**2.7. Applications of pigmented corn anthocyanins**

**2.4. Anthocyanin in pigmented corn husk**

78 Corn - Production and Human Health in Changing Climate

is different from other parts.

Purple corn (hybrid maize) kernel

Purple corn silk (*Zea mays* L. var. ceratina)

Husk is the least studied part of the corn; there is limited research about their anthocyanin composition; however, they had a high concentration of anthocyanins depending on corn variety [20]. Most recent reports show a deeper studied of the type of anthocyanins in purple husk which has more anthocyanin diacylated [19] but there is other report that found cyaniding-3-succinylglucoside instead of diacylated anthocyanin [20]. For that reason, more research is needed; due to the low information, it is not possible to ensure that corn husk composition

Extraction of anthocyanin is made with methanol solvent acid and the method most used is ultrasound-assisted extraction that shows better efficiency, although, microwave-assisted extraction, ohmic heating extraction and supercritical solvent extraction are also used. Liquid chromatography techniques are the most used in anthocyanin identification. **Table 2** shows

Structural anthocyanins have conjugation that provides stabilization of free radicals. Antioxidant activity is plenty reported in pigmented corn. Additionally, anthocyanin extract of pigmented corn has been used in *in vitro* and *in vivo* assays, **Table 3** shows some of the

**Extract of anthocyanin Biological activity Ref.** Red corn Inhibition proliferation of colorectal cancer cell *In vitro* Cell

> blood pressure, total cholesterol and plasma triglycerides. Improve glucose tolerance, liver and cardiovascular structure

Purple waxy corn cob Neuroprotective and memory enhancing effect [46]

Blue tortillas Learning capability In rats diet [47]

Cardioprotective activity In vitro [43]

Anti-obesity agent [21]

Purple corn Inhibition proliferation of colorectal cancer cell *In vitro* Cell

Purple maize flour Reduce visceral adiposity index, total body fat mass, systolic

Purple corn pericarp Adipogenesis, inflammation and insulin resistance in

and function

adipocytes

**Table 3.** Biological activity found in purple corn.

lines

lines

*In vivo* In rats diet

*In vitro* [45]

[42]

[42]

[44]

**2.5. Extraction methods and characterization of anthocyanins in pigmented corn**

the extraction methods used until 2018 and the anthocyanin content.

**2.6. Biological activity of pigmented corn anthocyanins**

activities studied where anti-obesity is the most recurrent.

Purple corn is used traditionally to make tortillas, atole, chips, popcorn and other type of food products. However, chemical studies of these food products are limited. Food industry is more interested in elaboration of products with a major quality and bioactive compounds content; in consequence, the development of new products with purple corn have been the most studied. Some of the developed products are presented in **Table 4**, where the main purpose was to find the best process to keep the major anthocyanins concentration.

Additionally, the anthocyanins are used to make photosensitizers from different colored parts of the corn including cob, husk and silk.

Furthermore, due to the low stability of anthocyanins, there are some studies related to this topic. The stability of anthocyanins has been improved using intermolecular copigmentation with gallic ferulic, caffeic acids, and results show that those acids do not protect the anthocyanins only have a hypochromic effect. There is a better protection by self-association. Other strategy is the encapsulated of anthocyanins in alginate-pectin hydrogel [49] and the spray-dried purple corn found that 5% of maltodextrin, 150°C and water are the best condition to obtain a soluble product with the major anthocyanin concentration [50]. Haggard in 2018 also found that beverage with more pelargonidin-3-glucoside concentration has a major half-life [10].


**Table 4.** Use of anthocyanins found in pigmented corn.
