Date of Publication

3-25-2025

Document Type

Master's Thesis

Degree Name

Master of Science in Chemistry

Subject Categories

Food Chemistry

College

College of Science

Department/Unit

Chemistry

Thesis Advisor

Aldrin P. Bonto

Defense Panel Chair

Mariafe N. Calingacion

Defense Panel Member

Rosario S. Sagum
Melissa S. Borlagdan

Abstract/Summary

Maize (Zea mays L.) is a vital alternative food source in the Philippines; however, its nutritional profile is often inadequate for supporting human growth. To enhance its nutritional value, nixtamalization an ancient Mesoamerican processing technique is employed. Traditional nixtamalization (TN) relies on highly alkaline pH sources, which pose environmental challenges, thereby prompting the exploration of alternative processing methods such as ultrasonic treatment. This study investigates the effects of ultrasonic treatment on the nixtamalization of two Philippine maize varieties, IPB Var 6 and LB Lagkitan, using calcium salts as a processing agent. Optimal processing conditions were determined using the Box-Behnken design (BBD) within a response surface methodology framework, comprising fifteen experimental runs per variety. Three key processing factors were evaluated: ultrasonic pretreatment time (5 to 15 minutes), cooking time (0 to 30 minutes), and steeping time (0 to 16 hours). Box-Cox transformation was utilized for model optimization, employing two-factor interaction (2FI) and linear models to predict maximum water absorption index (WAI) and water solubility index (WSI). For IPB Var 6, optimal conditions yielded a WAI of 2.43 g gel/g dry matter and a WSI of 4.95% (ultrasonic treatment = 15 min, cooking time = 10 min, steeping time = 8 h). LB Lagkitan demonstrated a higher WAI of 2.61 g gel/g dry matter and a WSI of 6.04% (ultrasonic treatment = 10 min, cooking time = 21 min, steeping time = 8 h). Ultrasonic treatment significantly enhanced pericarp removal and improved the physicochemical, morphological, and thermal properties of nixtamal. The use of calcium carbonate as the alkaline source facilitated controlled calcium absorption while reducing phosphorus levels after 8 hours of steeping. Further characterization revealed that IPB Var 6, recognized for its quality protein content, and LB Lagkitan, a waxy maize variety, exhibited apparent amylose contents of 23.7% and 7.59%, respectively. Ultraviolet-visible (UV-Vis) spectroscopy confirmed the high amylopectin content in LB Lagkitan, contributing to its superior hydration properties. Additionally, Fourier-transform infrared (FTIR) spectroscopy identified key components, including carbohydrates and amide groups, while scanning electron microscopy (SEM) showcased polygonal and irregular starch granules resulting from the reduced cooking time. Particle size distribution (PSD) indicated a decrease in granule size due to the lime source, although no significant correlation with final viscosity (VF) was found. Cooking and calcium-starch interactions were shown to significantly influence viscosity, gelatinization, retrogradation, and thermal stability. This study confirms that the integration of ultrasonic treatment enhances traditional nixtamalization, improves processing efficiency, and preserves the quality of nixtamal, offering a promising avenue for sustainable maize processing.

Abstract Format

html

Language

English

Format

Electronic

Keywords

Corn—Processing--Philippines; Ultrasonic waves; Corn—Thermal properties--Philippines

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Embargo Period

4-2-2027

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Available for download on Friday, April 02, 2027

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