Fibre-rich additives--the effect on staling and their function in free-standing and pan-baked bread

BACKGROUND: The use of dietary fibre in bread products is increasing because of consumer demand for healthier products. However, an increase in dietary fibre level changes the rheological properties of the dough and also the quality properties of the final bread product. In this study, effects on dough and bread staling were followed after replacing 3% of wheat flour by fibre‐rich additives (fine durum, oat bran, rye bran and wheat bran). Free‐standing and pan‐baked loaves were baked to compare the influence of baking method and loaf shape. RESULTS: All additives increased dough stability, with oat bran giving the greatest stability and longest development time. Parameters measured during storage were distribution, migration and loss of water, cutability, crumbliness, firmness and springiness. Furthermore, amylopectin retrogradation and amylase‐lipid complex formation were assessed. Oat bran provided similar or better results than the control for all staling parameters, while other additives gave no general improvements. Cutability reached a plateau when crumb firmness was ≥ 4 N. CONCLUSION: Small amounts of fibre‐rich additives had a significant influence on staling. However, the baking method (free‐standing or pan‐baked bread) had a greater impact on staling than the additives, thus displaying the importance of the baking method. Cutability was found to be related to firmness. Copyright © 2011 Society of Chemical Industry     

Relative importance of moisture migration and amylopectin retrogradation for pound cake crumb firming

Moisture migration largely impacts cake crumb firmness during storage at ambient temperature. To study the importance of phenomena other than crumb to crust moisture migration and to exclude moisture and temperature gradients during baking, crustless cakes were baked using an electrical resistance oven (ERO). Cake crumb firming was evaluated by texture analysis. First, ERO cakes with properties similar to those baked conventionally were produced. Cake batter moisture content (MC) was adjusted to ensure complete starch gelatinisation in the baking process. In cakes baked conventionally, most of the increase in crumb firmness during storage was caused by moisture migration. Proton nuclear magnetic resonance (¹H NMR) showed that the population containing protons of crystalline starch grew during cake storage. These and differential scanning calorimetry (DSC) data pointed to only limited amylopectin retrogradation. The limited increase in amylopectin retrogradation during cake storage cannot solely account for the significant firming of ERO cakes and, hence, other phenomena are involved in cake firming.     

Effect of common and new gums on the quality,physical, and textural properties of bakery products: A review

Hydrocolloids (gums) have a good functional characteristic such as emulsifying, gelling, solubility, and textural improvement. In the bakery products, hydrocolloids were used to improving dough performance, bread and cake characteristics, sensorial quality, and extension the products shelf life. Several studies reported the potential use of hydrocolloids in breads, biscuits, cakes, and pasta formulation. The present review summarized the effect of the most common and new hydrocolloids (xanthan, guar, Arabic, carrageenan, karaya, alginate, acacia, methylcellulose, carboxy methyl cellulose, hydroxyl propyl methyl cellulose, locust bean, balangu seed, wild sage seed, basil seed, and cress seed gums) on the rheological, physicochemical, textural, and quality characteristics of bakery products. Gums addition improved volume and porosity of the breads and cakes. Gums influence on the gelatinization and retrogradation of starch and decreased the retrogradation of starch. In the bakery products, hydrocolloids were used to improving mixing and increasing the shelf life of the products through moisture preservation and avoidance of syneresis in some frozen foods. This study summarized the influence of the most common and new hydrocolloids on the rheological, physicochemical, textural, and quality characteristics of bakery products. Addition of seeds gum to the breads, biscuits, cakes, and pasta formula led to an increase in the viscosity of the batter. Also, the firmness of bakery products showed that they became softer with increasing gum levels.     

