Effect of multiple freezing-thawing cycles on structural and functional properties of starch granules isolated from soft and hard wheat

Regulation of ice crystal growth in frozen dough: From the effect of gluten and starch fractions interaction on water binding - A review

The formation and growth of ice crystals are critical factors affecting the quality of frozen dough. Gluten and starch are the primary components of dough, and their hydration properties and effects on dough structure are crucial in determining the type of ice crystals formed. Gliadins, glutenins, A-type starch, and B-type starch are their refined components, each with distinct hydration properties and impact on dough structure. This review examines the structural properties and hydration properties of protein and starch components in frozen dough, as well as their individual and interactive influences on water absorption and the structural properties of frozen dough. Additionally, it explores changes at different structural levels during the interaction between protein and starch components in frozen dough. The review provides theoretical support for wheat breeding aimed at frozen flour products, ultimately contributing to the improvement of frozen dough quality and final product outcomes.

Freeze-thaw pretreatment improved the anti-digestibility and viscosity of corn starch/type-A gelatin complexes

Slowly digestible starches, known to confer health benefits, are often prepared via compounding with other substances. However, starch complexes often encounter problems such as low viscosity. This work aimed to develop a corn starch/type-A gelatin (CS/GA) complex that simultaneously exhibited rapidly digestible starch (RDS) reduction, and superior viscosity. The pH and drying temperature of the complexes were systematically optimized, and a novel freeze-thaw pretreatment (FTP) technique was innovatively introduced. This work investigated the effects of varying FTP cycles (ranging from 0 to 8) on the physicochemical properties of CS/GA complexes. Results showed that FTP significantly enhanced the viscosity of the complexes while effective RDS reduction. Notably, after six FTP cycles, the complexes attained optimal properties, characterized by the highest the complex index (CI), relative crystallinity (RC) and short-range molecular order, accompanied by the lowest RDS reduction of 46.24 %. The multivariate analysis revealed CI as the crucial parameter for altering the resistant starch (RS) content. Furthermore, FTP induced cracking on the surface of starch particles was observed. In conclusion, these results were of significance for developing CS-based food materials with RDS reduction, and high viscosity characteristics, such as noodles, corn porridge and sausage.

Cryoprotective effect of wheat starch granular surface proteins on frozen HMW and LMW glutenins: Structure, property and functionality across length scales

Although frozen dough technology has demonstrated significant benefits, the mechanisms underlying dough deterioration during freezing remain unclear. To overcome this obstacle, the effect of freezing-induced deteriorations of wheat starch granular surface proteins (SGSPs)-high/low molecular weight (HMW/LMW) glutenins complexes were analyzed from the molecular to macroscopic scales. After 7 cycles of freezing/thawing treatment, SGSPs-LMW complex showed a higher antifreeze stability than SGSPs-HMW complex. The freezable water content of SGSPs-HMW increased from 32 % to 39 %, indicating a marked migration and recrystallization of ice. In this situation, the interactions of SGSPs-HMW complex were affected and destabilized, leading to partially denatured and depolymerized molecular structures. Furthermore, the bulk protein aggregation network was also dissociated under the ice tearing and splitting, which irreversibly collapsed to small molecular protein particles. In comparison, the resistance of SGSPs-LMW complex on continued network disruption appear to be the key to maintain the quality of frozen dough.

Impact of freeze-thaw cycles on the physicochemical properties and structure-function relationship of potato starch with varying granule sizes in frozen dough

Starch, as a critical component of dough, significantly influences quality preservation during the freezing process. In particular, the fine structure of potato (B-type) starch in frozen processing is a subject of considerable interest. This study aims to investigate the intrinsic differences of B-type starch and the impact of freeze-thaw (F/T) treatment on its molecular structure and physicochemical properties. Chain length distribution and X-ray photoelectron spectroscopy were utilized to examine the structural characteristics of natural potato starch with different granule sizes. Furthermore, the fine structure, thermal properties, and rheological properties of the isolated starches after F/T treatment were analyzed. The results indicate that potato starch with smaller particle sizes exhibits higher surface CC and PO content along with a higher proportion of very short chains (DP < 6, 8.17 %) and long B chains (DP > 25, 20.68 %). The study found that after F/T treatment, the surface of small-sized starch granules was initially damaged, exhibiting threads on the surface centered on the umbilical point. Following F/T treatment, both the crystallinity (very large (VL): 24.52-18.36 %; small (S): 17.03-16.69 %) and short-range order (VL: 2.97-2.61; S: 2.71-2.35) of starch particle size decreased. Both the amylose content (20.88-14.57 %) and ΔH (10.15-8.62 J/g) of isolated starch after freeze-thaw-treated dough exhibited a decrease to varying degrees. With the exception of the fifth cycle, small-size starch particles exhibited relatively higher G' and G" values and showed significant changes as a result of F/T treatment, demonstrating high hardness and complex viscosity. Clarifying the physicochemical properties of potato starches with different granule sizes is expected to expand their applications in frozen dough.

