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).

Common beans as a source of food ingredients: Techno-functional and biological potential

Common beans are an inexpensive source of high-quality food ingredients. They are rich in proteins, slowly digestible starch, fiber, phenolic compounds, and other bioactive molecules that could be separated and processed to obtain value-added ingredients with techno-functional and biological potential. The use of common beans in the food industry is a promising alternative to add nutritional and functional ingredients with a low impact on overall consumer acceptance. Researchers are evaluating traditional and novel technologies to develop functionally enhanced common bean ingredients, such as flours, proteins, starch powders, and phenolic extracts that could be introduced as functional ingredient alternatives in the food industry. This review compiles recent information on processing, techno-functional properties, food applications, and the biological potential of common bean ingredients. The evidence shows that incorporating an adequate proportion of common bean ingredients into regular foods such as pasta, bread, or nutritional bars improves their fiber, protein, phenolic compounds, and glycemic index profile without considerably affecting their organoleptic properties. Additionally, common bean consumption has shown health benefits in the gut microbiome, weight control, and the reduction of the risk of developing noncommunicable diseases. However, food matrix interaction studies and comprehensive clinical trials are needed to develop common bean ingredient applications and validate the health benefits over time.

Characterization of Arrowhead-Derived Type 3 Resistant Starch Prepared by Ultrasound-Assisted α-Amylase Degradation

The effect of ultrasonic-assisted α-amylase hydrolysis on the structure and physicochemical properties of arrowhead-derived type 3 resistant starch (RS3) was studied. After ultrasound treatment, the yield of resistant starch reached 17.21%, significantly ( $p<0.05$ ) increased by 65.64%. Compared with RS3 prepared by traditional enzymolysis (RS3-E), the crystal form and chemical bond of RS3 prepared by ultrasonic-assisted enzymolysis (RS3-UAE) did not change, but its gelatinization temperature, relative crystallinity, enthalpy, and 1047/1022 values were improved to varying degrees. RS3-UAE exhibited a higher solubility, transparency, water absorption capacity, and higher swelling power at 70°C. The analysis results of iodine absorption, differential scanning calorimetry, X-ray diffraction, Fourier transform-infrared spectroscopy, and scanning electron microscopy demonstrated that RS3-UAE exhibited a more regular shape, smoother surface, higher crystallinity, stable double helix structure, and more ordered and denser structure. Therefore, ultrasound-assisted enzymatic technology is an effective way to prepare RS3, and it can improve the functional and structural properties of the prepared RS3 to a certain extent.

Effect of autoclave-cooling cycles combined pullulanase on the physicochemical and structural properties of resistant starch from black Tartary buckwheat

A starch-rich portion is produced as a by-product of black Tartary buckwheat processing. The effect of enzymatic combined with autoclaving-cooling cycles (one, two, or three times) on the physicochemical and structural properties of black Tartary buckwheat type 3 resistant starch (BRS) was evaluated. The autoclaving-cooling cycles enhanced solubility and reduced swelling, with the BRS content increasing from 14.12% to 25.18%. The high crystallinity of the BRS reflected a high molecular order. However, increasing the number of autoclaving-cooling cycles did not result in higher BRS content. The highest BRS yield in the autoclaved starch samples was 25.18% after double-autoclaving-cooling cycles. Furthermore, the autoclaving-cooling cycles altered the crystalline structure of black Tartary buckwheat, and the subsequent crystallinity changed from 36.33% to 42.05% to 38.27%. Fourier-transform infrared spectroscopy shows that the number of cycles results in more efficient double-helical packing within the crystalline lamella. Principal component analysis showed that the autoclaving-cooling cycle treatment leads to significant changes in the molecular structure of resistant starch (RS). These results indicated that autoclaving-cooling cycles might be a feasible way for producing RS from black Tartary buckwheat starch with better structural stability to expand their application range.

Optimization of Corn Resistant Starch Preparation by Dual Enzymatic Modification Using Response Surface Methodology and Its Physicochemical Characterization

Corn starch was dually modified using thermostable α-amylase and pullulanase to prepare resistant starch (RS). The concentration of starch liquid, the amount of added thermostable α-amylase, the duration of enzymatic hydrolysis and the amount of added pullulanase were optimized using RSM to increase RS content of the treated sample. The optimum pretreatment conditions were 15% starch liquid, 3 U/g thermostable α-amylase, 35 min of enzymatic hydrolysis and 8 U/g pullulanase. The maximum RS content of 10.75% was obtained, and this value was significantly higher than that of native corn starch. The degree of polymerization (DP) of the enzyme-modified starch decreased compared with that of native starch. The scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were performed to assess structural changes in native and pretreated starch. The effect of dual enzyme pretreatment on the structure and properties of corn starch was significant. Unlike the untreated one, the pretreated corn starch showed clear pores and cracks. Significant differences in RS contents and structural characterization between starch pretreated and untreated with dual enzymes demonstrated that the dual enzyme modification of corn was effective in enhancing RS contents.

