Retrogradation of sweet potato amylose and amylopectin with narrow molecular weight distribution

Resistant starch from yam: Preparation, nutrition, properties and applications in the food sector

Yam is a significant staple food and starch source, particularly in tropical and subtropical regions, holding the fourth position among the world's top ten tuber crops. Yam tubers are rich in essential nutrients and a diverse range of beneficial plant compounds, which contribute to their multifaceted beneficial functions. Furthermore, the abundant starch and resistant starch (RS) content in yam can fulfil the market demand for RS. The inherent and modified properties of yam starch and RS make them versatile ingredients for a wide range of food products, with the potential to become one of the most cost-effective raw materials in the food industry. In recent years, research on yam RS has experienced progressive expansion. This article provides a comprehensive summary of the latest research findings on yam starch and its RS, elucidating the feasibility of commercial RS production and the technology's impact on the physical and chemical properties of starch. Yam has emerged as a promising reservoir of tuber starch for sustainable RS production, with thermal, chemical, enzymatic and combination treatments proving to be effective manufacturing procedures for RS. The adaptability of yam RS allows for a wide range of food applications.

Formation and Application of Starch-Polyphenol Complexes: Influencing Factors and Rapid Screening Based on Chemometrics

Understanding the nuanced interplay between plant polyphenols and starch could have significant implications. For example, it could lead to the development of tailor-made starches for specific applications, from bakinag and brewing to pharmaceuticals and bioplastics. In addition, this knowledge could contribute to the formulation of functional foods with lower glycemic indexes or improved nutrient delivery. Variations in the complexes can be attributed to differences in molecular weight, structure, and even the content of the polyphenols. In addition, the unique structural characteristics of starches, such as amylose/amylopectin ratio and crystalline density, also contribute to the observed effects. Processing conditions and methods will always alter the formation of complexes. As the type of starch/polyphenol can have a significant impact on the formation of the complex, the selection of suitable botanical sources of starch/polyphenols has become a focus. Spectroscopy coupled with chemometrics is a convenient and accurate method for rapidly identifying starches/polyphenols and screening for the desired botanical source. Understanding these relationships is crucial for optimizing starch-based systems in various applications, from food technology to pharmaceutical formulations.

Effects of three glutenins extracted in acidic, neutral and alkaline urea solutions on the retrogradation of wheat amylose and amylopectin

Three glutenins (glutenin 1, glutenin 2, and glutenin 2) were extracted in acidic, neutral and alkaline urea solutions respectively. All of the three glutenins are rich in glutamic acid (Glu, >30 %) and proline (Pro, >20 %). Glutenin 1, extracted at pH 5, shows higher contents of hydrophilic amino acids as serine (Ser, 5.25 %), aspartic acid (Asp, 2.99 %), tyrosine (Tyr, 3.11 %), arginine (Arg, 2.09 %) and threonine (Thr, 2.11 %) than the other two glutenins. The retrogradation of three glutenins with amylose/amylopectin indicated that glutenin 1 showed significant inhibition effect on the retrogradation of wheat amylose. The characterizations of amylose retrograded with glutenin 1 by FT-IR, XRD, DSC and solid ¹³C NMR showed that new hydrogen bonds between Glu, Tyr and wheat amylose were formed, which prevented the formation of hydrogen bonds between amylose themselves. Glycosidic bonds between some hydroxyl groups of C6 in wheat amylose and certain hydroxyl groups of Ser and Thr in glutenin with specific chain length were present. The macromolecules with steric hindrance prevented the rearrangement of amylose into regular crystals. The retrogradation of wheat amylose was inhibited in this way. This study provides a key targeting step to control the retrogradation of amylose.

Effect of protein-starch interactions on starch retrogradation and implications for food product quality

Starch retrogradation is a consequential part of food processing that greatly impacts the texture and acceptability of products containing both starch and proteins, but the effect of proteins on starch retrogradation has only recently been explored. With the increased popularity of plant-based proteins in recent years, incorporation of proteins into starch-based products is more commonplace. These formulation changes may have unforeseen effects on ingredient functionality and sensory outcomes of starch-containing products during storage, which makes the investigation of protein-starch interactions and subsequent impact on starch retrogradation and product quality essential. Protein can inhibit or promote starch retrogradation based on its exposed residues. Charged residues promote charge-dipole interactions between starch-bound phosphate and protein, hydrophobic groups restrict amylose release and reassociation, while hydrophilic groups impact water/molecular mobility. Covalent bonds (disulfide linkages) formed between proteins may enhance starch retrogradation, while glycosidic bonds formed between starch and protein during high-temperature processing may limit starch retrogradation. With these protein-starch interactions in mind, products can be formulated with proteins that enhance or delay textural changes in starch-containing products. Future work to understand the impact of starch-protein interactions on retrogradation should focus on integrating the fields of proteomics and carbohydrate chemistry. This interdisciplinary approach should result in better methods to characterize mechanisms of interaction between starch and proteins to optimize their food applications. This review provides useful interpretations of current literature characterizing the mechanistic effect of protein on starch retrogradation.

Effects of Amylopectins from Five Different Sources on Disulfide Bond Formation in Alkali-Soluble Glutenin

Wheat, maize, cassava, mung bean and sweet potato starches have often been added to dough systems to improve their hardness. However, inconsistent effects of these starches on the dough quality have been reported, especially in refrigerated dough. The disulfide bond contents of alkali-soluble glutenin (ASG) have direct effects on the hardness of dough. In this paper, the disulfide bond contents of ASG were determined. ASG was mixed and retrograded with five kinds of amylopectins from the above-mentioned botanical sources, and a possible pathway of disulfide bond formation in ASGs by amylopectin addition was proposed through molecular weight, chain length distribution, FT-IR, ¹³C solid-state NMR and XRD analyses. The results showed that when wheat, maize, cassava, mung bean and sweet potato amylopectins were mixed with ASG, the disulfide bond contents of alkali-soluble glutenin increased from 0.04 to 0.31, 0.24, 0.08, 0.18 and 0.29 μmol/g, respectively. However, after cold storage, they changed to 0.55, 0.16, 0.26, 0.07 and 0.19 μmol/g, respectively. The addition of wheat amylopectin promoted the most significant disulfide bond formation of ASG. Hydroxyproline only existed in the wheat amylopectin, indicating that it had an important effect on the disulfide bond formation of ASG. Glutathione disulfides were present, as mung bean and sweet potato amylopectin were mixed with ASG, and they were reduced during cold storage. Positive/negative correlations between the peak intensity of the angles at 2θ = 20°/23° and the disulfide bond contents of ASG existed. The high content of hydroxyproline could be used as a marker for breeding high-quality wheat.