Corn / Maize
(From Zea mays, family Poaceae)
Description
Maize (corn) is a cereal grain originally domesticated in the Americas and now cultivated worldwide.
The kernel consists of pericarp (bran), starchy endosperm and germ, with colours ranging from yellow and white to red and purple in specialty varieties.
In the food industry it is mainly used as dry grain, grits, meals, flours, flakes, starches and syrups (e.g. glucose/fructose syrups) for bakery, snacks, polenta, breakfast cereals, beverages and baby foods.
Indicative nutritional values per 100 g
(yellow maize, dry grain)
Energy: 340–380 kcal
Carbohydrates: 70–75 g
sugars: 1–3 g
starch: 65–72 g
Fibre: 6–10 g (higher in wholegrain products)
Protein: 7–10 g
Lipids: 3–5 g
SFA (first occurrence – saturated fatty acids): 0.5–1 g (excess SFA intake is associated with higher cardiovascular risk, but contribution from plain maize is moderate)
MUFA: 1–1.5 g
PUFA: 1.5–2.5 g (mostly linoleic acid)
TFA: not present in any significant natural amount
Vitamins: B1, B3, B5, B6, folate; small amounts of vitamin E
Minerals: phosphorus, magnesium, potassium; traces of zinc, copper, manganese
Values vary with variety (dent, flint, waxy), degree of refinement (wholegrain vs refined) and processing.
Key constituents
Starch (mainly in the endosperm)
Proteins (zeins, glutelins) with moderate biological value
Lipids concentrated in the germ (linoleic and oleic acid)
Dietary fibre (corn bran: cellulose, hemicellulose, lignin)
Carotenoids (lutein, zeaxanthin) responsible for yellow colour
B-group vitamins and vitamin E (especially in the germ)
Minerals (P, Mg, K)
Phenolic antioxidants (e.g. ferulic acid in the bran)
Production process
(dry grain, grits and flours)
Cultivation and harvest: ears harvested at full physiological maturity.
Drying: reduction of kernel moisture (typically <14%) to ensure storability.
Shelling and cleaning: removal of kernels from cobs; removal of dust, broken kernels and foreign materials.
Storage in silos: controlled humidity and temperature to prevent mould and pests.
Milling:
Dry milling to produce grits, meals and flours (for polenta, snacks, bakery).
Wet milling to separate starch, gluten, fibre and germ (for starch, sweeteners, corn oil).
Optional refining: separation of bran and germ (degerminated corn) or production of wholemeal retaining all fractions.
Thermal treatments (if applicable): precooking, roasting, extrusion (flakes, breakfast cereals, extruded snacks).
Packaging in bags or other suitable containers.
All operations under GMP/HACCP, with control of moisture, pests and contaminants.
Physical properties
Whole kernels: hard or semi-hard, glossy, mostly yellow or white (other colours in specialty types).
Moisture (dry grain): approx. 12–14%
Bulk density: typically 700–800 g/L for grain; lower for grits and flours.
Solubility: starch is insoluble in cold water but gelatinises when heated.
Stability: good if properly dried and protected from moisture and infestation.
Sensory and technological properties
Flavour: mild, slightly sweet, cereal-like.
Colour: pale to deep yellow depending on carotenoid content.
Technological functionalities:
corn starch provides gelatinisation, thickening and structure in cooked products;
grits are suitable for polenta, extruded snacks, breakfast cereals;
corn flour gives colour, crispness and a sandy crumb texture in baked goods;
corn bran increases fibre and contributes texture.
Food applications
Nutrition & health
Source of complex carbohydrates and energy with relatively gradual release.
Protein content is moderate; amino acid profile is lysine limiting, so corn is often combined with other cereals or legumes for balance.
Yellow varieties provide carotenoids (lutein, zeaxanthin) with antioxidant roles.
Wholegrain forms provide significant fibre for digestive health.
Corn germ is rich in PUFA and vitamin E (when germ is retained or oil is used).
Glycaemic impact depends on refinement, particle size and cooking (e.g. dense polenta vs instant corn creams).
