Effect of freezing rate and frozen storage on the rheological properties and protein structure of non-fermented doughs

Components and physicochemical properties of mill streams: Effects on freeze-thaw stability and quality of frozen steamed bread dough

This study investigated the influence of five mill streams on the freeze-thaw (FT) stability of dough and steamed bread quality. The 1M2 stream (1st reduction) exhibited the longest stability time (7.24 min), maximum dough height (36.1 mm), and the highest specific volume (1.93 mL/g) of steamed bread. The 1S stream (1st sizing) had the highest water-extractable arabinoxylan content (0.62 %), which contributed to frozen dough stability and maintained a high specific volume (1.85 mL/g) throughout FT treatment. In contrast, the 3M stream (3rd reduction) showed the shortest stability time (5.83 min) and lowest specific volume (1.39 mL/g). Protein subunit and rheological analyses revealed that higher gliadin content in the 1M2 and 1S streams promoted dough extensibility, facilitating expansion during fermentation and steaming. These results demonstrate the key role of mill stream characteristics in determining dough FT stability and provide valuable insights for the use of specific mill streams in frozen dough.

Impact of freeze-thaw cycles on the structural and quality characteristics of soy protein gels with different 11S/7S protein ratios

Freeze-thaw (F-T) is the key factor affecting the quality changes of frozen soybean products. Therefore, this study investigated the effects of F-T on the structure and quality of soybean protein gels with different 11S/7S ratios. It was revealed that recrystallisation of ice crystals during the F-T treatment induced protein structural reorganization. This resulted in a reduction of the gels' water-holding capacity (WHC). F-T decreased the amount of soluble protein by encouraging protein buildup through disulfide bonds and hydrophobic contacts. 5 F-T results were the most significant. When the 11S/7S ratio exceeded 1:1.5, the F-T exerted a more disruptive effect on the protein gel, leading to an increase in β-sheet and random coil content. When 11S/7S was less than 1:1.5, F-T had less impact, and the decrease in WHC was reduced. This study provides theoretical support for regulating soybean protein components to improve the F-T stability of soybean protein gels.

Reducing flavor loss in precooked beef: The critical role of freezing processes

Flavor loss is a pain point during prepared dishes processing. As a key step during processing, the potential role of freezing in flavor regulation is less known. Hence, the aim of present study was to investigate how freezing affects flavor quality. In this work, simplify processing models of beef was established to describe the effects of different freezing methods-slow (SF), quick (QF), and liquid nitrogen (LNF) freezing-on the flavor retention of precooked beef. The results demonstrate that freezing rate exerts a significant in flavor loss, and high freezing rate (QF and LNF) can reduce key differential compounds (1-octen-3-ol, 2-pentylfuran, and nonanal) changing effectively. The correlation analysis further suggested that QF might strike a balance between forming smaller ice crystals and minimizing protein damage to the best flavor retention. These findings open new avenues of research to emphasizes the role of optimizing freezing processes in prepared dishes industrial production.

Elucidation on the quality improvement of dumpling wrappers by glycosylated potato protein under freeze-thaw cycle treatment

Dumplings are the favorite quick-frozen food for people in many countries. However, the formation and recrystallization of ice crystals damage the quality of dumpling wrappers during storage. Research has shown that proteins and polysaccharides can improve the quality of frozen dough and that the Maillard reaction can improve the functional properties of proteins and polysaccharides. Therefore, the effects of glycosylated protein between potato protein and xanthan gum (PXM) on the overall changes in dumpling wrappers during freeze-thaw cycles (FT) were studied in this study. The results showed that the addition of PXM (1 %) slowed the deterioration of texture and rheological properties and reduced the cooking loss rate and freezable water content of dumpling wrappers during FT, thus improving the texture quality of dumpling wrappers. Moreover, the addition of PXM delayed the changes in the contents of free sulfhydryl (SH) and disulfide (SS) bonds during storage, weakening the damage to the secondary structure and network structure of the protein. The reason for this difference may be that protein glycosylation significantly increases the zeta potential (13.5 %), surface hydrophobicity (63.9 %), emulsifying activity (192.6 %) and emulsification stability (116.7 %) of potato protein (PP). These results suggest that the application of the glycosylated protein provides a potentially feasible approach to improve the quality of frozen dumpling.

