Influences of lactic acid bacteria on technological, nutritional, and sensory properties of barley sour dough bread

Application of novel starter cultures for sourdough bread production

Effects of flour from different barley varieties on barley sour dough bread

A preocupação dos consumidores por produtos alimentícios mais saudáveis cresce cada dia mais. Sendo assim, é extremamente desafiador para a indústria de alimentos encontrar maneiras de satisfazer esse novo nicho de mercado, por meio de novos processos e produtos que utilizem menos ou eliminam os aditivos químicos e que ao mesmo tempo possuam melhores características nutricionais. Os pães estão entre os produtos de panificação mais consumidos mundialmente. Originalmente eram produzidos por fermentação natural, um processo capaz de fornecer mais sabor e aroma ao produto e aumentar o tempo de conservação. Este trabalho teve por objetivo avaliar a produção e aplicação da fermentação natural na elaboração de pães de forma com adição de polpa de araticum. O fermento natural foi avaliado quanto à contagem de bactérias láticas e pH. Os pães foram avaliados em relação ao volume específico, à cor instrumental, à atividade de água, à umidade, à textura instrumental, ao pH e acidez total titulável, à capacidade antioxidante, à avaliação de imagem das fatias e às propriedades sensoriais. Os resultados foram avaliados estatisticamente por análise de variância (ANOVA) e comparação de médias (teste de Tukey HSD) com confiabilidade de 95 %. Os pães com fermentação natural e adição de polpa de araticum demonstraram ter menor volume específico e maiores firmeza, capacidade antioxidante e aceitação sensorial pelos consumidores, quando comparados à formulação padrão. Os resultados sugerem que a fermentação natural é uma tecnologia promissora para ser utilizada resultando em um produto comercialmente viável.

In the present study, a novel Pediococcus pentosaceus SP2 strain, recently isolated from kefir grains, was evaluated as a starter culture in sourdough bread making. The novel starter was applied in fresh, freeze-dried, and freeze-dried immobilized (on wheat bran) form. The type of culture (fresh, freeze-dried, immobilized cells) influenced the bread characteristics. Specifically, the application of freeze-dried immobilized cells led to higher total titratable acidity (TTA) values (9.81 mL NaOH N/10), and the produced bread presented higher resistance to mold and rope spoilage. Moreover, the produced sourdough breads were significantly better in terms of pH, TTA, organic acids content, and resistance to mold and rope spoilage, compared to breads made with a commercial, wild microbiota, sourdough. The organic acids content was also significantly higher than the commercial sourdough sample (2.93 g/kg lactic acid; 1.01 g/kg acetic acid). Determination of volatile compounds through solid-phase microextraction (SPME) gas chromatography/mass spectrometry (GC/MS) analysis and sensorial assessments indicated no significant differences between the tested sourdough breads.

The sourdough fermentation method is identified as a complex microbial ecosystem stimulant by the spontaneous natural water starters process. At the fermentation time, lactic acid bacteria and yeast confer the resulting characteristic bread features such as staling of bread, and palatability. With the scope of highlighting fermentation, the investigation of starter culture is relevant in order to determine starch fractions of flour. The present article employed water from apple local varieties of Malang as a mixture of natural yeast. The research was conducted in two stages. The first stage was to get the best apple variety to produce the optimum quality of sourdough starter. The second was applying the best sourdough starter at various concentrations in bread formulation. Parameters observed included yeast, and lactic acid bacteria counts, pH, Total Titratable Acidity (TTA), lactic acid content, hardness, loaf volume, specific volume, and sensory properties of sourdough bread. There was an influence on the treatment of making a sourdough starter with different types of apple fruit and showed the best treatment if sourdough starter of fermented manalagi apple water with a pH value of 4.5, TTA value of 2.71 mL, the number of lactic acid bacteria of 5.6 × 1010 CFU/mL, and the number of yeast of 2.62 × 1011 CFU/mL.

