Effects of β-amylase treatment conditions on the gelatinization and retrogradation characteristics of wheat starch

Effects and molecular mechanisms of polyethylene microplastic oxidation on wheat grain quality

Polyethylene microplastics (PE MPs) are the main MPs in agricultural soils and undergo oxidation upon environmental exposure. However, the influence of MP oxidation on phytotoxicity (especially for crop fruit) is still limited. This study aimed to explore the effect of PE MP oxidation on crop toxicity. Herein, a combination of plant phenotyping, metabolomic, and transcriptomic approaches was used to evaluate the effects of low-oxidation PE (LOPE) and high-oxidation PE (HOPE) on wheat growth, grain quality, and related molecular mechanisms using pot experiments. The results showed that HOPE induced a stronger inhibition of wheat growth and reduction in protein content and mineral elements than LOPE. This was accompanied by root ultrastructural damage and downregulation of carbohydrate metabolism, translation, nutrient reservoir activity, and metal ion binding gene expression. Compared with HOPE, LOPE activated a stronger plant defense response by reducing the starch content by 22.87 %, increasing soluble sugar content by 44.93 %, and upregulating antioxidant enzyme genes and crucial metabolic pathways (e.g., starch and sucrose, linoleic acid, and phenylalanine metabolism). The presence of PE MPs in the environment exacerbates crop growth inhibition and fruit quality deterioration, highlighting the need to consider the environmental and food safety implications of MPs in agricultural soils.

Effect of Oat Beta-Glucan on Physicochemical Properties and Digestibility of Fava Bean Starch

The current research examined the impact of different concentrations of oat beta-glucan (OG) on the in vitro digestibility of fava bean starch (FS). Our pasting analysis demonstrated that OG effectively decreased the viscosity and regrowth of FS, suppressing its in situ regrowth while enhancing the in vitro pasting temperature. Moreover, OG markedly diminished amylose leaching and minimized the particle size of the pasted starch. Rheological and textural evaluations demonstrated that OG markedly diminished the viscoelasticity of the starch and softened the gel strength of the composite system. Structural analysis revealed that hydrogen bonding is the primary interaction in the FS-OG system, indicating that OG interacts with amylose through hydrogen bonding, thereby delaying starch pasting and enhancing the gelatinization characteristics of FS gels. Notably, the incorporation of OG resulted in a reduction in the levels of rapidly digestible starch (RDS) and slowly digestible starch (SDS) in FS, accompanied by a notable increase in resistant starch (RS) content, from 21.30% to 31.82%. This study offers crucial insights for the application of OG in starch-based functional foods.

Two-step modification of pullulanase and transglucosidase: A novel way to improve the gel strength and reduce the digestibility of rice starch

The multiscale structure, gel strength and digestibility of rice starch modified by the two-step modification of pullulanase (PUL) pretreatment and transglucosidase (TG) treatment for 6, 12, 18 and 24 h were investigated. The debranching hydrolysis of PUL produced some linear chains, which rearranged to form stable crystalline structures, reducing the digestible starch content, but weakening the gel strength. TG treatment connected some short chains to longer linear chains via α-1,6-glycosidic bonds, generating the structures of linear chain with fewer branches. The short branches promoted the interaction between starch molecules to form a more compact three-dimensional gel network structure, showing higher hardness and springiness. Moreover, these chains could form more stable crystals, reducing the digestible starch content, and the increase of branching degree inhibited digestive enzyme hydrolysis, reducing the digestion rate. The multiscale structure of starch tended to stabilize after TG treatment for 18 h, which could form a gel with stronger strength and lower digestibility than native starch gel. Therefore, the two-step modification of PUL and TG was an effective way to change the structure of rice starch to improve the gel strength and reduce the digestibility.

Influence of Storage Temperature on Starch Retrogradation and Digestion of Chinese Steamed Bread

Chinese steamed bread (CSB), which is widely consumed in East Asia, usually undergoes storage before consumption, but it is unclear how different storage temperatures affect CSB starch retrogradation and digestion properties, which are important for consumers. CSB was stored for 2 days at 25 °C, 4 °C, -18 °C, 4 °C/25 °C temperature cycling (i.e., 24 h at 4 °C, followed by 24 h at 25 °C) and -18 °C/ 25 °C temperature cycling. The results revealed for the first time that more orderly starch double helices are formed when CSB was stored at 4 °C or 4 °C/25 °C. Storage under -18 °C produced lower amounts of, but more heterogenous, starch double helices, with fewer B-type, but more V-type, crystallites. Compared to other storage temperatures, more long-range intermolecular interactions formed between the starch and protein at 4 °C or 4 °C/25 °C. CSB samples showed the slowest starch digestibility when stored at 4 °C. The impact of storage temperature on the starch retrogradation properties and digestibility of CSB also depended on the wheat variety, attributed to differences in the starch molecular structure. These results have significance and practical applications to help the CSB food industry to control starch retrogradation and digestibility. For example, CSB could be stored at 4 °C for 2 days in order to reduce its starch digestibility.