Unveiling the dynamic interactions of gluten-starch-water in frozen dough: An in-depth review

In recent decades, frozen dough has become an attractive means of preserving and offering the convenience of fresh-tasting foods while retaining their nutritional benefits. However, the frozen dough industry still faces significant challenges related to processing, freezing, and storage that affect the dough's quality and stability during thawing. Understanding the complex interactions between proteins (gluten, glutenin, gliadin, and glutenin macropolymers), starch dynamics (gelatinization and retrogradation), and water distribution-particularly how ice crystals interact with the gluten-starch matrix-is essential for improving frozen dough quality. This review also delves into the rheological properties resulting from the interplay of these components, emphasizing their collective impact on dough texture and stability. Additionally, it explores various freezing mechanisms and innovative strategies to reduce freeze damage, as well as practical challenges in translating theoretical insights into industrial applications. Finally, it proposes future strategies for improving the shelf life and quality of frozen dough by optimizing freezing methods and water distribution. Through a comprehensive synthesis of current literature, this review underscores the critical importance of gluten-starch-water interactions in frozen dough and highlights promising strategies for enhancing product performance and quality.

Revealing the influence mechanism of pre-fermentation degree and storage temperature fluctuations on frozen steamed bread dough quality

This study investigated the effects of pre-fermentation degree and storage temperature fluctuations on the gas cells, gluten protein, rheological properties of frozen dough, and quality of steamed bread. Three pre-fermentation degrees and four fluctuating temperatures (-10 °C, 0 °C, 10 °C, and 25 °C) were used. The gas cell size increased with the pre-fermentation degree; however, the gas cells merged and ruptured during temperature fluctuations. Sodium dodecyl sulfate extraction protein content and free sulfhydryl content increased by 3.07 % and 33.62 %, respectively, in the medium pre-fermentation group at 25 °C compared with those at -10 °C. The maximum strain of dough increased as pre-fermentation degree and fluctuating temperatures increased. The specific volumes of steamed bread with medium pre-fermentation degree were 1.87 mL/g at -10 °C and 1.47 mL/g at 25 °C. In conclusion, higher temperature fluctuations exceeding the freezing point exacerbated the dough and steamed bread quality, particularly in high pre-fermentation degree dough.

Effects of arabinoxylan extracted from vinegar residue on physicochemical and structural properties of gluten proteins obtained from freeze-thaw wheat dough

BACKGROUND

Arabinoxylan is commonly used as a hydrocolloid in frozen dough to improve the texture and the sensory qualities of the products. The effects of vinegar residue arabinoxylan (VRAX) on the secondary structures and microstructures of gluten proteins during freeze-thaw storage were studied, and the underlying mechanism governing these effects was clarified.

RESULTS

The results revealed that VRAX improved the textural properties of gluten proteins, but had a negative impact on their viscoelasticity. Additionally, the addition of VRAX increased the number of disulfide bonds and also improved the freezing tolerance of the gluten proteins. It was found that the enthalpy of the gluten proteins decreased by 19.78% following VRAX addition. As a result of the use of VRAX, the freezing procedure resulted in reduced formation of ice crystals, protecting the gluten network structure and preserving the dough's elasticity. The network structure of gluten proteins after VRAX treatment was more ordered and integrated relative to that of frozen blank control gluten proteins.

CONCLUSION

Overall, the freeze-thaw stability of the gluten proteins was enhanced by VRAX. These results suggest that VRAX has potential as an effective cryoprotectant in frozen dough. © 2024 Society of Chemical Industry.

Enhancing thermal stability and mechanical resilience in gelatin/starch composites through polyvinyl alcohol integration

In practical scenarios, destabilizing the physical attributes of natural polymers such as gelatin and starch occurs readily when exposed to specific moisture levels and heat. In this context, this work was carried out to assess the impact of PVA addition (up to 13 wt%) on the structure and physical properties of a 6:4 (w/w) gelatin/starch blend. The inclusion of PVA unfolded the molecular chains of gelatin and starch, thereby disrupting gelatin α-helices and impeding biopolymer crystallization. This facilitated hydrogen-bonding interaction between PVA and the two biopolymers, enhancing the stability of the molecular network structure. Rheological results indicate that composites (added with 4 % or 7 % PVA) with good compatibility exhibited excellent mechanical properties and deformation resistance. The addition of PVA elevated the gelling temperature (Tgel) of the composites from 41.31 °C to 80.33 °C; the tensile strength and elongation at break were increased from 2.89 MPa to 3.40 MPa and 341.62 % to 367.56 %, respectively; and the thermal stability was also apparently improved, signifying the effective enhancement of the physical properties of gelatin/starch-based composites and the broadening of their application scope. This work could provide insights into the development of biodegradable natural/synthetic polymer composites with application-beneficial characteristics.