Portion note
Allergens & intolerances
Corn is not a major allergen in most regulations, though rare allergies to corn proteins exist.
It is naturally gluten-free, suitable for coeliac diets if grown, milled and packed under conditions that avoid cross-contamination with gluten-containing cereals.
Individual intolerances must be evaluated based on the finished product and all its ingredients.
Storage & shelf-life
Dry grain:
stored in silos or bags in cool, dry, well-ventilated conditions;
moisture <14% to prevent mould and mycotoxin formation;
shelf-life: many months, often up to 12 months or more if well managed.
Flours and grits:
more sensitive to oxidation (especially if germ is present) and moisture;
must be kept in moisture- and oxygen-barrier packaging;
typical shelf-life: 6–12 months, shorter for wholemeal or germ-containing products.
Main risks:
Mould growth and mycotoxins (e.g. fumonisins, aflatoxins) if moisture/temperature are not properly controlled.
Insect infestation (weevils, grain moths), preventable via good integrated pest management.
Safety & regulatory
Subject to legal limits for:
mycotoxins (aflatoxins, fumonisins, zearalenone, etc.),
pesticide residues,
heavy metals.
Must comply with hygienic standards for cereal products (microbial load, absence of pathogens).
Production under GMP/HACCP, with full traceability from field to final ingredient.
For products aimed at infants and vulnerable groups, stricter contaminant limits apply.
Labeling
Typical names:
“maize” or “corn”,
“corn flour”,
“cornmeal”,
“corn grits”,
“corn bran”.
In compound foods, listed in descending order of weight.
For gluten-free products, “gluten-free” can be claimed only if analytical limits are met.
When used as starch/syrups, specific ingredients appear (e.g. “corn starch”, “glucose syrup (from corn)”, “high-fructose corn syrup” where applicable).
Troubleshooting
Mouldy odour or visible mould:
Insect infestation:
Rapid rancidity in flour:
Poor texture in baked goods:
Sustainability & supply chain
Main INCI functions (cosmetics)
(as “Zea Mays Starch”, “Zea Mays Kernel Extract”, “Zea Mays Germ Oil”)
Zea Mays Starch:
absorbent (sebum and moisture in powders, deodorants, make-up),
bulking agent and viscosity regulator.
Zea Mays Kernel Extract:
Zea Mays Germ Oil:
Used in body care, facial care, powder make-up and “natural” cosmetic lines.
Conclusion
Maize/corn is an extremely versatile and widely used cereal, forming the basis of grains, flours, grits, starches and syrups.
Technologically it provides structure, body, colour and thickening functions, while nutritionally it supplies complex carbohydrates, fibre in wholegrain form and several micronutrients.
When grown and processed in well-managed supply chains and under GMP/HACCP, maize is a safe, stable and high-quality ingredient suitable for a broad range of food applications, from traditional polenta and tortillas to modern snacks and plant-based products.
Mini-glossary
SFA – Saturated fatty acids: fats associated with increased cardiovascular risk when consumed in excess; maize contains only modest amounts in its native lipid fraction.
MUFA – Monounsaturated fatty acids: generally neutral or beneficial fats present in corn germ oil.
PUFA – Polyunsaturated fatty acids: include essential fatty acids (e.g. linoleic acid), abundant in corn germ oil but more prone to oxidation.
TFA – Trans fatty acids: associated with negative health effects when industrial; not a significant natural component of maize.
GMP/HACCP – Good Manufacturing Practices / Hazard Analysis and Critical Control Points, management systems ensuring hygiene, safety and quality.
BOD/COD – Biological / Chemical Oxygen Demand, indicators of the organic and chemical load of industrial wastewater, used to assess environmental impact.
Studies
The results of this study suggest that even though there were pigment losses, creole maize pigments show antioxidant and antimutagenic activities after nixtamalization process (1).
From corn they are industrially extracted:
- Fructose syrup or HFCS (High Fructose Corn Syrup)
- Glucose syrup
- Glucose-fructose syrup
- Maize syrup (unusual diction as the content should be specified, whether fructose or glucose. Glucose is sugar, so a component to be taken in moderation. Fructose is a low-calorie carbohydrate sweetener that, frankly, would be best avoided )
It has a low caloric content.
