Preparation and characterization of resistant starch type III from enzymatically hydrolyzed maize flour

Functionalization Methods of Starch and Its Derivatives: From Old Limitations to New Possibilities

It has long been known that starch as a raw material is of strategic importance for meeting primarily the nutritional needs of people around the world. Year by year, the demand not only for traditional but also for functional food based on starch and its derivatives is growing. Problems with the availability of petrochemical raw materials, as well as environmental problems with the recycling of post-production waste, make non-food industries also increasingly interested in this biopolymer. Its supporters will point out countless advantages such as wide availability, renewability, and biodegradability. Opponents, in turn, will argue that they will not balance the problems with its processing and storage and poor functional properties. Hence, the race to find new methods to improve starch properties towards multifunctionality is still ongoing. For these reasons, in the presented review, referring to the structure and physicochemical properties of starch, attempts were made to highlight not only the current limitations in its processing but also new possibilities. Attention was paid to progress in the non-selective and selective functionalization of starch to obtain materials with the greatest application potential in the food (resistant starch, dextrins, and maltodextrins) and/or in the non-food industries (hydrophobic and oxidized starch).

Enzymatic Modification of Starch Using Recombinant Genes from Sorghum in Escherichia coli: Insights and Potential Applications

SBEIIb (Sobic.004G163700), SSSIIa (Sobic.010G093400), and GBSSI (Sobic.010G022600) genes that regulate starch synthesis in sorghum endosperm were transferred into Escherichia coli by transgenic technology. SBEIIb, SSSIIa, and GBSSI enzymes were separated and purified through a Ni column and analyzed by electrophoresis with molecular weights and activities of 91.57 84.57, and 66.89 kDa and 551 and 700 and 587 U/μL, respectively. Furthermore, they were applied to starch modification, yielding interesting findings: the A chain content increased from 25.79 to 89.55% for SBEIIb-treated waxy starch, while SSSIIa extended the A chain to form DPs of the B chain, with A chain content decreasing from 89.55 to 37.01%, whereas GBSSI was explicitly involved in the synthesis of B1 chain, with its content increasing from 9.59 to 48.45%. Modified starch was obtained, which could be accurately applied in various industries. For instance, we prepared a sample (containing 89.6% A chain content) with excellent antiaging and antidigestion properties through SBEIIb modification. Moreover, higher RS3 (34.25%) and SDS contents (15.75%) of starch were obtained through the joint modification of SBEIIb and SSSIIa. These findings provide valuable insights for developing sorghum starch synthesis-related enzymes and offer opportunities for improving starch properties through enzymatic approaches.

Effect of calcium and magnesium on starch synthesis in maize kernels and its physiological driving mechanism

The content of kernel starch (STC), which is a fundamental indicator of the nutritional value of maize, is directly correlated with the grain's taste and aroma. Both calcium (Ca) and magnesium (Mg) are critical nutrients that play a significant role in the growth and development of maize, as well as in the synthesis of STC. To determine the physiological driving mechanisms of Ca and Mg effects on the accumulation of STC synthesis in maize kernels and the characteristics of their effects on endogenous hormones and enzymes of STC synthesis in maize leaves, our study applied foliar Ca and Mg fertilizers at various levels to maize prior to pollination. (1) The levels of Ca, Mg, indole-3-acetic acid (IAA), gibberellin (GA), and zeatin riboside (ZR) in maize leaves increased and then decreased after the supplementation of Ca and Mg. They peaked on the 32nd day after pollination. In contrast, the levels of abscisic acid (ABA) initially decreased and then increased. Ca and Mg had a negative correlation with ABA and a positive correlation with IAA, GA, and ZR. (2) As the levels of Ca and Mg increased, correspondingly rose the activities of enzymes responsible for STC synthesis and the content of STC and its components. Principally influencing the synthesis of STC were ABA, IAA, uridine diphosphate-glucose pyrophosphorylase (UDPG), granule-bound starch synthase (GBSS), and soluble starch synthase (SSS). (3) "IAA-UDPG or GBSS-STC" was the predominant physiological regulation pathway of Ca on kernel STC, whereas "IAA-GBSS-STC" was the dominant physiological regulation pathway of Mg on kernel STC. The regulatory impact of STC by UDPG and GBSS was positive, as were the effects of IAA on UDPG and GBSS. In conclusion, the accumulation of kernel starch was significantly enhanced by Ca and Mg supplementation via the modulation of endogenous hormone levels and key enzyme activities. This research identifies a viable approach to improve the nutritional composition of maize.