The doctoral thesis "Hull-less barley in sourdough fermentation" was developed from February 2020 to December 2023 in the Latvia University of Life Sciences and Technologies (LBTU) Food Institute (former Faculty of Food Technology) laboratories. The analyses of samples were conducted at the Institute of Agricultural Resources and Economics (AREI) of Stende Research Centre, Division of Smart Technologies (LBTU), Center of Food and Fermentation Technologies (TFTAK) in Estonia, Budapest University of Technology and Economics, Department of Applied Biotechnology and Food Science. Statistical data processing was conducted in collaboration with the Institute of Computer Systems and Data Science of the Faculty of Engineering and Information Technologies. The hypothesis of doctoral thesis: hull-less barley is an alternative raw material for sourdough fermentation and breadmaking. Research objects: hull-less barley spontaneous sourdough, with starter cultures fermented sourdough, as well as hull-less barley sourdough bread. The following theses have proved the hypothesis. 1. Under the influence of optimal technological fermentation parameters, the succession of typical sourdough microbiota occurs. 2. The microbiological and physical indicators of the spontaneous sourdough of hull-less barley resemble the characteristic indicators of active sourdough, and sourdough fermented with starter cultures can possess enhanced proteolytic activity. 3. The gluten content in hull-less barley sourdough fermentation decreases relative to its content in flour. 4. The content of non-starch polysaccharides affects the physical properties of bread. The aim of doctoral thesis: to study the fermentation of hull-less barley sourdough and evaluate its effect on the content of gluten and non-starch polysaccharides and the physical properties of barley bread. The tasks set to achieve the goals. 1. To determine the optimal technological parameters for the spontaneous fermentation of hull-less barley and the taxonomic composition of lactic acid bacteria and microscopic fungi. 2. To specify the microbiota succession in the spontaneous sourdough fermentation of hull-less barley. 3. To evaluate the quality indicators and rheological properties of hull-less barley sourdough fermented spontaneously and with starter cultures. 4. To study the physical properties of hull-less barley and wholegrain wheat bread prepared with hull-less barley sourdough. 5. To determine the gluten content in hull-less barley sourdough and hull-less barley bread. 6. To analyze the content of non-starch polysaccharides in hull-less barley and wholegrain wheat bread and to explain their effect on the physical properties of the bread. The thesis is summarized in three chapters. Chapter 1 characterizes the types of sourdough and describes the main influencing factors of sourdough. Reflected spontaneous sourdough microbiota. Characteristics of hull-less barley as an alternative raw material are given. The information regarding the structure of sourdough and dough is provided. An insight into changes in flour's chemical composition and physical properties during sourdough fermentation is provided. Chapter 2 outlines the materials and methods used in the study. Chapter 3 summarizes the results of the study.  The influence of variable factors in the three steps of fermentation of hull-less barley was characterized, and the optimal technological parameters were determined. Identified microbiota and analyzed its succession in the three steps of fermentation.  Microbiological (number of lactic acid bacteria, yeasts colony-forming units) physical (pH, complex viscosity, loss and storage moduli) and chemical (titratable acidity, proteolytic activity) indicators of hull-less barley sourdough summarized; structure formation and changes in sourdough and dough fermentation were analyzed.  The content of gluten in hull-less barley flour and sourdough was determined, and its changes in bread prepared with hull-less barley sourdough were analyzed.  The content of β-glucans, fructans, and mannans in bread prepared with hull-less barley sourdough was analyzed, and their influence on the physical properties of the bread was elucidated. A PhD thesis is written in Latvian, it consists of 100 pages, 16 tables, 23 images and 173 bibliographic sources and 4 appendices. The study was financed by the grants: “Strengthening Research Capacity at Latvia University of Life Sciences and Technologies” project “The biotechnological solutions for barley sourdough” (Contract No 3.2.-10 /125); Latvia University of Life Sciences and Technologies program project “Biologically active compound content in the developed barley bread” (Contract No 2020-LLU-141); “Transition to the new doctoral funding model at the Latvia University of Life Sciences and Technologies” (Contract No 8.2.2.0/ 20/I/001).

Impact of starter culture on biochemical properties of sourdough bread related to composition and macronutrient digestibility

Evaluation of Leuconostoc citreum HO12 and Weissella koreensis HO20 isolated from kimchi as a starter culture for whole wheat sourdough

This investigation is aimed at developing a new cereal-based product, with increased nutritional quality, by using Bifidobacterium pseudocatenulatum ATCC 27919 as starter in whole wheat sourdough fermentation and evaluating its performance. Four different sourdough levels (5%, 10%, 15%, and 20% on flour basis) in bread dough formulation were analysed. The effects of the use of bifidobacteria in sourdough bread were comparatively evaluated with controls (yeast and/or chemically acidified sourdough with antibiotics). The sourdough and dough fermentative parameters analysed were pH, total titratable acidity, d/l-lactic and acetic acids. Bread performance was evaluated by specific volume, slice shape, crumb structure and firmness, crust and crumb colour, pH, total titratable acidity, and d/l-lactic and acetic acids, phytate, and lower myo-inositol phosphate contents. The sourdough breads showed similar technological quality to the control sample, with the exception of specific bread volume (decreased from 2.46 to 2.22 mL/g) and crumb firmness (increased from 2.61 to 3.18 N). Sourdough inoculated with bifidobacteria significantly increased the levels of organic acids in fermented dough and bread. The Bifidobacterium strain contributed to the fermentation process, increasing phytate hydrolysis during fermentation owing to the activation of endogenous cereal phytase and its own phytase, resulting in bread with significantly lower phytate levels (from 7.62 to 1.45 μmol/g of bread in dry matter). The inclusion of sourdough inoculated with bifidobacteria made possible the formulation of whole wheat bread with positive changes in starch thermal properties and a delay and decrease in amylopectin retrogradation.