Rheological properties and microstructure of wheat flour dough systems with enzyme-hydrolyzed mashed potatoes

The interest in incorporating potatoes into wheat dough is increasing. However, potatoes exhibit significant viscosity during thermal processing, affecting product processing and quality. This study aims to find an effective method to reduce the viscosity of mashed potatoes. We aimed to compare the effects of different enzymes (α-amylase, β-amylase, and flavourzyme) and concentrations (0.01%, 0.05%, and 0.1%) on the micromorphology and rheological properties of mashed potatoes and potato-wheat dough. The impact of flavourzyme was the most significant (p<0.05). When enzyme concentration increased, viscosity decreased, and the degree of structural damage, indicated by increased porosity. Notably, the addition of flavourzyme can increase the content of sweet and umami free amino acids, improving the flavor of mashed potatoes. The scanning electron microscopy and confocal laser scanning microscopy images of potato-wheat dough revealed that enzyme-hydrolyzed mashed potatoes had improved homogeneity, reestablished the dough continuity, and strengthened the three-dimensional structure comprising proteins and starch. Notably, flavourzyme demonstrated the most significant effect on enhancing the protein-starch network structure. This was attributed to the exposure of functional groups resulting from protein hydrolysis, facilitating interaction with starch molecules. Our findings indicate that the addition of 0.1% flavourzyme (500 LAPU/g, pH 5.5, 55 ± 2°C, 30 min treated) was the most effective in reducing viscosity and reconstructing the gluten network. Enzymatic hydrolysis plays a vital role in the production of high-quality potato products, with particular importance in the baking industry, where flavourzyme exhibits significant potential. PRACTICAL APPLICATION: Enzymatic hydrolysis plays a vital role in the production of high-quality potato products, with particular importance in the baking industry, where flavourzyme exhibits significant potential.

Effect of modification by maltogenic amylase and branching enzyme on the structural and physicochemical properties of sweet potato starch

Sweet potato starch (SPSt) was treated sequentially with the combination of maltogenic amylase (MA) and branching enzyme (BE) (MA → BE) or BE and MA (BE→MA) to modify its structural and physicochemical properties. Following the MA → BE and BE→MA modifications, the degree of branching was increased from 12.02 % to 44.06 %; whereas, the average chain length decreased from 18.02 to 12.32. Fourier-transform infrared spectroscopy and digestive performance analysis indicated that the modifications reduced hydrogen bonds and increased resistant starch in SPSt. Rheological analysis revealed that the storage and loss moduli of the modified samples were lower than those of the control samples, except for starch treated with MA alone. X-ray diffraction measurements suggested that the re-crystallisation peak intensities of the enzyme-modified starches were lower than those of the untreated sample. The retrogradation resistance ability of the analysed samples followed the order: BE→MA-starches > MA → BE-starches > untreated starch. The relationship between the crystallisation rate constant and short branched chains (DP_6-9) was well described by linear regression. This study provides a theoretical foundation for retarding the retrogradation of starch, which can improve food quality and extend the shelf-life of enzymatically modified starchy foods.

Physicochemical properties and in vitro digestibility of highland barley starch with different extraction methods

The objective of this study was to compare the structural, thermal, rheological and digestive properties of highland barley starch (HBS) by different extraction methods. Five techniques were used to extract HBS: Alkali extraction, Ultrasound extraction, double enzyme extraction (DE), three enzyme extraction (TE) and ultrasonic assisted TE (U-TE). The results indicated that the Ultrasound extracted HBS had fewer Maltese crosses, lower molecular weight (Mw), and higher content of damaged starch (P < 0.05). Meanwhile, DE extracted HBS had higher Mw, and the content of short amylopectin than that of Alkali extracted HBS (P < 0.05). Additionally, the DE extracted HBS showed the highest relative crystallinity and good short-range ordered structure, which led to the outcome of stronger thermal stability and higher values of G' and G'' (P < 0.05). These results indicated that enzymatic extraction could better protect the resistance of HBS by protecting its physicochemical properties.