High freeze-thaw stability of Pickering emulsion stabilized by SPI-maltose particles and its effect on frozen dough

Pickering emulsions with good freeze-thaw stability are essential in frozen food applications. This study developed a high freeze-thaw stabilized soy protein isolate (SPI)-maltose (M) Pickering emulsion and applied it to frozen doughs to investigate and reveal its impacts on the processing properties of the frozen dough. The results showed that after the freeze-thaw cycle, with a volume ratio of 1:2 of SPI to M, the appropriate amount of M changed the structure of SPI. This resulted in the Pickering emulsion prepared by the SPI exhibiting the least droplet coalescence and the best freeze-thaw stability. The results of dough rheological properties, textural properties, and binding capacity with water demonstrated that Pickering emulsions effectively inhibited the loss of gluten protein network structure in the dough after freeze treatment and increased the binding capacity of gluten proteins with starch and water in the dough. The best results were obtained with the incorporation of 3 % SPI-M high freeze-thaw stability, where the amount of bound water following three freeze-thaw cycles was 4.27 times higher than in doughs without Pickering emulsion. Overall, this study is significant for enhancing the freeze-thaw stability of Pickering emulsions stabilized by proteins and providing a new application route for Pickering emulsions.

Quality analysis of dough and steamed bread under various freezing conditions

Freezing is a crucial step in the process of frozen foods. In this study, the effects of different freezing methods, including liquid nitrogen immersion freezing (LF), quick-freezing machine freezing (QF), packaging immersion freezing (PF), and ultralow temperature refrigerator freezing (UF), and freezing time (0, 15, 30, and 60 days) on the textural properties, dynamic rheological properties, water distribution, and structure of dough and the quality of end steamed bread were evaluated. Freezing resulted in a decline in the physicochemical properties of dough. UF- and QF-doughs had higher storage modulus and loss modulus, compared with PF- and LF-doughs. LF enhanced the textural attributes of the dough, resulting in reduced hardness and increased springiness. At 15 days of freezing, QF- and LF-doughs exhibited a compact and continuous structure with a smooth surface. Additionally, the correlation analysis elucidated that the weight loss rate and the bound water content of the dough had discernible impacts on the texture of both the dough and the resulting steamed bread. Overall, LF demonstrated a relatively high freezing efficiency and effectively maintained the quality of the dough for up to 15 days of freezing. These results offer valuable insights for the applications of freezing methods and time in frozen foods.

A comparative study of magnetic field on the maximum ice crystal formation zone and whole freezing process for improving the frozen dough quality

Magnetic field individually applied on the maximum ice crystal formation zone (MMF) and the whole freezing process (WMF) was compared to improve the quality of multiple freezing-thawing treated dough. All treatments showed that the breadmaking performances of magnetic field-assisted freezing were better than the conventional freezing. Especially, the WMF-treated breads exhibited higher resilience and lower firmness than MMF-treated breads. WMF treatment made dough remained a continuous and compact gluten-starch matrix while the starches and glutens got separated in MMF-treated dough. It could keep the gluten macropolymer from freezing-induced depolymerization with the decreased free sulfhydryl by 7.09% and more ordered secondary structure. WMF had positive effects on the homogeneous water distribution and high water-binding ability in frozen dough where the freezable water decreased from 32.47% to 30.77%. This comparative study of different freezing stages provided new insights into the better application of magnetic field on frozen dough-based food.

The effect of subzero temperatures on the properties and structure of soy protein isolate emulsions

Different freezing temperatures (-5, -20, -40 and -80 ℃) could change soy protein isolate (SPI) structure and emulsion properties. After freezing at -5 ℃ and -20 ℃, the structure of the SPI loosened, the fluorescence intensity was red shifted, and the proportion of Phe, Tyr and Trp exposed increased. With decreasing temperature, the surface hydrophobicity (H0 × 100), the number of sulfhydryl groups and the number of disulfide bonds all rose, then fell (-40 ℃), and rose again (-80 ℃). The β-sheet content in the protein secondary structure increased from 32.71% (control) to 50.66% (-40 ℃) and then decreased to 37.05% (-80 ℃), while the β-turn and random coil contents showed the opposite pattern, which also confirmed aggregation. The emulsification performance of SPI after freezing treatment was decreased. The results of this study provide theoretical support for future production of frozen foods with added SPI.