Nowadays, the consumer seeks to replace synthetic preservatives with biopreservation methods, such as sourdough in bread. Lactic acid bacteria (LAB) are used as starter cultures in many food products. In this work, commercial yeast bread and sourdough breads were prepared as controls, as well as sourdough breads with L. plantarum 5L1 lyophilized. The impact of L. plantarum 5L1 on the properties of bread was studied. Antifungal compounds and the impact on the protein fraction by the different treatments in doughs and breads were also analyzed. In addition, the biopreservation capacity of the treatments in breads contaminated with fungi was studied and the mycotoxin content was analyzed. The results showed significant differences with respect to the controls in the properties of the bread and a higher total phenolic and lactic acid content in breads with higher amounts of L. plantarum 5L1. In addition, there was a higher content of alcohol and esters. Furthermore, adding this starter culture produced hydrolysis of the 50 kDa band proteins. Finally, the higher concentration of L. plantarum 5L1 delayed fungal growth and reduced the content of AFB1 and AFB2 compared to the control.

This study investigates the nutritional enrichment of fufu, a staple African food, by controlling the fermentation of cassava root tuber using a starter culture. Lactic acid bacteria (LAB) were isolated from fermented cassava and analyzed for their technological properties. The physicochemical parameters, proximate and antinutrient content of the fufu samples were determined by standard analytical methods. Twelve LAB were identified as Lactobacilli plantarum (42%), L. acidophilus (25%), L. fermentum (17%), L. brevis (8%), and L. mesenteroides (8%). The LAB isolates produced lactic acid, diacetyl, and hydrogen peroxide ranging from 1.90-2.90, 1.30-2.10, and 1.10 -2.90 mg/mL respectively. Lactobacillus plantarum (FF8) was selected as a starter culture due to its exceptional ability to produce antimicrobial substances, leading to higher yields of lactic acid, diacetyl, and hydrogen peroxide, reducing the fermenting medium's pH. The pH changes in starter-induced fermented fufu (SIFF) and spontaneous fermented fufu (SFF) samples from 0 to 96 hours were 7.10 - 2.60 and 7.10 - 3.30, respectively, while the Total Titratable Acidity (TTA) increased from 0.71-1.79 and 0.28-0.51, respectively. Starter-induced fermented fufu (SIFF) has higher protein, fat, sodium, potassium, iron, zinc, phosphorus, and Vit. C, B1, and A content of 2.93, 0.23 (%) 596.4, 270.9, 8.93, 1.67, 296.67, 5.28, 0.24, and 0.31 (mg/100g) respectively, compared to spontaneous fermented fufu and a significant decrease in antinutrient content, such as cyanide, saponin, and phytates of 0.05, 0.16, and 0.06 (mg/100g), respectively. The study found that L. plantarum FF8 used as a starter culture, improves the nutritional value of fufu and reduces anti-nutrients, suggesting potential health benefits for consumers.

The appropriate solution to the problem of quality variability and microbial stability of traditional non-alcoholic pearl millet fermented beverages (NAPMFB) is the use of starter cultures. However, potential starter cultures need to be tested in the production process. We aimed to identify and purify bioburden lactic acid bacteria from naturally fermented pearl millet slurry (PMS) and assess their effectiveness as cultures for the production of NAPMFB. Following the traditional Kunun-zaki process, the PMS was naturally fermented at 37 °C for 36 h. The pH, total titratable acidity (TTA), lactic acid bacteria (LAB), total viable count (TVC) and the soluble sugar were determined at 3 h interval. The presumptive LAB bacteria were characterized using a scanning electron microscope, biochemical tests and identified using the VITEK 2 Advanced Expert System for microbial identification. The changes in pH and TTA followed a non-linear exponential model with the rate of significant pH decrease of 0.071 h−1, and TTA was inversely proportional to the pH at the rate of 0.042 h−1. The Gompertz model with the mean relative deviation modulus, 0.7% for LAB and 2.01% for TVC explained the variability in microbial growth during fermentation. The LAB increased significantly from 6.97 to 7.68 log cfu/mL being dominated by Leuconostoc, Pediococcus, Streptococcus and Enterococcus with an optimum fermentation time of 18 h at 37 °C and 4.06 pH. L. mesenteroides and P. pentosaceus created an acidic environment while E. gallinarum increased the pH of the pearl millet extract (PME). Innovative NAPMFB was produced through assessment of LAB from PMS to PME fermented with L. mesentoroides (0.05%) and P. pentosaceus (0.025%) for 18 h, thereby reducing the production time from the traditional 24 h.

