Different baking conditions may produce breads with similar physical qualities but unique starch gelatinization behaviour

The use of blackcurrant pomace and erythritol to optimise the functional properties of shortbread cookies

As a result of the production of blackcurrant juice, pomace is produced, which is a cheap, easy to further process raw material with high health benefits. The aim of the research was to develop a recipe for shortbread cookies based on blackcurrant pomace (0, 10, 30, 50%) and erythritol, and to assess their nutritional value (content of proteins, fats, sugars, dietary fibre, selected minerals and energy value), pro-health properties (antioxidant and anti-diabetic capacity) and sensory evaluation. The energy value of products with 50% of pomace sweetened with erythritol was nearly 30% lower compared to traditional cookies, while the content of dietary fibre was 10 times higher in products with the highest percentage of pomace. The antioxidant capacity and the total content of polyphenolic compounds increased with the increase in pomace content. The ability to inhibit α-amylase by shortbread cookies without pomace was about 400 times lower than those with 50% pomace. The results of the sensory evaluation showed that erythritol-sweetened cookies have more desirable characteristics compared to sucrose-sweetened cookies. Finally, it was proved that the proposed products are an excellent proposal for people struggling with food-dependent diseases, as well as being an opportunity to manage waste from the fruit industry.

Influence of blend proportion and baking conditions on the quality attributes of wheat, orange-fleshed sweet potato and pumpkin composite flour dough and bread: optimization of processing factors

Orange-fleshed sweet potato (OFSP) and pumpkin fruit are underutilized crops with great potential for the production of high-quality bread with health-enhancing properties. However, the incorporation of nonconventional flour in bread formula may influence the dough and bread quality properties. This study investigated the effect of partial substitution of wheat flour with OFSP (10–50%) and pumpkin flour (10–40%), baking temperature (150–200 °C) and baking time (15–25 min) on the quality properties of the composite dough and bread using response surface methodology (RSM). Dough rheological, bread physical and textural properties were analyzed, modelled and optimized using RSM. Satisfactory regression models were developed for the dough and bread quality attributes (R2 > 0.98). The dough development time, crust redness, hardness, and chewiness values increased while optimum water absorption of dough, specific volume, lightness, springiness, and resilience of bread decreased significantly (p < 0.05) with increasing incorporation of OFSP and pumpkin flour in the bread formula. Additionally, the specific volume, crust redness, crumb hardness, and chewiness of the composite bread increased significantly (p < 0.05) with increasing baking temperature from 150 to 180 °C but reduced at higher baking temperatures (≥ 190 °C). The staling rate declined with increased OFSP and pumpkin flour whereas increasing the baking temperature and time increased the bread staling rate. The optimized formula for the composite bread was 78.5% wheat flour, 11.5% OFSP flour, 10.0% pumpkin flour, and baking conditions of 160 °C for 20 min. The result of the study has potential applications in the bakery industry for the development of functional bread.

Graphical Abstract

Understanding how starch constituent in frozen dough following freezing-thawing treatment affected quality of steamed bread

Understanding how starch constituent in frozen dough affected bread quality would be valuable for contributing to the frozen products with better quality. To elucidate the underlying mechanism, starch was fractionated from multiple freezing-thawing (F/T) treated dough and reconstituted with gluten. Results showed that F/T treatment destructed the molecular and supramolecular structures of starch, which were more severe as the F/T cycle increasing. These structural disorganizations made water molecules easier to permeate into the interior of starch granules and form hydrogen bonds with starch molecular chains, which elevated the peak, breakdown, setback and final viscosity of starch paste. In addition, F/T treatment resulted in decreased specific volume (from 1.54 to 0.90 × 10³ m³/Kg) and increased hardness (from 42.98 to 52.31 N) for steamed bread. We propose the strengthened water absorption ability and accelerated intra- and inter-molecular rearrangement of starch molecules and weak stability of "starch-gluten matrices" would allow interpreting deteriorated bread quality.

Ultrasonic microencapsulation of oil-soluble vitamins by hen egg white and green tea for fortification of food

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Highly stable vitamin loaded microcapsules are synthesised by ultrasound.

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Egg white proteins provide robust shells to protect vitamins from degradation.

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External green tea/iron coating imparts UV filtering property to microcapsules.

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Microcapsules maintain structural integrity during food fortification.

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In-vitro digestion model shows the effective release of the encapsulated vitamin.

