Freezing Of Dough Research Articles

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

With the continuous 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, as a key research project in recent years, reduces the physical damage of food materials by reducing or changing the size of ice crystals in frozen products. In this study, different intensities of electrostatic fields were used to assist in the repeated freezing and thawing process 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. Finally, it was found that the freezing time of frozen dough added with electrostatic field assisted freezing processing was shortened, the decrease rate of hardness, viscosity, and elasticity was reduced, and the indicators of water distribution and protein secondary structure components were closer to those of fresh dough. 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. This article is protected by copyright. All rights reserved.

Effect of Freezing Wheat Dough Enriched with Calcium Salts with/without Inulin on Bread Quality.

Bread is a popular food that is widely consumed worldwide but has a short shelf life. Besides that, when incorporating prebiotics and calcium, aging mechanisms accelerate, further shortening the shelf-life. The objective of this work was to evaluate the effect of freezing storage on the rheological (loss tangent, tan δ) and thermal (glass transition temperature, Tg) properties of unfrozen dough, the fermentation times (tf), and the baking quality of wheat bread fortified with calcium and inulin. Formulations studied included wheat flour (control-C), flour with 1800 ppm Ca (calcium carbonate-CA, calcium citrate-CI or calcium lactate-LA), and flour with 2400 ppm Ca and 12% inulin (calcium carbonate-CA-In, calcium citrate-CI-In or calcium lactate-LA-In). Doughs were stored at −18 °C for 1, 7, 30 and 60 days. After storage, the rheological (oscillatory rheometry and texture profile analysis) and thermomechanical properties of the thawed doughs were measured. The quality parameters of breads determined consisted of specific volume (Vs), color, moisture, firmness, elasticity, and alveoli size characterization. Dough freezing neither changed viscoelasticity (tan δ) nor decreased hardness and adhesiveness up to the values observed for fresh wheat dough. The Tg of dough with calcium carbonate increased, while for samples with organic calcium salts, it (citrate and lactate) decreased. The tf of thawed dough significantly increased. The Vs of all breads did not change during the first 30 days but decreased after freezing the dough for 60 days (p < 0.05), probably due to the death of the yeasts. Crumb moisture decreased over time, and in all cases crumb C had the highest moisture content, suggesting a dehydration effect of the calcium salt. The firmness of CA, LA and C crumbs were similar and higher than that of CI (p < 0.05), suggesting a destabilizing effect of CI anion on gluten proteins. Inulin contributed to the depreciation of bread quality, mainly at 60 days of dough freezing storage. It can be concluded that during freezing storage, calcium improves the dynamic elasticity of the dough, although under extreme conditions it generates loaves of smaller volume. Principal component analysis (PCA) explained 66.5% of total variance. Principal component 1 (PC1) was associated with dough properties, and accounted for 44.8% of the total variance. In turn, PC2 was mainly related to baking quality parameters (fermentation time, browning index, firmness and springiness of crumbs), and explained 21.7% of the total variance. Fortification with calcium citrate should be recommended for dough freezing, as breads with softer crumbs were obtained under such conditions.

Effects of Physical and Chemical Factors on the Structure of Gluten, Gliadins and Glutenins as Studied with Spectroscopic Methods.

This review presents applications of spectroscopic methods, infrared and Raman spectroscopies in the studies of the structure of gluten network and gluten proteins (gliadins and glutenins). Both methods provide complimentary information on the secondary and tertiary structure of the proteins including analysis of amide I and III bands, conformation of disulphide bridges, behaviour of tyrosine and tryptophan residues, and water populations. Changes in the gluten structure can be studied as an effect of dough mixing in different conditions (e.g., hydration level, temperature), dough freezing and frozen storage as well as addition of different compounds to the dough (e.g., dough improvers, dietary fibre preparations, polysaccharides and polyphenols). Additionally, effect of above mentioned factors can be determined in a common wheat dough, model dough (prepared from reconstituted flour containing only wheat starch and wheat gluten), gluten dough (lack of starch), and in gliadins and glutenins. The samples were studied in the hydrated state, in the form of powder, film or in solution. Analysis of the studies presented in this review indicates that an adequate amount of water is a critical factor affecting gluten structure.

