Spray-dried and freeze-dried sourdough powders: Properties and evaluation of their use in breadmaking

Sourdough powder: physicochemical, microbiological properties and shelf-life stability in different package type

This study aims to optimize the culture condition of semi-liquid sourdough using Kombucha as a starter culture and to evaluate the physicochemical properties, microbial viability and recovering ability of sourdough powder when packaged in different types of packaging for 120 days. Optimal maturation time (103.47 h) and maximum leavening rate (1.27 mL/h) of sourdough were achieved at an incubation temperature of 34 °C and interval refreshment time at 7 h. The optimized culture was spray-dried using 3% Arabic gum (w/v) as a carrier agent yielding 35.86% powder with acceptable viability of 8.71 log CFU/g lactic acid bacteria and 9.03 CFU/g yeast. The sourdough powder was packed in four packaging (LDPE, vacuumed LDPE, aluminum foil laminated pouch and vacuumed aluminum foil laminated pouch) and exhibited comparable physicochemical properties during 120 days of storage. The viability of both lactic acid bacteria and yeast count in sourdough powder when packed in vacuumed aluminum foil laminated pouch showed higher stability for 90 days (6.18 log CFU/g and 6.82 log CFU/g) but reduced to below detection limit after 120 days (5.54 and 5.94 log CFU/g). This suggested that Kombucha sourdough powder packed in vacuumed aluminum laminated pouch could be stored for up to 90 days.

Exploring the Effects of Freeze-Dried Sourdoughs with Lactiplantibacillus pentosus 129 and Limosilactobacillus fermentum 139 on the Quality of Long-Fermentation Bread

Sourdough production is a complex fermentation process. Natural sourdough fermentation without standardization causes great variability in microbial communities and derived products. Starter cultures have emerged as alternatives to natural fermentation processes, which could improve bakery quality and produce bioactive compounds. This study aimed to evaluate the impacts of freeze-drying on the production and viability of sourdoughs with Lactiplantibacillus pentosus 129 (Lp) and Limosilactobacillus fermentum 139 (Lf), as well as their effects on the quality of long-fermentation bread. These strains were selected based on their better performance considering acidification and exopolysaccharide production capacity. Sourdough with Lp and Lf were propagated until the 10th day, when physicochemical and microbiological parameters were determined. The produced sourdoughs were freeze-dried, and bread samples were produced. The freeze-drying process resulted in high survival rates and few impacts on the metabolic activity of Lp and Lf until 60 days of storage. Incorporating Lp and Lf improved the microbiological and physicochemical properties of sourdough and long-fermentation breads. Tested freeze-dried sourdoughs led to reduced bread aging (higher specific volume and decreased starch retrogradation) and increased digestibility. The results show the potential of the freeze-dried sourdoughs produced with Lp and Lf as innovative strategies for standardizing production protocols for the bakery industry, especially for producing long-term fermentation bread.

Harnessing the Role of Three Lactic Acid Bacteria (LAB) Strains for Type II Sourdough Production and Influence of Sourdoughs on Bread Quality and Maillard Reaction Products

This study tested the effect of Companilactobacillus paralimentarius E-106, Lactiplantibacillus paraplantarum N-15 and Lactiplantibacillus plantarum SC-9 on the amount of Maillard reaction and aroma profile in bread making with main bread quality parameters. The specific volumes of sourdough and control breads were in the range of 2.97-3.04 cm3/g, and the control II bread had the highest hardness values on all days. The FAST index value was determined to be between 40.48% and 81.22% in all breads. The FAST index value was found to be higher in the control breads than in the sourdough breads. In the volatile compounds analysis, 72 volatile compounds were detected. The variety of volatile compounds in the breads with sourdough addition was higher than the control breads. Among the tested strains, Companilactobacillus paralimentarius E-106 demonstrated superior properties for bread characteristics in comparison to other strains as a type II sourdough starter. In summary, improved aroma profile and decreased Maillard reaction products can be provided by sourdough addition without changing the bread quality, along with meeting consumer demand for less additive use.

