| 1. |
- Chiau, Eulália, et al.
(författare)
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Softening of dried Vangueria infausta (African medlar) using maltodextrin and sucrose
- 2013
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Ingår i: African Journal of Food Science. - 1996-0794. ; 7:10, s. 382-391
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Tidskriftsartikel (refereegranskat)abstract
- Softening of dried Vangueria infausta using maltodextrin and sucrose was investigated experimentally. The pulp of V. infausta was dried in a convective dryer, the influence of drying temperature as well as relationship between water content and water activity were examined. In this study, 48 samples of V. infausta pulp, with and without maltodextrin or sucrose, were dried at air temperatures of 60 and 80°C, at a constant air velocity of 3 m/s, for 0-240 min, and until constant weight. The water content, water activity, hardness and toughness were evaluated throughout the drying process. Samples dried at 80°C exhibited shorter drying times than samples dried at 60°C. The water activity of fruit dried for 240 min at 80°C varied from 0.633 to 0.759, and the fruit was thus safe regarding microbiological spoilage. The hardness and toughness of the dried fruit pulp increased with the reduction in water content, and it was observed that samples of pure pulp became unacceptably hard and tough, when dried to the level needed to obtain microbiological stability. The addition of sucrose as well as maltodextrin has shown to be able to reduce the hardness as well as the toughness of the dried fruit pulp; which can be considered as a strategy to obtain dried fruit pulp with suitable consistency.
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| 2. |
- 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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| 3. |
- Guiamba, Isabel, 1963, et al.
(författare)
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Enhancing the retention of β-carotene and vitamin C in dried mango using alternative blanching processes.
- 2018
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Ingår i: African Journal of Food Science. - 1996-0794. ; 12:7, s. 165-174
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Tidskriftsartikel (refereegranskat)abstract
- The effects of microwave (MW) dry blanching of mango in comparison with conventional water blanching and blanching in closed plastic bags prior to hot air drying (70°C) were evaluated on the retention of vitamin C and β-carotene and on the activity of polyphenol oxidase (PPO) and ascorbic acid oxidase (AAO) enzymes. Blanching conditions for MW and water blanching were 2 min at 90°C high temperature and short time (HTST) or for 10 min at 70°C low temperature and low time (LTLT). PPO was completely inactivated by the blanching treatments, while low AAO activity remained. High retentions (~100%) of vitamin C were found in dried mango after blanching treatments HTST with MW and blanching in closed plastic bags, while lower retention was observed after LTLT with MW (81.8 ± 4.5%), and conventional water blanching 86.7 ± 2.6% (HTST) and 78.6 ± 2.5% (LTLT). Blanching resulted in partial oxidation of L-AA into dehydroascorbic acid (DHAA). Lower retention of all-trans-β-carotene was obtained in MW and HTST water blanched dried mango (82 to 90%) compared with LTLT water blanched dried mango (~100%). In all dried blanched mango samples the levels of 13-cis-β-carotene isomer increased. A slight darkening of colour was observed only in conventional blanched mango samples.
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| 4. |
- Hussein, J. B., et al.
(författare)
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Evaluation of drying methods on the content of some bio-actives (lycopene, β-carotene and ascorbic acid) of tomato slices
- 2016
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Ingår i: African Journal of Food Science. - 1996-0794. ; 10:12, s. 359-367
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Tidskriftsartikel (refereegranskat)abstract
- Tomato (Solanum lycopersycum L.) is one of the most important vegetables worldwide. As it is a relatively short duration crop and gives a high yield, it is economically attractive. Thus, the objective of this study was to evaluate the effect of drying method on the quality of the dried tomatoes based on three parameters viz; lycopene, ß-carotene and ascorbic acid contents. Thirty-six kilograms of tomatoes were sorted, cleaned, blanched and divided into three equal portions of 12 kg each. The tomatoes were sliced into 4, 6 and 8 mm, then sun, solar and hybrid dried, respectively. The value of lycopene content obtained for sun dried tomatoes ranged from 23.89 to 18.77 mg/100 g, solar dried ranged from 24.51 to 22.56 mg/100 g and hybrid dried ranged from 25.12 to 24.65 mg/100 g. The average value of β-carotene content obtained for sun dried tomatoes ranged from 4.12 to 3.72 mg/100 g, solar dried ranged from 4.94 to 4.25 mg/100 g and hybrid dried ranged from 4.98 to 4.65 mg/100 g. The values of ascorbic acid obtained for sun dried tomatoes ranged from 17.04 to 5.60 mg/100 g, solar dried ranged from 23.73 to 13.37 mg/100 g and hybrid dried ranged from 29.20 to 24.82 mg/100 g. Hybrid dried tomatoes slice showed higher retention of lycopene, ß-Carotene and ascorbic acid than both the solar and open sun dried methods.