Potato dietary fiber effectively inhibits structure damage and digestibility increase of potato starch gel due to freeze-thaw cycles

Repeated freeze-thaw (FT) cycles damage the quality of frozen starch-based foods and accelerate the digestion rate of starch. This study investigated how potato soluble dietary fiber (PSDF) affects the physicochemical characteristics and digestibility of potato starch (PS) after repeated FT cycles. Results indicated that repeated FT cycles of potato starch resulted in the enlargement of gel pores, an increase in hardness (from 322.5 g to 579.5 g), and a decrease in gel porosity, leading to reduced water-holding capacity (from 94.2 % to 85.4 %). However, the addition of PSDF stabilized the 3D structure of the PS/PSDF gel, with minimal fluctuations in hardness (413.0-447.5 g) and water-holding capacity (94.4-93.6 %). Meanwhile, PSDF enhanced intramolecular hydrogen bonding within starch molecules and promoted molecular interactions, increasing the PS/PSDF gel's helix structure; therefore, PSDF effectively addressed the increase in rapidly digestible starch caused by repeated FT cycles. Furthermore, PSDF might attach to the surface of starch particles, so limiting starch granule expansion and decreasing the peak viscosity increase caused by repeated FT cycles. The findings suggest that PSDF could be an effective component for improving the quality of potato starch-based frozen food.

Insight into the effect of potassium carbonate on the physicochemical and structural properties of starch isolated from hot-dry noodles

The objective of this study was to investigate the changes in physicochemical and structural properties of starch isolated from hot-dry noodles (HDNS) treated with different contents of potassium carbonate (K2CO3). The results demonstrated that the existence of K2CO3 increased the WHC and hardness of HDNS gel with an elevated storage modulus. Meanwhile, K2CO3 promoted the gelatinization of HDNS, which displayed higher viscosity and swelling power. Moreover, the relative crystallinity of HDNS were improved. K2CO3 facilitated the transformation of HDNS from an amorphous to a more ordered and crystalline structure. Simultaneously, the microscopic characteristics exhibited that K2CO3 promoted the partial fusion of starch particles to form aggregates, and the particle size became larger. In conclusion, the physicochemical and structural properties of HDNS were improved effectively with the incorporation of K2CO3, and the research results provided new insights for the processing of high-quality hot-dry noodles.

Effect of freezing rates on α-amylase enzymatic susceptibility, in vitro digestibility, and technological properties of starch microparticles

The aim of this study was to evaluate the effect of freezing rates using direct (LF: Liquid nitrogen) and indirect (RF: Cryogenic refrigerator and UF: ultra-freezer) methods at temperatures of (-20, -80, and - 196 °C) on the enzymatic susceptibility with α-amylase for microparticles. In vitro digestibility parameters and technological properties were also analyzed. Lower rates resulted in larger ice crystals, damaging the starch structure. Hydrolysis was more pronounced at slower rates RF: 0.07 °C/min and UF: 0.14 °C/min, yielding maximum values of RDS: 37.63% and SDS: 59.32% for RF. Type A crystallinity remained unchanged, with only a noted increase in crystallinity of up to 6.50% for FR. Starch pastes were classified as pseudoplastic, with RF exhibiting superior textural parameters and apparent viscosity. (RF: 7.18 J g-1 and UF: 7.34 J g-1) also showed lower values of gelatinization enthalpy. Freezing techniques were viable in facilitating the diffusion of α-amylase and reducing RS by up to 81%.

Effect of enzymatic hydrolysis of arabinoxylan on the quality of frozen dough during the subfreezing process

BACKGROUND

The objective of this investigation was to examine the impact of enzymatic hydrolysis of arabinoxylan (AX) on frozen dough quality under subfreezing conditions. The dough was subjected to freezing at -40 °C for 2 h and then stored at -9, -12, and -18 °C for 15 days. The water loss, freezable water content, water migration, and microstructure of the dough were measured.