Unlocking the potential of low FODMAPs sourdough technology for management of irritable bowel syndrome

Consumption of high FODMAP (Fermentable Oligo-, Di-, and Monosaccharides and Polyols) diet is the leading cause of alteration in the human gut microbiome, thereby, causing irritable bowel syndrome (IBS). Therefore, sourdough technology can be exploited for reduction of FODMAPs in various foods to alleviate the symptoms of IBS. Several microorganisms viz. Pichia fermentans, Lactobacillus fetmentum, Saccharomyces cerevisiae, Torulaspora delbrueckii, Kluyveromyces marxianus etc. have been identified for the production of low FODMAP type II sourdough fermented products. However, more research on regulation of end-product and volatilome profile is required for maximal exploitation of FODMAP-reducing microorganisms. Therefore, the present review is focused on utilisation of lactic acid bacteria and yeasts, alone and in synergy, for the production of low FODMAP sourdough foods. Moreover, the microbial bioprocessing of cereal and non-cereal based low FODMAP fermented sourdough products along with their nutritional and therapeutic benefits have been elaborated. The challenges and future prospects for the production of sourdough fermented low FODMAP foods, thereby, bringing out positive alterations in gut microbiome, have also been discussed.

Preparation of Sourdoughs Fermented with Isolated Lactic Acid Bacteria and Characterization of Their Antifungal Properties

Traditional sourdough is obtained using a mixture of flour and water stored at room temperature until acidification. Therefore, adding lactic acid bacteria (LAB) can improve the quality and safety of sourdough bread. Faced with this problem, four drying techniques-freeze-drying, spray-drying, low-temperature drying, and drying at low humidity-have been applied. Our goals were to isolate LAB strains with antifungal potential against Aspergillus and Penicillium fungi. The antifungal capacity was evaluated with agar diffusion, co-culture in overlay agar, and a microdilution susceptibility assay. In addition, the antifungal compounds generated in sourdough were analyzed. As a result, dried sourdoughs were prepared with Lactiplantibacillus plantarum TN10, Lactiplantibacillus plantarum TF2, Pediococcus pentosaceus TF8, Pediococcus acidilactici TE4, and Pediococcus pentosaceus TI6. The minimum fungicidal concentrations ranged from 25 g/L versus P. verrucosum and 100 g/L against A. flavus. A total of 27 volatile organic compounds were produced. Moreover, the lactic acid content reached 26 g/kg of dry product, and the phenyllactic concentration was significantly higher than the control. The P. pentosaceus TI6 exhibited a higher antifungal capacity in vitro and demonstrated a higher production of antifungal compounds compared to the other strains; therefore, further studies will evaluate the impact of this sourdough in bread manufacture.

Quality Characteristics of Novel Sourdough Breads Made with Functional Lacticaseibacillus paracasei SP5 and Prebiotic Food Matrices

Lacticaseibacillus paracasei SP5, isolated from kefir, was assessed as a starter culture for sourdough bread making in freeze-dried form, both free (BSP5 bread) and immobilised on wheat bran (BIWB) and on a traditional flour/sour milk food, ‘trahanas’ (BITR). Physicochemical characteristics, shelf-life, volatilome, phytic acid, and sensory properties of the breads were evaluated. The BITR breads had higher acidity (9.05 ± 0.14 mL of 0.1 M NaOH/10 g) and organic acid content (g/Kg; 2.90 ± 0.05 lactic, 1.04 ± 0.02 acetic), which justifies the better resistance against mould and rope spoilage (>10 days). The highest number of volatiles (35) and at higher concentration (11.14 μg/g) were also found in BITR, which is in line with the sensory (consumer) evaluation regarding flavour. Finally, higher reduction of phytate (an antinutrient) was observed in all L. paracasei SP5 sourdoughs (83.3–90.7%) compared to the control samples (71.4%). The results support the use of the new strain for good quality sourdough bread.

Characteristics of Mulberry Leaf Powder Enriched With γ-Aminobutyric Acid and Its Antioxidant Capacity as a Potential Functional Food Ingredient

To improve the functional properties of mulberry leaves, γ-aminobutyric acid (GABA) enrichment treatments were applied. The results showed that the combined treatment of sodium glutamate immersion, cold shock, and anoxic significantly increased the GABA content. HPLC analysis displayed that the quantity of some active phenolics was significantly increased after the treatment. The GABA-enriched mulberry leaf powders were subsequently prepared, and it was found that as the particle size decreased, their water and oil holding capacity and their swelling power decreased, while the angle of repose increased. The dissolution rate of GABA and total phenolics increased as the particle size decreased. Optical observations and SEM results revealed that the fiber structures of the particles were gradually destroyed as the particle size decreased. Further, FTIR analysis showed that the active compounds in the powders were not destroyed. M400 and M140 powder showed the maximum DPPH radical scavenging ability and AGEs inhibition capacity, respectively. Additionally, adding the powders effectively alleviated the staling of bread without any significant effect on taste.

