaceae from processing to digestion
Kruse, I. - \ 2015
Wageningen University. Promotor(en): Tiny van Boekel, co-promotor(en): Matthijs Dekker; Ruud Verkerk. - Wageningen : Wageningen University - ISBN 9789462573178 - 140
glucosinolaten - brassicaceae - koolsoorten - broccoli - spruitjes - warmtebehandeling - thermische afbraak - masticatie - spijsvertering - stomen - kookmethoden - glucosinolates - cabbages - brussels sprouts - heat treatment - thermal degradation - mastication - digestion - steaming - cooking methods


Glucosinolates are secondary metabolites of Brassica vegetables. Glucosinolates are not bioactive themselves, but their hydrolysis products isothiocyanates have been associated with health benefits. The concentrations of glucosinolates and their break down products are strongly affected by processing of the vegetables, but are also affected by digestion conditions.

During thermal treatment of Brassicaceae, such as domestic cooking, different mechanisms affecting the content of glucosinolates can take place and were modelled in the present study: Lysis of plant cells and compartments, leaching of glucosinolates into the cooking water and thermal degradation of glucosinolates in both the intact vegetable tissue and in the cooking water. These mechanisms were described mathematically and the model parameters for broccoli, Brussels sprouts, red cabbage and white cabbage were estimated based on experimental results. Differences between the thermostability of the same glucosinolates originating from different Brassicaceae could be detected, as well as differences between the thermostability of the same glucosinolates in the vegetable matrix compared to that in cooking water. This mathematical model and the estimated parameters can be used to simulate the different glucosinolate contents in prepared foods considering the processing method. This should be a useful tool in food research and industry to make predictions about the nutritional quality of foods and to optimize their health related quality attributes.

In broccoli, the glucosinolate glucoraphanin and its breakdown products were further studied in an in vitro digestion study and an in vivo chewing study with five subjects. Upon cell damage, e.g. during chewing, the glucosinolate glucoraphanin is hydrolyzed by the endogenous enzyme myrosinase and, depending on the environmental conditions, sulforaphane or sulforaphane nitrile are produced.

The effect of steaming time (raw or steamed for 1, 2 or 3 min) and meal composition (with and without addition of protein (bovine serum albumin or lipid (olive oil)) on the conversion of glucoraphanin were studied in an in vitro digestion model and the bioaccessibility of released breakdown products investigated. The main formation of sulforaphane and sulforaphane nitrile from glucoraphanin occurred during the in vitro oral phase. The content of glucoraphanin, sulforaphane and sulforaphane nitrile did not degrade after digestion. Sulforaphane concentrations were up to 10-times higher in raw and 1-min steamed broccoli samples after the digestion compared to broccoli that was steamed 2 or 3 min. The addition of bovine serum albumin and olive oil had no influence on the formation and bioaccessibility of sulforaphane or sulforaphane nitrile. Meal preparation seems to have a much more pronounced effect on SF formation and bioaccessibility compared to meal composition.

In an in vitro study the effect of chewing time (11 s, 22 s, 30 s and 40 s) on differently steamed broccoli ( raw or steamed for 0.5-min, 1-min 2-min and 3-min) was studied. Chewing time influenced the amount of hydrolysis of glucoraphanin in raw and short steamed broccoli that contains active myrosinase (raw, 0.5-min and 1-min steamed), but not in broccoli that had been steamed longer. Steaming time showed to influence the oral hydrolysis of glucoraphanin. Both chewing time and steaming time influence the enzymatic breakdown of glucoraphanin in the mouth. Longer chewing times of raw and short steamed broccoli (0.5-min and 1-min), which contains active myrosinase, lead to more hydrolysis.

