Stability of Natural Colorants of Plant Origin

In recent years, there have been studies that show a correlation between the hyperactivity of children and use of artificial food additives, including colorants. This has, in part, led to preference of natural products over products with artificial additives. Consumers have also become more aware of health issues. Natural food colorants have many bioactive functions, mainly vitamin A activity of carotenoids and antioxidativity, and therefore they could be more easily accepted by the consumers. However, natural colorant compounds are usually unstable, which restricts their usage. Microencapsulation could be one way to enhance the stability of natural colorant compounds and thus enable better usage for them as food colorants. Microencapsulation is a term used for processes in which the active material is totally enveloped in a coating or capsule, and thus it is separated and protected from the surrounding environment. In addition to protection by the capsule, microencapsulation can also be used to modify solubility and other properties of the encapsulated material, for example, to incorporate fat-soluble compounds into aqueous matrices. The aim of this thesis work was to study the stability of two natural pigments, lutein (carotenoid) and betanin (betalain), and to determine possible ways to enhance their stability with different microencapsulation techniques. Another aim was the extraction of pigments without the use of organic solvents and the development of previously used extraction methods. Stability of pigments in microencapsulated pigment preparations and model foods containing these were studied by measuring the pigment content after storage in different conditions. Preliminary studies on the bioavailability of microencapsulated pigments and sensory evaluation for consumer acceptance of model foods containing microencapsulated pigments were also carried out. Enzyme-assisted oil extraction was used to extract lutein from marigold (Tagetes erecta) flower without organic solvents, and the yield was comparable to solvent extraction of lutein from the same flowers. The effects of temperature, extraction time, and beet:water ratio on extraction efficiency of betanin from red beet (Beta vulgaris) were studied and the optimal conditions for maximum yield and maximum betanin concentration were determined. In both cases, extraction at 40 °C was better than extraction at 80 °C and the extraction for five minutes was as efficient as 15 or 30 minutes. For maximum betanin yield, the beet:water ratio of 1:2 was better, with possibly repeated extraction, but for maximum betanin concentration, a ratio of 1:1 was better. Lutein was incorporated into oil-in-water (o/w) emulsions with a polar oil fraction from oat (Avena sativa) as an emulsifier and mixtures of guar gum and xanthan gum or locust bean gum and xanthan gum as stabilizers to retard creaming. The stability of lutein in these emulsions was quite good, with 77 to 91 percent of lutein being left after storage in the dark at 20 to 22°C for 10 weeks whereas in spray dried emulsions the retention of lutein was 67 to 75 percent. The retention of lutein in oil was also good at 85 percent. Betanin was incorporated into the inner w1 water phase of a water1-in-oil-inwater2 (w1/o/w2) double emulsion with primary w1/o emulsion droplet size of 0.34 μm and secondary w1/o/w2 emulsion droplet size of 5.5 μm and encapsulation efficiency of betanin of 89 percent. In vitro intestinal lipid digestion was performed on the double emulsion, and during the first two hours, coalescence of the inner water phase droplets was observed, and the sizes of the double emulsion droplets increased quickly because of aggregation. This period also corresponded to gradual release of betanin, with a final release of 35 percent. The double emulsion structure was retained throughout the three-hour experiment. Betanin was also spray dried and incorporated into model juices with different pH and dry matter content. Model juices were stored in the dark at -20, 4, 20–24 or 60 °C (accelerated test) for several months. Betanin degraded quite rapidly in all of the samples and higher temperature and a lower pH accelerated degradation. Stability of betanin was much better in the spray dried powder, with practically no degradation during six months of storage in the dark at 20 to 24 °C and good stability also for six months in the dark at 60 °C with 60 percent retention. Consumer acceptance of model juices colored with spray dried betanin was compared with similar model juices colored with anthocyanins or beet extract. Consumers preferred beet extract and anthocyanin colored model juices over juices colored with spray dried betanin. However, spray dried betanin did not impart any off-odors or off-flavors into the model juices contrary to the beet extract. In conclusion, this thesis describes novel solvent-free extraction and encapsulation processes for lutein and betanin from plant sources. Lutein showed good stability in oil and in o/w emulsions, but slightly inferior in spray dried emulsions. In vitro intestinal lipid digestion showed a good stability of w1/o/w2 double emulsion and quite high retention of betanin during digestion. Consumer acceptance of model juices colored with spray dried betanin was not as good as model juices colored with anthocyanins, but addition of betanin to real berry juice could produce better results with mixture of added betanin and natural berry anthocyanins could produce a more acceptable color. Overall, further studies are needed to obtain natural colorants with good stability for the use in food products.Siirretty Doriast

