Thermo-physical assessment of bread during staling

An Impact Assessment of Par-Baking and Storage on the Quality of Wheat, Whole Wheat, and Whole Rye Breads

Par-baking technology increases the production efficiency of bread. However, the degree of par-baking can vary significantly amongst product types and intended sales markets, leading to substantial differences in the quality attributes of the finished product. The objective of this study was to explore the impact of the degree of par-baking on the technological quality of wheat, whole wheat, and whole rye bread (95, 75, and 50% of full baking time). More specifically, this study focused on the starch pasting behavior of different flour formulations, the crumb core temperature during par-baking, and the influence of the degree of par-baking on the bread characteristics of (composite) wheat bread as a function of storage time. The quality attributes of par-baked bread (0 and 4 days after par-baking) and fully baked bread (0 and 2 days after full baking) were assessed. A reduction in the degree of par-baking from 95 to 50% resulted over time in 19.4% less hardening and 8.6% more cohesiveness for the re-baked wheat breads. Nevertheless, it also negatively impacted springiness (-9.1%) and adhesion (+475%). It is concluded that using the core temperature to define the degree of par-baking is not sufficient for bread loaves intended to be consumed over time, but the results indicate that reducing the degree of par-baking can be beneficial for certain quality aspects of the breads.

Enhancement of Textural and Sensory Characteristics of Wheat Bread Using a Chickpea Sourdough Fermented with a Selected Autochthonous Microorganism

A traditional Greek sourdough, based on the fermentation of chickpea flour by an autochthonous culture, was evaluated as a wheat bread improver. The dominant indigenous microflora (Clostridium perfringens isolates) was identified by 16S rDNA analysis, and a selected strain (C. perfringens CP8) was employed to ferment chickpea flour to obtain a standardized starter culture (sourdough) for breadmaking. In accordance with toxin-typed strain identification, all isolates lacked the cpe gene; thus, there is no concern for a health hazard. Loaf-specific volumes increased with the addition of liquid, freeze-dried, and freeze-dried/maltodextrin sourdoughs compared to control bread leavened by baker's yeast only. Following storage (4 days/25 °C), the amylopectin retrogradation and crumb hardness changes (texture profile analysis) revealed a lower degree of staling for the sourdough-fortified breads. Modifications in the protein secondary structure of fortified doughs and breads were revealed by FTIR analysis. High amounts of organic acids were also found in the sourdough-supplemented breads; butyric and isobutyric acids seemed to be responsible for the characteristic 'butter-like' flavor of these products (sensory analysis). Overall, the addition of liquid or freeze-dried chickpea sourdough in wheat bread formulations can improve the specific volume, textural characteristics, and sensorial properties of loaves, along with extending bread shelf life.

Effects of different ratios of mannitol to sorbitol on the functional properties of sweet potato starch films

Sorbitol as a plasticizer is easily crystallized from starch film, resulting in the reduction in plasticizing effect. To improve the plasticizing performance of sorbitol in starch films, mannitol, an acyclic hexahydroxy sugar alcohol, was used to cooperate with sorbitol. The effects of different ratios of mannitol (M) to sorbitol (S) as a plasticizer on mechanical properties, thermal properties, water resistance and surface roughness of sweet potato starch films were investigated. The results showed that the surface roughness of starch film with M:S (60:40) was the smallest. The number of hydrogen bonds between plasticizer and starch molecule was proportional to the mannitol content starch film. With the decrease of mannitol contents, the tensile strength of starch films gradually decreased except for M:S (60:40). Moreover, the transverse relaxation time value of starch film with M:S (100:0) was the lowest, indicating that it had the lowest degree of freedom of water molecules. Starch film with M:S (60:40) is the most effective in delaying the retrogradation of starch film. This study offered a new theoretical basis that different ratios of mannitol to sorbitol improve different performances of starch films.