Hydrocolloids and Cryoprotectant used in Frozen Dough and Effect of Freezing on Yeast Survival and Dough Structure: A Review

Advantages of freezing of dough are reduction of losses caused by aging of products. But freezing deteriorates the baking quality of frozen bread dough. These include gradual loss of the dough strength, reduced yeast activity and deterioration in the texture of the final product. The negative effects of freezing and defrosting of dough can be reduced by incorporating hydrocolloids in dough. Furthermore Biogenic ice nucleators, such as extracellular ice nucleators (ECINs) isolated from Erwinia herbicola, are a group of lipoglyco proteinsthat has been demonstrated to minimize the supercooling. Ice nucleation materials function as heterogeneous ice nucleators to minimize the supercooling of water. Mechanism of cryoprotective effects from extracellular ice nucleators was possibly that ECINs helped in preserving the viability of yeast cells during freeze/thaw cycles. At the end of this study we reviewed the ultrasound-assisted freezing; this method can improve the quality of frozen food without the need for additional additives. DOI: http://dx.doi.org/10.3126/ijls.v9i3.12439 International Journal of Life Sciences 9 (3): 2015; 1-7

Impact of Sodium Alginate and Xanthan Gum on the Quality of Steamed Bread Made from Frozen Dough

The impact of freezing on dough rheology, fermentation performance, and final steamed bread quality was investigated in this study. Also, the incorporation of sodium alginate and xanthan gum into the frozen dough formulation, in comparison with 0.1% salt, was studied to test their suitability as frozen dough improvers. Incorporating these hydrocolloids into steamed bread revealed their totally different characteristics from those in baked bread. Freezing of dough led to diminished specific volumes of proofed dough and steamed bread, and it also caused higher crumb firmness for steamed bread. The incorporation of sodium alginate and xanthan gum did not improve the quality of the steamed bread but led to further reduction in specific volume and increase in crumb firmness at the higher levels of 0.3, 0.5, and 1.0% and 0.07 and 0.1%, respectively. Xanthan gum and sodium alginate showed dough strengthening effects by increasing resistance to uniaxial deformation, bubble burst stress, and declining dough weakening coefficients at these levels, but decreased dough extensibility and bubble burst strain were revealed at these concentrations tested.

Use of Enzymes to Minimize Dough Freezing Damage

The purpose of this investigation was to study the effect of pentosanase (Pn), glucose oxidase (Gox), and transglutaminase (TG) on frozen dough (−18 °C) and their influence on minimizing the damage caused by frozen storage. Bread characteristics were analyzed on day 0; after 3 and 9 weeks of frozen storage, specific loaf volume, crust color, and crumb texture and structure were analyzed. Dough expansion capacity and dough stickiness, extensibility, and viscoelasticity were determined. Frozen dough with high levels of Gox developed a larger bread volume than control dough (without added enzyme). The damage percentage caused by frozen storage in Gox samples was lower than in control samples, indicating that Gox increased dough strength and counteracted the depolymerization effect of gluten produced by ice crystal formation and the release of reducing substances from dead yeast cells during freezing. Samples with Pn developed a large bread volume after 9 weeks of frozen storage because of the formation of smaller pentosans, which result from Pn enzyme action. These pentosans were located in protein–starch–CO2 matrix interfaces and increased dough expansion capacity without gas loss, thus allowing a higher expansion during proofing. The intermediate level of TG was the only one to present a larger bread volume from frozen dough than control. The new isopeptidic bonds introduced by TG in the gluten proteins helped to mitigate the damage caused by dough freezing.

쌀가루 냉동반죽 제조 시 첨가제가 쌀빵의 품질에 미치는 영향

The effects of adding additives such as gum, emulsifier, and enzyme both individually and as mixtures to frozen rice bread dough on baking quality were examined. Rice flours containing 17% vital gluten, and gum/emulsifier/enzyme blends were mixed and stored in a freezer at -20C for 4 weeks. The rice doughs were removed from the freezer, thawed, and then followed the rice baking procedure. The dough freezing and frozen storage resulted in decreased volume of rice bread. The addition of guar gum/ sodium stearoyl lactylate (SSL)/ fungal α-amylase blend improved volume of the rice bread obtained from rice dough during frozen storage. An increase in firmness of crumb was observed in rice breads during 3 days of storage at 25 o C. Compared to the control dough without additives, addition of guar gum/ SSL blend or guar gum/ SSL/ fungal α-amylase blend into frozen dough significantly reduced the crumb firmness of rice bread, indicating a significant antistaling effect.

