Resistant Starch from Isolated White Sorghum Starch: Functional and Physicochemical Properties and Resistant Starch Retention After Cooking. A Comparative Study

Abstract

In an effort to promote the formation of resistant starch (RS), four different modification methods are applied to isolated white sorghum (WS) starch by subjecting the latter to heat‐moisture treatment (RSa), annealing (RSb), hydrolysis through pullulanase debranching enzyme (RSc), and dual autoclaving‐cooling cycles (RSd). Functional and physicochemical properties, individual RS content, and the behavior after cooking in terms of apparent RS retention (aRSr) of samples (i.e., WS, RSa, RSb, RSc, and RSd) are compared. Differences in thermal and pasting properties, in the ratio of ordered starch to amorphous starch, along with lower solubility and swelling power values, and greater water absorption capacity are measured in the four RS ingredients when compared to native WS starch. All the four modification methods prove to be similarly effective in increasing the amount of RS with respect to native WS starch, with an average 30% increase. However, based on the aRSr values, analyses revealed that the greater heat stability after cooking was obtained for RSb (93.7%) and decreased in the order of RSb>RSc>RSa = RSd>WS. Present results shed light on the properties of modified WS starch as a potential heat‐stable source of RS for food applications.

Characterization of Prata Banana (Musa AAB‐Prata) Starch: Native and Modified by Annealing

“…The annealing provides the rearrangement of ordered structure. Amylose–amylose interactions, which are considerably stronger than those of amylose–amylopectin or amylopectin–amylopectin, may restrict the accessibility of starch chains to enzyme action . The resistance to enzymatic digestion is also afforded by the interactions between amylose and amylopectin which provide starch a regular arrangement in the crystalline region .…”

In vitro evaluation of fermentation characteristics of type 3 resistant starch

“…Two novel RS-rich ingredients were also included (Table 1). In particular, novel retrograded sorghum starch (RS3s) was obtained by applying the procedure of annealing to isolated white sorghum starch as detailed by Giuberti et al (2019). After dispersion of isolated sorghum starch in distilled water (1:4 w/v starch to water), the mixture was incubated at 50 C for 24 h under continuous stirring.…”

“…The interest in thermostable forms of RS for possible food application is rising. In particular, thermally stable RS-rich ingredients can be added to foods with the aim to compensate RS losses derived from food processing (Wandee et al, 2017;Giuberti et al, 2019). To date, other than commercial RS3 ingredients (i.e., RS3m and RS3t), novel types of RS have been characterized for potential food application.…”

“…These methods have been successfully applied to native starch (i.e., source of RS2) with the aim to promote the formation of heat-stable forms of RS by altering to different extent the internal rearrangement of starch. In particular, the annealing method can promote structural changes within the amouphous and crystalline regions of starch, whereas the debranching procedure can allow obtaining greater number of linear short chains from amylopectin, thus contributing to increase the yield of retrograded starch (Giuberti et al, 2017(Giuberti et al, , 2019. These novel RS-rich ingredients have been deeply investigated in terms of functional and physicochemical properties, showing greater thermal stability (measured by differential scanning calorimetry, DSC), differences in the pasting properties (measured by Rapid Visco-Analyzer) as well as in the ratio of ordered starch to amorphous starch (measured by FT-IR analysis) when compared to the RS2 counterparts (Giuberti et al, 2017).…”

“…On the contrary, relatively little information is present on the fermentation behaviour of other types of RS, including RS type 3 (retrograded starch as a result of processing; RS3) (Wandee et al, 2017). This may be concerning since RS3-rich ingredients can promote a greater preservation of RS in cooked food products than the RS2 counterparts, due to a greater thermal stability in most cooking operations (Zhang et al, 2012;Wandee et al, 2017;Giuberti et al, 2019).…”