Production of Esterified Starches with Increased Resistant Starch Content by an α‐Hydroxy Acid‐Catalyzed Route

Abstract

Resistant starch (RS) refers to the portion of starch that is not broken down by human enzymes in the small intestine, and thus reaches the large bowel of healthy individuals. In the large bowel RS is fermented by colonic microflora producing short chain fatty acids (SCFA) – predominantly acetate, propionate, and butyrate – that are known to contribute substantially to large bowel health. Currently, there is an increasing interest in obtaining RS by esterification of starch with target SCFA, due to its capacity to deliver significant quantities of the particular esterified SCFA to the colon. In the current contribution an α‐hydroxy acid‐catalyzed methodology, which has recently proven useful for esterifying starch, was used to produce acetylated, propionylated, and butyrylated corn starch samples with varying degree of substitution (DS) (0.05–0.75). Results showed the suitability of the route to produce the RS4 starch type, with RS contents that increased with DS as a consequence of a larger steric hindrance effect caused by a higher number of ester groups introduced. Data also indicated that the DS conferred to starch was the key factor conditioning its resistance, whereas RS content showed to be independent of the resulting esterified starch structure and the type of ester group introduced.

A Green Process for Starch Oleate Synthesis by Cryptococcus sp. MTCC 5455 Lipase and Its Potential as an Emulsifying Agent

“…This suggested that crystallinity of starch was damaged on esterification and the molecular structure changed from a double helix pattern to a V‐ type single helix pattern. Similar changes in structure of acetylated and propionylated corn starch were reported by Han et al and Tupa et al…”

Potentially Health-Promoting Spaghetti-Type Pastas Based on Doubly Modified Corn Starch: Starch Oxidation via Wet Chemistry Followed by Organocatalytic Butyrylation Using Reactive Extrusion

“…Two solid-state 13 C CP MAS NMR peaks, attributed to carbonyl groups, were evidenced at ~173 and ~183 ppm for all pasta systems evaluated ( Figure 1 ). The first peak (~173 ppm) can be related to the newly formed ester linkage, whilst the second peak (~183 ppm) can be attributed to the unesterified Bu in the manner of BuAc [ 29 ]. This confirms that the butyrylation reaction occurred on the starch structure in all Bu-containing pasta systems in the presence and absence of the organocatalyst, and that unesterified Bu residues unavoidably persist in all pasta systems ( Figure 1 ).…”

“…However, another 13 C NMR peak between 31 and 33 ppm was also displayed for all pasta systems, which can only be related to the -CH 2 - linkages of the newly created ester groups. On the other hand, typical 13 C NMR peaks located between 20 and 30 ppm can only be exhibited due to the butyrylation reaction given on the starch [ 29 ]. This confirms that the butyrylation reaction occurred on both NSt and OSt, thus obtaining spaghetti-type pasta systems based on butyrylated starch for the first case, and doubly modified (oxidized-butyrylated) for the second case.…”

“…In contrast, An [ 26 ] observed an opposite trend, which was attributed to the fact that oxidation hydrolytically degraded amylopectin and amylose (specifically in the amorphous regions of starch – amylose), thus facilitating the action of α-amylase. Likewise, the chemical modification of starch via organocatalytic esterification reaction using short-chain fatty acid (SCFA) precursors such as sodium butyrate (C 4 H 7 NaO 2 —NaBu) has been little studied in order to (1) increase the RS content [ 27 , 28 , 29 ], (2) raise the beneficial effect they cause on colon health [ 30 , 31 , 32 , 33 ], (3) regulate cholesterol in the blood [ 34 ], (4) modulate oxidative stress of colonic mucosa [ 35 ] and (5) enhance the growth of the colonic probiotic microbiota [ 36 , 37 , 38 , 39 , 40 , 41 ]. Additionally, the use of NaBu as a precursor of Bu to be grafted (esterified) onto the starch structure with the aim of obtaining REx-processed butyrylated starches has not yet been studied.…”

Organocatalytic esterification of polysaccharides for food applications: A review

“…This has also justified the use of green organocatalysts aimed at the synthesis of esterified starches, mainly using acetic, butyric and propionic acids as donor agents (acylant). In this sense, acetylated, butyrylated or propionylated starches can increase the value of starch as dietary fiber (resistant starch) (Tupa et al, 2018), as they can resist amylolysis of the small gut (Annison, Illman, & Topping, 2003). These modified starches can thus be considered as prebiotic with potential health benefits (Annison et al, 2003), since upon reaching the large gut, they can, for example, be fermented by butyrogenic bacteria that are present in the Firmicutes and not in the Bacteroidetes (Hamaker & Tuncil, 2014), thus releasing and/or generating beneficial SCFAs (Annison et al, 2003;Gutiérrez, 2018a,b).…”