**2. Purple corn cob is a rich source of bioactive compounds**

The current state of knowledge shows us that purple corn cob represents a rich source of phenolic compounds, especially phenolic acids, flavonoids, and anthocyanins [6, 7].

Purple corn gained attention mainly because of its rich content in anthocyanins, but comparing the seeds (0.5–6.8 mg/g fresh weight) with the cob, the reported values regarding anthocyanins content were higher for the latest (0.8–71.5 mg/g fresh weight) [4].

Based on the previous statement, our focus is on a purple corn cob, as the anthocyanins content makes them potential contributors as natural colorants, varying from blue to red tonalities. Despite their great coloring capacity, these compounds have been increasingly used in the food industry due to their ability to confer bioactive properties to the products [8]. Along with a great coloring capacity, anthocyanins act as antioxidants and antibacterial compounds and help prevent cardiovascular diseases, cancer, diabetes, and have neuroprotective effects [9–13].

Regarding the anthocyanins content, some researchers characterized the purple corn cob. Among them, Díaz-García et al., obtained higher values than other studies, 41.32 ± 0.95 mg C3GE/g DW, compared with 9.30–15.16 mg C3GE/g DW, both using pH differential measurement [4, 14]. Using the same method, Lao and Giusti [15] obtained for the purple corn cob values ranging from 3.1 to 100.3 mg C3G/g. By using a conventional spectrophotometric method, Pascual-Teresa et al. obtained 34 g per 100 g powder, expressed in cyanidin-3-monoglucoside [16]. Another study showed that the anthocyanin content of purple corn cob was calculated to be 92.3 ± 2.1 mg/100 g, expressed in cyanidin-3-glucoside [17]. A much higher value of anthocyanins was presented in another study, where the authors obtained 1219.4 mg/100 g [18]. The comparison between the anthocyanin contents in purple corn cob is difficult as there are several factors to consider, including the harvesting region, methods used by researchers, storage time, and genetic differences [19].

The profile of anthocyanins present in purple corn cob has been characterized by Fernandez-Aulis et al., by identifying the structures using HPLC method, are fragments corresponding to cyanidin, pelargonidin, and peonidin, and they are: cyanidin-3-glucoside, cyanidin-3-(6″-malonyl) glucoside, pelargonidin-3-glucoside, peonidin-3-glucoside, pelargonidin-3-(6″-malonyl) glucoside, and peonidin-3-(6″ malonyl) glucoside, which was in accordance with the previous reports. Among these, the main anthocyanin was cyanidin-3-(6″-malonyl) glucoside obtained in case of enzymatic assisted extraction [20]. Moreover, cyanidin-3-(6″-ethylmalonyl) glucoside, pelargonidin-3-(6″-ethylmalonyl) glucoside, and peonidin-3-(6″-ethylmalonyl) glucoside are three more compounds identified by Pascual-Teresa et al. besides those mentioned above [16].

*Purple Corn Cob: Rich Source of Anthocyanins with Potential Application in the Food Industry DOI: http://dx.doi.org/10.5772/intechopen.107258*

**Figure 1.**

*Comparison between rich in anthocyanin sources and purple corn cob based on the concentration (mg/100 g), reported by different authors a—[17], b—[18], c—[14], d—[4], e—[15], f—[16], g—[17], h—[7], i—[21], j— [22], k—[23], l—[24], m—[25], n—[26], o—[27], p—[28], q—[29], r—[30], s—[31], t—[32], u—[33], v—[34].*

The reported results suggest that purple corn cob can be considered a promising source of anthocyanins, and this statement can be strengthened by comparing values with other dietary sources, remarked for their rich content in anthocyanins. As shown in **Figure 1**, purple corn cob is a valuable waste that can be successfully used as a rich source of anthocyanins, and by this, an important number of applications can be taken into consideration.

Throughout the years, purple corn gained attention due to its recognized antioxidant property, becoming consumed as food, but also incorporated in new products, fact highlighted too by international data bases, as in 2009, Peru exported total value of US\$9,782,564, while in 2013, the export reached the approximate value of US\$17,981,398 [19, 35]. In 2015, AgriFutures Australia reported a total of 7000 tones as being traded globally each year, with the majority producer, Peru, and for 348 tones, China [36]. National Institute of Statistics and Information Science analyzed the purple corn production index from 1990 to 2018, highlighting the fact that the data reached an all-time high in April 2018 [37]. As the production is rising and the consumption per capita has increased from 6.8 to 12.3 kg per year [19], the amount of generated waste is also recording higher values, the cob representing 15% of the purple corn ear [38]. Also, taking into consideration its richness in bioactive compounds and its growing range of applications, purple corn cob is becoming a topic of interest for future studies.