We report the microencapsulation of oil soluble vitamins (A, D and E) using a one pot ultrasonic process and raw egg white proteins as a shell material. Green tea catechin/iron complex coating method was further developed to impart UV filtering property to the microcapsules in order to protect the encapsulated nutrients from photodegradation. The microcapsules showed antibacterial properties and long shelf-life. The encapsulated vitamins were protected from degradation upon heating, UV irradiation, simulated storage/transit and cooking processes. The in-vitro digestion study showed that functional vitamin D can be potentially released in the gastrointestinal tract improving vitamin D availability by more than 2-fold compared to the free vitamin. The vitamin D microcapsules were highly stable and maintained their microstructures once incorporated into staple food products. The low-cost egg white shell encapsulated vitamins can improve the nutritional value of staple food products to combat maternal and child malnutrition.

The effect of baking conditions on protein digestibility, mineral and oxalate content of wheat breads

Different baking conditions were used in order to evaluate its effects on bread aspects. Doughs were baked at 160, 190 and 220 °C, during 9, 12, 15 and 20 min, and characterized in relation to color change, oxalate and mineral concentration, and protein digestibility. The higher the baking temperature and time, the higher the crust color change, the lower the oxalate concentration, and the higher the amount of some macro minerals. Protein digestibility may also be favored, however it does not follow a linear correlation. Although it is not possible to obtain a condition that favors the content of all minerals, protein digestibility and reduces oxalate content, the use of high temperatures and times is important as it can reduce oxalate and thereby prevent its associated problems. Understanding how to optimize it during baking could be used to produce breads with a higher mineral bioavailability, an important strategy for food industry and also when using alternative flours.

Baking Effect on Resistant Starch Digestion from Composite Bread Produced with Partial Wheat Flour Substitution

The consumption of composite flour, such as green banana and corn flour, is related to maintain stable blood glucose levels, due to high resistant starch levels. However, most of these studies have conducted analyses of unprocessed food such as flour. Therefore, this study aimed to evaluate the effect of baking on resistant starch concentration and digestion from bread produced with partial wheat flour substitution. Response surface methodology was used to evaluate bread physical-chemical characteristics, and then, sensorial and nutritional qualities of the bread were evaluated. The feasibility of incorporating 40% of corn flour was demonstrated, while incorporation of 20% produced bread with similar characteristics to the control; for green banana flour, these levels were 20 and 10%, respectively. Resistant starch levels of composite breads were also enhanced by in vitro analyses. On the other hand, in vivo blood glucose levels evidenced that the ingestion of breads produced with partial wheat flour substitution by green banana or corn flour promoted a more important peak in blood glucose levels in comparison with control bread, which was never previously presented in the literature. Bread ingestion rapidly increased the blood glucose levels of rats; once during the baking process, starch granules become gelatinized and therefore easily digestible. Furthermore, this study also highlighted the lack and need for future investigation of wheat flour-substituted baked goods, in order to better understand mechanical properties formation and also product digestibility.

Comparison of the Functionality of Exopolysaccharides Produced by Sourdough Lactic Acid Bacteria in Bread and Steamed Bread

Exopolysaccharides (EPSs) produced by lactic acid bacteria improve the quality of bread; however, their functionality in steamed bread is unknown. This study aimed to compare the impact of EPS produced during sourdough fermentation on the quality of bread and steamed bread. Sourdoughs were fermented with EPS-producing Fructilactobacillus sanfranciscensis, Weissella cibaria, and Leuconostoc mesenteroides; Latilactobacillus sakei LS8 and chemically acidified sourdough were prepared as controls. EPS production generally enhanced the specific volume, improved the texture, and reduced the staling rate of bread. The effect of EPS on steamed bread quality was more pronounced when compared to its effect on bread quality. Remarkably, the beneficial effects of F. sanfranciscensis bread quality were largely independent of EPS formation and may relate to gluten modifications rather than EPS production. In conclusion, the direct comparison of sourdough and EPS functionality in steaming and baking provides novel insights for the optimization of commercial (steamed) bread production.

Evaluation of wheat flour substitution type (corn, green banana and rice flour) and concentration on local dough properties during bread baking

Different bread formulations, which provide different dough structures, were studied in order to better understand the effect of wheat flour substitution, flour type and concentration on dough development during baking, and their relationship with physical properties of the final product. Breads were produced with partial substitution of wheat flour by corn (CF), green banana (GF) and rice flour (RF), at different concentrations, and then baked at different times. Wheat flour substitution by CF, GF and RF in bread reduces heat transfer to the dough center by about 21%, 35% and 20%, respectively; and the water loss by about 5%, 15% and 0%, respectively. Those reductions were more influenced by flour type, than flour concentration. When wheat flour is substituted, the mechanisms of water migration are modified, once the pore system of bread dough is more discrete and stiffens later. Calculated thermal conductivity and diffusivity of the different flours used, and its correlations with average composite-bread heating rates (0.93) and water loss (0.85), respectively, indicates that thermal properties of composite bread dough could represent an important issue to be explored in dough systems with reduced gluten concentration.