IMPROVEMENT OF SHELF LIFE STABILITY OF CAKES

ABSTRACT

The effects of new ingredient strategies to slow down starch retrogradation rate in cakes were investigated. In this study, devil's fudge cakes were formulated using gum, modified starch and enzyme technology. Cake samples that were prepared with combinations of gums, bacterial amylases and pregelatinized starch were found to have slower starch retrogradation rates. An accelerated shelf life protocol was followed to observe the effect of predescribed ingredients on slowing the starch retrogradation rate. The samples were evaluated for moisture content, water activity, texture and thermal properties, as well as morphological characteristics. The staling rate was found to be accelerated by the fluctuations in temperature from high to low temperatures. Modified starches, enzymes and gums were found to decrease the rate of staling and improve product quality. The formulated cakes were found to have 25% lower toughness and hardness values as compared with the control product. It was found that for all the cake formulations, there was a significant decrease in both hardness and toughness values, whereas springiness values did not change much. The basic differences within formulations were created by incorporation of gums, enzymes, soluble fibers, emulsifiers and modified flours in the cake.

PRACTICAL APPLICATIONS

Nutritional balance is quite important for each individual. For certain groups of people, based on their activity levels, high energy supplies are required to help them to achieve their optimal performance. Cakes, waffles and pancakes are in the group of breakfast bakery items that provide high energy for these groups of people. In bakery food products, staling reactions start before microbial deteriorations; as a result, they are the major factor in determining shelf life. Cakes that are acceptable to the consumers should be moist and soft in texture. Starch retrogradation is the primary mechanism determining the shelf life of the product. Although the product is microbiologically safe, the adverse affects of starch crystals on textural properties is the main cause of product rejection by the consumer, which leads to huge economical losses. The current methods of controlling starch retrogradation lean on technologies of the 1980s. Despite several studies on bread staling, there is hardly any study on the staling mechanism of cakes and other bakery food items. This study provides information on how to retard staling in cakes by the use of an in‐house developed accelerated shelf life protocol.     

Effects of sourdough and enzymes on staling of high-fibre wheat bread

The effects of sourdough and enzyme mixture (α-amylase, xylanase and lipase) on the specific volume, staling and microstructure of wheat pan bread supplemented with wheat bran were studied. Staling of bread was followed for 6 days by measuring the crumb firmness, changes in crystallization of amylopectin (DSC), increase in signal from the solid phase (NMR) and by light microscopy. The most effective treatment in improvement of quality was the combination of bran sourdough and enzyme mixture. During storage the rate of changes in crumb firmness, amylopectin crystallinity and rigidity of polymers were greatest for the white wheat bread. The most pronounced microstructural changes were swelling of starch granules and separation of amylose and amylopectin in the starch granules. Least changes in crumb firmness, amylopectin crystallinity and rigidity of polymers were observed in bran sourdough bread with enzymes. In contrast to white wheat bread, the starch granules were very much swollen in bran sourdough bread with enzyme mixture. This was hypothesized to be due to the higher water content of bran bread, and degradation of cell wall components leading to altered distribution of water among starch, gluten and bran particles during storage.     

Starch affecting anti-staling agents and their function in freestanding and pan-baked bread

Anti-staling agents with different mechanisms were added to a normal white wheat bread to investigate the relation between bread staling, amylopectin retrogradation and water-related properties (i.e. water content and distribution between crumb and crust). Bread was baked both as pan-baked and freestanding loaves. The anti-staling agents maltogenic α-amylase, distilled monoglyceride and lipase had a direct influence on starch retrogradation, whereas gluten and waxy wheat flour diluted the amylopectin content or changed the ratio between amylose and amylopectin. The degree of staling was measured as the firmness and springiness, together with two new methods, crumbliness and cutability. In addition, the degrees of amylopectin retrogradation and amylose–lipid complex formation were analyzed by differential scanning calorimetry, and the water content, water loss and water migration were measured. The addition of α-amylase improved most staling parameters, although the changes were not as large as expected. Furthermore, monoglyceride and lipase increased the formation of amylose–lipid complexes, but only lipase gave better results regarding the specific volume and firmness. Increased amylose–lipid complex formation was seen to increase water migration from crumb to crust. Adding 10% waxy wheat flour appeared to lead to a slight overall improvement i.e. lower water migration and better cutability. Adding gluten or 3% waxy wheat flour only improved the specific volume. The method of baking the loaves, i.e. freestanding or pan-baked, had a greater influence than the anti-staling agents, which shows that bread quality is not always improved by starch affecting anti-staling agents without process changes.     

