| 1. |
- Bengtsson, Anton, 1979, et al.
(författare)
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Effects of thermal processing on the in vitro bioaccessibility and microstructure of beta-carotene in orange-fleshed sweet potato
- 2010
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Ingår i: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 58:20, s. 11090-11096
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Tidskriftsartikel (refereegranskat)abstract
- The effects of different preparation methods on the bioaccessibility of beta-carotene in orange-fleshed sweet potato (OFSP), an important food crop in sub-Saharan Africa, have been evaluated using an in vitro digestion procedure. The preparation methods included, on fresh roots, boiling followed by pureeing and oil addition (BOL) and homogenization followed by boiling and oil addition (HOM); on milled flour from freeze-dried fresh roots, cooking of porridge followed by oil addition (POA) and oil addition to flour followed by cooking of porridge (POB). The retention of all-trans-beta-carotene ranged from 58% (POB) to 72% (BOL). The presence of oil during heating resulted in a significantly higher formation of 13-cis-beta-carotene for the POB-treated samples than for the other samples. The efficiency of micellarization of all-trans-beta-carotene after in vitro digestion was 50% (HOM), 48% (POB), 31% (POA), and 16% (BOL). Brightfield microscopy of the cell structure after processing and in vitro digestion showed a high degree of cell-wall rupture for the HOM-treated samples, whereas cells appeared intact for the BOL samples. Also, coherent anti-Stokes Raman scattering (CARS) microscopy showed smaller beta-carotene bodies residing in the HOM samples than in the BOL samples after digestion. These results suggest that the in vitro bioaccessibility of beta-carotene in an OFSP meal can be improved by processing methods that promote cell-wall rupture.
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| 2. |
- Brackmann, Christian, 1973, et al.
(författare)
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Visualization of β-carotene and starch granules in plant cells using CARS and SHG microscopy
- 2010
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Ingår i: Journal of Raman Spectroscopy. - : Wiley. - 0377-0486 .- 1097-4555. ; 42:4, s. 586-592
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Tidskriftsartikel (refereegranskat)abstract
- Information on the content and bioavailability of provitamin A carotenoids, such as beta-carotene, in plant foods is of great interest due to the widespread vitamin A deficiency in developing countries. While the amount of beta-carotene can readily be quantified with analytical techniques, there is limited information on beta-carotene morphology in native plant materials. Here, we introduce nonlinear microscopy for three-dimensional, label-free imaging of carotenoids in fresh and thermally treated plant tissues, providing quantitative information at single-aggregate level and detailed insight into their distribution. Carotenoids in orange-fleshed sweet potato (OFSP), carrot, and mango were visualized by coherent anti-Stokes Raman scattering (CARS) microscopy and, in the case of OFSP, related to the plant-matrix morphology by simultaneous second-harmonic generation (SHG) microscopy of starch granules. Sizes, shapes, densities, and location of different types of carotenoid bodies were quantified. While OFSP and carrot showed heterogeneous rod-shaped bodies with high carotenoid densities indicated by higher CARS signals, the carotenoid-filled lipid droplets in mango appeared as homogeneous low-density aggregates of rounded shape. In addition, beta-carotene densities and morphologies in OFSP were studied after thermal processing, showing that the bodies remain intact despite significant changes of the surrounding starch granules.
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| 3. |
- Eduardo, Maria, 1965, et al.
(författare)
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Consumers’ acceptance of composite cassava-maize-wheat breads using baking improvers
- 2014
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Ingår i: African Journal of Food Science. - 1996-0794. ; 8:7, s. 390-401
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Tidskriftsartikel (refereegranskat)abstract
- A consumer test of composite cassava:maize:wheat (40:10:50) breads prepared with improvers, 0.3% emulsifiers, either as lecithin (LC) or diacetyl tartaric ester of mono-diglycerides (DATEM), and 3% hydrocolloids, either as high-methylated pectin (HM pectin) or carboxymethyl cellulose (CMC), was carried out in supermarkets in Mozambique. Overall acceptance and sensory attributes such as appearance, texture, smell, flavour, and crumb and crust colour were evaluated, and the consumption pattern and purchase intent were determined using a structured questionnaire. Composite bread quality characteristics, such as specific volume, crust colour, moisture content and firmness, were assessed instrumentally.The consumers’ overall acceptance of the composite bread with a mixture of roasted and sundried cassava flours and added HM pectin and LC had a score of 7.58, which was slightly higher than 7.28 for the composite bread with roasted cassava flour. The hedonic test showed that the perceived overall quality of the optimized composite bread based on roasted cassava flour with CMC and DATEM had a score of 7.47, which was significantly higher than the corresponding bread with HM pectin and LC (7.01), but not significantly different from commercial wheat bread (7.82). Crust colour and crumb colour and firmness correlated highly with their perceived sensorial counterpart properties.