Suitable for coeliacs.
Also used for animal feed.
Genetically modified crops (GMCs) were first introduced to commercial agriculture in 1996, and approximately 181.5 million hectares of GMCs were grown worldwide in 2014. These GMCs have produced significant benefits over the past two decades (Clive, 2015). A recent meta-analysis by Klumper and Qaim concluded that the wide adoption of GM technology has reduced the usage of chemical pesticides, in addition to increasing crop yields to improve farmers' profits (Wilhelm and Matin, 2014). Despite the obvious positive effects of GMCs, public controversy over on the unintended, unexpected, and uncontrolled negative effects of GMCs are still ongoing. There is considerable concern that the introduction of exogenous DNA sequences and enzymes into the target plant genome in GMCs might result in unintended effects, and these negative effects may affect both human health and the environmental safety (Ioset et al., 2006). Therefore, determination of these potential unintended effects necessary and scientists should perform bio-assessment analyses to guarantee the safety of GMCs (1).
Corn studies
References__________________________________________________________________
(1) Mendoza-Díaz S, Ortiz-Valerio Mdel C, Castaño-Tostado E, Figueroa-Cárdenas Jde D, Reynoso-Camacho R, Ramos-Gómez M, Campos-Vega R, Loarca-Piña G. Antioxidant capacity and antimutagenic activity of anthocyanin and carotenoid extracts from nixtamalized pigmented Creole maize races (Zea mays L.). Plant Foods Hum Nutr. 2012 Dec;67(4):442-9. doi: 10.1007/s11130-012-0326-9
Abstract. Nixtamalization process is the first step to obtain maize based products, like tortillas; however, in both the traditional and commercial processes, white grain is generally preferred. Creole maize races, mainly pigmented varieties, have increasingly attention since these are rich in anthocyanins and carotenoids. The aim of this investigation was to evaluate the antioxidant and antimutagenic activity of rich anthocyanins and carotenoids extracts from creole maize races before (grain) and after (masa and tortilla) the nixtamalization process. Most anthocyanins and carotenoids were lost during nixtamalization. Before nixtamalization, blue and red genotypes contained either higher antioxidant capacity and anthocyanin contents (963 ± 10.0 and 212.36 ± 0.36 mg of cyanidin-3-glucoside eq/100 g, respectively) than the white and yellow genotypes. However, the highest carotenoid levels were displayed by red grains (1.01 ± 0.07 to 1.14 ± 0.08 μg of β-carotene eq/g extract). Anthocyanins losses were observed when the blue grains were processed into masa (83 %) and tortillas (64 %). Anthocyanins content correlated with antiradical activity (r = 0.57) and with 2-aminoanthracene -induced mutagenicity inhibition on TA98 and TA100 (r = -0.62 and r = -0.44, respectively). For white grains, nixtamalization also reduced carotenoids (53 to 56 %), but not antioxidant activity and 2-Aa-induced mutagenicity. Throughout the nixtamalization process steps, all the extracts showed antimutagenic activity against 2-aminoanthracene-induced mutagenicity (23 to 90 %), displaying higher potential to inhibit base changes mutations than frameshift mutations in the genome of the tasted microorganism (TA100 and TA98, respectively). The results suggest that even though there were pigment losses, creole maize pigments show antioxidant and antimutagenic activities after nixtamalization process.
Amador-Rodríguez KY, Martínez-Bustos F, Silos-Espino H. Effect of High-Energy Milling on Bioactive Compounds and Antioxidant Capacity in Nixtamalized Creole Corn Flours. Plant Foods Hum Nutr. 2019 Jun;74(2):241-246. doi: 10.1007/s11130-019-00727-9.