Een jasje voor het bloeden
Kleis, R. ; Lammeren, A.A.M. van; Korsuize, C.A. - \ 2015
Resource: nieuwssite voor studenten en medewerkers van Wageningen UR 9 (2015)17. - ISSN 1389-7756 - p. 18 - 19.
aesculus - bomen - plantenziekteverwekkende bacteriën - pseudomonas syringae pv. aesculi - ziektebestrijding - methodologie - temperatuur - warmtebehandeling - verwarming - trees - plant pathogenic bacteria - disease control - methodology - temperature - heat treatment - heating
Een groot deel van de kastanjebomen in ons land bloedt. De oorzaak is een lastig te bestrijden bacterie. Wageningse wetenschappers hebben nu een oplossing die even simpel als geniaal is: verwarmen.
Quality of traditionally processed shea (Vitellaria paradoxa) kernels and shea butter
Honfo, G.F. - \ 2015
Wageningen University. Promotor(en): Tiny van Boekel; M.M. Soumanou, co-promotor(en): Anita Linnemann. - Wageningen : Wageningen University - ISBN 9789462572737 - 237
sheaboter - voedselbereiding - plantaardige vetten - warmtebehandeling - extractie - inheemse kennis - kwaliteit - achteruitgang (deterioration) - benin - vitellaria paradoxa - shea butter - food preparation - plant fats - heat treatment - extraction - indigenous knowledge - quality - deterioration


The shea tree is an endogenous and multipurpose tree from the Savanah zone of Africa, mostly used for its fruits and the fat extracted from its kernels, commonly known as shea butter. The butter is used for cooking and medicinal purposes by local populations, and in cosmetic products as well as a cocoa butter substitute in chocolate in others areas of Africa and at the international level. The butter is generally extracted by traditional methods, which vary throughout the production zones but involve some common processing operations viz. boiling of the fresh nuts, sun drying, shelling, crushing, roasting, milling, churning, and heating. This thesis investigated the influence of traditional processing of shea on quality attributes of shea kernels and butter.

The results showed that 2 mains techniques (differing in the heat treatment applied to the fresh nuts) are used to process shea fruits after their collection: the boiling followed by sun drying technique and the smoking technique. Boiled and sundried kernels contained a higher fat content (48 % dw) and yielded more butter (30 % of kernel mass) than smoked kernels that had a fat content of 39 % dw. The butter extracted from the boiled kernels had a better quality than the butter from smoked kernels with respect to the unsaponifiable fraction (7 %), tocopherol compounds (125 mg/g), peroxide value (8 meq O2/kg), and FFA (2 %). Some processing operations, namely the storage of fresh nuts as related to their boiling time and the roasting of kernels, were optimized using the response surface method to design the experiments. The conditions to obtain an optimal quality of kernels are to store the nuts for 3 days and boil them for 28 ± 3 min. Subsequently, optimal roasting conditions for kernels were found to be 15 min at 171 ºC, which resulted in kernels with a fat content of 49 % dw, a butter yield of 32 %, and butter with a FFA of 1.2 %. The results also revealed that shea butter extracted from roasted kernels contained more volatile compounds (58) than that from unroasted kernels (27). Additionally, storage temperature and storage duration significantly affected some quality characteristics of shea butter, whereas the influence of local packaging materials was less pronounced

Shea processors are advised to process shea fruits by integrating the optimal conditions of storage of fresh nuts, boiling and roasting found in this research, then pack the butter in clean and opaque plastic and store it in a relatively cool area to maintain the quality of the product during prolonged storage periods. Areas for future research were identified for further improvements of local shea processing.

Aaltjesdoding in tulp en narcis : partijenproef stengelaaltjes zomer 2012
Dam, M.F.N. van; Doorn, J. van; Haaster, A.J.M. van; Vreeburg, P.J.M. ; Korsuize, C.A. ; Boer, F.A. de; Dees, R.H.L. - \ 2014
bloembollen - vermeerderingsmateriaal - gewasbescherming - aaltjesdodende eigenschappen - hittebestendigheid - warmtebehandeling - narcissus - tulpen - siergewassen - ornamental bulbs - propagation materials - plant protection - nematicidal properties - heat stability - heat treatment - tulips - ornamental crops
Worden aaltjes 100% in de tulpen en narcissen gedood? Is er sprake van temperatuurgewenning van de aaltjes en heeft de voorwarmte daar invloed op?