RESULTS

The dough containing 0.8% cellulase enzymatically hydrolyzed AX (CAX) required the shortest duration when traversing the maximum ice-crystal formation zone (6.5 min). The dough with xylanase enzymatically hydrolyzed AX (XAX) demonstrated a faster freezing rate than the dough with CAX. The inclusion of both XAX and CAX in the dough resulted in the lowest freezable water loss and reduced freezable water content and free-water content levels, whereas the inclusion of xylanase-cellulase combined with enzymatically hydrolyzed AX resulted in higher free-water content levels. The textural properties of the subfreezing temperature dough were not significantly different from the dough stored at -18 °C and sometimes even approached or surpassed the quality observed in the control group rather than the dough stored at -18 °C. In addition, the gluten network structure remains well preserved in XAX- and CAX-containing doughs with minimal starch damage.

CONCLUSION

The enzymatic hydrolysis of AX from wheat bran can be used as a useful additive to improve the quality of frozen dough. © 2024 Society of Chemical Industry.

Effects of freeze-thaw cycles on the quality of Hot-dry noodles: From the moisture, starch, and protein characteristics

Freeze-thaw cycles (FTC) could cause damage to food during storage. The effects of different FTC on Hot-dry noodles (HDN) in terms of quality, moisture, starch, and protein characteristics were studied. This study showed that FTC decreased the texture properties and water absorption of HDN. Meanwhile, cooking loss was significantly increased after FTC. The water content of HDN was decreased and water migration was increased during FTC. In addition, results showed that FTC destroyed the order structure and increased the crystallinity of starch in HDN. Under FTC, the disulfide bond of HDN was broken, the free sulfhydryl group was increased, and the electrophoretic patterns confirmed the protein depolymerization. The microstructure also showed that the gluten network became incomplete and starch was exposed outside the substrate. This study expounded the mechanism of HDN quality deterioration during FTC, which laid a foundation for the development and improvement of frozen and freeze-thaw noodles.

Fabrication and characterization of complex coacervates utilizing gelatin and carboxymethyl starch

BACKGROUND

Modified polysaccharides have greatly expanded applications in comparison with native polysaccharides due to their improved compatibility and interactions with proteins and active compounds in food-related areas. Nonetheless, there is a noticeable dearth of research concerning the utilization of carboxymethyl starch (CMS) as a microcapsule wall material in food processing, despite its common use in pharmaceutical delivery. The development of an economical and safe embedding carrier using CMS and gelatin (GE) holds immense importance within the food-processing industry. In this work, the potential of innovative coacervates formed by the combination of GE and CMS as a reliable, stable, and biodegradable embedding carrier is evaluated by turbidity measurements, thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and rheological measurements.

RESULTS

The results indicate that GE-CMS coacervates primarily resulted from electrostatic interactions and hydrogen bonding. The optimal coacervation was observed at pH 4.6 and with a GE/CMS blend ratio of 3:1 (w/w). However, the addition of NaCl reduced coacervation and made it less sensitive to temperature changes (35-55 °C). In comparison with individual GE or CMS, the coacervates exhibited higher thermal stability, as shown by TGA. X-ray diffraction analysis shows that the GE-CMS coacervates maintained an amorphous structure. Rheological testing reveals that the GE-CMS coacervates exhibited shear-thinning behavior and gel-like properties.

CONCLUSION

Overall, attaining electroneutrality in the mixture boosts the formation of a denser structure and enhances rheological properties, leading to promising applications in food, biomaterials, cosmetics, and pharmaceutical products. © 2023 Society of Chemical Industry.

Effects of nitrogen application on physicochemical properties of rice starch under elevated temperature

Nitrogen fertilization can mitigate the negative effects of high temperatures on rice. In this study, we simulated dynamic field temperature increases using a free-air temperature enhancement system. Changes in the physicochemical properties of starch were investigated under increasing nitrogen fertilization during the grain-filling stage. We observed that the application of nitrogen at elevated temperatures (ETN) did not change the chain length distribution compared with elevated temperatures (ET) alone; however, it did significantly increase the heights of the first and second amylose peaks. Specifically, ETN significantly decreased the height of fifth amylopectin and relative crystallinity, and the changes it introduced in the physicochemical properties of starch were greater than those of ET. Overall, these changes in starch properties may be associated with the ability of nitrogen to facilitate the maintenance of rice quality at high temperatures.

