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result(s) for
"Greiner, Ralf"
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Edible solid lipid nanoparticles (SLN) as carrier system for antioxidants of different lipophilicity
by
Mayer-Miebach, Esther
,
Greiner, Ralf
,
Oehlke, Kathleen
in
Acids
,
Antioxidants
,
Antioxidants (Nutrients)
2017
Ferulic acid (FA) and tocopherol (Toc) loaded solid lipid nanoparticles (SLN) were prepared by a hot homogenisation method. The particle size distribution, zeta potential and melting behaviour of the SLN as well as the stability, encapsulation efficiency and radical scavenging activity of FA and Toc in the SLN were analysed. The different formulations containing up to 2.8 mg g-1 of FA or Toc were stable during at least 15 weeks of storage at room temperature. Despite partial degradation and / or release of FA and Toc during storage, significant radical scavenging activity was maintained. DSC measurements and radical scavenging tests after different time periods revealed that the re-structuring of the lipid matrix was connected to the enhanced antioxidant activity of Toc but did not affect the activity of FA.
Journal Article
A 1-phytase type III effector interferes with plant hormone signaling
by
Balcke, Gerd
,
Tissier, Alain
,
Nagel, Oliver
in
6-Phytase - genetics
,
6-Phytase - metabolism
,
631/449/2169/2673
2017
Most Gram-negative phytopathogenic bacteria inject type III effector (T3E) proteins into plant cells to manipulate signaling pathways to the pathogen’s benefit. In resistant plants, specialized immune receptors recognize single T3Es or their biochemical activities, thus halting pathogen ingress. However, molecular function and mode of recognition for most T3Es remains elusive. Here, we show that the
Xanthomonas
T3E XopH possesses phytase activity, i.e., dephosphorylates phytate (
myo
-inositol-
hexakis
phosphate, InsP
6
), the major phosphate storage compound in plants, which is also involved in pathogen defense. A combination of biochemical approaches, including a new NMR-based method to discriminate inositol polyphosphate enantiomers, identifies XopH as a naturally occurring 1-phytase that dephosphorylates InsP
6
at C1. Infection of
Nicotiana benthamiana
and pepper by
Xanthomonas
results in a XopH-dependent conversion of InsP
6
to InsP
5.
1-phytase activity is required for XopH-mediated immunity of plants carrying the
Bs7
resistance gene, and for induction of jasmonate- and ethylene-responsive genes in
N. benthamiana
.
Plant pathogens translocate type III effector (T3E) proteins that may be recognized by plants to trigger immunity. Here, the authors show that the
Xanthomonas
T3E XopH possesses a novel 1-phytase activity that is required for XopH-mediated immunity of plants carrying the
Bs7
resistance gene.
Journal Article
Efficient extracellular production of α-amylase in Bacillus subtilis under the influence of xylose-inducible promoter
by
Abdelmigid, Hala Mohamed
,
Greiner, Ralf
,
Amjad, Quratulain
in
bacillus expression systems
,
catabolic repression
,
recombinant amylase
2025
This study focuses on the development of a xylose-inducible system to produce recombinant α-amylase from the bacterium Thermoactinomyces vulgaris 94-2A (amyTV) in the Bacillus expression system. To achieve this, a gene cassette was constructed using pWH1520 shuttle vector, containing a PxylA promoter comprising glucose box and amyTV gene. The cassette was initially cloned in Escherichia coli for replication and subsequently, introduced into the Bacillus subtilis (GSB26) for expression. To optimize the secretion of α-amylase, different concentrations of xylose were used as inducers. It was found that the maximum amylase activity was achieved when 2% xylose was used as the inducer. Furthermore, using glucose alone and in combination with xylose as inducers indicated that glucose acted as a catabolic repressor for amyTV expression. Moreover, protein was efficiently secreted and did not accumulate in the cellular fractions, even at high expression levels.
Journal Article
Influence of Different Nanomaterials on Growth and Mycotoxin Production of Penicillium verrucosum
by
Kotzybik, Kathrin
,
Gräf, Volker
,
Geisen, Rolf
in
Additives
,
Agglomerates
,
Anthropogenic factors
2016
Nanoparticles are ubiquitous in the environment. They originate from anthropogenic or natural sources or they are intentionally produced for different purposes. There exist manifold applications of nanoparticles in modern life leading unavoidably to a confrontation and interaction between nanomaterial and living organisms. Based on their wide distribution tending to increase steadily, the influence of particles based on silica and silver, exhibiting nominal sizes between 0.65 nm and 200 nm, on the physiology of the mycotoxigenic filamentous fungus Penicillium verrucosum was analyzed. The applied concentration and time-point, the size and the chemical composition of the particles was shown to have a strong influence on growth and mycotoxin biosynthesis. On microscopic scale it could be shown that silver nanoparticles attach to the mycelial surface. Moreover, silver nanoparticles with 0.65 nm and 5 nm in size were shown to internalize within the cell, form agglomerates in the cytoplasm and associate to cell organelles.
Journal Article
Advancements in Non-Thermal Processing Technologies for Enhancing Safety and Quality of Infant and Baby Food Products: A Review
2024
Breast milk is the main source of nutrition during early life, but both infant formulas (Ifs; up to 12 months) and baby foods (BFs; up to 3 years) are also important for providing essential nutrients. The infant food industry rigorously controls for potential physical, biological, and chemical hazards. Although thermal treatments are commonly used to ensure food safety in IFs and BFs, they can negatively affect sensory qualities, reduce thermosensitive nutrients, and lead to chemical contaminant formation. To address these challenges, non-thermal processing technologies such as high-pressure processing, pulsed electric fields, radio frequency, and ultrasound offer efficient pathogen destruction similar to traditional thermal methods, while reducing the production of key process-induced toxicants such as furan and 5-hydroxymethyl-2-furfural (HMF). These alternative thermal processes aim to overcome the drawbacks of traditional methods while retaining their advantages. This review paper highlights the growing global demand for healthy, sustainable foods, driving food manufacturers to adopt innovative and efficient processing techniques for both IFs and BFs. Based on various studies reviewed for this work, the application of these novel technologies appears to reduce thermal processing intensity, resulting in products with enhanced sensory properties, comparable shelf life, and improved visual appeal compared to conventionally processed products.
