*Carotenoids in Cassava (*Manihot esculenta *Crantz) DOI: http://dx.doi.org/10.5772/intechopen.105210*

#### **Table 1.**

*Carotenoids from cassava and other tuber crops (fresh weight).*

and cocoyam also had higher all trans β-carotene content across the accessions studied. The mean value of this carotenoid was higher in cassava, as stated in Ceballos et al. [5], compared with yam and cocoyam. Mean for TCC quantified by HPLC ranged from 2.73 to 11.51 μg/g. In yam, the TCC varied among the studied genotypes. The variety of cocoyam studied had high TCC (14.79 μg/g) compared with yam (11.99 μg/g).

## **4. Various prediction tools for carotenoids in Cassava**

Selection for a trait can be made based on phenotypes or genotype using molecular tools. The physical outlook of organisms, which includes all seen and quantitative characters that can be accessed from the outer part of the plant, is the phenotype. This comprises attributes that provide structural phenotypic information such as counts, dimensions, colors, etc., as well as physiological attributes such as photosynthetic efficiencies, water content, surface properties, etc., resulting from genotype and environmental interactions [50].

Carotenoid phenotyping in cassava is very essential as it measures and quantifies its total carotene content. To ensure optimal quality of breeding programs, there must be an understanding of crop genotype interaction with the environment, and this is expressed by the proceeding genotypes and monitored by phenotyping [51]. As breeding for higher carotenoid levels in cassava advances, selection is a major drawback, as some means of predicting total carotenoid content may be really expensive such as the use of high-performance liquid chromatography.

Further, color intensity in cassava roots has been observed to be closely related to quantity of carotenoids in the roots [10]. While visual selection is useful for separating white from yellow root cassava, it cannot efficiently distinguish the salient differences between yellow roots. Other methods exist to quantify carotenoids or check color intensity such as the use of near-infrared spectroscopy (NIRS) [8], but here, we compare some frequently used phenotyping methods for carotenoids in cassava.

Different instruments employed to predict carotenoids in cassava roots are as itemized below:

#### **4.1 Near-infrared spectroscopy (NIRS)**

This technique measures the interrelationship between electromagnetic radiation and the vibrational properties of chemical bonds, which results in the absorption of part of the radiation energy. The visible spectra cover between 380 nm and 780 nm and capture mainly information on pigmentation due to the carotenoids present in the root [52]. NIRS aims to analyze a sample such as to get from it qualitative and quantitative information about its physical and chemical composition. This it does by treating spectra mathematically so as to obtain the relevant information in the spectra, which is connected to the character of interest [44]. Its principle of action involves calibration of the spectrometer in order to develop mathematical models that will connect the standard values to a linear combination of the values of absorbance. NIRS allows the timely screening of many samples and variables and measures samples in different states, i.e., both in solid and liquid forms. When compared with other phenotyping methods, it is a fast and nondestructive alternative for analyzing several constituents simultaneously while requiring minimal to no sample preparation. It is economical and possesses no hazard to the environment [53].

The NIRS provides quality phenotyping method for field-based breeding programs especially where there are no standard laboratories, therefore reducing the need to transport samples from the field while also cutting out the need for sample procession [8, 53]. In NIRS, calibration and data obtained can be shared between spectrometers, thus increasing the chances of developing a network of high-throughput phenotyping technique for screening cassava roots [9].
