Effect of maize soaking, germination and fermentation on phytate content and its contribution towards improving nutrients bioavailability

Abstract

The presence of phytate in plants-based food is considered a threat to proper nutrition in developing countries and in particular in rural areas. There is evidence of micronutrient deficiencies due to the presence of phytate in plant-based diets. People from low income households are most affected by diets rich in phytate. The aim of this study was to investigate different processes through which phytate reduction in maize can be achieved. Maize soaking, germination and fermentation were conducted and their effects on phytate reduction and potential improvement of minerals (Fe and Zn) bioavailability was investigated.
Maize (Zea mays) is a staple food in Rwanda, and the National Government has in place policies to assist and encourage the maize cultivars in the area. Therefore, for its importance in Rwanda and in other developing countries going through the same situation, Maize was selected as the material for this investigation.
Maize (Zea Mays) kernels were transported from Rwanda and divided in two batches. One batch was subjected to milling. The second batch was subjected to soaking for 24h and thereafter, the soaked grains were allowed to germinate for 80h at room temperature (18oC).
After germination, the grains were dried and milled. Four processes of fermentation were conducted, 3 of them using maize flour from batch 1 and the fourth one using maize flour from second batch. 1.Spontaneous fermentation of raw maize flour, 2. fermentation of raw maize flour with Lactobacillus plantarum299v®, 3. Fermentation of raw maize flour with yoghurt containing viable Lactobacillus casei (5%), 4. Fermentation of maize flour resulted from soaked and germinated grains, fermentation was conducted with Lactobacillus plantarum299v®. The suspension for fermentation were prepared by mixing flour and de-ionized water at ration of 1:2 (w/v), the suspension was allowed to ferment at 30oC until pH was reduced below 4.3.
pH, TTA (Titratable acidity) and dry matter for phytate and protein analysis were determined after every 4 hours. Sample for dry matter were dried in oven at 105oC until constant weight. Soaking was found to reduce phytate at the rate of 12.55%. Both soaking and germination provided 32% of phytate reduction. Spontaneous fermentation of raw maize flour, fermentation of raw maize flour with Lactobacillus plantarum299v®, fermentation of raw maize flour with yoghurt containing viable Lactobacillus casei and fermentation of maize flour from soaked and germinated grains with Lactobacillus plantarum 299v® showed 51.85%, 65.29%, 68.71% and 85.60% of phytate reduction respectively. The protein increased by 8.2%, 9.3%, 10.3% and 7.3% respectively. The Zinc contents in dry matter found in fermented maize were 0.01725±0.0004g*kg-1and, 0.01485±0.0004g*kg-1, 0.01365±0.0012g*kg-1, and lastly 0.01735±0.0000g*kg-1 respectively. Theoretical value of 0.024g*kg-1 found in white maize flour aws used in this study due to lack of actual laboratory results. The initial molar ratio of Phy:Zn and Phy: Fe in raw maize flour was 40.88±0.00 and 34.01±0.00 respectively. In fermented maize flour were 26.68±1.50and 16.37±1.39, 22.37±0.91and 11.80±0.08, 22.01±2.03 and 10.64±0.04, and finally 7.93±0.53 and 4.89±0.31, respectively. Compared to the recommended threshold for estimating mineral bioavailability of <15 and <1 for Phy:Zn and Phy:Fe respectively, this study confirmed that zinc bioavailability in fermented maize flour from soaked and germinated grains was improved to levels to increase zinc absorption.
The results from ANOVA, showed that, Phytate was reduced significantly in all the fermentation processes where p<0.05, the high rate of phytate reduction was observed in fermented maize flour from soaked and germinated grains compared to fermentation processes.
Soaking and germination processes showed to reduce phytate to some extent. The fermentation processes resulted to be more effective to reduce high levels of phytic acid content and when fermentation is conducted after soaking and germination, the levels of phytate are reduced in such a way that the estimated bioavailability of zinc is significantly improved.

Popular Abstract

Micronutrients deficiencies are a challenge to health in low income household of developing country, where almost all the population depends on plant-based foods. The plants-based food has been found to contain large amount of nutrient absorption inhibitors including phytate. The phytate has capacity to bind the divalent minerals and make insoluble complex molecules which cannot be utilized by human body. Thus, aggravating the malnutrition caused by inadequate intake of minerals that are no synthesized by the human body.
The aim of this study was to investigate reliable, user friendly and affordable processing methods that can be employed by people in rural areas to reduce the amount of phytate in maize. Maize remains one of the major staple foods in most developing countries, particularly, Sub Saharan Africa including Rwanda, Tanzania, Congo etc..
In order to reduce phytate in maize, the maize flour was subjected to different processing strategies such as soaking, germination and four types of fermentation. All these processes proved to be effective for reducing phytate content. The greater potential in phytate reduction was observed once the fermentation of flour from soaked and germinated grains were conducted prior lactic acid fermentation. The results from calculated molar ratio of phytate:iron, and phytate:zinc showed that the estimated mineral bioavailability is improved in all fermented flours compare to unfermented ones.
Finally, the evidence obtained in this study indicates that fermented maize flour is low in phytate compare to unfermented maize flour. Fermentation is easy to conduct, user friendly, affordable and generally advantageous in practical and economic considerations. As a dietary strategy, fermentation has the potential to improve minerals bioavailability and combat minerals deficiencies that are highly prevalent in low income households that have limited access to animal-based foods.

• author: Nsabimana, Samuel
• supervisor: Claudia Lazarte
• organization: Food Technology and Nutrition (M.Sc.)
• course: KLGM01 20191
• year: 2019
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Phytate, zinc, iron, deficiencies, bioavailability, fermentation, food technology, livsmedelsteknologi
• language: English
• id: 8984928
• date added to LUP: 2019-07-04 14:46:21
• date last changed: 2019-07-04 14:46:21