Kookadvies narcis en bijzondere bolgewassen 2013-2014 : onderzoek naar de schadegrens van narcis en enkele bijzondere bolgewassen bij de warmwaterbehandeling tegen stengelaaltjes
Vreeburg, P.J.M. ; Leeuwen, P.J. van; Korsuize, C.A. ; Trompert, J.P.T. - \ 2014
Lisse : Praktijkonderzoek Plant & Omgeving BBF - 35
gewasbescherming - tuinbouw - bloembollen - narcissus - temperatuur - warmtebehandeling - cultivars - heetwaterbehandeling - schade - nematoda - plant protection - horticulture - ornamental bulbs - temperature - heat treatment - hot water treatment - damage
Het stengelaaltje (Ditylenchus dipsaci) is in de bollen een quarantaine-organisme waarvoor een nultolerantie geldt. Een aantasting door stengelaaltjes wordt de laatste jaren bij narcis op gemiddeld 20 bedrijven gevonden ondanks de toegepaste standaard warmwaterbehandeling (wwb). Bij tulp ligt dit aantal slechts een weinig lager. Daarnaast worden er jaarlijks 2 à 3 partijen bijzondere bolgewassen aangetroffen met een aantasting. Uit onderzoek bij PPO is bekend dat in narcis stengelaaltjes voorkomen die door het huidige advies (binnen 3 weken na rooien, 1 week voorwarmte bij 30°C, 24 uur voorweken en een warmwaterbehandeling van 4 uur 47°C) niet volledig worden bestreden. De adviezen voor een warmwaterbehandeling van bijzondere bolgewassen dateren vaak van voor 1983. In 2012/2013 is bij PPO gestart met een onderzoek waarin onderzocht wordt of de bestrijding van het stengelaaltje in narcis en bijzondere bolgewassen verbeterd kan worden door de watertemperatuur van de warmwaterbehandeling te verhogen. In 2013/2014 is dit onderzoek vervolgd. Bij narcis zijn ook veel behandelingen uitgevoerd binnen een week na rooien zonder voorwarmte bij 30°C en zonder voorweken. Reden was dat dan mogelijk het lastige voorweken niet meer nodig is omdat de stengelaaltjes minder kans krijgen in te drogen gedurende de langere bewaring en de hogere bewaartemperatuur. Bij de cultivars Tête-à-Tête, Tahiti en Geranium was een warmwaterbehandeling tot 4 uur 47°C zonder opbrengstderving mogelijk. Soms was er wel enige schade aan het gewas en bloemen. Bij Bridal Crown was 4 uur 45°C of 2 uur 47°C maximaal haalbaar, hetgeen mogelijk een gevolg was van de relatief lage temperatuur gedurende de dagen dat de bollen na rooien op het veld lagen te drogen. Koken gedurende 4 uur bij 47 of 49°C binnen 3 weken na voorwarmte bij 30° en hoger en voorweken, was voor alle cultivars mogelijk met uitzondering van Tahiti waar 49°C te hoog was. Opvallend was ook dat een “cultuurkook” van 2 uur 45°C half september uitgevoerd vaak lichte gewas- en bloemschade liet zien en dat bij Tahiti de opbrengst zelfs lager was. Bij de bijzondere bolgewassen werd het onderzoek van vorig jaar herhaald, maar soms met een ander type van het gewas, hetgeen mogelijk mede de reden was dat de resultaten iets afweken van vorig jaar. Ook dit jaar bleek dat op Allium aflatunense Purple Sensation, Chionodoxa luciliae (vorig jaar Violet Beauty), Muscari White Magic (vorig jaar armeniacum) en Scilla siberica zonder schade een hogere kooktemperatuur kan worden toegepast dan nu wordt geadviseerd, waarbij soms wel de voortemperatuur moet worden verhoogd. Een warmwaterbehandeling van 4 uur 47°C was bij alle bijzondere bolgewassen mogelijk, waarbij een voortemperatuur van 34°C soms wel beter was. Een warmwaterbehandeling van 4 uur 49°C was niet haalbaar bij Scilla siberica en gaf enige schade bij Chionodoxa luciliae, leidde tot minder bloemen bij Allium aflatunense Purple Sensation en had geen effect op de bolgroei van Allium en Muscari White De schade werd daarbij na een voortemperatuur bij 34°C altijd (veel) minder dan na een voortemperatuur van 30°C.