Assessment of freeze damage in tuber starch with electrical impedance spectroscopy and thermodynamic, rheological, spectrographic techniques

In this study, we aimed to use electrical impedance spectroscopy (EIS) to assess the freeze-damage level of starches from potato tubers treated with multiple freezing-thawing (FT) cycles. The results showed that the relationship between the physicochemical properties of starches and the impedance characteristics of starch paste is temperature-dependent. As the temperature rises to 70-90 °C, the impedance modules show a significant correlation with the amylose and mineral contents, gelatinization and pasting properties, short-range ordered structure, relative crystallinity, and damage level within the range of 10-1 MHz (p < 0.01). This could be because FT leads to a reduction in amylose and ion content. Compared to a high level of freeze-damaged starch (FDS), a low level of FDS has less amylopectin and more amylose. Additionally, the ions could be typically evenly distributed throughout the unbranched linear amylose structure in starch paste. At the peak gelatinization temperature, the starch paste made from a low level of FDS exhibits a weakened network structure, allowing more unbound water for ion movement and enhancing electric conduction. In conclusion, EIS can predict the damage level and properties of FDS, which can benefit the frozen starchy food industry.

Structural and physicochemical characteristics of wheat starch as influenced by freeze-thawed cycles and antifreeze protein from Sabina chinensis (Linn.) Ant. cv. Kaizuca leaves

The effects of freeze-thawed cycles (FTs) and a new antifreeze protein from Sabina chinensis (Linn.) Ant. cv. Kaizuca leaves (ScAFP) on the structure and physicochemical characteristics of wheat starch were studied. The mechanical breaking exerted by ice crystals on starch granules during FTs gradually deepened, sequentially squeezing the surface (2-6 FTs), amorphous region (8 FTs) and crystalline region (10 FTs) of starch granules. These changes led to reduced thermal stability, increased retrogradation tendency, and weakened gel network structure. The addition of ScAFP retarded the damage of ice crystals on starch granule structure and crystal structure during FTs, and significantly reduced the retrogradation tendency. Compared with native starch, the hardness of freeze-thawed starch without and with added ScAFP after 10 FTs decreased by 17.85% and 9.22%, respectively, indicating ScAFP improved the gel texture properties of freeze-thawed starch. This study provides new strategies for improving the quality of frozen starch-based foods.

Effect of melting combined with ice recrystallization on porous starch preparation: Pore-forming properties, granular morphology, functionality, and multi-scale structures

In this work, critical melting (CM) combined with freeze-thawing treatment (FT, freezing at -20 ℃ and -80 ℃, respectively) was used to prepare porous starch. The results showed that CM combined with the slow freezing rate (-20 ℃) can prepare porous starch with characteristics of grooves and cavities, while combined with the rapid freezing rate (-80 ℃) can prepare with holes and channels, especially after repeating FT cycles. Compared with the native counterpart, the specific surface area, pore volume, and average diameter of CMFT-prepared porous starch were significantly increased to 4.07 m2/g, 7.29 cm3/g × 10-3, and 3.57 nm, respectively. CMFT significantly increased the thermal stability of starch, in which the To, Tp, and Tc significantly increased from 63.32, 69.62, and 72.90 (native) to ∼69, 72, and 76 °C, respectively. CMFT significantly increased water and oil absorption of porous starch from 91.20 % and 72.00 % (native) up to ∼163 % and 94 %, respectively. Moreover, CMFT-prepared porous starch had a more ordered double-helical structure, which showed in the significantly increased relative crystallinity, semi-crystalline lamellae structure, and the proportion of the double helix structure of starch. The synergistic effect of melting combined with ice recrystallization can be used as an effective way to prepare structure-stabilized porous starch.

Use of a compound modifier to retard the quality deterioration of frozen dough and its steamed bread

To retard the quality deterioration of the dough during frozen storage, the effects of a compound modifier (CM) comprised of sodium stearoyl lactate, VC, and β-glucanase on the properties of the frozen dough, as well as the quality of the frozen dough steamed bread were investigated. The results revealed that CM restricted the migration of water in the dough and improved its rheological properties. Furthermore, CM minimized the deterioration of specific volume and textural properties, and prevented starch retrogradation in the frozen dough steamed bread. Moreover, the addition of CM strengthened the secondary structure of gluten protein and formed a more resilient gluten network. The microstructure of the frozen dough steamed bread showed that CM reduced the damage caused by ice crystals on the gluten network. Overall, the use of CM strengthened the gluten network and effectively delayed the quality deterioration of the frozen dough, thus is potential as an improver for frozen dough.