Effect of different carbohydrases on fresh bread texture and bread staling

The effect of cellulase, xylanase and #-glucanase on the properties of wheat bread and its staling during storage was studied. The presence of the carbohydrases tested led to breads with high specific volume compared to the control. The texture profile analysis was greatly modified in that the firmness of bread crumb was reduced by all the carbohydrases. A kinetic study of the firmness along with the storage by the Avrami equation showed that the presence of carbohydrases produced softer crumbs and also reduced the rate of bread firming, although no great differences were found between enzymes. Since retrogradation of starch is one of most important factors related to bread staling, the modification of the amylopectin retrogradation was measured by scanning calorimetry. Those studies showed that all the carbohydrases decrease the starch retrogradation, and that the xylanases had the greatest effect. The simultaneous analysis of the firming and starch retrogradation results revealed that the anti-staling effect of xylanase might be due to the retardation in the starch retrogradation, while in the case of cellulase and #-glucanase some other mechanism should be implied in their anti-staling action.     

Effect of frozen storage time on the bread crumb and aging of par-baked bread

The effect of frozen storage time of par-baked bread on the bread crumb and staling of bread obtained after thawing and full baking is described. The moisture content, hardness and retrogradation enthalpy of the amylopectin were determined in the par-baked bread and in the full baked bread after 7, 14, 28 and 42 days of frozen storage at −25 °C. In addition, the effect of frozen storage on the crumb microstructure was analyzed by cryo scanning electron microscopy (Cryo-SEM). The moisture content of both partially and full baked bread decreased with the time of frozen storage. The crumb hardness of the par-baked bread after different periods of frozen storage was kept constant, while that of their full baked counterpart increased with the time of frozen storage. In both types of breads, the enthalpy of amylopectin retrogradation did not vary with the period of frozen storage. The staling, measured as hardness increase and amylopectin retrogradation, increased along the frozen storage. The changes observed on the frozen par-baked bread after thawing were attributed to the damage of bread structures produced by the ice crystallization, and the microstructure study support that conclusion.     

Bread Staling: Changes During Storage Caused by the Addition of Calcium Salts and Inulin to Wheat Flour

The objective of this work was to study changes in staling parameters of wheat bread formulated with different calcium salts (carbonate, citrate, or lactate) and inulin. The moisture content and texture of crumbs were studied. Moreover, the effect of calcium and inulin levels on crumb firmness during storage was estimated by fitting the Avrami equation. Starch retrogradation and the amylose-lipid complex were evaluated by differential scanning calorimetry (DSC) and X-ray diffraction. Crumbs with high inulin content retained water during storage, regardless of the nature of the calcium salt used. In addition, they presented lower loss of elasticity and cohesiveness than the control crumb. Crumbs with calcium citrate and low inulin content produced the lowest increase in crumb firmness. In addition, elasticity and cohesiveness of crumbs containing low amount of inulin and organic salts were almost maintained. The salt that favored the retrogradation process was calcium lactate with high inulin content, evidenced by the shorter half-time obtained with the kinetic studies. Also, the increase in crystallinity of B-type starch in crumbs with organic calcium salts and high inulin content, correlates with the highest values of retrogradation enthalpy obtained by DSC.     

The impact of baking time and bread storage temperature on bread crumb properties

Two baking times (9 and 24 min) and storage temperatures (4 and 25 °C) were used to explore the impact of heat exposure during bread baking and subsequent storage on amylopectin retrogradation, water mobility, and bread crumb firming. Shorter baking resulted in less retrogradation, a less extended starch network and smaller changes in crumb firmness and elasticity. A lower storage temperature resulted in faster retrogradation, a more rigid starch network with more water inclusion and larger changes in crumb firmness and elasticity. Crumb to crust moisture migration was lower for breads baked shorter and stored at lower temperature, resulting in better plasticized biopolymer networks in crumb. Network stiffening, therefore, contributed less to crumb firmness. A negative relation was found between proton mobilities of water and biopolymers in the crumb gel network and crumb firmness. The slope of this linear function was indicative for the strength of the starch network.     