Verification of autoclaving-cooling treatment to increase the resistant starch contents in food starches based on meta-analysis result

Autoclaving-cooling is a common starch modification method to increase the resistant starch (RS) content. The effect of this method varies depending on the type of crop and treatment condition used. The objectives of this study were to verify the autoclaving-cooling treatment based on a meta-analysis result and to evaluate the physicochemical properties of modified starches. The meta-analysis study used 10 articles from a total of 1,293 that were retrieved using the PRISMA approach. Meta-analysis showed that the optimal treatments of autoclaving-cooling process that increase the RS content significantly, was in starch samples from the cereal group (corn, oats, rice) (SMD: 19.60; 95% CI: 9.56-29.64; p < 0.001), with water ratio 1:4 (SMD: 13.69; 95% CI: 5.50-21.87; p < 0.001), using two cycles of autoclaving-cooling (SMD: 16.33; 95% CI: 6.98-25.67; p < 0.001) and 30 min of autoclaving heating (SMD: 12.97; 95% CI: 1.97-23.97; p < 0.001) at 121°C (SMD: 12.18; 95% CI: 1.88-22.47; p < 0.001). Verification using corn flour and corn starch showed a significant increase in RS contents from 15.84 to 27.78% and from 15.27 to 32.53%, respectively, and a significant decrease in starch digestibility from 67.02 to 35.74% and from 76.15 to 28.09%, respectively. Treated sample also showed the pasting profile that was stable under heating and stirring.

Infrared heating under optimized conditions enhanced the pasting and swelling behaviour of cowpea starch

Native starches are not suitable for industrial use and must be modified for improved functionality. In this study, the effect of moisture preconditioning and infrared heating time on physicochemical properties of cowpea starch was investigated using a two-factor central composite rotatable design. Factors (moisture levels:10-40 g/100 g starch and infrared heating time:10-60 min) with their corresponding α mid-point values resulted in 13 experimental runs. Selected functional and pasting properties were determined as response variables. Starch samples produced under optimized conditions were compared with corn starch and their physicochemical properties determined. Except for pasting temperature, cowpea starch prepared using the optimal conditions (moisture: 46.21 g/100 g starch, dry basis and heating time of 32.88 min) had higher functional and pasting properties compared with the native cowpea starch. Infrared heating significantly reduced the gelatinization temperatures of cowpea starch but did not significantly change that of the corn starch. The crystallinity and double-helical order structure of moisture conditioned cowpea starch also reduced after modification. Cowpea starch showed a bigger granule size, higher swelling power but lower water absorption capacities and pasting properties compared with the control. The infrared heating process is a novel and promising modification method for improving the swelling properties of starch.

Physicochemical and multi-scale structural alterations of pea starch induced by supercritical carbon dioxide + ethanol extraction

The objective of this study was to establish the impacts of supercritical fluid extraction (SFE) processing on the physicochemical properties of pea flour and the structure of isolated pea starch. A significant (p < 0.05) increase in protein content and reduction in several pasting and thermal parameters as measured by rapid visco-analyzer and differential scanning calorimeter were observed after SFE. Additionally, SFE increased starch digestibility as determined by an in vitro starch digestion assay. An increased amylopectin content and crystallinity along with the loss of double helix content was supported by size exclusion chromatography and FT-IR data, respectively. X-ray diffraction and scanning electron microscopy showed minimal alterations of starch, by SFE, in long-range crystalline and morphological structure of starch granules, respectively. The data demonstrated SFE influenced the physicochemical and structural characteristics of pea starch. These outcomes illustrated that SFE might be a green and novel technology for starch modification.

Cooking and sensorial quality, nutritional composition and functional properties of cold-extruded rice/white bean gluten-free fettuccine fortified with whole carob fruit flour

A different rice/white bean-based gluten-free fettuccine (rice 0-100%, bean 0-100%) fortified with 10% carob fruit has been developed. The proximate composition, total and resistant starch, and total, soluble and insoluble dietary fibre content as well as the cooking and sensorial quality of uncooked and cooked pasta were determined. All the novel gluten-free fettuccine forms showed good cooking quality (cooking loss < 10%) highlighting that those containing the carob fruit had better nutritional and healthy profiles than the commercial gluten-free rice pasta; they were low in fat (10-fold) and high in protein (on average 3.6-fold) with resistant starch (16%) and dietary fibres (2.4-fold). The cooking process increased (p < 0.05) the protein and total dietary fibre content but reduced the total and resistant starch. The addition of carob fruit increased the total dietary fibre content, thus improving the functional value of fettuccine. Considering the sensorial analysis, fettuccine produced with 40% bean and 10% carob could be well accepted by consumers and can be advised as a functional food.

Development, structure and in vitro digestibility of type 3 resistant starch from acid-thinned and debranched pea and normal maize starches

Type 3 resistant starch (RS3) was developed from native pea starch through acid thinning, debranching and recrystallization, and the resultant pea RS3 was then characterized and compared with that generated from native normal maize starch. Starting from the respective native starches, the modification method yielded 68.1% of RS3 from pea and 59.6% from normal maize. The particles of pea and normal maize RS3 showed a coarse surface and irregular shapes and sizes. Both pea and normal maize RS3 displayed the B-type X-ray diffraction pattern, with 41.0% and 37.7% relative crystallinity, respectively. In vitro starch digestibility assay revealed that pea RS3 - in both uncooked and cooked states - was less digestible by amylolytic enzymes than normal maize RS3 because the former possessed double-helical crystallites of a more compact structure. The information presented in the study is valuable for the development of RS ingredient from pea starch for food applications.