Phytate degradation in composite wheat/cassava/sorghum bread: Effects of phytase-secreting yeasts and addition of yeast extracts.

Iron deficiency anemia is highly prevalent in developing countries due to the consumption of cereal-based foods rich in phytate that chelates minerals such as iron and zinc making them unavailable for absorption by humans. The aim of the present study was to degrade phytic acid in composite flour (wheat/cassava/sorghum) bread by the addition of phytase-producing yeasts in the baking process to achieve a phytate-to-iron molar ratio <1 and a phytate-to-zinc molar ratio <15, ratios needed to achieve an enhanced absorption by humans. The high-phytase (HP)-producing yeasts were two (YD80 and BY80) that have been genetically modified by a directed mutagenesis strategy, and TY13 isolated from a Tanzanian lactic fermented maize gruel () and selected as naturally HP yeast.

Effects of blanching, acidification, or addition of EDTA on vitamin C and β-carotene stability during mango purée preparation.

The impact of acidification with citric acid, addition of EDTA or water blanching at high temperature, and short time (HTST) conducted at 90°C for 4 min, on the retention of vitamin C (L-AA and DHAA) and β-carotene was studied in mango purée 30 min after crushing. HTST blanching prior to matrix disruption into purée resulted in complete inactivation of polyphenol oxidase (PPO) and minor residual activity (8%) of ascorbic acid oxidase (AAO). The retention of total vitamin C was 100% in blanched purées and in purée with EDTA and about 90% in purées at pH 3.

Effect of hydrocolloids and emulsifiers on the shelf-life of composite cassava-maize-wheat bread after storage.

The objective of this study was to evaluate the effect of hydrocolloids and/or emulsifiers on the shelf-life of composite cassava-maize-wheat (ratio 40:10:50) reference bread during storage. Added hydrocolloids were carboxymethylcellulose (CMC) and high methoxyl pectin (HM pectin) at a 3% level (w/w) and/or the emulsifiers diacetyl tartaric acid esters of monoglycerides (DATEM), lecithin (LC), and monoglycerides (MG) at a 0.3% level (w/w).

Effect of Infrared Blanching on Enzyme Activity and Retention of β-Carotene and Vitamin C in Dried Mango.

The objectives of this work were to evaluate infrared (IR) dry blanching in comparison with conventional water blanching prior to hot air drying of mango to inactivate polyphenol oxidase (PPO) and ascorbic acid oxidase (AAO) enzymes, and to study its effect on color change and retention of vitamin C and β-carotene. Mango cylinders were blanched under similar temperature-time conditions either by IR heating or by immersion in a water bath during 2 min at 90 °C (high-temperature-short-time-HTST) or for 10 min at 65 °C (low-temperature-long-time-LTLT). After blanching mango was hot air dried at 70 °C.

Secretion of non-cell-bound phytase by the yeast Pichia kudriavzevii TY13.

Aims: Mineral deficiencies cause several health problems in the world, especially for populations consuming cereal-based diets rich in the anti-nutrient phytate. Our aim was to characterize the phytate-degrading capacity of the yeast Pichia kudriavzevii TY13 and its secretion of phytase.

Methods And Results: The phytase activity in cell-free supernatants from cultures with 100% intact cells was 35-190 mU ml(-1) depending on the media.