Comparative study of soluble soybean polysaccharides on bread staling under acidic conditions

Effect of soluble soybean polysaccharides (SSPS) and acidic condition on the bread staling of crumb and crust were evaluated in bread characteristics, water migration, starch retrogradation, and flavor. Bread characteristic analysis showed SSPS and acidic conditions significantly improved bread quality during storage, maintaining crumb softness. The staling rate of the synergistic group under SSPS and acidic condition decreased by 49.46% compared to the control group. This retardation was associated with water migration and starch retrogradation. SSPS and acidic conditions restricted the water migration from crumb to crust. A synergy between SSPS and acidification restrained the relative crystallinity and retrogradation enthalpy in bread crumbs and crust during storage. The scores plot and heat map analysis indicated SSPS and acidic condition was facilitated the flavors retention in the crumb and crust after stored 7-days. This study suggested SSPS and acidic conditions might be beneficial for extending bread shelf-life.

Influence of Wheat-Mesquite (Prosopis L.) Composite Flour on Dough Rheology and Quality of Bread

The purpose of this study was to evaluate the effect of wheat-mesquite composite flour on the rheology of dough and the quality of bread. The farinographic analysis showed a decrease in the development time and stability of the dough with an increase in the mixing tolerance index. The share of mesquite flour increased the value of loss and storage moduli and reduced the dough’s susceptibility to stress. The mesquite flour addition increased the bread volume by about 17% and the number of large pores >5 mm. The brightness of the crumb containing mesquite flour decreased from 75.3 to 58.6 and the proportion of yellow colour increased from 19.9 to 26.4 in relation to the control bread. The bread with mesquite flour had a significantly softer crumb during storage in comparison with wheat bread, indicating a reduction in the staling. These observations were also confirmed by lowering the disintegration enthalpy of the retrograded amylopectin from 3.33 J/g for the control sample to 1.95 J/g for the bread containing 10% of mesquite flour.

Sodium chloride replacement by potassium chloride in bread: Determination of sensorial potassium threshold and effect on dough properties and breadmaking quality

High sodium intakes represent an important risk factor for hypertension, cardiovascular diseases and kidney diseases. Even during the current COVID-19 pandemic, hypertension was related to higher mortality rate in patients with coronavirus. Thus, it is necessary to apply strategies to reduce or replace sodium content in food most widely consumed, like bread. This work aimed at determining the sensorial potassium threshold when potassium chloride is used as a sodium chloride replacer in bread formulation, and at analyzing the effects of such replacement on the properties of dough and on the technological and sensorial quality of bread. A decrease was observed in dough rheological properties with NaCl reduction in the formulation. Sensorial potassium threshold was determined and KCl was used in bread formulation as a NaCl replacement up to 0.92% of the regular salt content (2%) undetected by its characteristic taste. NaCl reduction resulted in bread with lower specific volume, higher firmness, faster staling and clearer crust. KCl bread showed similar technological to 2% NaCl bread. Finally, it was possible to replace 50% of NaCl with KCl without reducing quality and consumer acceptability.

Impact of exogenous maltogenic α-amylase and maltotetraogenic amylase on sugar release in wheat bread

The use of exogenous maltogenic α-amylases or maltotetraogenic amylases of bacterial origin is common in wheat bread production, mainly as antistaling agents to retard crumb firming. To study the impact of maltogenic α-amylase and maltotetraogenic amylase on straight dough wheat bread, we performed a discovery-driven proteomics approach with commercial enzyme preparations and identified the maltotetraogenic amylase P22963 from Pelomonas saccharophila and the maltogenic α-amylase P19531 from Geobacillus stearothermophilus, respectively, as being responsible for the amylolytic activity. Quantitation of mono-, di- and oligosaccharides and residual amylase activity in bread crumb during storage for up to 96 h clarified the different effects of residual amylase activity on the sugar composition. Compared to the control, the application of maltogenic α-amylase led to an increased content of maltose and especially higher maltooligosaccharides during storage. Residual amylase activity was detectable in the breads containing maltogenic α-amylase, whereas maltotetraogenic amylase only had a very low residual activity. Despite the residual amylase activities and changes in sugar composition detected in bread crumb, our results do not allow a definite evaluation of a potential technological function in the final product. Rather, our study contributes to a fundamental understanding of the relation between the specific amylases applied, their residual activity and the resulting changes in the saccharide composition of wheat bread during storage.

