Characterization of phi112, a Molecular Marker Tightly Linked to the o2 Gene of Maize, and Its Utilization in Multiplex PCR for Differentiating Normal Maize from QPM

Quality Protein Maize (QPM) contains higher amounts of essential amino acids lysine and tryptophan. The QPM phenotype is based on regulating zein protein synthesis by opaque2 transcription factor. Many gene modifiers act to optimize the amino acid content and agronomic performance. An SSR marker, phi112, is present upstream of the opaque2 DNA gene. Its analysis has shown the presence of transcription factor activity. The functional associations of opaque2 have been determined. The putative transcription factor binding at phi112 marked DNA was identified through computational analysis. The present study is a step towards understanding the intricate network of molecular interactions that fine-tune the QPM genotype to influence maize protein quality. In addition, a multiplex PCR assay for differentiation of QPM from normal maize is shown, which can be used for Quality Control at various stages of the QPM value chain.

Improvement in nutritional quality of traditional unleavened flat bread using Quality Protein Maize

Maize grains are consumed majorly in the form of unleavened flat bread (chapatti) in the South East Asian region. The landraces are better accepted for their chapatti-making attributes such as grain color and good organoleptic properties. However, these cultivars are low in essential amino acids, particularly lysine and tryptophan content. Hence, an investigation was performed to identify maize genotypes with high nutritional value coupled with good chapatti-making qualities. Seven genotypes, comprising two Quality Protein Maize (QPM) hybrids, two normal maize hybrids, and three normal white maize landraces were assessed for their physical characteristics, proximate composition, and chapatti-making quality. Landrace 593 showed the highest protein and ash content. Flours obtained from different genotypes were significantly different (p ≤ 0.001) in terms of protein content, color value, textural, as well as mineral content. PMH 10 and IQMH 203 exhibited the highest and lowest hydration index, respectively. Two QPM hybrids showed significantly higher lysine and tryptophan content as compared to other genotypes. QPM hybrids were identified as the promising material with improved nutritional quality with respect to chapatti making. In combination with mustard greens, maize chapatti constitutes an important traditional delicacy in north India. The enhanced nutritional quality of QPM chapattis is an added advantage. We show the differentiation of chapattis made from QPM and normal maize using a rapid protocol developed previously. This is expected to enable the development and quality control of commercial enterprises based on high protein quality QPM.

Physicochemical evaluation and Fourier transform infrared spectroscopy characterization of quality protein maize starch subjected to different modifications

Abstract

Quality protein maize (QPM) is a biofortified maize rich in lysine and tryptophan, essential amino acids required in human nutrition. This research therefore characterizes native and modified starches from QPM by evaluating the physicochemical properties, Fourier transform infrared spectra (FTIR), and pasting properties. The native QPM starch was modified by oxidation, acetylation, pregelatinization, and acid thinning techniques. The starch yield of native QPM was 43.80%, while that of modified starches were from 88.22 to 98.34%. The moisture content of the native and modified starches was from 4.56 to 9.20 g/100g. Modifications significantly (P ≤ 0.05) reduced the lipid, protein, and amylose contents of the QPM. While the native starch had 0.72 g/cm³ bulk density, modified starches were between 0.59 and 0.88 g/cm³; chemical modification reduced the bulk density and physical modification increased it. In addition, all the modifications except oxidation significantly (P ≤ 0.05) increased water absorption capacity. The oil absorption of the starch samples was increased by modification techniques used with the exception of physical modification. Chemical modification reduced the viscosity of QPM starch while physical modification increased it. The reducing sugar content of the starch was reduced by both the physical and chemical starch modification techniques. Acetylated sample exhibited the highest swelling power while acid‐thinned sample had the least. The major functional groups identified via FTIR were OH, C‐H, C=H, and C≡H. Modifications did not affect the functional groups as all the native and modified starches (except oxidized sample) all have similar spectrum and bands stretch.

Practical Application

The study contributes to existing knowledge on valorization of modified starch from quality protein maize. Profiling the chemical attributes of modified starches is especially valuable in novel food processing techniques.

Storage influence on the functional, sensory and keeping quality of quality protein maize flour

Apart from nutritional values functional and sensory properties affect the behavior of food system and its acceptability for consumption during storage. Hence keeping quality of maize flour (HQPM-7) with and without lime treatment(control) was studied in terms of functional (bulk density, pH, swelling capacity, water and oil absorption capacity, least gelation concentration, peroxide value), sensory (appearance, color, taste, texture, mouth feel and overall acceptability) and rolling parameters (water absorption by flour, rolling quality, diameter after baking ) for a period of 6 months under room temperature (25 ± 5 °C) in two types of packages viz, LDPE cover (P) and plastic box (B). Physical parameters such as length, breadth and thickness (11.26-10.52 mm, 9.67-9.14 mm, & 4.72-3.95 mm) were reduced in lime treated grains compared to control. Significant increase (p ≤ 0.05) in ash content of lime treated flour (1.67 ± 0.01 g) was observed compared to control (1.5 ± 0.02 g). Calcium content of lime treated maize flour increased significantly (p ≤ 0.05) from 48 to 136 mg. There is a significant reduction in functional properties of flour after 3 and 2 months irrespective in polyethylene cover and plastic box. The properties like rolling quality, diameter after baking and water uptake by the flour were reduced significantly (p ≤ 0.05) after 4 months of storage in treated and after 1 month in control samples. Sensory scores of roti (dry pan cake) decreased significantly after 3 months of storage with an overall acceptability score of 4.0 and 3.4. In control samples mean taste (3.6), mouth feel (3.8) as well as OAA scores (3.8) decreased after second month. Hence lime treated maize flour with added nutritional benefits is suitable for making rotis of good palatability and can be stored in LDPE covers up to 3 months.