Toward function starch nanogels by self-assembly of polysaccharide and protein: From synthesis to potential for polyphenol delivery

Nanogels formed by self-assembly of natural proteins and polysaccharides have attracted great interest as potential carriers of bioactive molecules. Herein, we reported that carboxymethyl starch-lysozyme nanogels (CMS-Ly NGs) were prepared using carboxymethyl starch and lysozyme by green and facile electrostatic self-assembly, and the nanogels served as epigallocatechin gallate (EGCG) delivery systems. The dimensions and structure of the prepared starch-based nanogels (i.e., CMS-Ly NGs) were characterized by dynamic light scattering (DLS), ζ-potential, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermal gravimetric analyzer (TGA). FT-IR and 1H NMR spectra together confirmed the formation of CMS; FT-IR spectra confirmed the formation of CMS-Ly NGs; XRD spectra confirmed the disruption of the crystal structure of lysozyme after electrostatic self-assembly with CMS, and further confirmed the formation of nanogels. TGA demonstrated the thermal stability of nanogels. More importantly, the nanogels showed a high EGCG encapsulation rate of 80.0 ± 1.4 %. The CMS-Ly NGs encapsulated with EGCG exhibited regular spherical structure and stable particle size. Under the simulated gastrointestinal environmental conditions, CMS-Ly NGs encapsulated with EGCG showed the controlled release potential, which increased its utilization. Additionally, anthocyanins can also be encapsulated in CMS-Ly NGs and showed slow-release properties during gastrointestinal digestion in the same way. Cytotoxicity assay also demonstrated good biocompatibility between CMS-Ly NGs and CMS-Ly NGs encapsulated with EGCG. The findings of this research suggested the potential application of protein and polysaccharides-based nanogels in the delivery system of bioactive compounds.

Characterization and Differentiation of Grain Proteomes from Wild-Type Puroindoline and Variants in Wheat

Premium wheat with a high end-use quality is generally lacking in China, especially high-quality hard and soft wheat. Pina-D1 and Pinb-D1 (puroindoline genes) influence wheat grain hardness (i.e., important wheat quality-related parameter) and are among the main targets in wheat breeding programs. However, the mechanism by which puroindoline genes control grain hardness remains unclear. In this study, three hard wheat puroindoline variants (MY26, GX3, and ZM1) were compared with a soft wheat variety (CM605) containing the wild-type puroindoline genotype. Specifically, proteomic methods were used to screen for differentially abundant proteins (DAPs). In total, 6253 proteins were identified and quantified via a high-throughput tandem mass tag quantitative proteomic analysis. Of the 208 DAPs, 115, 116, and 99 proteins were differentially expressed between MY26, GX3, and ZM1 (hard wheat varieties) and CM605, respectively. The cluster analysis of protein relative abundances divided the proteins into six clusters. Of these proteins, 67 and 41 proteins were, respectively, more and less abundant in CM605 than in MY26, GX3, and ZM1. Enrichment analyses detected six GO terms, five KEGG pathways, and five IPR terms that were shared by all three comparisons. Furthermore, 12 proteins associated with these terms or pathways were found to be differentially expressed in each comparison. These proteins, which included cysteine proteinase inhibitors, invertases, low-molecular-weight glutenin subunits, and alpha amylase inhibitors, may be involved in the regulation of grain hardness. The candidate genes identified in this study may be relevant for future analyses of the regulatory mechanism underlying grain hardness.

Optimization of freezing methods and composition of frozen rice dough reconstituted by glutinous rice starch and gluten

This study investigated the effects of four different freezing methods on the texture of rice dough reconstituted by glutinous rice starch and gluten, and the changes of properties of rice dough with different gluten ratios after liquid nitrogen (LF) treatment. The profiles of frozen rice dough were studied by texture analyzer, low-field NMR, SEM, FT-IR, DSC, CLSM, X-RD and RVA. Results revealed that with the slowing down of freezing rate, the damage of freezing process to starch granules and protein structure in frozen rice dough increases, resulting in the increase of damaged starch, the decrease of protein ordered structure, the change of bound water in frozen rice dough to free water, the decrease of frozen rice dough hardness and elasticity, the decrease of storage modulus (G') and the deterioration of frozen rice dough texture. The addition of gluten in frozen rice dough will increase the short-range ordered structure and crystal structure of starch, reduce the digestibility of starch, and change the viscosity characteristics of frozen rice dough. Based on the experimental results, adding 10 % gluten is more suitable for making frozen rice dough, while LF has the least effect on frozen rice dough texture.