Different approaches for increasing the shelf life of partially baked bread: Low temperatures and hydrocolloid addition

Partially baked bread is a product with short shelf life that requires sub-zero temperatures for extending it. The storage of par-baked bread at low temperatures and the addition of bread improvers with antistaling effects, such as hydroxypropylmethylcellulose (HPMC), are very attractive alternatives for extending the shelf life of these products. In this study, staling during storage of partially baked bread (in the presence and absence of HPMC) at low temperatures (2 °C) is studied in terms of hardness increase and amylopectin retrogradation. Simultaneously, the staling of the derived full baked breads when stored at 25 °C is assessed. During the storage of par-baked bread at low temperatures, progressive crumb hardening and rapid crystallization of the amylopectin chains were produced. However, heat applied during full baking reversed those processes, and the extent of that improvement was dependent on the time of par-baked bread storage. Concerning the staling of the derived full baked bread, the time of par-baked bread storage did not significantly (P < 0.05) affect the staling process of the resulting full baked breads. The addition of HPMC decreased the crumb hardness in both par-baked and full baked breads, and also promoted a reduction of the amylopectin retrogradation. Overall results indicate that HPMC addition significantly retards the staling of par-baked bread during its storage at low temperatures and, moreover, the same effect is observed in the full baked bread.     

The staling of bread: an X-ray diffraction study

Bread crumb X-ray patterns were analysed by different methods, the objective being to provide more in-depth knowledge of the relationships among starch crystallinity, amylopectin retrogradation and bread firming. Both crumb-firming and amylopectin retrogradation increased with storage time. However, total mass crystallinity grade and relative crystallinity increased only in the first 24 h. The determination of starch crystallinity requires the separation of the crystalline and amorphous intensities, which is sometimes arbitrary, so it would be useful to improve this methodology. Different methods used to determine total crystallinity grade only show the differences existing between fresh and stored bread. B-type crystal structure—corresponding to the amylopectin retrogradation—increased during bread storage, showing a high correlation with bread-firming and storage time. This fact emphasized the above results and suggested that amylopectin retrogradation is an important component to the elucidation of bread staling.     

Rheological,Physical, and Sensory Attributes of Gluten‐Free Rice Cakes Containing Resistant Starch

In this study the effect of resistant starch (RS) addition on gluten‐free cakes from rice flour and tapioca starch physical and sensorial properties was investigated. Increase in RS concentration made cake batters less elastic (drop of G'(ω), G''(ω) values) and thinner (viscosity decreased). Cakes specific volume increased with an increase in RS level and was maximized for 15 g/100 g RS, although porosity values were significantly unaffected by RS content. Crumb grain analysis exhibited a decrease in surface porosity, number of pores and an increase in average pore diameter as RS concentration increased. During storage, cake crumb remained softer in formulations with increasing amounts of RS. Sensory evaluation of cakes demonstrated the acceptance of all formulations, with cake containing 20 g/100 g RS mostly preferred. Gluten‐free cakes with improved quality characteristics and high nutritional value can be manufactured by the incorporation of RS.     

The anti-staling effect of pre-gelatinized flour and emulsifier in gluten-free bread