Effect of ice structuring proteins from winter wheat on thermophysical properties of dough during freezing

Ice structuring proteins (ISPs) are proteins that can modify and inhibit the growth of ice. ISPs may improve the quality of frozen dough by stabilizing ice crystals and maintaining the texture of frozen dough. In this study, effects of ISPs from winter wheat were examined on the thermophysical properties of dough, which include freezing point depression, freezable water fraction, apparent specific heat, and effective thermal conductivity. The thermophysical properties were measured by differential scanning calorimetry (DSC) and line source probe methods. The results showed that, compared to the control, adding 0.6% ISPs induced a maximum freezing point depression of 0.23 °C and decreased the amount of freezable water by 8%. ISPs had little effect on the apparent specific heat and the effective thermal conductivity in the unfrozen ranges. However, the thermophysical properties in the frozen ranges were significantly affected by ISPs. The determined thermophysical properties are important to model heat transfer during freezing of dough.

Properties of bread made from frozen dough containing waxy wheat flour

The quality of bread made from frozen dough is diminished, and staling rate is increased by changes that occur during freezing and storage. New cultivars of waxy wheat flour (WWF), containing higher levels of amylopectin, may help improve the quality of baked products. Bread quality and staling were investigated for bread containing 0–45% WWF and 55–65% water after freezing and 90-day frozen storage. The specific volume was highest with 15% WWF substitution and 60% water in bread made from both unfrozen and frozen dough. With higher levels of WWF and lower water content, bread staling rates decreased. Bread with higher levels of WWF were darker and had greater color variation. 1H NMR studies showed that bread with greater WWF and water had higher transverse relaxation ( T 2) times (9–11 ms), but less change in T 2 during storage. This research demonstrated that specific combinations of WWF and water produced a better quality of bread after dough freezing.

Combined effects of dough freezing and storage conditions on bread quality factors

The combined effects of dough freezing rate, storage temperature and time on bread quality were studied. Yeasted bread dough was frozen using four freezing rates, and stored between −10 °C and −35 °C for up to 180 days. Dough stored at −10 °C or −20 °C and frozen at 18–39 °C/h resulted in higher specific volume and softer bread, but higher rates of staling, and was related to relatively high yeast activity. NMR studies showed that while frozen dough stored at −30 °C or −35 °C produced bread with lower volume, it also had reduced staling rates. Crust color was lighter and more uniform for slower frozen dough stored at −10 °C or −20 °C. Longer frozen dough storage produced darker, less uniform colored crust. Increased understanding of the combined effects of processing conditions is essential for producing better quality dough and bread. This research demonstrated that specific combinations of freezing rates and storage conditions contribute to better bread quality and staling.

The influence of carboxymethylcellulose, xanthan and guar-gum addition in bread dough before freezing on metabolism and viability of Saccharomyces cerevisiae

Doughs were prepared with different concentrations of carboxymethylcellulose, xanthan, and guar-gum (0.1, 0.2 and 0.3% in doughs), freezed at -20?C and analyzed after 0, 7, 15 and 30 days. Pure Saccharomyces cerevisiae culture was isolated from dough and was cultivated under optimal conditions during 24 hrs to determine the following parameters: specific growth rate, fermentative activities and cytochromes contents in intact cells with the aim of determining the respiration intensity. During freezing of dough for 30 days, the percentage of living cells from dough surface was 53.11% and from the middle 54.95%. Carboxymethylcellulose in concentration of 0.3 and 0.5% increased number of survived cells on the surface to 70.64, and 70.28% and in the middle to 74.79, and 76.54%, respectively. Guar-gum increased number of survived cells only in concentration of 0.1% on the surface to 70.17% and in the middle of the dough to 75.26%. The mean specific growth rate decreased by approximately 10% during 30 days of storage at -20?C. Content of cytochromes in intact cells decreased in all samples during freezing.

Characterization of a Torulaspora delbrueckii diploid strain with optimized performance in sweet and frozen sweet dough

Torulaspora delbrueckii is a baker's yeast that is highly tolerant to freeze–thaw stress, making it suitable for frozen dough technology. The T. delbrueckii strain PYCC5321, isolated from traditional bread dough, combines this tolerance with a high degree of ionic and osmotic stress resistance. However, the industrial use of this strain for frozen and sweet frozen baking is hampered by its small cell size, which causes clogging problems at the filtering stage. Here, we report the construction of a stable diploid strain of T. delbrueckii PYCC5321, which we named Td21-2n. The new strain was more than 2.7-fold bigger than their haploid counterpart, whereas biomass yield, stress resistance and sweet dough leavening ability were found to be similar in both strains. Moreover, the gassing power of the diploid after dough freezing also remained unaltered. Thus, Td21-2n meets the requirements necessary for industrial production and is suitable for application in frozen sweet baking products.

