Scanning Electron Microscopy and Crystallinity of starches granules from cowpea, black and carioca beans in raw and cooked forms

Abstract

Beans are a vital food for the population around the world because it contains a relatively high amount of protein, vitamins, fiber, and minerals, being an important vegetable source of iron, particularly when combined with ascorbic acid and cysteine. The starch content in the seed is between 45 and 60%. This paper evaluated the granular structure of starches from common beans (Phaseolus vulgaris) and cowpea (Vigna unguiculata) in raw and cooked forms by Scanning Electron Microscopy (SEM), and their crystallinity by X-ray diffraction (DR-X). By SEM, was observed the occurrence of gelatinization phenomenon in cowpea and carioca beans, and the resistance to this event in black beans. By DR-X, the diffraction angles found in this work are more consistent with the classification of the standard polyphorm A. The Relative Crystallinity (RC) of black bean cowpea and carioca beans, observed by X-ray diffraction, varied significantly.

Xanthosoma riedelianum starch for use in the food industry

“…The crystallinity index, determined from the total areas and peaks of the X-ray diffractograms, is an important parameter that influences the physical, mechanical, and technological properties of starch. The crystallinity found for X. riedelianum starch was of 41.20%, considered high, but within the range suggested by Miranda et al (2019), between 15 and 45% for native starches. Higher values like the one obtained in the present study imply greater granular stability, which, consequently, reduces the swelling capacity of the granule, making it more resistant to the gelatinization process (Singh et al, 2004).…”

Starch Granules from Cowpea, Black, and Carioca Beans in Raw and Cooked Forms

“…In image A, the ellipsoid format of the starch granule is visualized (magnification 9.81 Kx), and in image B it is possible to observe the presence of cracks on the surface of the granule (magnification of 19.89 Kx), both refer to raw samples. The images of cooked samples (C magnification of 275 x and D and 29.01 Kx) reveal the stable structure of the black bean seed, suggesting a relation with the difficulties in its cooking (HTC phenomenon), requiring a longer cooking time for complete gelatinization, compared to the other samples studied [28]. Ambigaipalan et al [26], by SEM images, did not find the presence of cracks in black bean grains.…”

“…In image A granules of starch attached to the cotyledon cell wall and its reniform shape (magnification 5.52 Kx) can be visualized, and in B bulges on the surface of the granule (magnification 30.36 Kx) can be perceived, both refer to raw samples. In the images of cooked samples with different optical amplifications (C 400 x and D 19.14 Kx), it is noticed that the starch granules were grouped, losing their crystalline structure due to gelatinization [28].…”

“…In image A, the ellipsoid formed of the starch granules (magnification 6.00 Kx) is observed, and in image B one perceives protrusions on the surface of the granule (magnification 15.61 Kx), both refer to raw samples. In the images of cooked samples (C 370 x and D 15.61 Kx), with different optical amplifications, it is noticed that the starch granules were grouped, losing their crystalline structure due to gelatinization [28].…”

A review on the physicochemical properties and potential food applications of cowpea (Vigna unguiculata) starch

“…The morphology of CS (Fig. 1) has been widely studied using scanning electron microscopy (SEM) (Abu et al , 2006; Huang et al , 2007; Ashogbon & Akintayo, 2013; Kaptso et al , 2016; Ratnaningsih et al , 2016; Miranda et al , 2019; Ratnaningsih et al , 2020; Rengadu et al , 2020a). However, some authors also used a light microscope (LM) to explain the morphology of CS (Agunbiade & Longe, 1999; Mwangwela et al , 2007; Atuobi et al , 2011).…”