The use of gluten-free products is increasing since an increasing number of people (1–2 %) are suffering from Celiac disease and thereby need a gluten-free diet. Gluten-free bread tends to have shorter shelf life and quality compared with white wheat bread. In this study, 3 % (flour basis) of pre-gelatinized oat and barley flour as well as an emulsifier were added to a gluten-free mix to increase the water content by 1.5–2 %, affect the starch retrogradation and the formation of amylose lipid complex. The staling was followed measuring the firmness (texture analyzer), water content and distribution (nuclear magnetic resonance), amylopectin retrogradation and the formation of amylose–lipid complex (differential scanning calorimetry) in order to see the impact of both macroscopic and molecular changes on firmness. Both gluten-free bread and a white wheat bread were used as control loaves. Largest specific volume was found in the gluten-free control. The firmness varied with both the specific volume and the point of measurement. The amount of retrograded amylopectin increased the firmness, although this effect was dependent on the type of bread, in terms of distribution and availability of the water within the system. The proton relaxation time, which was representing movable water, decreased during storage and revealed that both the amylopectin retrogradation and the lipid complex formation were affecting the rigidity of the amorphous domain and not only the crystalline regions. In contrast to the other recipes, the use of emulsifier caused limited retrogradation and a low correlation between the texture properties and time-dependent events.     

Combined Effects of Baking Conditions and Bacterial α-Amylases on Staling Kinetics of Degassed and Porous Bread Crumb

Enzymes such as ??-amylase are extensively used to retard the staling process. Enzymes are acting both during fermentation and during baking. The objective of this work was to determine the relative action of ??-amylase during fermentation and during baking. The impact of the baking conditions (time, temperature) was also considered. To attain this aim, a degassed bread crumb was baked in a miniaturized system using two programs of baking: heating rates 10.27 and 6.88?°C/min corresponding to 180 and 220?°C baking temperatures, respectively. Mechanical and thermodynamic properties of the degassed crumb were assessed during aging of bread by determining the Young??s modulus E, the amount of freezable water, and the melting enthalpy of retrograded amylopectin. A first-order kinetic model was used to determine the different parameters of staling kinetics. Results showed that the hardening of crumb increased during storage. The kinetics were faster for samples baked with fast heating rate than for those baked with slow heating rates. The use of enzymes decreased the Young??s modulus but did not have any effect on the staling rate. Calorimetric analysis of the starch retrogradation showed a reduction of the amount of freezable water during storage with an increase of retrograded amylopectin. A comparison between mechanical properties of conventional crumb and of the degassed dough confirmed that experimental data fitted correctly the Gibson and Ashby??s model.     

Evaluation of performance of dough and bread incorporating chia (Salvia hispanica L.)

As a result of the opinion given by the European Food Safety Authority about the safety of chia seed (Salvia hispanica L) and whole ground chia seed as food ingredients, they may be placed on the market in the European Community as novel food ingredients to be used in bread products. The objective of the present investigation was to develop new cereal-based products with increased nutritional quality by using chia and ground chia seeds (whole chia flour, semi-defatted chia flour and low-fat chia flour) in order to evaluate its potential as a bread-making ingredient. The samples with chia addition significantly increased the levels of proteins, lipids, ash and dietary fibre in the final product compared to the control sample. Breads with seeds or ground seeds showed similar technological quality to the control bread, except for the increase in specific bread volume, decrease in crumb firmness and change in crumb colour. Sensory analysis showed that the inclusion of chia increased overall acceptability by consumers. The thermal properties of the starch did not alter substantially with the inclusion of chia. However, the incorporation of chia inhibited the kinetics of amylopectin retrogradation during storage, which would be directly related to the delay in bread staling.     

Effect of HPMC addition on the microstructure, quality and aging of wheat bread

The effect of hydroxypropylmethylcellulose (HPMC) addition on a basic bread formulation is described. The effect of HPMC as bread improver and antistaling agent was analysed in terms of microstructure. Bread quality was assessed by physical parameters (volume, width/height ratio, moisture content and hardness), crumb grain structure (number of air cells, cells area and the ratio between cells area and total area) and sensory evaluation (appearance, aroma, taste and texture). Bread staling was determined by following both the hardness increase and the starch retrogradation during storage. The microstructure was analyzed by cryo scanning electron microscopy (cryo-SEM). The results confirm the ability of the HPMC for improving fresh bread quality and for delaying staling. The presence of HPMC decreased the hardening rate of the bread crumb and also retarded the amylopectin retrogradation. The microstructure analysis revealed the possible interaction between the HPMC and the bread constituents, which could partially explain the antistaling effect of this hydrocolloid.     