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| 4. |
- Eduardo, Maria, 1965, et al.
(författare)
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Effect of cassava flour characteristics on properties of cassava-wheat-maize composite bread types
- 2013
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Ingår i: International Journal of Food Science. - : Hindawi Publishing Corporation. - 2356-7015 .- 2314-5765. ; 2013
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Tidskriftsartikel (refereegranskat)abstract
- Replacement of wheat flour by other kinds of flour in bread making is economically important in South East Africa as wheat is mainly an imported commodity. Cassava is widely available in the region, but bread quality is impaired when large amounts of cassava are used in the bread formulation. Effect of differently processed cassavas (sun-dried, roasted and fermented) on composite cassava-wheat-maize bread quality containing cassava levels from 20 to 40% (w/w) was evaluated in combination with high-methylated pectin (HM-pectin) added at levels of 1 to 3% (w/w) according to a full factorial design. Addition of pectin to cassava flour made it possible to bake bread with acceptable bread quality even at concentration as high as 40%. In addition to cassava concentration, the type of cassava flour had the biggest effect on bread quality. With high level of cassava, bread with roasted cassava had a higher volume compared with sun-dried and fermented. The pectin level had a significant effect on improving the volume in high level roasted cassava bread. Crumb firmness similar to wheat bread could be obtained with sun-dried and roasted cassava flours. Roasted cassava bread was the only bread with crust colour similar to wheat bread.
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| 5. |
- Eduardo, Maria, 1965, et al.
(författare)
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Effect of hydrocolloids and emulsifiers on baking quality of composite cassava-maize-wheat breads
- 2014
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Ingår i: International Journal of Food Science. - : Hindawi Limited. - 2356-7015 .- 2314-5765. ; :479630
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Tidskriftsartikel (refereegranskat)abstract
- Cassava is widely available worldwide but bread quality is impaired when cassava is used in the bread formulation. To overcome this problem, different improvers were tested in the preparation of composite cassava-maize-wheat (CMW) breads. Emulsifiers, diacetyl tartic acid ester of monoglycerides (DATEM), sodium stearoyl-2-lactylate (SSL), and lecithin (LC); and hydrocolloids, carboxymethylcellulose (CMC) and high-methylated pectin (HM pectin) were added during dough preparation of the composite flours (cassava-maize-wheat, 40: 10: 50). Each emulsifier was tested in combination with the hydrocolloids at levels of 0.1, 0.3, and 0.5% while hydrocolloids were used at a level of 3%. Bread quality attributes such as specific loaf volume, crust colour, crumb moisture, and firmness were measured. The specific volume of the fresh breads significantly improved with the addition of hydrocolloids (7.5 and 13%) and in combination with emulsifiers (from 7.9 to 27%) compared with bread produced without improvers. A significant improvement of brownness index and firmness of the composite flours breads was achieved with the addition of hydrocolloids and emulsifiers. The results show that emulsifiers and hydrocolloids can significantly improve the baking quality of CMW breads and thereby enhance the potential for using locally produced flours in bread baking.
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| 6. |
- Hellström, Andreas, 1980, et al.