Development of a Wet-Granulated Sourdough Multiple Starter for Direct Use

The search for sourdough starters for the direct production of baked goods with all the advantages of biological sourdough fermentation is still a crucial issue. In this study, 43 Lactic Acid Bacteria strains isolated from mature sourdoughs were evaluated for features of technological interest and tested for fermentation ability. Three microbial combinations were selected and used to produce bread. Based on GC-MS and sensory analysis, bread made by using the three combinations of strains was characterized by a more complex aroma profile with the prevalence of VOCs typical of sourdough bread. To set up the best way to keep microbial viability upon drying, the three combinations were subject to freeze-drying and wet granulation, with the latter being used for the first time for food starters’ stabilization. Wet granulation ensured optimal strains’ viability. Surprisingly, the height attained by mature sourdoughs when inoculated with wet granulated starters was constantly higher than the height reached by sourdoughs made with the same starters as fresh cells. The microbial combination E75-B72 exhibited the best performances and may represent a starter able to ensure sourdough bread production in 16 h of fermentation at 28 °C.

Statistical Approach to Potentially Enhance the Postbiotication of Gluten-Free Sourdough

Fermented products are permanently under the attention of scientists and consumers, both due to nutritional importance and health promoting effects. The fermented functional foods contribute to a more balanced diet and increase the immune responses (among many other health effects) with positive implications for quality of life. In this sense, improving the sourdough’s fermentation to boost the biotic (postbiotic and paraprobiotic) properties of the sourdough-based products has positive impacts on the nutritional and functional properties of the final baked products. These enhanced sourdoughs can be obtained in controlled fermentation conditions and used as sourdough bread improvers or novel bioingredients. In this context, our work aimed to optimize, using statistical tools, a gluten-free sourdough based on chickpea, quinoa, and buckwheat fermentation with selected lactic acid bacteria (LAB) to enhance its postbiotic properties. The most important biotechnological parameters were selected by Plackett–Burman Design (PBD) and then Response Surface Methodology (RSM) was applied to evaluate the interactions between the selected factors to maximize the gluten-free sourdough’s properties. As a result, the optimized fermented sourdough had antimicrobial activity with inhibition ratios between 71 and 100% against the Aspergillus niger, Aspergillus flavus, Penicillium spp. molds and against the Bacillus spp endospore-forming Gram-positive rods. The optimized variant showed a total titratable acidity (TTA) of 40.2 mL NaOH 0.1N. Finally, the high-performance liquid chromatography (HPLC) analysis highlighted a heterofermentative profile for the organic acids from the optimized sourdough. Among flavonoids and polyphenols, the level of caffeic and vanillic acids increased after lactic acid fermentation. The comparison between the optimized sourdough and the control evidenced significant differences in the metabolite profiles, thus highlighting its potential postbiotication effect.

Innovations in Sourdough Bread Making

The application of sourdough is considered to be a key tool for the production of high-quality bread. Several advantages have been presented through the application of sourdough in bread making, such as increased shelf life, improved aromatic profiles and sensory characteristics, increased nutritional value, and health benefits. Technological benefits have also been recorded, such as the successful application of sourdough in gluten-free breads. Likewise, an upsurge of interest in sourdough applications in bread making as well as in other foodstuffs (pasta) has been witnessed in recent years. Many factors are considered important for sourdough preparations; however, the proper selection of the starter cultures is considered the most central. This Special Issue of Fermentation aims to disseminate recent innovative research regarding sourdough bread making, as well as authoritative reviews that compile information from previously published material.

Recent Trends in Pretreatment of Food before Freeze-Drying

Drying is among the most important processes and the most energy-consuming techniques in the food industry. Dried food has many applications and extended shelf life. Unlike the majority of conventional drying methods, lyophilization, also known as freeze-drying (FD), involves freezing the food, usually under low pressure, and removing water by ice sublimation. Freeze-dried materials are especially recommended for the production of spices, coffee, dried snacks from fruits and vegetables and food for military or space shuttles, as well as for the preparation of food powders and microencapsulation of food ingredients. Although the FD process allows obtaining dried products of the highest quality, it is very energy- and time consuming. Thus, different methods of pretreatment are used for not only accelerating the drying process but also retaining the physical properties and bioactive compounds in the lyophilized food. This article reviews the influence of various pretreatment methods such as size reduction, blanching, osmotic dehydration and application of pulsed electric field, high hydrostatic pressure or ultrasound on the physicochemical properties of freeze-dried food and drying rate.