In situ observation of the freezing process in wheat dough by confocal laser scanning microscopy (CLSM): Formation of ice and changes in the gluten network

Freezing of bread dough is widely applied in food industry. However, freezing impairs the baking performance of dough, which is largely attributed to structural changes as induced by ice formation. The aim of the present investigation was to image ice formation during freezing of dough and to assess the structural changes in the gluten network. A confocal laser scanning microscope (CLSM) equipped with a freezing stage was used to follow ice formation in the reflection and transmission (bright field) mode. Wheat dough with air inclusions served as a model for fermented dough. The gas pores and the ice crystals could be imaged by confocal laser reflection. Ice formation was initiated at the gas pore interface, where large ice crystals were formed during a freezing time of 4 h at −15 °C. The freezing of gluten samples stained with rhodamin was followed in the fluorescence mode. The cryoconcentration of gluten could be observed, but no irreversible changes in the microstructure of gluten were detected upon thawing. It is concluded that the gas pore interfaces in dough are preferential sites for ice nucleation, favouring the growth of ice crystals in these regions and by this a freeze induced redistribution of water in dough.

Effect of emulsifier and guar gum on micro structural, rheological and baking performance of frozen bread dough

The influence of mono- and diacylglycerols esterified to mono- and diacetyltartaric acid (DATEM) and guar gum on dynamic rheological behaviour, starch gelatinization, microstructure and bread properties of frozen dough were analysed. The results obtained showed that the dough freezing and storage at −18 °C decreased the bread quality. The dough freezing and frozen storage provoked a decrease in the complex modulus (G ∗) and the storage modulus ( G′) showing a reduction in dough firmness and elasticity. Structural damage caused on dough ultra structure through frozen storage was observed by scanning electron microscopy. Starch gelatinization was affected by additives and by dough storage at −18 °C. DATEM and gum guar improved volume and texture of bread obtained from non-frozen and frozen dough, but neither DATEM nor gum guar could avoid the effect of dough frozen storage on the dynamic rheological parameters and microstructure damage.

Effect of freezing and frozen storage on the gelatinization and retrogradation of amylopectin in dough baked in a differential scanning calorimeter

Frozen and non-frozen dough were baked in a differential scanning calorimeter (DSC) pan (heated in the calorimeter at temperatures similar to those of the center of the crumb during baking) and were aged at different temperatures. Gelatinized dough (DSC-baked dough) was heated again in the DSC. This methodology permitted us to study the effects of dough freezing and frozen storage on gelatinization and retrogradation of starch. During storage of frozen doughs at −18 °C an increase in the gelatinization enthalpy after 150 day of storage was observed. At 230 days of frozen storage a decrease in the onset temperature and an increase in the gelatinization temperature range was also detected. An increase of starch retrogradation with time of storage in frozen conditions was observed. During the aging of dough baked in DSC, a higher retrogradation temperature range was detected together with a faster retrogradation of starch at low temperature of aging.

Effect of Chemical Modification, pH Change, and Freezing on the Rheological, Solubility, and Electrophoretic Pattern of Wheat Flour Proteins

ABSTRACT: In this study the effect of chemical modification and freezing of dough on the characteristics of wheat proteins and the rheological properties of dough was investigated. A slight increase in the protein solubility and disappearance of protein bands in the range of 55 to 70 KDa was observed when samples were frozen for 6 to 8 weeks. Ascorbic acid decreased and cysteine and bisulfite increased solubility of wheat proteins. Dough stability increased as pH was raised above 6.5. Two protein bands in the range of 55 to 60 KDa appeared in ascorbic acid treated doughs and the intensity of bands of less than 6.5 KDa increased in cysteine or bisulfite treated doughs. Several protein bands in the range of 30, 50, and 90 KDa appeared when the pH was raised to 7.0 and above. The results of this study suggest that high‐ molecular‐weight proteins of wheat flour have a major influence on the properties of dough and that these proteins are affected by chemical treatment, pH change, and freezing.