(författare)
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Biodiversity and phytase capacity of yeasts isolated from Tanzanian togwa
- 2010
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Ingår i: International Journal of Food Microbiology. - : Elsevier BV. - 1879-3460 .- 0168-1605. ; 136:3, s. 352-358
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Tidskriftsartikel (refereegranskat)abstract
- The focus of the present investigation was on the Tanzanian fermented food togwa as a source for dietary iron and zinc, and the potential for mineral availability improvements using selected yeasts. To establish the content of target minerals and main inhibitor for intestinal uptake, iron and zinc as well as the mineral chelating phytic acid, (IP6 or phytate) were determined in naturally fermented togwa. Yeasts were isolated from sorghum, maize and cassava based togwa, and identified by sequencing the D1/D2 region of the LSU rRNA gene. The isolated yeasts were subsequently screened for phytase activity.The total iron content in sorghum, maize and cassava based togwa were 41.5 (±7.2), 85.4 (±31.9) and 28.6 (±3.8) μg/g dw (dry weight) respectively. The zinc content was 12.3 (±3.1), 11.0 (±1.1) and 6.4 (±4.5) μg/g dw in sorghum, maize and cassava based togwa, and the phytate content in the three varieties were 2.6±1.2, 4.7±0.8 and 0.4±0.4 μmol/g dw respectively. The phytate levels in the sorghum and maize based togwa are expected to substantially reduce the availability of iron. The molar ratio phytate to iron for these two varieties were estimated to be 3.5:1 and 3.1:1 respectively. In general, a phytate to iron molar ratio below 1 is needed to increase the availability of iron.Among 26 isolates, 9 different species could be distinguished: Issatchenkia orientalis, Pichia anomala, Pichia norvegensis, Pichia burtonii, Pichia guilliermondii, Kluyveromyces marxianus, Saccharomyces cerevisiae, Hanseniaspora guilliermondii and Candida glabrata. The strains were screened for phytase activity in YPD supplemented with 0.5 mM IP6. Of 26 screened strains, the phytase activity was most prominent in strains of I. orientalis and H. guilliermondii. The strains and data constitute a basis for further improvements of iron andzinc bioavailability in togwa.
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| 7. |
- Hellström, Andreas, 1980, et al.
(författare)
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Degradation of phytate by Pichia kudriavzevii TY13 and Hanseniaspora guilliermondii TY14 in Tanzanian togwa
- 2012
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Ingår i: International Journal of Food Microbiology. - : Elsevier BV. - 1879-3460 .- 0168-1605. ; 153:1-2, s. 73-77
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Tidskriftsartikel (refereegranskat)abstract
- The fermented cereal-based gruel togwa is used as weaning food for children in Tanzania. Togwa is rich in minerals but these are often not available for uptake in the human intestine due to natural inhibitors, such as phytate (IP 6). The yeasts Pichia kudriavzevii TY13, Hanseniaspora guilliermondii TY14 and TY20, isolated from Tanzanian togwa, and selected for high phytase activity in complex yeast medium YPD, were now studied regarding their ability to degrade IP 6 in maize-based model togwa. A modified constitutively high-phytase producing Saccharomyces cerevisiae BY80 and commercial Aspergillus ficuum phytase were included for comparison. In addition, a strain of Lactobacillus plantarum was included in the model-togwa set-up.All yeasts in the study grew and reached final cell density 1.5-2 log units higher than the start value. S. cerevisiae BY80 degraded 85% of the IP 6 in 48h; the same degradation level as with A. ficuum phytase (89%). Of the togwa-isolated yeasts, P. kudriavzevii TY13 and H. guilliermondii TY14 showed strong phytate degradation in the model-togwa; 95% or more of the initial IP 6 was degraded after 48h. This corresponds to a remaining level of 0.4 and 0.3μmol IP 6/g dw. Co-inoculation with L. plantarum did not increase IP 6 degradation. Moreover, fermentation with P. kudriavzevii TY13 yielded a successive increase in inorganic phosphate (P i), from 0.7 to 5.4mM, suggesting a phytase production in TY13 which is fairly insensitive to P i repression. The study shows that phytate in a model togwa is available for yeast phytase enzymes, and addresses the importance of strain selection for effectively degrading the phytate. Certain yeasts originating from togwa seem to have developed a natural high phytase production, and P. kudriavzevii TY13 and H. guilliermondii TY14 seem particularly well adapted to phytate degradation in togwa, and is our choice for further studies and strain improvement.
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| 8. |
- Svelander, Cecilia, 1980, et al.
(författare)
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Processing of tomato: Impact on in vitro bioaccessibility of lycopene and textural properties
- 2010
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Ingår i: Journal of the Science of Food and Agriculture. - : Wiley. - 1097-0010 .- 0022-5142. ; 90:10, s. 1665-1672
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Human studies have demonstrated that processing of tomato can greatly increase lycopene bioavailability. However, the difference between processing methods is not widely investigated. In the current study different thermal treatments of tomato were evaluated with regard to their impact on in vitro bioaccessibility and retention of lycopene and β-carotene as well as textural properties. Thermal treatments used were low (60°C) and high (90°C) temperature blanching followed by boiling. RESULTS: Lycopene was relatively stable during thermal treatment, whereas β-carotene was significantly (P
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