Effects of Chain Length and Degree of Unsaturation of Fatty Acids on Structure and in Vitro Digestibility of Starch–Protein–Fatty Acid Complexes

Abstract

The effects of chain length and degree of unsaturation of fatty acids (FAs) on structure and in vitro digestibility of starch-protein-FA complexes were investigated in model systems. Studies with the rapid visco analyzer (RVA) showed that the formation of ternary complex resulted in higher viscosities than those of binary complex during the cooling and holding stages. The results of differential scanning calorimetry (DSC), Raman, and X-ray diffraction (XRD) showed that the structural differences for ternary complexes were much less than those for binary complexes. Starch-protein-FA complexes presented lower in vitro enzymatic digestibility compared with starch-FAs complexes. We conclude that shorter chain and lower unsaturation FAs favor the formation of ternary complexes but decrease the thermal stability of these complexes. FAs had a smaller effect on the ordered structures of ternary complexes than on those of binary complexes and little effect on enzymatic digestibility of both binary and ternary complexes.

Starch–lipid and starch–lipid–protein complexes: A comprehensive review

“…A model system containing sorghum starch, whey proteins, and FAs (palmitic acid [PA], oleic acid, or linoleic acid) showed a prominent viscosity peak during the RVA cooling (i.e., setback) stage and a HPSEC peak that eluted between the amylose and amylopectin peaks; these observations were attributed to the formation of starch–lipid–protein complexes (Zhang & Hamaker, 2004; Zhang et al., 2003). Subsequent studies using different starch–lipid–protein mixtures confirmed the formation of ternary complexes (Shah et al., 2011; Wang et al., 2017; Zhang & Hamaker, 2004; Zhang et al., 2010, 2018). Addition of long chain FAs alone (e.g., PA, oleic acid, or linoleic acid) to starch has a small effect on final pasting viscosity during the setback stage (Figure 2a), whereas the addition of βLG to these starch–FA pasting systems led to the occurrence of a distinct viscosity peak during this stage of RVA protocol (Figure 2b).…”

“…Addition of long chain FAs alone (e.g., PA, oleic acid, or linoleic acid) to starch has a small effect on final pasting viscosity during the setback stage (Figure 2a), whereas the addition of βLG to these starch–FA pasting systems led to the occurrence of a distinct viscosity peak during this stage of RVA protocol (Figure 2b). The addition of βLG to pasting systems containing starch and medium chain FAs (e.g., lauric acid [LA] and decanoic acid) increases the intensity of the cooling stage viscosity peak, compared to the corresponding starch–FA mixture (Figure 2c) (Wang et al., 2017; Zheng et al., 2018). These studies further confirmed that starch, FAs, and protein can form ternary complexes during a heating–cooling process.…”

“…In contrast, ternary complexes did not form in a model system containing starch, monoglyceride, and βLG during RVA pasting (Chao et al., 2018). Differential scanning calorimetry (DSC) and XRD studies of the ternary complex indicate that the aliphatic tail of the FA interacts with amylose, whereas the negatively charged carboxyl group of the FA associates with the protein; amylose, as a neutral molecule, is not considered to contribute to the ionic interactions (Wang et al., 2017; Zhang & Hamaker, 2004; Zheng et al., 2018).…”

“…In some cases, the assembly of amylose–lipid complexes is facilitated by protein molecules (Chao et al., 2018; Wang, Wang, Liu, Wang, & Copeland, 2017; Zhang & Hamaker, 2004; Zhang, Maladen, & Hamaker, 2003; Zhang, Maladen, Campanella, & Hamaker, 2010; Zheng et al., 2018). Several studies have confirmed the formation of ternary starch–lipid‐protein complexes during food processing, which led to alterations in starch properties such as pasting and gelatinization, digestion rate, and rheological behavior (Shah, Zhang, Hamaker, & Campanella, 2011; Wang et al., 2017; Zhang & Hamaker, 2003, 2005; Zheng et al., 2018).…”

“…In some cases, the assembly of amylose–lipid complexes is facilitated by protein molecules (Chao et al., 2018; Wang, Wang, Liu, Wang, & Copeland, 2017; Zhang & Hamaker, 2004; Zhang, Maladen, & Hamaker, 2003; Zhang, Maladen, Campanella, & Hamaker, 2010; Zheng et al., 2018). Several studies have confirmed the formation of ternary starch–lipid‐protein complexes during food processing, which led to alterations in starch properties such as pasting and gelatinization, digestion rate, and rheological behavior (Shah, Zhang, Hamaker, & Campanella, 2011; Wang et al., 2017; Zhang & Hamaker, 2003, 2005; Zheng et al., 2018). The water solubility of some proteins (e.g., β‐lactoglobulin [βLG]) allows the starch–lipid–protein complexes to be dispersed in aqueous solution so that it can be used as a nanocarrier for small water‐insoluble molecules, thus broadening the range of potential applications such complexes for the delivery and release of bioactives (Bhopatkar et al., 2015; Feng et al., 2017; Wang, Zheng, & Chao, 2019; Zhang, Bhopatkar, Hamaker, & Campanella, 2015).…”