Investigating the potential of slow-retrograding starches to reduce staling in soft savory bread and sweet cake model systems

The potential anti-staling property of starches with slow-retrograding amylopectin was studied in soft wheat bread and cake model systems. Normal rice, waxy rice, and wheat starches were processed by drum drying or extrusion, and native starch was used as a comparator. Extrusion processing causing amylopectin fragmentation can reduce intermolecular retrogradation of rice starch. Starches were incorporated into model breads and cakes as partial replacements for flour on a dry weight basis (3 and 6% for cakes, 5 and 15% for breads). Starches pregelatinized by extrusion had moderate molecular fragmentation, as indicated by RVA and HPSEC-MALLS-RI. Starches previously shown to have lower intermolecular retrograding amylopectin (normal rice, waxy rice) resulted in minor to moderate reductions in hardness and other textural properties as indicated by texture profile analysis (TPA) in breads and cakes upon storage for up to 12 wk. A higher degree of starch fragmentation is suggested to produce lower staling. Incorporation of normal and waxy rice starches resulted in softer breads and cakes than wheat starch, which could be attributed to the shorter external and internal amylopectin chains of rice starch. Higher inclusion (15%) of slow-retrograding waxy rice in the bread model system showed the most potential for anti-staling property.

The effect of the stale bread flour addition on flour and bread quality

In this study, the effect of the flour, which was obtained from stale bread, on flour and bread quality was investigated. The bread that was staled at refrigerator for 7 days was prepared as whole and crumb, and was grinded to convert into flour. The staled whole and crumb bread flours were stored at −18 °C and used to replace 0, 15, 30 and 45% of wheat flour. Then microbiological and physicochemical properties of flours; physical, textural and sensory properties of bread obtained from these composite flours were investigated. We concluded that stale bread flour could be used for bread production at the level of 15%. If the total bread production and consumption is considered, this addition level could provide a significant amount of waste bread recycling each year.

Effects on bread and oil quality after functionalization with microencapsulated chia oil

BACKGROUND

Omega-3 and omega-6 fatty acids-rich oils suffer oxidation reactions that alter their chemical and organoleptic quality. Microencapsulation can be a powerful tool for protection against ambient conditions. In the present study, the addition of microencapsulated chia oil as an ingredient in bread preparations and its effect on the technological and chemical quality of breads was investigated.

RESULTS

Microencapsulation of chia oil was carried out by freeze-drying with soy proteins as wall material and oil release was determined under in vitro gastric and intestinal conditions. Encapsulated oil-containing bread showed no differences in specific volume, average cell area, firmness and chewiness with respect to control bread. Unencapsulated oil-containing bread showed a marked increase in hydroperoxide values respect to control, whereas encapsulated oil-containing bread values were not affected by baking and bread storage. The fatty acid profiles showed a decrease of 13% and 16%, respectively, in α-linolenic acid in the encapsulated and unencapsulated oils with respect to bulk chia oil. Sensory analysis showed no significant differences between bread samples.

CONCLUSION

The addition of encapsulated chia oil did not alter the technological quality of breads and prevented the formation of hydroperoxide radicals. A ration of encapsulated oil-containing bread contributes 60% of the recommended dietary intake of omega-3 fatty acids. © 2018 Society of Chemical Industry.

Impact of local hydrothermal treatment during bread baking on soluble amylose, firmness, amylopectin retrogradation and water mobility during bread staling