Warmwaterbehandeling van tulpen 2014 : Voortzetting van onderzoek (5e jaar) naar temperatuurtolerantie van tulpenbollen en de doding van stengelaaltjes in narcissen en tulpen
Dam, M.F.N. van - \ 2014
Lisse : Praktijkonderzoek Plant & Omgeving B.V. - 27
tulpen - ditylenchus dipsaci - warmtebehandeling - heetwaterbehandeling - bestrijdingsmethoden - kritische temperatuur - cultivars - koken - tulips - heat treatment - hot water treatment - control methods - critical temperature - boiling
De afgelopen jaren is er met succes onderzoek gedaan naar het vinden van een werkbare methode om tulpenstengelaaltjes in tulpen te bestrijden door een warmwaterbehandeling. Tulpen blijken redelijk bestand tegen koken gedurende 4 uur bij 47 en 48°C en er is 100% aaltjesdoding bij 48°C. Er treedt opbrengstver-lies op door de behandeling bij deze temperaturen, maar door een hoge voorwarmte te geven wordt dat verlies beperkt. Hiermee is er een alternatief gevonden voor het nu verplicht vernietigen van een partij na constatering van aaltjesziekte. Het onderzoek richtte zich de eerste jaren op een goede behandelwijze waarbij de tulpen zo weinig mogelijk opbrengst verliezen en waarbij tevens de aaltjesdoding 100% is. Daarna werd een serie van 8 cultivars getest om te zien of cultivars verschillend reageren. Daaruit kwam voor het eerst naar voren dat er t.a.v. opbrengstverlies gevoelige en ongevoelige cultivars zijn. In het afgelopen jaar werd nog met 4 cultivars gewerkt. Er werd in dit onderzoek ook getest of koken zonder voorwarmte en voorweken, direct na rooien een mogelijk oplossing was. Hiermee kan de procedure mogelijk worden vereenvoudigd. Er werden andere temperaturen gegeven 1, 2 en 3 uur bij 43 of 45°C aan dezelfde 4 cultivars als die hierboven worden genoemd. Kookschade werd hierbij waargenomen vanaf 3 uur 45°C. Dat bleek ook de behandeling te zijn die minstens gegeven moet worden om goede aaltjesdoding te krijgen. Warmwaterbehandeling zonder voorwarmte is nog geen toegelaten methode voor aaltjeszieke partijen. De opbrengstverliezen van deze behandeling zullen sterk afhangen van de temperaturen in de grond op het moment van rooien.
Het verhogen van de biogasopbrengst door middel van thermische drukhydrolyse van de voeding van de vergister; verwachte toename van opbrengst aan biogas t.o.v. toename van proceskosten
Kootstra, A.M.J. ; Visser, C.L.M. de - \ 2014
Lelystad : ACRRES - 24
biogas - gasproductie - bio-energie - voorbehandeling - warmtebehandeling - drukbehandeling - co-vergisting - kosten-batenanalyse - biobased economy - gas production - bioenergy - pretreatment - heat treatment - pressure treatment - co-fermentation - cost benefit analysis
Deze studie is opgezet om na te gaan of de extra opbrengst aan biogas opweegt tegen de extra kosten die moeten worden gemaakt om een Thermische Druk Hydrolyse (TDH) proces te koppelen aan een vergister. Er is berekend hoe hoog de te verwachten extra investeringskosten en operationele kosten zijn, en ook hoe hoog de te verwachten extra baten zijn. Bij de baten zijn verschillende scenario’s doorgerekend, uitgaande van verschillende niveaus van extra gasopbrengst, waarde van het geproduceerde methaan en warmteterugwinning. Van de beoogde scenario’s wordt alleen in het uiterste geval een klein positief resultaat behaald. De conclusie is dat het THD proces onder de bestudeerde omstandigheden als niet-rendabel moet worden beoordeeld. Hoewel de hoge operationele kosten (35%) zeker niet onbelangrijk zijn, zijn met name de kapitaalskosten te hoog.
