Physico-chemical properties of extrudates and their relation to lipid incorporation and lipid oxidation

Extrusion cooking is a key technology in food processing used to produce a wide range of products and extrudates such as cereals, cornflakes and snacks. In addition, extrusion plays a central role in the production of animal food. The oxidation of lipids in extrudates is problematic as this is associated with considerable quality deteriorations. Most conspicuous is the rancid off-flavour. Lipids can interact differently with the matrix in an extrudate and be incorporated into the matrix to different degrees. The aim of this thesis is to understand the relationship between lipid oxidation and the structural properties of the extrudate and the interaction of lipids with the matrix in order to create a basis for reducing oxidation processes in extrudates. A fractionated lipid extraction was developed, which enabled the characterization and investigation of oxidation processes in different regions of an extrudate. Three fractions were obtained which can be assigned to surface lipids, lipids adsorbing on the inner lamellas of the extrudate and matrix-incorporated lipids. Matrix-incorporated lipids are finely dispersed in the amylose-amylopectin matrix and can only be extracted after an amylase treatment which causes a degradation of the starch matrix. It was shown that the water content of the extrusion mass influences the microstructure and the expansion. The higher the proportion of lipids incorporated in the matrix, the higher is the oxidative stability of the extrudate. Furthermore, the effects of a lipid-based coating on lipid oxidation in extrudates with different microstructures were investigated. Coating with MCT oil inhibited lipid oxidation in corn extrudates beyond the effects of dilution. This effect was particularly pronounced in porous extrudates, as it could be shown that the coating adheres mainly to the surface, migrates only slightly into the core and closes micro cracks. The formation of radicals in model systems and extrudates was investigated by electron paramagnetic resonance spectroscopy. The extrusion process formed stable protein radicals and lipid radical concentration increased simultaneously with the formation of hydroperoxides in the model system. In addition, it was demonstrated that the reaction rate of lipid oxidation is influenced by the matrix. However, the logarithmic plot of the reaction rate, based on the increase of hydroperoxide formation after the lag phase, led to an overestimation of lipid oxidation at room temperature and requires the application of more complex models. Within this thesis, different mechanisms and matrix effects could be identified that influence lipid oxidation during extrusion and storage. They provide a basis for the derivation of factors to increase the oxidative stability of extrudates

Interlaboratory study on lipid oxidation during accelerated storage trials with rapeseed and sunflower oil analyzed by conjugated dienes as primary oxidation products

11 Páginas.-- 5 Figuras.-- 2 Tablas.-- Material suplementarioAccelerated storage tests are frequently used to assess the oxidative stability of foods and related systems due to its reproducibility. Various methods and experimental conditions are used to measure lipid oxidation. Differences between laboratories make it necessary to determine the repeatability and reproducibility of oxidation tests performed under the same conditions. The objective of the present interlaboratory study was to evaluate the outcome of a storage test for two different bulk oils, sunflower oil (SFO) and rapeseed oil (RSO), during a period of 9 weeks at 20°C, 30°C, 40°C, and 60°C. Sixteen laboratories were provided with bottled oils and conducted the storage tests according to a detailed protocol. Lipid oxidation was monitored by the formation of conjugated dienes (CD) and the activation energy (Ea) was determined for comparative purposes and statistically evaluated. An increase in CD formation was observed for both oils when the storage temperature was increased in all laboratories. The Ea,1 ranged from 47.9 to 73.3 kJ mol−1 in RSO and from 27.8 to 62.6 kJ mol−1 in SFO, with average values of 58.2 and 46.8 kJ mol−1, respectively. The reproducibility coefficients were 10.9% and 18.2% for RSO and SFO, respectively. Practical applications: In order to compare results on oxidative stability of foods derived from different studies, the reproducibility of storage tests and methods employed to evaluate the oxidation level should be considered. This study provides fundamental data on the reproducibility of lipid oxidation under accelerated storage conditions and defines important parameters to be considered for the conduction of experiments.Open access funding enabled and organized by Projekt DEAL. We thank Brökelmann + Co – Oelmühle GmbH + Co for the donation of the vegetable oils. The authors gratefully acknowledge Lina Stuthmann from the Food Technology Division, Kiel University and Inge Holmberg from the National Food Institute, Technical University of Denmark for their skillful help.Peer reviewe

Recent Advances in Dietary Sources, Health Benefits, Emerging Encapsulation Methods, Food Fortification, and New Sensor-Based Monitoring of Vitamin B₁₂: A Critical Review

In this overview, the latest achievements in dietary origins, absorption mechanism, bioavailability assay, health advantages, cutting-edge encapsulation techniques, fortification approaches, and innovative highly sensitive sensor-based detection methods of vitamin B12 (VB12) were addressed. The cobalt-centered vitamin B is mainly found in animal products, posing challenges for strict vegetarians and vegans. Its bioavailability is highly influenced by intrinsic factor, absorption in the ileum, and liver reabsorption. VB12 mainly contributes to blood cell synthesis, cognitive function, and cardiovascular health, and potentially reduces anemia and optic neuropathy. Microencapsulation techniques improve the stability and controlled release of VB12. Co-microencapsulation of VB12 with other vitamins and bioactive compounds enhances bioavailability and controlled release, providing versatile initiatives for improving bio-functionality. Nanotechnology, including nanovesicles, nanoemulsions, and nanoparticles can enhance the delivery, stability, and bioavailability of VB12 in diverse applications, ranging from antimicrobial agents to skincare and oral insulin delivery. Staple food fortification with encapsulated and free VB12 emerges as a prominent strategy to combat deficiency and promote nutritional value. Biosensing technologies, such as electrochemical and optical biosensors, offer rapid, portable, and sensitive VB12 assessment. Carbon dot-based fluorescent nanosensors, nanocluster-based fluorescent probes, and electrochemical sensors show promise for precise detection, especially in pharmaceutical and biomedical applications