Combined ultrasound and germination treatment on the fine structure of highland barley starch

Drying kinetics and quality characteristics of ultrasound-assisted germination of quinoa grains: A study on functional properties, mineral content and bioactive compounds

Quinoa (Chenopodium quinoa Willd.), an Andean grain, has garnered attention from cereal-based industries as a functional ingredient. This study evaluated functional properties, minerals, bioactive compounds and structural properties of Pre-treatments assisted germination of quinoa grains JQ-778 including, Only germinated seeds (OGS), soaked germinated seeds (SGS), ultrasound at 28 & 40 frequencies (US 28 kHz & US 40 kHz) for 30 min in a Biochemical-Incubator of 96-hour period at 25 °C, 12/12 h dark and light circle, followed by drying at temperatures 50 °C, 60 °C, 70 °C & combined (70, 60, 50 °C). Midilli-Kuck model shows the best fits on drying data closely followed by Hii model, respectively. According to the thermodynamic parameters entropy yielded negative values while Gibbs free energy & enthalpy decreased as the drying temperature increased. Ultrasonic pre-treatments significantly altered functional properties, minerals content and bioactive compounds of quinoa grains (p ≤ 0.05). In US group, quinoa's magnesium, calcium, and potassium content increased from 124.17 to 143.59, 84.7-86.83, and 428.72-448.67 mg/100 g, respectively. Copper ranges from 0.77 to 1.04 mg/100 g, whereas iron 4.76-5.64, Manganese 3.09-3.51 and zinc 2.26-3.51 mg/100 g. Ultrasound assisted germination, especially US 28 kHz dried at 50 °C, showed the highest content of hydroxycinnamic acid, whereas US 40 kHz dried at 60 °C showed hydroxybenzoic acid of quinoa grains. US 40 kHz at 60 °C found rutin 22.62 µg/g, Quercetin 17.58 µg/g, while Kaempferol at 50 °C 24.51 µg/g, demonstrating a 2.5 to 4-fold increase in flavonoids and phenolic acid profiles in ultrasound pre-treated germinated quinoa grains. XRD showed no significant shifts in main peaks, although germinated samples showed intensity variations, suggesting crystallinity modifications. SEM pictures showed germinated quinoa aggregation at different temperatures, with a film-like substance covering and linking the aggregates, possibly a starch aggregates are coupled to lipids and incorporated in a protein matrix.

The changes in the sprout compositions and starch properties of Chinese yam (Dioscorea opposita Thunb.) during germination

Chinese yam (Dioscorea opposita Thunb.) tubers are renowned for their nutritional and medicinal properties. However, the effects of germination on their sprout composition and starch properties remain poorly understood. This study investigated the biochemical changes of Chinese yam sprouts, and analyzed the structure, physicochemical properties and digestibility of Chinese yam starch during controlled germination. Germination significantly enriched the nutritional profile of Chinese yam sprouts, with notable increases in amino acids, phenolic compounds, particularly at 16 and 24 d of germination. Germinated starch samples had lower A and B1 chains, storage modulus, short-range order, and higher B3 chains, amylose content, relative crystallinity and resistant starch level than the ungerminated sample. Besides, the XRD peaks (15°, 17°, 18°, 22°) of the germinated starch conformed to the polycrystalline diffraction pattern of A-type starch. Germination enhanced the functional composition of the sprouts and the anti-digestibility of starch. The findings demonstrated that germination enhanced the health-promoting properties of sprouts, offering a promising strategy to develop functional ingredients for functional foods.

The molecular structure of leaf starch from three cereal crops

Plants produce storage and transient starches in seeds and in leaves, respectively. Understanding molecular fine structure and synthesis of transient starch can help improve plant quality (e.g. by helping breeders produce slowly digested amylopectin, which is beneficial for human nutrition). In the present study, leaf starches from rice, wheat and barley were isolated with cesium chloride gradient centrifugation. Starch fine structure was measured using size-exclusion chromatography and flurophore-assisted carbohydrate electrophoresis. The chain-length distribution (CLD) of amylopectin leaf starch was trimodal in wheat and barley leaf starch. The global peak of leaf starch was at degree of polymerization (DP) 22, and leaf amylopectin containeds more long branches, which are generally considered to hinder starch digestion, suggesting that leaf-specific starch synthesis enzymes could be expressed in the endosperm by genetic modification to produce amylopectin with more long chains, which would be more slowly digested, with advantages to human health. HYPOTHESIS: The biosynthetic processes for leaf starch and storage starch in a given plant species will show significant differences.

