Effect of static magnetic field on the quality of frozen bread dough

Effect of magnetic fields on the structure, properties, baking performance of frozen wheat dough at different frozen stage

As an emerging physical technology, magnetic fields have been used to improve the quality of frozen and refrigerated foods. This study compared the effect of applying a static magnetic field (2 mT) at different stages of freezing and storage on the quality of frozen dough. Results suggested that the magnetic field significantly impacted frozen dough quality. It not only prevented the formation of ice crystals during the pre-freezing stage but also inhibited ice crystal growth during the following frozen storage. This effect helped to maintain the integrity of gluten proteins and their adhesion to starch granules by preventing the breakage of disulfide bonds and the depolymerization of gluten macromolecules. It was also observed that yeast inactivation and glutathione release were reduced, resulting in improved air retention and air production capacity of the dough. This, in turn, led to a more appealing volume and texture quality of the finished bread.

The impact of magnetic field-assisted freeze-thaw treatment on the quality of foxtail millet sourdough and steamed bread

Foxtail millet and sourdough are used to make foxtail millet sourdough steamed bread to improve the flavor and taste. Compared with the conventional freeze-thaw treatment (CFT), the effect of magnetic field-assisted freeze-thaw treatment (MFT) on the storage quality of foxtail millet sourdough and steamed bread is explored. The results showed that compared with CFT, MFT shortened the phase transition time of dough; decreased the water loss rate, the water mobility, and the freezable water content; increased the fermentation volume; stabilized the rheological properties; and minimized the damage of freezing and thawing to the secondary structure and microstructure of the gluten. In addition, an analysis of the specific volume, texture, surface color, and texture structure showed that MFT was beneficial to slowing the deterioration of the steamed bread texture. Finally, MFT effectively inhibited the growth and recrystallization of ice crystals during freezing and thawing, improving the quality of millet dough and steamed bread.

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 sanxan on water and ice crystal status of salt free frozen cooked noodles during freeze-thaw cycles

This study compared four biocolloids (sanxan, xanthan gum, curdlan, and guar gum) in different concentrations to replace NaCl in improving the recooking quality of salt free frozen cooked noodles (SF-FCNs). Sanxan outperformed NaCl and other biocolloids significantly improving the firmness (21.0%), chewiness (63.5%), and toughness (15.4%) of SF-FCNs after 10 freeze-thaw (FT) cycles. The results of the freezing-thawing curves showed SF-FCNs had prior FT stability when sanxan was added at 1.2%. Subsequently, the result of differential scanning calorimetry and nuclear magnetic resonance revealed sanxan reduced the content and mobility of freezable water while increasing the content of bound water. The scanning electron microscope, mercury intrusion, and optical microscopy analyses indicated that sanxan reduced the size and volume of ice crystals and the structural damage of SF-FCNs by controlling the water. The work contributes to a theoretical framework for enhancing SF-FCNs quality through precise water and ice crystal control.

Effects of different thawing methods on physical and physicochemical properties of frozen dough and quality of corresponding steamed bread

The thawing method is critical for the final quality of products based on the frozen dough. The effects of ultrasound thawing, proofer thawing, refrigerator thawing, water bath thawing, ambient thawing, and microwave thawing on the rheology, texture, water distribution, fermentation characteristics, and microstructure of frozen dough and the properties of steamed bread were investigated. The results indicated that the ultrasound thawing dough had better physicochemical properties than other doughs. It was found that ultrasound thawing restrained the water migration of dough, improved its rheological properties and fermentation capacity. The total gas volume value of the ultrasound thawing dough was reduced by 21.35% compared with that of unfrozen dough. The ultrasound thawing dough displayed a thoroughly uniform starch-gluten network, and an enhanced the specific volume and internal structure of the steamed bread. In conclusion, ultrasound thawing effectively mitigated the degradation of the frozen dough and enhanced the quality of steamed bread.

