Impact of annealing on the susceptibility of wheat, potato and pea starches to hydrolysis with pancreatin

Heat-moisture-treated rice starches with different amylose and moisture contents as stabilizers for nonfat yogurt

Food producers are interested in enhancing native starch properties without chemical modifications. Here, rice starches were physically modified via heat-moisture treatment (HMT) using different amylose (high, medium, low, and waxy) and moisture (15 %, 20 %, 25 %, and 30 %) contents. Hydration properties and pasting viscosities differed for different amylose and moisture contents. The HMT starch with high amylose content and 15 % moisture (High_HMT15) exhibited the highest final viscosity (6.16 Pa.s), and 31.7 % and 35.1 % increased amount of resistant starch compared to native starch in the granule and paste states, respectively. Hence, High_HMT15 was used as a stabilizer for nonfat yogurt. The nonfat yogurt prepared with 1.0 % High_HMT15 as the stabilizer exhibited 37.3 % reduced whey separation, 2.8 times increased viscosity, a high total solids content, and acceptable sensory properties compared to the nonfat yogurt without starch. These HMT starches can replace chemically modified starches derived from other grains in various food applications.

Multi-Scale Structural Insights into Enzymatically Hydrolyzed Lentil Starch Concentrates Prepared by In Vitro Method Using Different Types of Enzymes

This study was undertaken to investigate the enzymatic hydrolysis of lentil starch concentrates from conventional cooked seeds (CCLSC) by the action of different types of enzymes, including pancreatin (PC-EHSC), heat-stable α-amylase (HS-EHSC), β-amylase (βA-EHSC), amyloglucosidase (AMG-EHSC), and multi-enzymes (βA-HS-AMG-EHSC); their multi-scale structural characteristics of the enzymatic hydrolysis products of lentil starch concentrates were compared. The morphological features distinguished among different samples. The Fourier-transform infrared spectroscopy and solid-state ¹³C CP/MAS NMR spectral features indicated the possible formation of a binary and ternary complex among amylose, protein and lipids. The X-ray diffraction results revealed that the V-type characteristic diffraction peaks were more obvious for samples including PC-EHSC and βA-EHSC, which was in line with their lowest polydispersity index (DP_n). PC-EHSC and βA-EHSC also showed an increased peak intensity of the scattering maximum on the small-angle X-ray scattering spectra, whereas CCLSC exhibited an overall lower peak intensity within the studied q range of scattering. The highest XRD crystallinity and the lowest DP_n value obtained for PC-EHSC indicated that the starch polymers modified by pancreatin could produce glucan chains with a comparatively homogenous M_w distribution that are readily recrystallized by hydrogen bonding through chain aggregation. Comparatively, the lowest relative crystallinity for HS-EHSC obtained from XRD suggested that thermostable α-amylolysis was unfavorable for the formation of starch structure with a higher degree of molecular order. This study could provide useful information for the needed research to obtain a deeper understanding of the impact of different amylolysis actions on the structural organization of starch hydrolysates and to provide a theoretical foundation for the development of fermentable enzymatically hydrolyzed starch with well-tailored physiological properties.

Effects of heat-moisture treatment on the thermal, functional properties and composition of cereal, legume and tuber starches-a review

Several methods are currently employed in the modification of starch obtained from different botanical sources. Starch in its native form is limited in application due to retrogradation, syneresis, inability to withstand shear stress as well as its unstable nature at varying temperatures and pH environment. Modification of starch is therefore needed to enhance its food and industrial application. A primary and safe means of modifying starch for food and industrial use is through hydrothermal methods which involves heat-moisture treatment and annealing. Heat-moisture treatment (HMT) is a physical modification technique that improves the functional and physicochemical properties of starch without changing its molecular composition. Upon modification through HMT, starches from cereals, legumes and tuber crops serve as important ingredients in diverse food, pharmaceutical and industrial processes. Although changes in starch initiated by HMT have been studied in starches of different plant origin, this work further provides insight on the composition, thermal and functional properties of heat-moisture treated starch obtained from cereals, legumes and tuber crops.

Physicochemical and rheological properties and in vitro digestibility of heat moisture treated and annealed starch of sohphlang (Flemingia vestita) tuber

The effect of heat moisture treatment (HMT) and annealing (ANN) on physicochemical and rheological properties and in vitro digestibility of starch extracted from sohphlang (Flemingia vestita) was studied. Modification by HMT and ANN increased amylose content and water absorption capacity. For all modified samples, solubility, swelling power and amylose leaching progressively increased with increasing temperature (50-90 °C). Modified starches exhibited higher contents of SDS and RS and lower content of RDS as compared to native starch for both cooked and uncooked samples. The rheological properties of starch pastes were investigated by the power law model. The starch paste samples exhibited shear thinning characteristics and phase angle was closer to 0°. HMT-30 and ANN-80 exhibited greater impact on in vitro digestibility and rheological behaviour among the HMT and ANN starches, respectively. Thus, ANN and HMT could be used for modification of sohphlang starch making them suitable for application in food systems like pasta and noodles.