Synthesis and Functions of Resistant Starch

Resistant starch (RS) has become a popular topic of research in recent years. Most scholars believe that there are 5 types of RS. However, accumulating evidence indicates that in addition to starch-lipid complexes, which are the fifth type of RS, complexes containing starch and other substances can also be generated. The physicochemical properties and physiologic functions of these complexes are worth exploring. New physiologic functions of several original RSs are constantly being discovered. Research shows that RS can provide health improvements in many patients with chronic diseases, including diabetes and obesity, and even has potential benefits for kidney disease and colorectal cancer. Moreover, RS can alter the short-chain fatty acids and microorganisms in the gut, positively regulating the body's internal environment. Despite the increase in its market demand, RS production remains limited. Upscaling RS production is thus an urgent requirement. This paper provides detailed insights into the classification, synthesis, and efficacy of RS, serving as a starting point for the future development and applications of RS based on the current status quo.

Preparation and characterization of debranched starches: Influence of botanical source and debranching time

The influence of botanical source (waxy corn, glutinous rice, tapioca and potato), either based on crystallization or morphology, and the debranching time (6-48 h) on the physicochemical properties of debranched starches (DBSs) were systematically investigated. The divergence of depolymerization among different botanical sources within same hydrolysis time suggested that the debranching treatment was not only depending on the molecular profile and crystalline structure, but also related with the granular size and morphology of native starches. Fourier transformation infrared spectroscopy (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) suggested that long-term debranching reaction produced DBSs with improved degree of crystallization and reduced iodine binding capacity. Simulated in-vitro digestion assay showed that the proportion of digestive fractions from different botanical originated DBSs differed greatly. Additionally, prolonging the debranching time yielded increased level of resistant starch. The study may provide guidance for exploring DBSs with various molecular weight to fulfill their tailored applications.

Effect of Storage Time and Temperature on Digestibility, Thermal, and Rheological Properties of Retrograded Rice

Retrogradation is defined as the recrystallization or realignment of amylose and amylopectin chains upon cooling of gelatinization starch gels. The storage conditions such as the storage time and temperature are crucial factors that influence and govern the degree of retrogradation and in turn, affect the formation of resistant starch and alteration of thermal and rheological properties. This article investigates the effect of storage time and temperature on the properties of retrograded rice starch. Rice kernels of five different indigenous varieties, namely Diasang lahi, Khaju lahi, Dhusuri bao, Omkar, and Bili rajamudi were cooked by boiling in water and stored at 4 °C and -20 °C for 6 and 12 h, respectively. Differential scanning calorimetry (DSC) studies revealed in raw form that Bili rajamudi exhibited the highest peak gelatinization temperature (T_p, °C) at 79.05 °C whereas Diasang lahi showed the least T_p at 56.12 °C. Further, it was indicated that the T_p and degree of retrogradation (DR%) also increase with increasing time and decreasing temperature of storage. All samples stored at -20 °C for 12 h exhibited the highest degree of retrogradation DR%. Amongst all five varieties stored at -20 °C for 12 h, Omkar exhibited the highest %DR, followed by Bili rajamudi, Khaju lahi, Dhusuri bao, and Diasang lahi. A negative correlation was also established between T_p and resistant starch content (RS%). It was also observed that the resistant starch (RS%) content increased with the increasing time and decreasing temperature of storage. A strong negative correlation was observed between RS% and non-resistant starch (NRS%). Further, rheological studies indicated that retrogradation also affects the viscosity and dynamic rheological properties of starch. In this study, it was evident that extending storage duration from 6 to 12 h and lowering temperature from 4 to -20 °C impact retrogradation of rice starch, which in turn affects the starch's gelatinization, digestibility, and rheology. Rice starch retrograded at lower temperatures for a longer period could prove to be extremely beneficial for development of food products with better textural properties and high RS content or low glycemic index.

Prebiotic potential of enzymatically prepared resistant starch in reshaping gut microbiota and their respond to body physiology

The increase in consumer demand for high-quality food products has led to growth in the use of new technologies and ingredients. Resistant starch (RS) is a recently recognised source of fibre and has received much attention for its potential health benefits and functional properties. However, knowledge about the fate of RS in modulating complex intestinal communities, the microbial members involved in its degradation, enhancement of microbial metabolites, and its functional role in body physiology is still limited. For this purpose, the current study was designed to ratify the physiological and functional health benefits of enzymatically prepared resistant starch (EM-RSIII) from maize flour. To approve the beneficial health effects as prebiotic, EM-RSIII was supplemented in rat diets. After 21 days of the experiment, EM-RSIII fed rats showed a significant reduction in body weight gain, fecal pH, glycemic response, serum lipid profile, insulin level and reshaping gut microbiota, and enhancing short-chain fatty acid compared to control. The count of butyrate-producing and starch utilizing bacteria, such as Lactobacillus, Enterococcus, and Pediococcus genus in rat’s gut, elevated after the consumption of medium and high doses of EM-RSIII, while the E. coli completely suppressed in high EM-RSIII fed rats. Short-chain fatty acids precisely increased in feces of EM-RSIII feed rats. Correlation analysis demonstrated that the effect of butyrate on functional and physiological alteration on the body had been investigated during the current study. Conclusively, the present study demonstrated the unprecedented effect of utilising EM-RSIII as a diet on body physiology and redesigning gut microorganisms.