Retrogradation behaviors of damaged wheat starch with different water contents

The retrogradation behaviors of five damaged wheat starches (DS) after milling 0, 30, 60, 90, and 120 min with different water contents (33, 50, 60 %) were evaluated. Milling treatment increased DS content and developed an agglomeration of small particles. After 7 days of storage, the recrystallinity and long-range ordered structure of starch pastes were increased with the contents of DS and water. This process led to a lower setback viscosity and poor leaching of amylose. LF-NMR indicated a conversion from tightly bound water and free water to weakly bound water. During storage, DS12 with 60 % water content had the highest retrogradation tendency where the retrogradation enthalpy increased by 1.5 J/g and 2.2 J/g compared with DS0 with 60 % and DS12 with 33 % water content. DS with higher water content promoted the water mobility and made the starch molecular chains migrated conveniently. These changes facilitated the recrystallinity process during retrogradation period.

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.

Evaluating the effects of low-frequency alternating magnetic field thawing on oxidation, denaturation, and gelling properties of porcine myofibrillar proteins

The impact of low-frequency alternating magnetic field thawing (LF-MFT) on the physicochemical and gelling properties of porcine myofibrillar proteins (MP) was studied. Results showed that compared to atmosphere thawing (AT), LF-MFT helped in inhibiting the oxidation and denaturation of protein during thawing, thereby maintaining a superior MP gel (P < 0.05). In particular, LF-MFT-4 (LF-MFT at 4 mT) could decrease the oxidation of MP, which might be due to having a higher content of total sulfhydryl and less carbonyl of MP than other thawing treatments. The denaturation of MP was reduced since LF-MFT-4 led to less aggregation and degradation than AT. The gelling properties were also retained, and a compact and homogeneous network structure was formed after LF-MFT-4, resulting in excellent water retention. These findings suggested that LF-MFT-4 improved the gelling properties of MP by inhibiting its oxidation and denaturation, demonstrating a potential application of LF-MFT in meat thawing.

Regulation of the Ice Ⅰ to Ice III high pressure phase transition meta-stability in milk and its bactericidal effects

This study was focused on a novel approach of creating perturbations under high pressure (HP) meta-stable Ice Ⅰ to Ice Ⅲ phase transition and its bactericidal effects. Experiments were carried out under subzero high pressure processing conditions using Escherichia coli suspended in milk, and the microbial inactivation before and after the meta-stable state regulation was compared. The phase transition position of unperturbed milk was 302 MPa/-37.5 °C. The volume change resulting from the phase transition was employed as the perturbation mechanism. Glucose (5 %, 20 %) and sodium chloride solutions (5 %, 20 %) were used as regulatory sources. Glucose solutions accelerated the phase change of the milk better than the sodium chloride solution and resulted in an optimum phase transition position of milk at 243 MPa/-30.6 °C. The induced perturbations accelerated meta-stable transformation and enhanced the microbial destruction. At 330 MPa/3s, compared to the unfrozen samples, the lethality of E. coli in the frozen-regulated samples significantly increased by 1.79 log. The relationship between the E. coli inactivation within the phase change pressure range and the pressure was not continuous, but a segmented one, both before and after meta-stable state regulation. A higher level of E. coli destruction was accomplished by a 5 min pressure-holding of frozen samples at 220 MPa and 280 MPa as compared to the one-pulse and two-pulses treatments without holding time. The maximum lethality of 6.73 log was achieved at 280 MPa/5 min in the frozen-regulated application.

Improvement in the quality of frozen dough for fried flour products by electrostatic field-assisted freezing

BACKGROUND

With the development of the food industry, frozen dough technology has gradually become an indispensable part of dough processing but its quality is often reduced due to freezing during the production process. Electrostatic field-assisted freezing (EF) technology, a key research project in recent years, reduces the physical damage to food materials by reducing or changing the size of ice crystals in frozen products.

RESULTS

In this study, different intensities of electrostatic fields were used to assist in the repeated freezing and thawing of dough. The effects of electrostatic fields on the freezing nucleation process were evaluated by measuring dough freezing curves, low field nuclear magnetic resonance, and melting enthalpy. It was found that the freezing time of frozen dough added with electrostatic field-assisted freezing processing was shortened, the rate at which hardness, viscosity, and elasticity decreased was reduced, and the indicators of water distribution and protein secondary structure components were closer to those of fresh dough.