Journal Article
Emulsion-based systems for delivery of food active compounds : formation, application, health and safety
A comprehensive text that offers a review of the delivery of food active compounds through emulsion-based systems Emulsion-based Systems for Delivery of Food Active Compounds is a comprehensive recourse that reviews the principles of emulsion-based systems formation, examines their characterization and explores their effective application as.
Bacterial Communities Associated with the Cycling of Non-Starch Polysaccharides and Phytate in Aquaponics Systems
by
Al-Mahrouqi, Nahad
,
Greiner, Ralf
,
Menezes-Blackburn, Daniel
in
amylases
,
Aquaculture
,
Aquaponics
2021
Aquaponics are efficient systems that associate aquatic organisms’ production and plants by recirculating water and nutrients between aquaculture and hydroponic tanks. In this study, we characterised the bacterial communities in the freshwater aquaponics system that can mineralise polysaccharides and phytate by producing carbohydrate-degrading enzymes and phytases, by 16S rRNA gene sequencing and in vitro culture techniques. Around 20% of the operational taxonomic units (zOTUs) identified were previously reported to carry fibre-degrading enzyme putative genes, namely β-glucanase (1%), xylanase (5%), or cellulases (17%). Ten % of the zOTUs were previously reported to carry putative genes of phytases with different catalytic mechanisms, namely β-propeller (6%), histidine acid phytases (3%), and protein tyrosine phytase (<1%). Thirty-eight morphologically different bacteria were isolated from biofilms accumulated in fish and plant compartments, and identified to belong to the Bacilli class. Among these, 7 could produce xylanase, 8 produced β-glucanase, 14 produced cellulase, and 11 isolates could secrete amylases. In addition, Staphylococcus sp. and Rossellomorea sp. could produce consistent extracellular phytate-degrading activity. The PCR amplification of β-propeller genes both in environmental samples and in the isolates obtained showed that this is the most ecologically relevant phytase type in the aquaponics systems used. In summary, the aquaponics system is abundant with bacteria carrying enzymes responsible for plant-nutrient mineralisation.
Journal Article
Effect of Traditional Household Processes on Iron, Zinc and Copper Bioaccessibility in Black Bean (Phaseolus vulgaris L.)
by
Feitosa, Sabrina
,
Greiner, Ralf
,
Almeida, Deusdélia T.
in
Anemia
,
anti-nutrients
,
antinutritional factors
2018
Micronutrient deficiencies are a major public health problem. Beans are an important plant-based source of iron, zinc and copper, but their absorption is reduced in the presence of anti-nutrients such as phytates, polyphenols and tannins. Soaking and discarding the soaking water before cooking is unanimously recommended, but this can result in mineral loss. Data on the consequences for mineral bioaccessibility is still limited. This study aimed to evaluate iron, zinc and copper bioaccessibility in black beans cooked (regular pan, pressure cooker) with and without the soaking water. For that, three batches of black beans were investigated in triplicate, each split in nine parts (raw grains and four different household processes in duplicate) and analyzed by applying the quarter technique, resulting in a grand total of 164 samples. Minerals were quantified by ICP-MS (inductively coupled plasma mass spectrometry), myo-inositol phosphates (InsP5, InsP6) by HPLC (high-performance liquid chromatography) ion-pair chromatography, total polyphenols using Folin-Denis reagent and condensed tannins using Vanillin assay. Mineral bioaccessibility was determined by in vitro digestion and dialysis. All treatments resulted in a statistically significant reduction of total polyphenols (30%) and condensed tannins (20%). Only when discarding the soaking water a loss of iron (6%) and copper (30%) was observed, and InsP6 was slightly decreased (7%) in one treatment. The bioaccessibility of iron and zinc were low (about 0.2% iron and 35% zinc), but copper presented high bioaccessibility (about 70%). Cooking beans under pressure without discarding the soaking water resulted in the highest bioaccessibility levels among all household procedures. Discarding the soaking water before cooking did not improve the nutritional quality of the beans.
Journal Article
Updated safety evaluation of the food enzyme phospholipase A2 from the genetically modified Trichoderma reesei strain RF8793
by
Solano, Marize
,
Van Loveren, Henk
,
Gadermaier, Gabriele
in
Body weight
,
EC 3.1.1.4
,
EFSA‐Q‐2014‐00411
2025
The food enzyme phospholipase A2 (phosphatidylcholine 2‐acylhydrolase; EC 3.1.1.4) is produced with the genetically modified Trichoderma reesei strain RF8793 by AB Enzymes GmbH. In a previous opinion, the total organic solids (TOS) values could not be calculated, which led to the inability to establish the representativeness of the batch used for toxicological examination and to calculate the dietary exposure. In this assessment, EFSA completes the safety evaluation of this food enzyme by taking into account the chemical compositional data from new food enzyme batches. The food enzyme is intended to be used in three food manufacturing processes. Dietary exposure to the food enzyme–TOS was estimated to be up to 0.008 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90‐day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 1000 mg TOS/kg bw per day, the highest dose tested, which, when compared with the estimated dietary exposure, results in a margin of exposure of at least 125,000. Based on the new data and the previous evaluation, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.
Journal Article