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| 5. |
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| 6. |
- Vilanculos, Serafina, 1961, et al.
(författare)
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Degradation of phytate in composite wheat/cassava/sorghum bread by activation of intrinsic cereal phytase
- 2021
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Ingår i: African Journal of Food Science. - 1996-0794. ; 15:1, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to degrade the phytic acid content in composite wheat/cassava/ sorghum bread by activating intrinsic cereal phytases during the baking process. The aim was to reach a phytate:iron molar ratio <1 to achieve an enhanced iron absorption in humans. Means to activate the phytase included dough preparation at different pH values and temperature as well as pre-soaking of the sorghum flour before baking. The phytic acid and mineral content was measured by high-performance ion chromatography. In the composite bread without pH adjustment of the dough, the phytate content was 1.58 μmol/g. After adjustment of the dough pH to 4.3, the phytate content in the composite bread decreased to 0.86 μmol/g. Soaking of the sorghum flour at 22°C for 3 h at pH 4.3 before baking, further decreased the phytate content to 0.58 μmol/g. Increasing the soaking temperature to 37°C and addition of 10% wheat flour resulted in a phytate content of 0.14 μmol/g in the composite bread, that is a reduction by 97% of the initial phytate content. The phytate:iron molar ratio was then 0.70 and the phytate:zinc molar ratio was 1.1 that is expected to have a positive effect on the absorption of both minerals in humans.
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| 7. |
- Vilanculos, Serafina, 1961, et al.
(författare)
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Phytate degradation in composite wheat/cassava/sorghum bread: Effects of preincubation of Pichia kudriavzevii TY13 and presence of yeast extract.
- 2022
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Ingår i: African Journal of Food Science. - 1996-0794. ; 16:12, s. 310-318
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Tidskriftsartikel (refereegranskat)abstract
- Diet based on whole cereal flours is associated with a high prevalence of iron deficiency anemia and zinc deficiency in low/middle-income countries. Such flours contain high content of phytate that chelates minerals such as iron and zinc, making them unavailable for absorption by humans. To improve the mineral absorption, a phytate:iron molar ratio <1 and a phytate:zinc molar ratio <5 is needed to be achieved. This study aimed to improve the phytate degradation in composite wheatcassava-whole sorghum flour bread by adding a phytase releasing yeast Pichia kudriavzevii TY13 in baking, preincubated or not, with addition of yeast extract. The phytate and mineral contents were measured by high-performance ion chromatography. Addition of P. kudriavzevii TY13 to the composite flour dough and fermentation for 2 h at room temperature resulted in a 98% phytate degradation. However, the same phytate reduction in the composite bread was achieved after 1 h fermentation at room temperature with addition of preincubated P. kudriavzevii TY13 plus yeast extract. Increasing the fermentation temperature to 30°C, the phytate content was equally low after fermentation for 1 h with P. kudriavzevii TY13 (preincubated or not) plus yeast extract. In conclusion, a faster reduction of phytate in composite bread was obtained by increasing the fermentation temperature, and addition of P. kudriavzevii TY13 (preincubated or not) with added yeast extract. The phytate to iron molar ratio was then 0.2 and the phytate to zinc molar ratio 0.6, which strongly indicates an improved bioavailability of both minerals from such a bread.
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