The improvement of texture properties and storage stability for kappa carrageenan in developing vegan gummy candies

BACKGROUND

As plant-based foods have become more mainstream in recent years, carrageenan has been used to replace animal-derived gelatin in confectionery products. However, texture defects and water seepage during storage limit the development of kappa carrageenan (KC) gummy candies.

RESULTS

This study evaluated the effects of hydrocolloids on the texture properties and storage stability of KC gummy candies. The results showed that 4 g kg^-1 carboxymethylcellulose (CMC) composited with 20 g kg^-1 KC formed a flexible gummy candy with low fragility and limited water seepage during storage. Further investigation revealed that 4 g kg^-1 CMC promoted side-by-side intermolecular aggregation of KC helices through hydrogen bonding, which stabilized a denser network structure compared to the pure KC hydrogel. However, high CMC proportions (8-12 g kg^-1 ) led to electrostatic repulsion that dominated in the system, inhibiting the gel-forming process and thus resulting in a weak gel structure with accelerated syneresis.

CONCLUSION

This study found that 4 g kg^-1 CMC was able to improve the flexibility and decrease unacceptable fragility of KC gummy candies, with water seepage decreased during storage significantly. It provided preliminary evidence for utilizing hydrocolloids to adjust texture and control water migration in KC gels, and has potential to promote wide development of vegan gummy candies. © 2021 Society of Chemical Industry.

Valorization of Starch to Biobased Materials: A Review

Many concerns are being expressed about the biodegradability, biocompatibility, and long-term viability of polymer-based substances. This prompted the quest for an alternative source of material that could be utilized for various purposes. Starch is widely used as a thickener, emulsifier, and binder in many food and non-food sectors, but research focuses on increasing its application beyond these areas. Due to its biodegradability, low cost, renewability, and abundance, starch is considered a "green path" raw material for generating porous substances such as aerogels, biofoams, and bioplastics, which have sparked an academic interest. Existing research has focused on strategies for developing biomaterials from organic polymers (e.g., cellulose), but there has been little research on its polysaccharide counterpart (starch). This review paper highlighted the structure of starch, the context of amylose and amylopectin, and the extraction and modification of starch with their processes and limitations. Moreover, this paper describes nanofillers, intelligent pH-sensitive films, biofoams, aerogels of various types, bioplastics, and their precursors, including drying and manufacturing. The perspectives reveal the great potential of starch-based biomaterials in food, pharmaceuticals, biomedicine, and non-food applications.

Effects of Quinoa Flour on Wheat Dough Quality, Baking Quality, and in vitro Starch Digestibility of the Crispy Biscuits

Quinoa is a pseudo-cereal which has excellent nutritional and functional properties due to its high content of nutrients, such as polyphenols and flavonoids, and therefore quinoa serves as an excellent supplement to make healthy and functional foods. The present study was aimed to evaluate the quality characteristics of wheat doughs and crispy biscuits supplemented with different amount of quinoa flour. The results showed that when more wheat flour was substituted by quinoa flour, proportion of unextractable polymeric protein to the total polymeric protein (UPP%) of the reconstituted doughs decreased and the gluten network structure was destroyed at a certain substitution level. The content of B-type starch and the gelatinization temperature of the reconstituted flours increased. The storage modulus, loss modulus, development time, and stability time of the dough increased as well. Moreover, hardness and toughness of the formulated crispy biscuits significantly decreased. Analyses suggested that starch digestibility was reduced and resistant starch content increased significantly. Taken together, quinoa flour improved dough rheological properties, enhanced the textural properties, and increased resistant starch content in crispy biscuits, thus adding to high nutritional value.