Effect of hydrothermal treatment on physicochemical properties of amorphous granular potato starch (AGPS)

Using restructuring technology, A- or B-type crystalline granular potato starch was produced from amorphous granular potato starch (AGPS). AGPS was prepared using ethanol-heat processing, and hydrothermal treatments were performed with different moisture contents (18, 29, 200% d.b.) and temperatures (4, 25, 40, 60, 80 °C) for 3 weeks. AGPS showed no endothermic peak in a DSC thermogram, while hydrothermally treated AGPS (HAGPS) revealed endothermic peaks. In X-ray diffraction, AGPS displayed an amorphous pattern, and HAGPS displayed A- or B-type crystalline patterns depending on treatment temperature and moisture content. Neither AGPS nor HAGPS had typical RVA pasting curves, and their viscosities gradually increased. Raman spectroscopy and FT-IR confirmed that ordered structure and crystalline regions increased in HAGPS. Resistant starch (RS) and slowly digestible starch (SDS) contents of HAGPS increased but rapidly digestible starch (RDS) content decreased compared to AGPS. These results elucidated that hydrothermal treatment could change the physicochemical properties of AGPS and produce an identical material, such as granular potato starch with A-type and B-type crystalline granular potato starch.

The molecular structure, morphology, and physicochemical property and digestibility of potato starch after repeated and continuous heat-moisture treatment

The multiscale structural, physicochemical, and digestible properties of potato starch before and after heat-moisture treatment were investigated, and further compared between repeated heat-moisture treatment (RHMT) and continuous heat-moisture treatment (CHMT). After heat-moisture treatment, there appeared partial disruption and pits on the starch granules, and the birefringence edges of HMT starch particles became blurred. Besides, the molecular weight of samples conspicuously decreased after two kinds of treatments. The crystal type of HMT starches transformed from B-type to C-type according to X-ray analysis. A decrease in the solubility and swelling power in high temperatures were identified. The pasting temperature, the gelatinization transition temperature (T_o , T_p , T_c ), and the slowly digestible starch (SDS) content of HMT starches were significantly higher than native potato starch, while the peak viscosity, the trough viscosity, the final viscosity, the breakdown, and the gelatinization enthalpy (ΔH) of RHMT and CHMT potato starches decreased compared to the native. RHMT potato starches displayed significantly higher relative crystallinity degree and gelatinization transition temperatures. The cooling process of RHMT in which the linkage between the recombinant amylose/amylopectin was enhanced compared with CHMT, which contributed to that RHMT potato starches exhibited greater advantages in practical applications. PRACTICAL APPLICATION: The described RHMT and CHMT starches provide new ideas for the study of modified starch. Furthermore, this study revealed the mechanism of heat-moisture processing provided some instructions to the application of RHMT potato starch.

Effect of repeated heat-moisture treatments on the structural characteristics of nanocrystals from waxy maize starch

The effect of repeated heat-moisture treatment (RHMT) on the structural characteristics of waxy maize starch nanocrystals was investigated. Compared with native waxy maize starch (WMS), waxy maize starch nanocrystals (WMSNs) changed the crystalline pattern from A-type to B-type, and displayed the lower crystallinity (RC), molecular order (MO), enthalpy (∆H) and double-helix (DH) content, indicating a reduction in the long- and short-range orders of starch molecules. Single heat-moisture treatment significantly increased values, including RC, MO, α (power law exponent obtained by SAXS), ∆H, DH, and the melting temperatures (To, Tp and Tc), while repeated heat-moisture treatment further increased values of these parameters except ∆H, indicating the reinforcement of the long- and short-range orders of WMSNs. In addition, repeated heat-moisture treatment also caused a gradual conversion from B-type to "A + B"-type (Cb, Cc to Ca polymorphs in sequence) and finally to A-type crystallites.

Effect of steam parboiling and hot soaking treatments on milling yield, physical, physicochemical, bioactive and digestibility properties of buckwheat (Fagopyrum esculentum L.)