Development of Fermented Rice Water to Improve the Quality of Garaetteok, a Traditional Korean Rice Cake

In the rice processing industry, wastewater is an inevitable by-product of rice washing. To increase the utilization of washed rice water (WRW), seven types of fermented washed rice water (FWRW) were prepared using lactic acid bacteria (LAB) and carbohydrate hydrolase. The total concentration of small maltooligosaccharides (MOSs) in the amyloglucosidase (AMG) treatment groups was about ten times higher than in the untreated groups. After 6 h of fermentation, six of the seven FWRW samples reached a pH of 4 due to the increased concentration of organic acids and could, therefore, be used as food acidity regulators. To confirm the applicability of FWRW, the traditional Korean rice cake garaetteok was prepared with FWRW and stored at 4 °C for 5 days. A texture profile analysis (TPA) revealed that the hardness of garaetteok treated with FWRW was significantly lower than that of untreated garaetteok following storage. Differential scanning calorimetry (DSC) showed that FWRW retarded the retrogradation of garaetteok during storage. The addition of FWRW using Lactobacillus reuteri with an AMG group was particularly effective for inhibiting microbial activity in garaetteok during storage. These results suggest that FWRW using AMG-added L. reuteri can be used as a novel food additive for improving the quality of traditional Korean starch foods and could also reduce the volume of waste WRW.

Effects of Different Extraction Methods on the Gelatinization and Retrogradation Properties of Highland Barley Starch

The purpose of this study was to compare the gelatinization and retrogradation properties of highland barley starch (HBS) using different extraction methods. We obtained HBS by three methods, including alkali extraction (A-HBS), ultrasound extraction (U-HBS) and enzyme extraction (E-HBS). An investigation was carried out using a rapid viscosity analyzer (RVA), texture profile analysis (TPA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier-transform infrared spectrometry (FTIR). It is shown that the different extraction methods did not change the crystalline type of HBS. E-HBS had the lowest damaged starch content and highest relative crystallinity value (p < 0.05). Meanwhile, A-HBS had the highest peak viscosity, indicating the best water absorption (p < 0.05). Moreover, E-HBS had not only higher G′ and G″ values, but also the highest gel hardness value, reflecting its strong gel structure (p < 0.05). These results confirmed that E-HBS provided better pasting stability and rheological properties, while U-HBS provides benefits of reducing starch retrogradation.

Effect and mechanism of glycerol monostearate dimer (GMS-D) and baking-treatment on the structure, in vitro digestion of gelatinized potato starch-GMS-D

With the increasing progress of society and in-depth scientific research, dietary regulations, especially sustained glucose releases, are regarded as an effective and significant way to lighten or even cut the emergence of diabetes. In this research, the starch-lipid complex gelatinized potato starch-glycerol monostearate dimer (GPS-GMS-D) was developed to provide a low-glycemic index functional food component for type 2 diabetes. Briefly, the higher complexation index (CI, 71.02%), lower rapidly digestible starch (RDS, 35.57%), and lower estimated glycemic index (eGI, 52.34%) were referred to as GPS-GMS-D. It was assumed that the solid V-type crystal structure, induced with the helix between GMS-D and GPS due to high amylose, high saturation, and low steric hindrance, contributed to the lower digestibility. In addition, baking treatment for 5 min was systematically exerted to improve the flavor of GPS-GMS-D with a relatively high CI (59.98%) and low eGI (54.15%). It was believed that rapid dehydration and close interaction during baking treatment could slow down the decomposition of GPS-GMS-D and conversions of starch fractions. Therefore, these results suggested that the as-developed GPS-GMS-D was a promising low GI functional dietary food component for diabetes mellitus, and a suitable baking post-thermal treatment was successfully proposed to enhance the flavor of GPS-GMS-D. PRACTICAL APPLICATION: The higher amylose and solid V-type crystal structure in gelatinized potato starch-glycerol monostearate dimer (GPS-GMS-D) would induce the formation of slowly digestive starch (SDS) and resistant starch (RS) to suppress enzymatic hydrolysis. Moreover, the flavor of GPS-GMS-D was enhanced with appropriate and moderate thermal processing (baking), which was likely to improve the quality of life of a person with diabetes. Thus, we believe that GPS-GMS-D is a promising functional food component for diabetes mellitus.