Fabrication and Characterization of Whey Protein—Citrate Mung Bean Starch—Capsaicin Microcapsules by Spray Drying with Improved Stability and Solubility

Capsaicin was microencapsulated in six different wall systems by spray drying whey protein and citrate mung bean starch at various ratios (10:0, 9:1, 7:3, 5:5, 3:7, 1:9, 0:10) to improve its stability and water solubility and reduce its pungency. The morphological, rheological, storage stability, and physicochemical properties of capsaicin emulsion and capsaicin microcapsules were characterized. As a result, the yield of six capsaicin microcapsules was 19.63–74.99%, the encapsulation efficiency was 26.59–94.18%, the solubility was 65.97–96.32%, the moisture content was lower than 3.63% in all systems, and particle size was broadly distributed in the range of 1–60 μm. Furthermore, microcapsules with high whey protein content in the encapsulation system had an excellent emulsifier effect and wetness, smooth particle surface, and higher lightness (L*). Moreover, the system formed by composite wall materials at a ratio of whey protein to citrate mung bean starch of 7:3 had the highest retention rate and the best stability. The overall results demonstrate that whey protein combined with citrate mung starch through spray drying could be a promising strategy to produce microcapsules of poorly water-soluble compounds such as capsaicin.

Assessment of Physicochemical and Rheological Properties of Xylo-Oligosaccharides and Glucose-Enriched Doughs Fermented with BB-12

Simple Summary

Xylo-oligosaccharides (XOS) are considered indigestible fibers that could support the growth of potentially beneficial gut microbes, thus classified as “prebiotics”. Prebiotics are “a substrate that is selectively utilized by host microorganisms conferring a health benefit” as defined by the International Scientific Association for Probiotics and Prebiotics. The current work aimed to study the effect of XOS and glucose addition on wheat flour sourdough fermented with Bifidobacterium animalis subsp. lactis (BB-12) strain in terms of organic acid production and on the rheological properties of the doughs. The effect of XOS addition increased the production of organic acids, and positively influenced the rheological properties of the dough. Additionally, after frozen storage, there were no significant viscoelastic changes in the dough structure, which indicates that xylo-oligosaccharides improved the water retention capability of the dough. Through fermentation carbohydrates like, glucose, xylose, maltose, and XOS were consumed, and a high quantity of lactic and acetic acid were produced, organic acids with roles in the flavor generation and sensorial properties of the final product. This study showed the potential use of XOS as food ingredient in sourdoughs for bakery products manufacturing with improved quality and rheological properties.

Abstract

Xylo-oligosaccharides (XOS) are considered non-digestible fibers produced mainly from agricultural biomass and are classified as “emerging prebiotic” compounds. Since XOS were shown to promote the growth of bifidobacteria in the gut with potential effects on one’s health, scientists used them as food ingredients. For example, the addition of XOS in bakery products could improve their physicochemical characteristics. The current work aimed to investigate the effect of XOS and glucose addition on wheat flour sourdough fermented with Bifidobacterium animalis subsp. lactis (BB-12) strain in terms of organic acid production. The effect on viscoelastic changes during frozen storage and after the thawing process was also studied. The results showed that the viability of BB-12 increased slightly with the increase in XOS and glucose concentrations, which determined dough acidification due to accumulation of organic acids, that positively influenced the dough’s rheological properties such as a higher elasticity before and after frozen storage. With 10% XOS-addition, the acetic acid quantity reached 0.87 ± 0.03 mg/L, and the highest lactic acid concentration was found in the 10% XOS-enriched doughs, the glucose-enriched doughs and in the control sample (100% wheat dough). The quantity of glucose, maltose, XOS, and xylose decreased until the end of fermentation.

Effect of multiple freezing/thawing cycles on the physicochemical properties and structural characteristics of starch from wheat flours with different gluten strength

The physicochemical properties and structural characteristics of starches from three wheat flours with different gluten strength (S-YM20, S-ZM27, and S-ZM366) during freezing/thawing (F/T) cycles were studied. After F/T treatment, the damaged starch content of these three starches all increased, and the lowest increment of damaged starch content after 8 F/T cycles was S-ZM366; the most serious distribution of particle surface concave hole and fracture was S-YM20, followed by S-ZM27 and S-ZM366; additionally, the results of solubility, swelling power, thermal stability and pasting properties indicated S-ZM366 exhibited the strongest resistance to F/T cycles. The differences of freezing resistance among the three starches were possibly ascribed to the differences in compositions, crystallinity and microstructure among these three starches. This study provides theoretical contribution to the development of frozen dough industry from the perspective of wheat variety.