Post-harvest hydrothermal processing of grains are targeted at improving milling performances and nutritional properties. In this study, the effects of two hydrothermal processes, namely steam parboiling and soaking in boiling water for different durations on properties of buckwheat (Fagopyrum esculentum L.) grown in the Indian Himalayan regions were assessed. Both treatments significantly improved milling yield. Changes in grain section morphology were evidenced under scanning electron microscope. Milder processing for 5 and 10 min mostly exerted annealing effect, represented by increased intensities of X-ray diffraction peaks. Starch gelatinization occurred upon prolonged processing for 15 and 20 min. This resulted in decreased crystallinity, increased sedimentation volume, paste thinning during rapid viscosity analysis and lower thermal transition in differential scanning calorimetry. Marginal changes in oil uptake suggested limited protein denaturation. Natural antioxidant compounds were variably denatured. Maillard browning was indicated by CIE L* a* b* colour and antioxidant levels. The starchy flour samples showed partial resistance to enzymatic amylolysis post retrogradation. Soaking in boiling water can be considered as a feasible alternative to conventional steam parboiling for better milling yield of buckwheat. Altered physicochemical and nutritional properties of buckwheat suggested that the hydrothermally modified flours can be used in ready to eat therapeutic food products.

Structural characterization of Peruvian carrot (Arracacia xanthorrhiza) starch and the effect of annealing on its semicrystalline structure

Structural characteristics of native and annealed Peruvian carrot (Arracacia xanthorrhiza) starches were determined and compared to those of cassava and potato starches. Peruvian carrot starch presented round and irregular shaped granules, low amylose content and B-type X-ray pattern. Amylopectin of this starch contained a large proportion of long (DP > 37) and short (DP 6-12) branched chains. These last ones may contribute to its low gelatinization temperature. After annealing, the gelatinization temperatures of all starches increased, but the ΔH and the crystallinity increased only in Peruvian carrot and potato starches. The annealing process promoted a higher exposure of Peruvian carrot amylose molecules, which were more quickly attacked by enzymes, whereas amylopectin molecules became more resistant to hydrolysis. Peruvian carrot starch had structural characteristics that differed from those of cassava and potato starches. Annealing affected the semicrystalline structure of this starch, enhancing its crystallinity, mainly due to a better interaction between amylopectin chains.

The impact of single and dual hydrothermal modifications on the molecular structure and physicochemical properties of normal corn starch

Effect of single and dual hydrothermal modifications with annealing (ANN) and heat-moisture treatment (HMT) on molecular structure and physicochemical properties of corn starch was investigated. Normal corn starch was modified by ANN at 70% moisture at 50 degrees C for 24h and HMT at 30% moisture at 120 degrees C for 24h as well as by the combination of ANN and HMT. The apparent amylose content and swelling factor (SF) decreased on ANN and HMT, but amylose leaching (AML) increased. These changes were more pronounced on dual modification. The crystallinity (determined by X-ray diffraction), the gelatinization enthalpy (determined by differential scanning calorimetry) and ratio of 1047 cm(-1)/1022 cm(-1) (determined by Fourier transform infrared spectroscopy) slightly increased on ANN and decreased on HMT. The ANN and subsequent HMT (ANN-HMT) resulted in the lowest crystallinity, gelatinization enthalpy and ratio of 1047 cm(-1)/1022 cm(-1). The gelatinization temperature range decreased on ANN but increased on HMT. However, the gelatinization range of dually modified starches (ANN-HMT and HMT-ANN) was between ANN starch and HMT starch. Birefringence remained unchanged on ANN but slightly decreased on HMT as well as dual modification. Average chain length and amount of longer branch chains (DP> or =37) remained almost unchanged on ANN but decreased on HMT and dual modifications (ANN-HMT and HMT-ANN). HMT and dual modifications resulted in highly reduced pasting viscosity. ANN and HMT as well as dual modifications increased RDS content and decreased SDS and RS content.

Acid hydrolysis of native and annealed starches and branch-structure of their Naegeli dextrins

Eight commercial starches, including common corn, waxy corn, wheat, tapioca, potato, Hylon V, Hylon VII, and mung bean starch, were annealed by a multiple-step process, and their gelatinization characteristics were determined. Annealed starches had higher gelatinization temperatures, reduced gelatinization ranges, and increased gelatinization enthalpies than their native starches. The annealed starches with the highest gelatinization enthalpies were subjected to acid hydrolysis with 15.3% H2SO4, and Naegeli dextrins were prepared after 10 days' hydrolysis. Annealing increased the acid susceptibility of native starches in the first (rapid) and the second (slow) phases with potato starch showing the greatest and high amylose starches showing the least changes. Starches with a larger shift in onset gelatinization temperature also displayed a greater percent hydrolysis. The increase in susceptibility to acid hydrolysis was proposed to result from defective and porous structures that resulted after annealing. Although annealing perfected the crystalline structure, it also produced void space, which led to porous structures and possible starch granule defects. The molecular size distribution and chain length distribution of Naegeli dextrins of annealed and native starches were analyzed. The reorganization of the starch molecule during annealing occurred mainly within the crystalline lamellae. Imperfect double helices in the crystalline lamellae improved after annealing, and the branch linkages at the imperfect double helices became protected by the improved crystalline structure. Therefore, more long chains were observed in the Naegeli dextrins of annealed starches than in native starches.