Mogelijke doorbraak in genezing kastanjebloedingsziekte
Kuik, A.J. van; Lammeren, A.A.M. van - \ 2014
De Boomkwekerij 2014 (2014)7. - ISSN 0923-2443 - p. 22 - 23.
aesculus - houtachtige planten als sierplanten - plantenziekteverwekkende bacteriën - warmtebehandeling - bestrijdingsmethoden - landbouwkundig onderzoek - proeven - ornamental woody plants - plant pathogenic bacteria - heat treatment - control methods - agricultural research - trials
Hoewel er al een flink aantal preparaten en middelen is geprobeerd, moeten beheerders meestal lijdzaam toezien hoe hun paardenkastanjes door de kastanjebloedingsziekte wegkwijnen. Wellicht dat een nieuwe doorbraak in onderzoek door Wageningen UR daarin verandering brengt. De bacterie blijkt met een warmtebehandeling goed te doden.
Is kastanjebloedingsziekte te genezen?
Lammeren, A.A.M. van; Kuik, A.J. van - \ 2014
Tuin en Landschap 36 (2014)6. - ISSN 0165-3350 - p. 32 - 33.
aesculus - houtachtige planten als sierplanten - plantenziekteverwekkende bacteriën - warmtebehandeling - bestrijdingsmethoden - landbouwkundig onderzoek - proeven - ornamental woody plants - plant pathogenic bacteria - heat treatment - control methods - agricultural research - trials
Hoewel er al een flink aantal preparaten en middelen is geprobeerd, moeten beheerders meestal lijdzaam toezien hoe hun paardenkastanjes door de kastanjebloedingsziekte wegkwijnen. Wellicht dat een nieuwe doorbraak in onderzoek door Wageningen UR daarin verandering brengt. De bacterie blijkt met een warmtebehandeling goed te zijn te doden.
Warmwaterbehandeling (wwb) lelie effectief, maar niet altijd zonder schade
Slootweg, G. - \ 2013
BloembollenVisie 2013 (2013)285. - ISSN 1571-5558 - p. 18 - 19.
lelies - bloembollen - warmtebehandeling - rassen (planten) - cultivars - plantenziektebestrijding - proeven - lilies - ornamental bulbs - heat treatment - varieties - plant disease control - trials
Een warmwaterbehandeling kan bij lelies ingezet worden om een flink aantal ziekten en plagen te bestrijden. In 2011 werd al vastgestled dat Oriëntals geen schade ondervinden van kookbehandeling, mits er ook voor-en nabehandeld wordt. PPO ging na of dit ook geldt voor lelies uit de andere groepen.
Thermische voorbehandeling van rundveedrijfmest en maïsstro gevolgd door vergisting
Hoeksma, P. - \ 2013
Lelystad : WUR - ACRRES (PPO 563) - 21
bio-energie - co-vergisting - voorbehandeling - warmtebehandeling - rendement - biogas - digestaat - gasproductie - biobased economy - bioenergy - co-fermentation - pretreatment - heat treatment - returns - digestate - gas production
De doelstelling van dit onderzoek was: 1) Vaststellen op praktijkschaal van het effect van thermische behandeling middels TurboTec technologie op het economisch rendement van co-vergisting van rundveedrijfmest in combinatie met maïsstro; 2) Vaststellen van het effect van thermische behandeling op de samenstelling, bemestingswaarde en verwerkbaarheid van het digestaat.