Effects of Frozen Storage Time, Thawing Treatments, and Their Interaction on the Rheological Properties of Non-Fermented Wheat Dough

In this study, the effects of frozen storage time, thawing treatments, and their interaction on the rheological properties of non-fermented dough were evaluated. Texture profile analysis (TPA), rheological measurements, including strain/frequency sweep, and creep-recovery measurement were applied to the dough. Compared with unfrozen fresh dough, the frozen storage time (S) and thawing treatment (T) influenced almost all indicators significantly, and their mutual effects (S × T) mainly affected the hardness and springiness. Frozen time was the main factor resulting in the destruction of non-fermented dough during the thawing treatments. Moreover, refrigerator thawing (4 °C) produced a dough with minimal changes in the rheological properties, regardless of the frozen storage time. Meanwhile, microwave thawing resulted in lower G' and lower zero shear viscosity (η0) values, as well as higher maximum creep compliance (Jmax) and hardness values. Moreover, the difference between the three thawing treatments was exacerbated after 30 days of frozen storage. SEM images also showed that long-term frozen storage combined with microwave thawing seriously destroyed the rheological properties, structural stability, and inner microstructure of the dough.

The Effect of Terminal Freezing and Thawing on the Quality of Frozen Dough: From the View of Water, Starch, and Protein Properties

Frozen dough is suitable for industrial cold chain transportation, but usually experiences temperature fluctuations through the cold chain to the store after being refrigerated in a factory, seriously damaging the product yield. In order to analyze the influence mechanism of temperature fluctuation during the terminal cold chain on frozen dough, the effects of terminal freezing and thawing (TFT) on the quality (texture and rheology) and component (water, starch, protein) behaviors of dough were investigated. Results showed that the TFT treatment significantly increased the hardness and decreased the springiness of dough and that the storage modules were also reduced. Furthermore, TFT increased the content of freezable water and reduced the bound water with increased migration. Additionally, the peak viscosity and breakdown value after TFT with the increased number of cycles were also increased. Moreover, the protein characteristics showed that the low-molecular-weight region and the β-sheet in the gluten secondary structure after the TFT treatment were increased, which was confirmed by the increased number of free sulfhydryl groups. Microstructure results showed that pores and loose connection were observed during the TFT treatment. In conclusion, the theoretical support was provided for understanding and eliminating the influence of the terminal nodes in a cold chain.

Ultrasonic Treatment of Corn Starch to Improve the Freeze-Thaw Resistance of Frozen Model Dough and Its Application in Steamed Buns

Modification of corn starch using ultrasonic waves to improve its freeze-thaw resistance in frozen model doughs and buns. Analysis was performed by rheometry, low-field-intensity nuclear magnetic resonance imaging, Fourier infrared spectroscopy, and scanning electron microscopy. The results showed that the addition of ultrasonically modified corn starch reduced the migration of water molecules inside the model dough, weakened the decrease of elastic modulus, and enhanced the creep recovery effect; the decrease in α-helical and β-fold content in the model dough was reduced, the destruction of internal network structure was decreased, the exposed starch granules were reduced, and the internal interaction of the dough was enhanced; the texture of the buns became softer and the moisture content increased. In conclusion, ultrasound as a physical modification means can significantly improve the freeze-thaw properties of corn starch, providing new ideas for the development and quality improvement of corn-starch-based instant frozen pasta products.

Effect of subfreezing storage on the qualities of dough and bread containing pea protein

BACKGROUND

In this paper, -6, -9 and -12 °C were selected as subfreezing temperatures of dough containing pea protein based on the results of low-field nuclear magnetic relaxation time. The effect of storage at subfreezing temperatures on dough properties was then investigated and compared with sample storage at -18 °C.

RESULTS

The pH value, springiness, resilience, cohesiveness of dough and sensory score of bread gradually decreased and the hardness and water loss rate of dough gradually increased with the extension of storage time. However, dough hardness, viscoelasticity and fermentation volume were maintained more effectively in subfreezing storage than in -18 °C storage. The subfreezing temperature could alleviate the damage of gluten network structure in frozen dough by ice crystals and was beneficial in maintaining the elasticity of gluten proteins. The network system of pea protein, gluten protein and starch granules in dough storage at -9 and -12 °C was more tightly connected and the microstructure was similar to that at -18 °C. There was no significant difference between the quality of bread made from the dough stored at subfreezing temperature and that stored at -18 °C for 1-6 weeks, and the preservation effect at -12 °C was closer to that at -18 °C.

CONCLUSION

Subfreezing storage can keep the stability of dough containing pea protein close to traditional frozen storage (-18 °C), which provides a new method for storage and transportation of frozen dough. © 2022 Society of Chemical Industry.

