Browsing by Subject "Coloring food"

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"Coloring foods" - development of a suitable cultivation and harvesting system for florets of safflower (Carthamus tinctorius L.)
(2021) Steberl, Kathrin; Graeff-Hönninger, Simone
‘Natural colorants’ usually refer to pigments that are obtained from renewable raw materials such as plants. After the invention of the first synthetic dye in the 19th century, the demand for natural colorants decreased. Studies in recent years, which for example, report on the environmentally harmful and toxic effects of artificial colorants, have led, among other things, to a ban on some synthetic colorants in the EU and to a steady increase in demand for natural colorants again. Safflower (Carthamus tinctorius L.) is known as a colorant-providing plant because of the red (carthamin) and yellow colorants (carthamidin) contained in the florets. Carthamidin is an interesting colorant for the food industry due to its water-soluble properties. Due to the increasing demand for ‘Coloring Foods’, the already existing cultivation area of safflower, which is mainly in Turkey, India or China, will not be sufficient in the future. There are many open questions regarding the possible cultivation of safflower in Germany or Europe. So far, there are no recommendations for the cultivation and harvesting of safflower to obtain the florets. The manual harvesting practiced in the previous cultivation areas is not an economically viable option in Europe. For the production of safflower florets there are also many uncertainties regarding the potential yield. The given challenges for the cultivation of safflower as a food colorant were dealt with in the present dissertation and resulted in the following objectives: • to examine the effect of different cultivars, row spacing, sowing densities and harvest dates on yield parameters for safflower floret production under European conditions, • to investigate a mechanical harvest with a combine harvester with regard to quality parameters, threshing and carthamidin yield, • to evaluate and modify the DSSAT CROPGRO safflower model to simulate floret yield under European conditions. For this purpose, field trials were conducted in 2017 and 2018. Based on these experiments, three scientific publications have been produced, which form the main part of this dissertation. Publication I investigated different cultivation parameters, such as two different cultivars, row spacing and sowing densities and their effect on the number of branches, capitula, floret yield, carthamidin content and yield at five different harvest dates. In this respect, it was shown that a lower sowing density of 40 plants m-² produced a higher number of branches, capitula and higher yields of florets and carthamidin. The Chinese cultivar achieved the highest carthamidin yields on the third harvest date in 2018 with 34.14 kg ha^-1. Publication II evaluated the differences of two cultivars, three threshing parameter settings at five harvest dates for their threshing yield, dry matter content, carthamidin content and yield. The highest carthamidin yields (19 kg ha^-1) were achieved on the last two harvest dates with the Chinese cultivar and the threshing parameter setting P3. Publication III focused on the modification of the plant growth model CROPGRO for safflower to simulate seed yield and the integration of a new subroutine to simulate the floret yield of two safflower cultivars in two years. It was shown that key variables, such as specific leaf area simulation, could be improved by modifying the model (RMSE: 0.82–24.14 cm^-2 g^-1 and d-index: 0.73–0.78). By analogy with a variable already integrated into the model (pod harvest index) and the introduction of new variables (PETALX, HIPIN, HIPMX), the floret yield could be simulated for the first time (RMSE: 97.24 kg ha^-1 and d-index: 0.79). Both the modification and the new approach have improved the simulation of growth as well as seed and floret yield. The cultivation of ‘Coloring Foods’ could bring benefits to farmers. In addition to the expansion of crop rotation, the biodiversity and the currently much discussed image of agriculture could be improved. On the one hand, the present dissertation could show that the cultivation of safflower is possible in Germany or Europe. Furthermore, a suitable cultivation and harvesting system could be determined. This could help to reduce the current limitations for the production of florets in Germany and Europe, not only for safflower but also for other ‘Coloring Foods’. As a result, cultivation could be made more attractive and more economical in order to be able to meet the increasing demand in the future on a regional basis.
High molecular weight λ-carrageenan improves the color stability of phycocyanin by associative interactions
(2022) Buecker, Stephan; Grossmann, Lutz; Loeffler, Myriam; Leeb, Elena; Weiss, Jochen
Phycocyanin is a protein-chromophore structure present in Arthrospira platensis commonly used as a blue-colorant in food. Color losses of phycocyanin can be reduced by electrostatic complexation with λ-carrageenan. The aim of this study was to investigate the effect of molecular weight (MW) of λ-carrageenan on the color stabilization of electrostatic complexes formed with phycocyanin and λ-carrageenan. Samples were heated to 70 or 90°C at pH 3.0 and stored at 25°C for 14 days. The MW of λ-carrageenan was reduced by ultrasound treatments for 15, 30, 60, and 90 min. Prolonged ultrasonication had a pronounced effect on the Mw, which decreased from 2,341 to 228 kDa (0–90 min). Complexes prepared with low MW λ-carrageenan showed greater color changes compared to complexes prepared with high MW λ-carrageenan. The MW had no visible effect on color stability on day 0, but green/yellow shifts were observed during storage and after heating to 70°C. Medium MW showed less color stabilization effects compared to low MW when heated to 70°C. Moreover, for solutions prepared with ultrasonicated λ-carrageenan, significant hue shifts toward green/yellow, and precipitation were observed after a heat treatment at 90°C. In addition, the sizes of the complexes were significantly reduced (646–102 nm) by using ultrasonicated λ-carrageenan, except for the lowest MW λ-carrageenan when heated to 90°C. Overall, these findings demonstrated that decreasing the MW of λC had adverse effects on the color stability of PC:λC complexes heated to 70 and 90°C.
Improving the colloidal stability of pectin–phycocyanin complexes by increasing the mixing ratio
(2024) Buecker, Stephan; Gibis, Monika; Bartmann, Laura; Bussler, Sara; Weiss, Jochen
In the food industry, the phycobiliprotein phycocyanin acts as a color pigment or the functional part of the superfood “Spirulina.” It is industrially extracted from Arthrospira platensis. Current scientific research is focusing on finding complex partners with the potential to stabilize phycocyanin against its sensitivity toward heating and pH changes. Less attention is paid to the factors that influence complexation. This study focuses on the mixing ratio of phycocyanin with pectin. Phycocyanin concentration was fixed, and the mixing ratios ranged from 0.67 to 2.50 (pectin:phycocyanin). All samples were analyzed for their color, size, microscopic structure, zeta potential, and sedimentation stability before and after heating at 85°C. It was found that increasing the pectin content fostered the initial interactions with the protein and chromophore, resulting in a color shift from blue to turquoise. The size of the complexes decreased from several micrometers to nanometers with increasing pectin concentration. Those smaller complexes that were formed at a mixing ratio of 2.5 showed a higher colloidal stability over a period of ∼2 days. It is suggested that at a low mixing ratio (0.67), phycocyanin cannot be completely entrapped within the complexes and attaches to the complex surface as well. This results in aggregation and precipitation of the complexes upon heating. With increasing aggregation and consequently size as well as density of the complexes, sedimentation was accelerated.