Characterization of the time evolution of starch structure from rice callus

Oil-in-water emulsion activity and stability of short-term retrograded starches depend on starch molecular size, amylose content, and amylopectin chain length

BACKGROUND

Natural emulsifiers are increasingly preferred by the food industry to meet consumers' demand for 'clean-label' emulsion products. In the present study, 10 short-term retrograded starches with unique molecular structures were explored to examine the relationships between starch structures and their ability to form stable oil-in-water emulsions.

RESULTS

Waxy maize starch showed the largest value of contact angle and conductivity of emulsion, whereas potato and lentil starch showed the lowest value of contact angle and conductivity of emulsion, respectively. Emulsion prepared by rice starch showed the lowest, whereas that of sweet potato starch showed the highest value of viscosity. Consequentially, the emulsion stabilized with waxy maize and tapioca starch showed the smallest and less polydisperse droplets, resulting in a much higher emulsifying index. On the other hand, emulsion prepared with potato starch showed the highest stability compared to other starches. Correlation analysis suggested that starches with larger molecular size, a lower amylose content and shorter amylopectin short chains had a higher emulsification ability, whereas the amount of starch molecular interactions formed during short-term retrogradation revealed no obvious linking to emulsion performances.

CONCLUSION

These findings provided food industry with exciting opportunities to develop 'clean-label' emulsions with desirable properties. © 2024 Society of Chemical Industry.

The important role of starch fine molecular structures in starch gelatinization property with addition of sugars/sugar alcohols

The relationship between the fine structure of starch and its gelatinization properties is not well studied, particularly in relation to the influence of sugar or sugar alcohol. In this study, seven starches with distinct molecular structures were investigated to determine how different sugars and sugar alcohols affect their gelatinization properties. The inclusion of sugars and sugar alcohols resulted in a significant elevation of starch gelatinization temperatures (∼ 8 °C), especially with sucrose, isomaltose and isomalt. Nevertheless, the influence of these sugars/ sugar alcohols on the gelatinization temperature range and enthalpy change varied depending on the particular starch varieties. According to the correlation analysis, sugars and sugar alcohols mainly exert their impact on the starch gelatinization temperature range and enthalpy change by possibly interacting with amylose chains possessing a degree of polymerization ranging from 100 to 1000 (p < 0.05) and inhibiting the amylose leaching during gelatinization. These findings help a better understanding of the complex relationship between starch fine structure and gelatinization properties under the influence of sugars and sugar alcohols.

Consecutive reaction kinetics model reveals the nature of long-term rice amylopectin retrogradation characteristics

Starch retrogradation involves nucleation and crystal growth steps, while their relative contribution to the overall retrogradation kinetics and relations with starch fine molecular structures have not been elucidated. In this study, a consecutive reaction kinetics model (CRK) was developed to fit long-term retrogradation kinetics curves for 10 rice starches with distinct molecular structures. Starch chain-length distributions (CLDs) and melting enthalpy kinetics curves for these starches were obtained from our published data. It was shown that these melting enthalpy kinetics curves can be satisfactorily deconvoluted by the CRK model into a combination of nucleation and crystal growth curves. Correlation analysis between CRK model-fitted parameters with starch CLDs showed that starch retrogradation nucleation and crystal growth steps were controlled by distinct starch fine molecular structures. These results have practical applications, as it enables a separate regulation of nucleation and crystal growth steps during retrogradation process of starch-based foods for desirable nutritional properties.

Align resistant starch structures from plant-based foods with human gut microbiome for personalized health promotion

Resistant starch (RS) is beneficial for human health through its interactions with gut microbiota. However, the alignment between RS structures with gut microbiota profile and consequentially health benefits remain elusive. This review summarizes current understanding of RS complex structures and their interactions with the gut microbiota, aiming to highlight the possibility of manipulating RS structures for a targeted and predictable gut microbiota shift for human health in a personalized way. Current definition of RS types is strongly associated with starch digestion behaviors in small intestine, which does not precisely reflect their interactions with human gut microbiota. Distinct alterations of gut microbiota could be associated with the same RS type. The principles to describe the specificity of different RS structural characteristics in terms of aligning with human gut microbiota shift was proposed in this review, which could result in new definitions of RS types from the microbial perspectives. To consider the highly variable personal features, a machine-learning algorithm to integrate different personalized factors and better understand the complex interaction between RS and gut microbiota and its effects on individual health was explained. This review contains important information to bring interactions between RS and gut microbiota to translational practice.

Leached starch content and molecular size during sorghum steaming for baijiu production is not determined by starch fine molecular structures

Sorghum steaming properties are important for both flavor and brewing efficiency of baijiu (Chinese alcohol liquor). However, it is currently unclear with respects to structural factors that affect sorghum steaming properties during baijiu production. In this study, starch fine molecular structures were characterized by size-exclusion chromatography and fluorophore-assisted carbohydrate electrophoresis for 8 sorghum varieties used in baijiu production. Starch crystalline structures and ordering of double helices were characterized by the X-ray diffraction and differential scanning calorimetry. Results showed that only small differences were observed for starch molecular size distributions and chain-length distributions in the raw sorghum flour. Of significance, the leached starch content and molecular size during steaming was very different among these sorghum varieties. Furthermore, Spearman correlation analysis showed that there was no significant correlation between starch fine structural parameters with the leached starch content. On the other hand, the correlation analysis showed that leached starch molecular size was negatively correlated with starch crystallinity, while positively correlated with the onset and peak gelatinization temperatures. It is concluded that the sorghum steaming property is controlled by the starch crystalline structures instead of starch fine molecular structures. These results could help the baijiu industry to produce baijiu with more desirable properties.

Causal relations among starch fine molecular structure, lamellar/crystalline structure and in vitro digestion kinetics of native rice starch

Causal relations among starch fine molecular structures, lamellar/crystalline structures, and the in vitro digestion kinetics of native rice starches.

A combined action of amylose and amylopectin fine molecular structures in determining the starch pasting and retrogradation property

Starch fine molecular structures are of essentially important in determining its pasting and retrogradation properties. In this study, 10 different starches from various botanical sources were selected to investigate the combined action of amylose and amylopectin molecules in determining the starch physicochemical properties. Correlation between starch structural parameters with the pasting and retrogradation properties showed that amylose and amylopectin CLDs do not affect these properties in isolation. Such as, the amount of amylose long chains and amylopectin short chains are both positively correlated with the melting temperatures and enthalpy of retrograded starches. Furthermore, relatively longer amylose short to medium chains can result in higher trough and breakdown viscosity, while higher amount of amylopectin medium to long chains result in higher peak viscosity. The results help a better understanding of the importance of amylose and amylopectin fine molecular structures in determining starch functional properties.

Diurnal changes in Sorghum leaf starch molecular structure

Control of the fine structure of transitory starch synthesized during the day in leaves is required for its normal degradation during the subsequent night. In this study, the molecular structure of transitory starch from Sorghum leaves over the diurnal cycle was characterized using size-exclusion chromatography. This is the first study of diurnal changes in the chain-length distribution (CLD) of amylopectin and amylose over the entire range of chain lengths, and in the size distribution of whole starch molecules. It was found that the outer layers of leaf starch granules, which were synthesized during the daytime and degraded during the night, contained more large molecules, including amylopectin with more short chains and more branching, than those in the inner layers. The outer layers also had lower amylose content. Starch molecular sizes in leaves are much smaller than in grain starch. The starch structures observed are likely to give optimal energy control during plant growth. Lack of this control may contribute to poor plant growth.