Abstract. This study aimed at evaluating the effect of high-energy milling (HEM) and traditional nixtamalization (TN) on bioactive compounds and antioxidant capacity in nixtamalized creole corn flours obtained from a maize genotype cultivated under rainy temporal conditions in the Mexican semidesert. Four creole grains, including San José de Gracia white and blue (WG and BG), Negritas (NG), and Ahualulco white corn grains (SG), were used. For HEM nixtamalization, corn grains were hammer-milled; then, two different conditions were evaluated: treatment H1, with raw flours with 14% moisture content and 1.1% Ca(OH)2, and treatment H2, with raw corn flours with a 23% moisture content and 1.4% Ca(OH)2. The TN process was utilized as a control. TN recorded significant losses in luminosity value L* (p < 0.05), while HEM nixtamalized blue corn flours remained close to -b* values, that is, near to those of raw flour. Anthocyanin content showed higher content values in HEM treatments compared with TN (759.55 and 252.53 mg cyanidin 3-O-β-D-glucoside (C3G)/kg, respectively) (p < 0.05). Total soluble phenolic content was higher in HEM nixtamalization compared with the traditional process, except for WH2 and SH2 (H2 treatment for WG and SG). Two redundant radical scavenging assays were used: antioxidant capacity (DPPH assay) exhibited less value in nixtamalized flours than in raw flour (p < 0.05). Antioxidant activity by (ABTS) assay was higher in HEM than in TN. Nixtamalized flours produced by HEM demonstrated more improvement in nutraceutical properties than those produced employing TN.
(2) Tan Y, Yi X, Wang L, Peng C, Sun Y, Wang D, Zhang J, Guo A, Wang X. -- Comparative Proteomics of Leaves from Phytase-Transgenic Maize and Its Non-transgenic Isogenic Variety. Front Plant Sci. 2016 Aug
Abstract. To investigate unintended effects in genetically modified crops (GMCs), a comparative proteomic analysis between the leaves of the phytase-transgenic maize and the non-transgenic plants was performed using two-dimensional gel electrophoresis and mass spectrometry. A total of 57 differentially expressed proteins (DEPs) were successfully identified, which represents 44 unique proteins. Functional classification of the identified proteins showed that these DEPs were predominantly involved in carbohydrate transport and metabolism category, followed by post-translational modification. KEGG pathway analysis revealed that most of the DEPs participated in carbon fixation in photosynthesis. Among them, 15 proteins were found to show protein-protein interactions with each other, and these proteins were mainly participated in glycolysis and carbon fixation. Comparison of the changes in the protein and tanscript levels of the identified proteins showed that most proteins had a similar pattern of changes between proteins and transcripts. Our results suggested that although some significant differences were observed, the proteomic patterns were not substantially different between the leaves of the phytase-transgenic maize and the non-transgenic isogenic type. Moreover, none of the DEPs was identified as a new toxic protein or an allergenic protein. The differences between the leaf proteome might be attributed to both genetic modification and hybrid influence.
Tan Y, Tong Z, Yang Q, Sun Y, Jin X, Peng C, Guo A, Wang X. Proteomic analysis of phytase transgenic and non-transgenic maize seeds. Sci Rep. 2017 Aug 23;7(1):9246. doi: 10.1038/s41598-017-09557-8.
Abstract. Proteomics has become a powerful technique for investigating unintended effects in genetically modified crops. In this study, we performed a comparative proteomics of the seeds of phytase-transgenic (PT) and non-transgenic (NT) maize using 2-DE and iTRAQ techniques. A total of 148 differentially expressed proteins (DEPs), including 106 down-regulated and 42 up-regulated proteins in PT, were identified. Of these proteins, 32 were identified through 2-DE and 116 were generated by iTRAQ. It is noteworthy that only three proteins could be detected via both iTRAQ and 2-DE, and most of the identified DEPs were not newly produced proteins but proteins with altered abundance. These results indicated that many DEPs could be detected in the proteome of PT maize seeds and the corresponding wild type after overexpression of the target gene, but the changes in these proteins were not substantial. Functional classification revealed many DEPs involved in posttranscriptional modifications and some ribosomal proteins and heat-shock proteins that may generate adaptive effects in response to the insertion of exogenous genes. Protein-protein interaction analysis demonstrated that the detected interacting proteins were mainly ribosomal proteins and heat-shock proteins. Our data provided new information on such unintended effects through a proteomic analysis of maize seeds.
Corn 
Beauveria bassiana
