**6. Conclusions**

**5. Changes of phenolic compounds during processing (nixtamalization)** 

Nixtamalization results in multiple changes in the chemical components of the maize grain. Under the traditional process, the cooking water has high pH (∼12) which hydrolyzes the ester bond by which ferulic acid is linked to cell wall components. The grain structure that is mostly affected by this process is the pericarp, which becomes partially or fully hydrolyzed [45, 46]. As the most abundant phenolic in the grain, the hydrolysis of the ester linkage between the ferulic acid and the cell wall components causes the soluble fraction to be higher in nixtamalized maize products relative to that found in the whole grain, white maize. However, in colored maize that contains anthocyanin pigments, the soluble fraction is reduced due to the significant loss of anthocyanins [47–49]. According to the information presented in **Table 4**, in white maize grain soluble pheno‐ lics increase by about 26% when the grains are processed into tortillas, while in red maize grain, they are reduced by 20%. The magnitude of the reduction varies according to the grain color and the origin of the genetic material. The cooking of the tortilla results in an additional loss of pheno‐

**SP IP TP Ferulic References**

Raw 34.7 ± 0.4 226.0 ± 6.3 260.7 ± 6.1 120.45 De la Parra et al. [48]

Raw 167.4 474.49 Mora‐Rochin et al. [49]

Raw 38.2 ± 0.4 205.6 ± 4.5 243.8 ± 4.6 130.3 De la Parra et al. [48]

Raw 149.2 532.16 Mora‐Rochin et al. [49]

Raw 45.5 ± 0.5 220.7 ± 0.5 266.2 ± 0.7 123.01 De la Parra et al. [47]

Raw 140.1 336.49 Mora‐Rochin et al. [49]

SP: soluble phenolics; IP: insoluble phenolics; TP: total phenolics; WG: white grain; RG: red grain; BG: blue grain.

**(mg FAE/100 g DW)**

When nixtamalization is performed by the extrusion method, total phenolic losses in maize grain are lower than those resulting from the traditional method [49]. The differences were

**Table 4.** Phenolic compounds in raw grain and tortillas obtained by the traditional nixtamalization process, from maize

lic compounds, but much less significant that resulting from nixtamalization [47].

Tortilla 47.2 ± 1.8 119.0 ± 6.2 166.2 ± 6.2 85.16

Tortilla 85.4 101.66

Tortilla 30.5 ± 0.7 106.0 ± 3.6 136.5 ± 2.9 73.83

Tortilla 89.8 208.12

Tortilla 39.1 ± 1.5 122.7 ± 0.6 161.8 ± 2.1 101.36

Tortilla 86.3 187.79

**of maize grain**

**Phenolic compounds in maize grain**

WG

RG

BG

grains with different colors.

**(mg GAE/100 g** 

226 Phenolic Compounds - Natural Sources, Importance and Applications

**DW)**

Phenolic compounds are present in the maize grain in free or soluble and bound or insoluble form. The insoluble fraction is the most abundant, but the most chemically diverse is the soluble fraction. There exists greater diversity of phenolic compounds in the grain of maize with anthocyanin‐type pigments than in the white maize grain. Phenolic acids are the most abundant phenolic compounds in maize grain, followed by flavonoids, particularly antho‐ cyanins in the blue red and purple maize grain. Phenolic amines are present in the pericarp of white maize grain and grain containing anthocyanin pigments, being most abundant in the latter. Nixtamalization significantly reduces the content of phenolics present in maize grain, in white grain maize, they are lost mainly as ferulic acid, while in the maize grain that con‐ tains anthocyanin pigments, in addition to ferulic acid, anthocyanins are almost entirely lost.