Impact of sodium chloride on wheat flour dough for yeast-leavened products. II. Baking quality parameters and their relationship

BACKGROUND: The traditional use of sodium chloride (NaCl) fulfills various important rheological, technological and sensory properties in the manufacturing of yeast‐leavened products. However, the use of NaCl in food production has been discussed controversially since a high intake of sodium seems to be associated with hypertension. This study investigates the baking quality parameters of wheat breads containing various levels of NaCl (0–40 g NaCl kg^?1flour). RESULTS: Crumb firmness and rate of bread staling decreased with decreasing NaCl levels. A slight increase in loaf volume was observed based on the increased yeast leavening ability resulting from additional NaCl. Higher crumb retrogradation (measured by differential scanning calorimetry) was observed with low NaCl levels. CONCLUSION: The retrogradation effect is based on the theory that NaCl probably leads to Na⁺ inclusion in starch molecules during storage and thus reduces retrogradation. Further, significant (P?0.05) linear relationships (r ≥ 0.829) between Rheofermentometer results, bread volume and crumb firmness were found, suggesting a predictability of bread quality by measurement of gas release. Copyright © 2011 Society of Chemical Industry     

Adequacy of wholegrain non-wheat flours for layer cake elaboration

Flours (white and wholegrain flours) from wheat, rye, triticale, barley and tritordeum were used to elaborate layer cakes. The pasting properties (RVA) and the water-absorption (doughLab) of flours were analyzed. The batter characteristics (density, G′, G″, tan δ, consistency and flow index), and the cake characteristics (cake volume, crumb and crust colour and texture after 1 and 7 days) were studied. A sensorial evaluation of the cakes was also performed. Wholegrain flours showed higher pasting temperature and water-absorption, but lower peak time and viscosity than white flours. Its batters showed lower density and consistency and higher G′, G″, tan δ and n values. Wholegrain cakes showed lower specific volume, symmetry, colour characteristics, and staling rate but higher initial firmness. Considering the different cereals, barley showed the most different behaviour in flour, batter and cake characteristics. DoughLab analysis was very interesting to understand the adequacy of flours to cake elaboration, since significant correlations were found between water-absorption and specific volume, symmetry and firmness. Little differences in the consumer test were obtained between wheat and non-wheat cakes. Wholegrain non-wheat cakes could be a good alternative to white flour wheat cakes, due to their adequate technological properties and their nutritional advantages.     

Influence of Gluten-free Flours and their Mixtures on Batter Properties and Bread Quality

Gluten is a major component of some cereals and is responsible for flour technological characteristics to make bakery products. However, gluten must be eliminated from the diet of celiac patients because its ingestion causes serious intestinal damage. The objectives of this study were to assess the effect of different flours and their mixtures on thermal and pasting properties of batters, and to study the quality parameters and staling rate of gluten-free breads. Starch gelatinization temperatures and enthalpies depended on batter composition. Soy flour addition had a higher effect on rice than on corn starch, indicating some differential interaction between starch and proteins. Inactive soy flour incorporation improved all bread quality parameters in both corn- and rice-based breads. Higher batter firmness of formulations with soy addition (extrusion force was doubled in rice/soy and rice/corn/soy batters with regard to rice and rice/corn batters) partially explained higher specific volume (rice breads: 1.98 cm³/g; rice/soy 90:10 2.51 cm³/g, corn/soy 90:10: 2.05 cm³/g, whereas corn/soy 80:20: 2.12 cm³/g), as these batters retained more air during proofing. The staling rate was decreased by soy flour incorporation on rice (staling rate of rice breads with 10% soy diminished 52%, and with 20% of soy addition, 77%, both regarding to 100% rice breads) and corn formulation (the staling rate of corn/soy 80:20 breads was 5.9% lower than corn/soy 90:10) because of the high water-holding capacity of soy proteins and the interactions established with amylopectin that could retard the retrogradation process. Breads made with rice, corn, and soy flours showed the best quality attributes: high volume, good crumb appearance, soft texture, and low staling rate.