Development of a processing technology for the in-situ fortification of nixtamalized corn in rural Guatemala

Torres Aguilar, Pablo

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https://hdl.handle.net/2142/45298 Copy

Description

Title

Development of a processing technology for the in-situ fortification of nixtamalized corn in rural Guatemala

Author(s)

Torres Aguilar, Pablo

Issue Date

2013-08-22T16:35:16Z

Director of Research (if dissertation) or Advisor (if thesis)

Andrade, Juan

Department of Study

Nutritional Sciences

Discipline

Nutritional Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Nixtamalized masa
• fortification
• iron chelate
• Guatemala.

Abstract

Statement of the problem: Iron deficiency anemia (IDA) is major health concern in Guatemala. Strategies to target IDA, including food fortification and supplementation, have been used with limited impact in low income, rural populations. Food insecurity, reduced dietary diversity, diets rich in Fe absorption inhibitors and low consumption of animal products and fortified foods contribute to the underlying causes of IDA. The basic diet for these populations are self-produced corn and beans, which during stress periods constitute about 80% of their daily caloric intake. High frequency of consumption, accessibility and cultural practices make nixtamalized corn (NC) a suitable staple for stealth fortification with iron. Fortification of NC for tortillas at the point of wet grinding could be an effective strategy against IDA in rural Guatemala. In this work, the author proposes stealth fortification of masa for tortillas with chelated iron by mixing a highly enriched extruded product with NC during traditional wet grinding. Approach: Extruded fortified pellets for NC fortification were manufactured using a 1:1 (w/w) combination of corn grits and brown rice. Extrusion process was performed using a Welly puffing extruder. It used a single screw fixed at 120 rpm delivering 65.63 g material /min through a circular hole die (3.1 mm) at an average temperature of 153 ±3.1 °C. A single blade cutter set at 450 rpm was used to shape pellets. Fluid delivery of iron into pellets was accomplished by using a peristaltic pump. Iron fortification solutions containing 92.25 mg/mL and 150 mg/mL of NaFeEDTA and ferrous bisglycinate, respectively, were directly pumped into feeding end of the extruder. NC was cooked using a traditional recipe (1% lime, 2 h @105°C) and steeped for 10 h. Iron fortified pellets were mixed with NC at 12.5, 25 and 50 g pellets / kg NC in a bucket. NC was ground into masa using a Burr mill. Color, texture and iron content were determined in the pellets and masa. The effect of wet grinding and fortification level on iron concentrations were assessed by two-way ANOVA. The effect of fortification on color and texture of masa within an 8-h period was assessed using repeated measures ANOVA. Results: Final pellets dimensions (LxWxH mm) were 17.07±1.06, 11.94 ±1.54, 11.40± 1.08. Iron concentrations were 0.30±0.01 and 0.66±0.01 mg Fe/g of pellet representing Fe recoveries of 85.7 and 71.5% for FeNaEDTA and ferrous bisglycinate pellets, respectively. Constant process for Fe incorporation into pellet was observed after 15 min of extrusion. Non fortified nixtamalized masa iron concentration was 26.7 ± 4.3 mg Fe per kg masa (db). Fortification of nixtamalized corn at 3 levels, 12.5, 25 and 50 mg of pellet/kg NC resulted in increased iron concentrations in masa (P<0.05). Masa fortified with NaFeEDTA pellets showed higher variability in Fe content, which was farther from the expected levels than that fortified with ferrous bisglycinate pellets. Distribution of iron was evaluated by differences on iron concentration using a sample collection scheme (i.e., top, middle, and bottom) without further mixing. No significant sampling effects were found among the Fe fortified masa treatments. However, %RSD was excessively high (1.84 to 87.28%) within treatments using the sampling scheme proposed. Iron recoveries for NaFeEDTA fortified masa were lower than those observed in ferrous bisglycinate fortified masa. High variability within the sample masked the addition of NaFeEDTA. Highest Fe recovery (56.6%) was observed in masa fortified with 50 g pellet/ kg NC. Iron fortification affected both color and texture of masa. The effect of time was associated with masa hardness. Conclusion: The creation and evaluation of a super-fortified iron pellet was achieved. The use of NaFeEDTA or ferrous bisglycinate as iron formulas worked well in the pellet and resulted in specific characteristics in terms of maximum iron content, color and texture. The production of these pellets was feasible using liquid delivery to infuse iron solutions into pellets. Nonetheless, incorporation of iron into pellets requires further optimization. The replication of traditional nixtamalization process under controlled conditions was also achieved. A Burr mill and a bucket where necessary to mix iron fortified pellets with NC, yielding masa with specific characteristic in terms of color and texture, which were different from the non fortified control. The high variability in the redistribution of iron led to poor recoveries for certain iron types and levels, especially NaFeEDTA at 12.5 and 25 g/kg NC. Thus, the addition of iron into NC delivered in fortified pellets was not feasible using manual mixing in the bucket and grinding in the Burr mill, at least at the lowest levels of iron evaluated. It is possible that modifying pellet density, optimizing iron solubilization at higher pH, and kneading masa after grinding, as customary in Guatemala households, could help uniform iron dispersion in NC masa.

Graduation Semester

2013-08

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Copyright 2013 Pablo Torres-Aguilar

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