Opschaling aangepaste CATT behandeling aardbei(moeder)planten tegen de plantparasitaire nematode Meloidogyne hapla : resultaten onderzoek 2012
Kruistum, G. van; Verschoor, J. ; Hoek, J. - \ 2013
Lelystad : PPO AGV (PPO 3250232400) - 19
aardbeien - plantmateriaal - vermeerderingsmateriaal - plantenparasitaire nematoden - pratylenchus penetrans - meloidogyne hapla - warmtebehandeling - gewasbescherming - kleinfruit - nematodenbestrijding - strawberries - planting stock - propagation materials - plant parasitic nematodes - heat treatment - plant protection - small fruits - nematode control
In 2012 zijn 16 partijtjes aardbeiplanten van verschillende rassen, herkomst en planttypen behandeld volgens de standaardmethode bij 35 °C en de nieuwe methode: korter behandelen gedurende 40 uur en de temperatuur in de 2e fase opvoeren naar 40 °C. Na behandeling en een korte opslagperiode zijn de partijtjes incl. onbehandeld op 8 mei 2012 uitgeplant. De nieuwe CATT behandeling bleek even succesvol te zijn als de standaardmethode. Er werden geen verschillen tussen de rassen (Darselect, Elsanta, Figaro, Korona, Sonata, Symphony en Honeoye) vastgesteld. In een sub-proef is gebleken dat het tijdstip van een CATT behandeling flexibel, ook direct na laat rooien in januari, kan worden uitgevoerd. Vastgesteld is dat de enkele, na een aangepaste CATT behandeling, nog in de (moeder)planten aanwezige wortelknobbelaaltjes niet voldoende vitaal zijn om tot reproductie en vermeerdering te komen, zelfs niet na een groeiseizoen. Ook de dochterplanten bleven na de aangepaste CATT behandeling vrij van besmetting.
Warmwaterbehandeling lelie: effect van verlaagde voor- en natemperatuur bij Oriëntals en verhoogde kooktemperatuur bij Longiflorum-, LA- en OT- hybriden
Slootweg, G. ; Aanholt, J.T.M. van - \ 2013
Lisse : Praktijkonderzoek Plant en Omgeving BBF - 23
bloembollen - lelies - heetwaterbehandeling - temperatuur - effecten - warmtebehandeling - landbouwkundig onderzoek - ornamental bulbs - lilies - hot water treatment - temperature - effects - heat treatment - agricultural research
In de teelt van Oriëntals komen veel partij- overdraagbare ziekten en plagen voor, zoals het wortellesie - aaltje, bladaaltjes en bollenmijten, maar ook bacteriën en schimmels. In eerder onderzoek van PPO is duidelijk geworden dat Oriëntals heel goed een warm waterbehandeling bij 41°C in alleen water kunnen verdragen mits deze wordt toegepast in combinatie met 2 dagen voor - en nawarmte bij 20°C. Het is niet bekend hoe lelies uit de groep van de Longiflorum, LA - en OT - hybriden reageren op een warmwaterbehandelin g bij 41°C in combinatie met voor - en nawarmte. Omdat niet alle telers de mogelijkheid hebben voor - en nawarmte te geven bij 20°C is ook onderzocht of bewaring bij lagere ‘schuur’ temperaturen voor en na de warmwaterbehandeling een w armwaterbehandeling bij 41 °C zonder schade mogelijk maakt .
CATT warmtebehandeling aardbei(moer)planten Succesvol tegen aardbeimijt, maar aaltjes zijn er ook niet blij mee
Kruistum, G. van; Hoek, H. ; Verschoor, J.A. - \ 2012
aardbeien - fruitgewassen - fruitteelt - gewasbescherming - ziektebestrijdende teeltmaatregelen - warmtebehandeling - plagen - uitrusting voor plagenbestrijding - strawberries - fruit crops - fruit growing - plant protection - cultural control - heat treatment - pests - pest control equipment
CATT (Controlled Atmosphere Temperature Treatment) behandeling van aardbei(moer)planten is door PPO Lelystad en Food & Biobased Research (FBR) Wageningen in samenwerking met Plantum ontwikkeld ter bestrijding van aardbeimijt.
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