Autochthonous lactic acid bacteria in gluten-free sourdoughs produce nutritional and technological improvements in quinoa and buckwheat breads

Functional sourdough millet bread rich in dietary fibre -an optimization study using fuzzy logic analysis

Chestnuts are very perishable fruits, whose quality may be compromised during postharvest handling. Damage can be caused both by insects and fungi. Water curing, a commonly used postharvest method, is based on soaking fruits in water typically for about one week. Factors that affect effectiveness of water curing have only been explained partially. A decrease in pH, likely imputable to a light fermentation caused by lactic acid bacteria, may inhibit the growth of moulds. In this study a Lactobacillus pentosus strain was selected for its ability to inhibit fungi, and used as a starter culture during water curing. As second goal, a reduction of the environmental impact of the process was evaluated by using water that had been re-cycled from a previous curing treatment. Experiments were performed on pilot as well as on farm scale. In all trials, microbial dynamics were evaluated by means of a polyphasic approach including conventional and molecular-based analyses. According to results, the employment of an adjunct culture appears as a very promising opportunity. Even if no reduction in the duration of the process was achieved, waters exhibited a minor microbial complexity and fruits did not lose the natural lustre after the process. The second part of the project focused on the development of novel foods chestnut-based in order to seasonally adjust the offer and use the surplus of undersized production, providing, at the same time, a response to the growing demand for healthy and environmentally friendly products. Broken dried chestnuts were employed to prepare purees to be fermented with six different strains of Lactobacillus rhamnosus and Lactobacillus casei. The fermented purees were characterized by a technological and sensorial point of view, while the employed strains were tested for their probiotic potential. Conventional in vitro tests have indicated the six lactobacilli strains as promising probiotic candidates; moreover, being the strains able to grow and to survive in chestnut puree at a population level higher than 8 Log CFU mL-1 along 40 days of storage at 4°C, the bases for the production of a new food, lactose-free and with reduced fat content, have been laid. Subsequently, the effect of indigestible chestnut fiber and of chestnut extract on the viability of selected lactic acid bacteria strains was evaluated. Twelve strains were selected, on the basis of tolerance to low pH values and bile salts, and submitted to exposition to simulated gastric or bile juice in presence of chestnut extract with or without immobilization in chestnut fiber. The presence of chestnut extract proved to play a significant role on the gastric tolerance improvement of lactobacilli. The recorded protective effect could not be simply related to the starch or reducing sugars content. RP-HPLC demonstrated that in the chestnut flour, there are one or more hydrophobic peptides or oligopeptides, which specifically offer a marked resistance to simulated gastric juice, albeit present at low concentration. These beneficial effects proved to be dependent by the cultivar used to produce the flour. Moreover, were evaluated the suitability of chestnut extract as carrier for spray drying of two probiotic Lactobacillus rhamnosus strains and to develop a probiotic food chestnut based. The optimal settings for the spray-drying processes were defined and the loads of undamaged cells in the dried powders were quantified. Spray-dried cultures were incorporated into an anhydrous basis for chestnut mousse developed ad hoc. In this form, viable cells remained stable over 108 CFU g-1 during a 3 months long storage at 15°C. Sensorial analysis did not highlighted significant differences (p < 0.05) in preference between probiotic-supplemented and control mousses. Results suggest that chestnut mousse, a food product naturally rich in antioxidant compounds, may represent an excellent carrier for probiotics delivering. Finally, chestnut flour was even evaluated for the production of bakery goods gluten-free. Microbial dynamics in the chestnut-based sourdoughs were evaluated by PCR-DGGE. The impact of fermentation on volatile organic compounds formation during sourdoughs maturation was evaluated by means of gas chromatography coupled to mass spectrometry (GC/MS). Members of the Lactobacillus plantarum group and Pediococcus pentosaceous dominated the sourdough ecosystems. Nevertheless, RAPD-PCR allowed recording a relevant genotypic biodiversity among strains coming from gluten-free flour combinations. A total of 59 volatile compounds were identified, mainly alcohols, esters, acids, aldehydes and ketones. Principal component analysis of samples at the beginning and at the end of ripening offered a good separation of the samples and highlighted the effect of fermentation on the sensorial profile.