Changes of aggregation and structural properties of heat-denatured gluten proteins in fast-frozen steamed bread during frozen storage

The aim of this research was to clearly clarify the deterioration mechanism of heat-denatured gluten proteins by exploring the change of aggregation and structural characteristics of heat-denatured gluten proteins in the steamed bread system and the steamed gluten system during frozen storage. An increase in the total SDS-soluble protein content was determined, which mainly attributed to the soluble monomer protein content increased. Combined with the significant increase of free sulfhydryl, from 3.12 μmol/g to 5.06 μmol/g and 2.64 μmol/g to 3.29 μmol/g, respectively, it can be inferred that the proteins depolymerization induced by frozen storage was mainly involved in the breakdown of heat-induced glutenin-gliadin disulfide cross-linking. Frozen storage induced the conversion of random coil structure to β-sheet structure and a ruptured microstructure with small fragment was observed. Moreover, the protein of steamed bread system was easier to depolymerize than that of the steamed gluten system.

Further interpretation of the strengthening effect of curdlan on frozen cooked noodles quality during frozen storage: Studies on water state and properties

Curdlan has been applied to weaken the quality deterioration of frozen cooked noodles (FCN) during frozen storage. However, the underlying mechanism is still unclear. In this paper, an A/LKB-F probe was used for texture profile analysis and mercury intrusion was firstly used for analyzing ice crystals state in three dimensions. Meanwhile, a systematic study on the water state was conducted, as well as the freeze-thawed stability of FCN under curdlan intervention during frozen storage. The results showed that 0.5% curdlan significantly (P < 0.05) alleviated the decrement in hardness, chewiness and extension, and enhanced the freeze-thawed stability of FCN. This was closely associated with the fact that the addition of curdlan minimized freezable water content, inhibited water mobility and migration, and raised the homogeneity of ice crystals in FCN. This study provides more comprehensive theories for the strengthening effect of curdlan on FCN quality from the perspective of water state.

Frozen-dough baking potential of psychrotolerant Saccharomyces species and derived hybrids

Despite Saccharomyces cerevisiae being a synonym for baker's yeast, the species does not perform well in all baking-related conditions. In particular, dough fermentation, or proofing, is compromised by the species' sensitivity to the low and freezing temperatures that are often used in modern bakeries. Here, screening trials that included representatives of all known Saccharomyces species, showed that S. cerevisiae was generally the most sensitive member of the genus with respect to cold and freezing conditions. We hypothesized therefore that the superior cold tolerance of the non-S. cerevisiae yeast would enable their use as frozen-dough baking strains. To test this, the different yeast species were incorporated into doughs, flash frozen and kept in a frozen state for 14 days. During the proofing stage, dough development was lower in doughs that had been frozen, relative to fresh doughs. This reduction in fermentation performance was however most pronounced with S. cerevisiae. The psychrotolerant yeasts S. eubayanus, S. jurei and S. arboricola showed a strong capacity for post-freeze proofing in terms of dough development and duration of lag phase prior to fermentation. The superior proofing power of these species resulted in breads that were significantly softer and less dense than those prepared with S. cerevisiae. A sensory panel could distinguish the S. cerevisiae and non-S. cerevisiae breads based on their physical properties, but aroma and taste were unaffected by the species employed. To further improve frozen dough baking properties, S. eubayanus, S. jurei and S. arboricola were crossed with baker's yeast through rare mating, and hybrids with improved proofing capacities in both fresh and frozen doughs relative to the parents were created. The use of S. jurei and S. arboricola in baking represents the first potential technological application of these species.

Effects of oligosaccharides on particle structure, pasting and thermal properties of wheat starch granules under different freezing temperatures

The effects of fructooligosaccharides (FOS), galactooligosaccharides (GOS), and xylooligosaccharides (XOS) on gelatinization, retrogradation, thermal properties and particle size of wheat starch at different freezing temperatures were studied. The results showed that the wheat starch porosity, particle size, peak viscosity increased with increasing freezing temperature. With the addition of 16% oligosaccharides to starch, the porosity, particle size, crystallinity, initial gelatinization temperature, peak value, breakdown and retrogradation viscosity of the starch granules significantly decreased in the order of XOS > GOS > FOS. However, the pasting temperature of the granules increased. The addition of oligosaccharides (especially XOS, which has the most significant effect in inhibiting starch retrogradation) can inhibit the formation of starch crystal structures to a certain extent, reduce the damage from ice crystals to starch granules and delay starch retrogradation. Therefore, functional oligosaccharides can be used as a potentially effective additive to increase freezing stability in frozen starch-based foods.