CONCLUSION

This experiment used electrostatic field-assisted freezing to reduce the damage to the dough structure during the freezing process, improve the quality of frozen dough and fried products, and improve the freezing efficiency of frozen dough. It provides a new idea for the study of frozen dough. © 2023 Society of Chemical Industry.

Influence of magnetic field on gluten aggregation behavior and quality characteristics of dough enriched with potato pulp

This study investigated the effect of varying magnetic field intensities (ranging from 0 to 10 mT) on the quality characteristics of dough with 40 % potato pulp substitution (DPP). The results indicated that the DPP fermented with a 4 mT magnetic field exhibited a significant enhancement in the combination of water and substrate, thereby elevating the viscoelastic properties of DPP through reinforcing the stability of gluten network. Meanwhile, DPP treated with a 4 mT magnetic field exhibited the highest amount of disulfide bonds (11.64 μmol SS/g sample). This is accompanied by a prominent cross-linkage structure, as evidenced by SDS-PAGE and CLSM. Notably, the application of a magnetic field substantially augments the dough's capacity to retain gas during fermentation. In addition, the application of magnetic field significantly increased the wet gluten content (20.85 %, P < 0.05) in DPP, which improved tensile properties and an acceptable color profile. The introduction of a magnetic field induces gluten aggregation, which in turn results in heightened particle size distribution and ζ-potential values. In conclusion, this study emphasize the potential of magnetic field technology as a viable method to enhance the overall quality attributes of dough enriched with potato pulp substitution.

Static magnetic field improvement of the quality of rice dumpling subjected to freeze-thaw cycles: Roles of phase transition of water and changes in structural and physicochemical properties of glutinous rice flour

This study aimed to investigate the effect of static magnetic field (SMF, 0-10 mT) on the quality of rice dumplings subjected to 7, 14, 21, and 28 freeze-thaw cycles. The underlying mechanism was explored by monitoring changes in water phase transition, water distribution, and structural and physicochemical properties of rice flour. Results suggested that SMF enables the formation of small ice crystals by accelerating freezing rate, shortening phase transition time, and increasing bound water content, which attributes to reducing the mechanical damage on starch granules and thus improves the quality of frozen rice dumpling. After 7-28 freeze-thaw cycles, SMF treatment increased the whiteness by 0.08-1.58, reduced the cracking ratio by 1.67 %-8.34 %, decreased the water loss ratio by 0-0.75 %, and significantly improved the texture of cooked rice dumplings. This study confirmed the feasibility of SMF in improving the quality of rice dumpling, which contributes to expanding the applications of magnetic freezer in the preservation of starch-based foods.

Effect of Tea Polyphenols on the Storage Stability of Non-Fermented Frozen Dough: Protein Structures and State of Water

The usage of tea polyphenols (TPs) as a natural food additive into non-fermented frozen dough (NFFD) has rarely been investigated, and results have been controversial. Hence, this study investigated the effect of TPs at various levels (0, 0.5, 1, and 2%) on the quality of NFFD stored from 0 to 4 weeks. The rheological characteristics, water state, protein, and its microstructure were analyzed by DSC, LF-NMR, SDS-PAGE, FT-IR, and SEM, respectively. Results showed that the 0.5% TP group delayed the deterioration of protein and inhibited the water migration in dough throughout the whole frozen storage period. In addition, the 0.5% TP group enhanced the rheological properties of NFFD and stabilized the sulfhydryl content and the secondary structure in the gluten network. On the contrary, opposite phenomena were found in the 1 and 2% TP groups, which might be due to the induction of excess hydroxyl groups from TPs. In conclusion, our results suggested that a proper addition of TPs, but not an excessive amount (>1%), exhibited beneficial effects in maintaining the quality of NFFD during the 4-week frozen storage. Moreover, this paper elucidated the mechanism of TPs in influencing the protein structure and water state of NFFD during storage and provided new insight into its application in dough-based foods.