Encapsulation of betalain into w​/o​/w double emulsion and release during in vitro intestinal lipid digestion

A water-in-oil-in-water (w/o/w) double emulsion was prepared with water extract of red beet as the inner water phase, rapeseed oil as the oil phase and polysaccharides solution as the outer water phase. Polyglycerol polyricinoleate and polar lipid fraction from oat were used as emulsifiers for primary water-in-oil (w/o) emulsion and secondary w/o/w emulsion, respectively. Their mean droplet sizes were approximately 0.34 μm and 5.5 μm, respectively. The double emulsion showed a high encapsulation efficiency of 89.1% and had a pink coloration due to encapsulated betalain. The double emulsion was subjected to in vitro intestinal lipid digestion and the evolution of structures and release of betalain were monitored. During the first 2 h of digestion, coalescence of the inner water phase droplets was observed, and the sizes of the double emulsion droplets increased quickly because of aggregation. This period also corresponded to release of betalain, reaching about 35%. After 3 h of digestion, no more release was measured, corresponding to no further increase in droplet sizes. In contrast, the encapsulation efficiency and droplet sizes were not affected after 3 h in the same digestion conditions but without the bile salts and lipase, showing they were responsible for the release.</p

Suberin of Potato (Solanum tuberosum Var. Nikola): Comparison of the Effect of Cutinase CcCut1 with Chemical Depolymerization

Chemical and enzymatic depolymerizations of suberin isolated from potato peel (Solanum tuberosum var. Nikola) were performed under various conditions. Enzymatic hydrolysis with cutinase CcCut1 and chemical methanolysis with NaOMe of suberin yielded monomeric fragments, which were identified as TMS derivatives with GC-MS and GC-FID. The solid, hydrolysis-resistant residues were analyzed with solid state (13)C CPMAS NMR, FT-IR, and microscopic methods. Methanolysis released more CHCl(13)-soluble, material than the cutinase treatment when determined gravimetrically. Interestingly, cutinase-catalyzed hydrolysis produced higher proportions of aliphatic monomers than hydrolysis with the NaOMe procedure when analyzed by GC in the form of TMS derivatives. Monomers released by the two methods were mainly alpha,omega-dioic acids and omega-hydroxy acids, but the ratios of the detected monomers were different, at 40.0 and 32.7% for methanolysis and 64.6 and 8.2% for cutinase, respectively. Thus, cutinase CcCut1 showed higher activity toward ester bonds of alpha,omega-dioic acids than toward the bonds of omega-hydroxy acids. The most abundant monomeric compounds were octadec-9-ene-1,18-dioic acid and 18-hydroxyoctadec-9-enoic acid, which accounted for ca. 37 and 28% of all monomers, respectively. The results of the analyses of the chemical and enzymatic hydrolysis products were supported by the spectroscopic analyses with FT-IR and CPMAS (13)C NMR together with the analysis of the microstructures of the hydrolysis residues by light and confocal microscopy

Elintarvikevalmistaja kuluttajan ja värimarkkinan välissä

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Enzyme-Assisted Oil Extraction of Lutein from Marigold (Tagetes erecta) Flowers and Stability of Lutein during Storage

Marigold (Tagetes erecta) flowers are a rich source of lutein pigment, which is usually extracted with organic solvents. In this study, lutein was extracted from marigold flowers with enzyme-assisted oil extraction without using organic solvents. Extraction produced oil that contained 0.36 mg/ml lutein (present as lutein esters but calculated as free lutein), and the yield was comparable to solvent extraction. The oil containing lutein was used to produce oil-in-water emulsions with different polysaccharide mixtures as stabilizers and some emulsions were also spray dried. Wet emulsions, dry emulsions, and oil containing lutein were stored in the dark at 20&ndash;22&deg;C for 10 weeks, and the amount of lutein esters was monitored during storage. Stability of lutein was good in oil (85% of the initial amount) and in wet emulsions (77&ndash;91%) but slightly worse in spray-dried emulsions (67&ndash;75%). Enzyme-assisted oil extraction of lutein from marigold flowers is a potential alternative to solvent extraction with comparable efficiency. In addition, there are no solvent residues in the lutein preparation. Preliminary storage tests showed good stability of lutein in oil or in emulsions stored in the dark at room temperature, and these preparations could be used in different food products.</p

Enzyme-assisted oil extraction of lutein from marigold (Tagetes erecta) flowers and stability of lutein during storage

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Consumer acceptance and stability of spary dried betanin in model juices

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Properties of an oil in water (o/w) emulsions made using polar lipid fraction from oats (Avena sativa)

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