Recent development in evaluation methods, influencing factors and control measures for freeze denaturation of food protein

Frozen storage is most widely adopted preservation method to maintain food freshness and nutritional attributes. However, at low temperature, food is prone to chemical changes such as protein denaturation and lipid oxidation. In this review, we discussed the reasons and influencing factors that cause protein denaturation during freezing, such as freezing rate, freezing temperature, freezing method, etc. From the previous literatures, it was found that frozen storage is commonly used to prevent freeze induced protein denaturation by adding cryoprotectants to food. Some widely used cryoprotectants (for example, sucrose and sorbitol) have been reported with higher sweetness and weaker cryoprotective abilities. Therefore, this article comprehensively discusses the new cryopreservation methods and providing comparative study to the conventional frozen storage. Meanwhile, this article sheds light on the freeze induced alterations, such as change in functional and gelling properties. In addition, this article could be helpful for the prolonged frozen storage of food with minimum quality related changes. Meanwhile, it could also improve the commercial values and consumer satisfaction of frozen food as well.

Effect of carboxymethyl chitosan on the storage stability of frozen dough: State of water, protein structures and quality attributes

Carboxymethyl chitosan (CMCh), an ampholetic chitosan derivative, has found broad applications in the food industry. However, its cryo-protective properties remained less explored compared to other viscous polysaccharides, such as carboxymethyl cellulose, carrageenan etc., which have been widely utilized as frozen food additives. In this study, we investigated the effect of CMCh addition to frozen dough in terms of water state, protein structure, and the textural properties of prepared frozen dumpling wrappers. Results indicated that CMCh restricted the water migration in dough and delayed protein deterioration during frozen storage. Specifically, the content of freezable water in dough was reduced and the water distribution became more uniform as reflected by DCS and LF-NMR analysis. CMCh also stabilized disulfide bond and secondary structures of the protein, leading to inhibition of dough rheology changes. Accordingly, the obtained frozen dumplings wrappers demonstrated decreased cracking rate and water loss, and improved textural properties. Moreover, CMCh with higher degree of carboxymethyl substitution (DS: 1.2, CMCh-B) exhibited better cryo-protective effects compared to CMCh of lower DS (DS: 0.8, CMCh-A). Our study provides novel insights and scientific basis for the development of ampholetic polysaccharides as high-performance food additives.

Moisture Distribution and Structural Properties of Frozen Cooked Noodles with NaCl and Kansui

The effects of NaCl (1-3%) and kansui (0.5-1.5%) on the quality of frozen cooked noodles (FCNs) were investigated, which provided a reference for alleviating the quality deterioration of FCNs. Textural testing illustrated that the optimal tensile properties were observed in 2% NaCl (N-2) and the maximum hardness and chewiness were reached at 1% kansui (K-1). Compared to NaCl, the water absorption and cooking loss of recooked FCNs increased significantly with increasing kansui levels (p < 0.05). Rheological results confirmed NaCl and kansui improved the resistance to deformation and recovery ability of thawed dough; K-1 especially had the highest dough strength. SEM showed N-2 induced a more elongated fibrous protein network that contributed to the extensibility, while excessive levels of kansui formed a deformed membrane-like gluten network that increased the solid loss. Moisture analysis revealed that N-2 reduced the free water content, while K-1 had the lowest freezable water content and highest binding capacity for deeply adsorbed water. The N-2 and K-1 induced more ordered protein secondary structures with stronger intermolecular disulfide bonds, which were maximally improved in K-1. This study provides more comprehensive theories for the strengthening effect of NaCl and kansui on FCNs quality.

New insights into the alleviating role of starch derivatives on dough quality deterioration caused by freeze

The alleviating role of starch derivatives on the quality deterioration of frozen steamed bread dough was investigated in terms of derivative structure, the bread characteristics and dough properties including freezable water contents, yeast activity as well as dough viscoelasticity. The addition of starch derivatives including short-clustered maltodextrin (SCMD), DE2 maltodextrin (MD) and pregelatinized starch (PGS) significantly increased the specific volume and decreased the hardness of steamed bread compared with Control bread after 8-week frozen storage. Lower freezable water content was found in PGS dough than SCMD dough, which was consistent with the results of water absorption index of starch derivatives. The analysis of dough gassing rate and yeast survival ratio demonstrated SCMD could provide more cryoprotection for yeast cells. Meanwhile, a higher elastic module and a more continuous gluten-network structure of SCMD dough were found after 8-week frozen storage. These results indicated starch derivatives especially SCMD were promising to be used as the alternative improvers in frozen dough production.