The impact of hydrothermal processing undergone by bread dough during baking on the degree of starch granule disruption, on leaching of soluble amylose, on water mobility, on firmness and on amylopectin retrogradation during staling has been investigated. Two heating rates during baking have been considered (4.67 and 6.31 °C/min) corresponding respectively to baking temperature of 220 and 240 °C. An increase in firmness and in the amount of retrogradated amylopectin accompanied by a decrease in freezable water has been observed during staling. Although a lower heating rate yielded in larger amount of retrogradated amylopectin retrogradation, it resulted in a lower firmness. Additionally, the amount of soluble amylose and the relaxation times of water measured by Nuclear Magnetic Resonance NMR (T20, T21 and T22) decreased during staling. It was demonstrated that the amount of soluble amylose was higher for bread crumb baked at lower heating rate, indicating that an increasing amount of amylose is leached outside the starch granules. This was corresponding to a greater amount of retrograded amylopectin during staling. Moreover, it was found that the degree of gelatinization differs locally in a same bread slice between the top, the centre and the bottom locations in the crumb. This was attributed to the differences in kinetics of heating, the availability of water during baking and the degree of starch granule disruption during baking. Based on first order kinetic model, it was found that staling kinetics were faster for samples baked at higher heating rate.

The use of potato fibre to improve bread physico-chemical properties during storage

Bread staling reduction is a very important issue for the food industry. A fibre with high water holding capacity, extracted from potato peel, was studied for its ability to reduce bread staling even if employed at low level (0.4 g fibre/100 g flour). Physico-chemical properties (water activity, moisture content, frozen water content, amylopectin retrogradation) and (1)H Nuclear Magnetic Resonance molecular mobility were characterised in potato fibre added bread over 7 days of storage. Potato fibre addition in bread slightly affected water activity and moisture content, while increased frozen water content and resulted in a softer bread crumb, more importantly when the optimal amount of water was used in the formulation. Potato fibre also reduced (1)H NMR molecular mobility changes in bread crumb during storage. Potato fibre addition in bread contributed to reduce bread staling.

Probiotic edible films as a new strategy for developing functional bakery products: The case of pan bread

In the present paper, a novel approach for the development of probiotic baked cereal products is presented. Probiotic pan bread constructed by the application of film forming solutions based either on individual hydrogels e.g. 1% w/w sodium alginate (ALG) or binary blends of 0.5% w/w sodium alginate and 2% whey protein concentrate (ALG/WPC) containing Lactobacillus rhamnosus GG, followed by an air drying step at 60 °C for 10 min or 180 °C for min were produced. No visual differences between the bread crust surface of control and probiotic bread were observed. Microstructural analysis of bread crust revealed the formation of thicker films in the case of ALG/WPC. The presence of WPC improved significantly the viability of L. rhamnosus GG throughout air drying and room temperature storage. During storage there was a significant reduction in L. rhamnosus GG viability during the first 24 h, viable count losses were low during the subsequent 2-3 days of storage and growth was observed upon the last days of storage (day 4-7). The use of film forming solutions based exclusive on sodium alginate improved the viability of L. rhamnosus GG under simulated gastro-intestinal conditions, and there was no impact of the bread crust matrix on inactivation rates. The presence of the probiotic edible films did not modify cause major shifts in the mechanistic pathway of bread staling - as shown by physicochemical, thermal, texture and headspace analysis. Based on our calculations, an individual 30-40 g bread slice can deliver approx. 7.57-8.98 and 6.55-6.91 log cfu/portion before and after in-vitro digestion, meeting the WHO recommended required viable cell counts for probiotic bacteria to be delivered to the human host.

Bread Staling: Updating the View

Staling of bread is cause of significant product waste in the world. We reviewed the literature of the last 10 y with the aim to give an up-to-date overview on processing/storage parameters, antistaling ingredients, sourdough technology, and measurement methods of the staling phenomenon. Many researchers have been focusing their interest on the selection of ingredients able to retard staling, mainly hydrocolloids, waxy wheat flours (WWF), and enzymes, but different efforts have been made to understand the molecular basis of bread staling with the help of various measurement methods. Results obtained confirm the central role of amylopectin retrogradation and water redistribution within the different polymers in determining bread staling, but highlighted also the importance of other flour constituents, such as proteins and nonstarch polysaccharides. Data obtained with thermal, spectroscopy, nuclear magnetic resonance, X-ray crystallography, and colorimetry analysis have pointed out the need to encourage the use of one or more of these techniques in order to better understand the mechanisms of staling. Results so far obtained have provided new insight on bread staling, but the phenomenon has not been fully elucidated so far.