Combined physicochemical and transcriptomic analyses reveal the effect of the OsGA20ox1 gene on the starch properties of germinated brown rice

Genes play a pivotal role in regulating the germination of cereal grains; however, there is limited research on the impact of germination genes on the physicochemical properties of germinated cereal starch. We investigated the effects of the OsGA20ox1 gene on the multiscale structural features and adhesion behavior of germinated brown rice starch. Compared to the knockout lines group, the wild type exhibited a decrease in double-helix content (62.74 %), relative crystallinity (47.39 %), and short-range molecular ordering (2.47 %), accompanied by enhanced erosion on the surface of starch granules. The damage to glycosidic bonds at the double-helix level and the heightened structural amorphization (90.95 %) led to reduced entanglement and interaction among starch molecules, ultimately resulting in reduced characteristic viscosity. Further transcriptomic analysis revealed that OsGA20ox1 could regulate the expression of starch-related enzyme genes in the starch metabolism pathway during germination of brown rice. This study contributes to understanding the role of germination genes in promoting the physicochemical properties of starch in germinated grains, thereby opening up new avenues for the improvement of plant-based starch, and paving the way for further research in this field.

Germination-induced modifications of starch structure, flour-processing characteristics, and in vitro digestive properties in maize

Current research on maize germination suffers from long sampling intervals, and the relationship between the starch structure and the processing properties of flour in maize is still unclear. This study observed the effect of germination on the structure and composition of maize starch and the processing properties of maize flour over a 72 h period using a short interval sampling method. At 36 h, the short-range ordered structure, crystallinity, and enthalpy of starch reached the highest values of 1.02, 34.30%, and 9.90 J/g, respectively. At 72 h, the ratios of rapidly-digested starch (RDS) and slowly-digested starch (SDS) enhanced to 29.37% and 28.97%; the RS content reduced to 35.37%; and the flow properties of the starch were improved. This study enhances the understanding of the effects of germination on the processing properties of maize starch and flour, determines the appropriate application, and recommends the use of germination in the food industry.

Investigating the impact of ultrasound-assisted cellulase pretreatment on the nutrients, phytic acid, and phenolics bioaccessibility in sprouted brown rice

This study aimed to elucidate the impact of ultrasound-assisted cellulase (UC) pretreatment on nutrients, phytic acid, and the bioavailability of phenolics during brown rice sprouting. It sought to unveil the underlying mechanisms by quantifying the activity of key enzymes implicated in these processes. The sprouted brown rice (SBR) surface structure was harmed by the UC pretreatment, which also increased the amount of γ-oryzanol and antioxidant activity in the SBR. Concurrently, the UC pretreatment boosted the activity of phytase, glutamate decarboxylase, succinate semialdehyde dehydrogenase, Gamma-aminobutyric acid (GABA) transaminase, chalcone isomerase, and phenylalanine ammonia lyase, thereby decreasing the phytic acid content and increasing the GABA, flavonoid, and phenolic content in SBR. In addition, UC-pretreated SBR showed increased phenolic release and bioaccessibility during in vitro digestion when compared to the treated group. These findings might offer theoretical direction for using SBR to maximize value.

Pulsed light treatment enhances starch hydrolysis and improves starch physicochemical properties of germinated brown rice

BACKGROUND

Recently, germinated brown rice (GBR) has gained substantial attention as a functional food because of its nutritional attributes. Notably, pulsed light technology (PLT) has emerged as a promising tool for enhancing rice germination and, consequently, has improved the nutritional and functional qualities of GBR-derived products. However, further research is required to comprehensively understand the impact of PLT on GBR physicochemical properties. The present study aimed to investigate the stimulating effects of PLT on starch hydrolysis, starch structure and functional properties of GBR.

RESULTS

The PLT substantially boosted α-amylase activity during brown rice germination, leading to a 10.9% reduction in total starch content and a 17.3% increase in reducing sugar content, accompanied by elevated free water levels. Structural analysis indicated no changes in starch crystalline types, whereas gelatinization temperature slightly increased. Pasting properties exhibited a significant drop in peak viscosity. Scanning electron microscopy showed surface erosion of starch granules with microstructural changes. Furthermore, correlation analysis established positive links between α-amylase activity, reducing sugar accumulation, starch structure and functional properties in GBR.

CONCLUSION

The present study demonstrates that PLT enhanced the physicochemical properties of GBR starch, significantly improving the stability of GBR products, thereby contributing to expanded applicability of rice starch in the food industry. © 2023 Society of Chemical Industry.