Browsing by Subject "fermentation"

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  • Parnanen, Pirjo; Nikula-Ijäs, Pirjo; Sorsa, Timo (2019)
    Fermented lingonberry juice was designed to be used as a mouthwash. Our aim was to study the antimicrobial and anti-inflammatory effects of the mouthwash in the oral cavity. A clinical study of 30 adult participants was performed. A total of 20 participants used 10 mL of the mouthwash twice daily for two weeks and 10 participants used 20 mL twice daily for one week. Streptococcus mutans, Candida and Lactobacilli were cultivated at the beginning, after the mouthwash period and after a washout period. At the same timepoints an additional oral mouthrinse was collected for chair-side/point-of-care (POC)-PerioSafe (R)/OraLyzer (R) aMMP-8 quantitative on-line evaluation, and an oral clinical investigation was performed. Mean Streptococcus mutans and Candida counts, visible plaque index (VPI) and bleeding on probing (BOP) were reduced, and Lactobacilli counts increased during the lingonberry mouthwash period. The aMMP-8 mouthrinses showed reduced values in both test groups when compared to the startpoint. The mouthrinse aMMP-8 reduction correlated with the reductions in microbial counts, VPI and BOP. Based on the results, fermented lingonberry juice seems a promising aid in oral homecare, diminishing the microbial and related proinflammatory burden by balancing the oral microbial flora and gradually lowering the inflammatory load in the oral cavity.
  • Verni, Michela; Vekka, Anna; Immonen, Mikko; Katina, Kati; Rizzello, Carlo Giuseppe; Coda, Rossana (2022)
    Aims The aim of this study was to investigate the effectiveness of bread as substrate for gamma-aminobutyric acid (GABA) biosynthesis, establishing a valorization strategy for surplus bread, repurposing it within the food chain. Methods and Results Surplus bread was fermented by lactic acid bacteria (LAB) to produce GABA. Pediococcus pentosaceus F01, Levilactobacillus brevis MRS4, Lactiplantibacillus plantarum H64 and C48 were selected among 33 LAB strains for the ability to synthesize GABA. Four fermentation experiments were set up using surplus bread as such, added of amylolytic and proteolytic enzymes, modifying the pH or mixed with wheat bran. Enzyme-treated slurries led to the release of glucose (up to 20 mg g(-1)) and free amino acid, whereas the addition of wheat bran (30% of bread weight) yielded the highest GABA content (circa 800 mg kg(-1) of dry weight) and was the most suitable substrate for LAB growth. The selected slurry was ultimately used as an ingredient in bread making causing an increase in free amino acids. Conclusions Besides the high GABA concentration (148 mg kg(-1) dough), the experimental bread developed in this study was characterized by good nutritional properties, highlighting the efficacy of tailored bioprocessing technologies as means to mitigate food wastage. Significance and Impact of Study Our results represent a proof of concept of effective strategies to repurpose food industry side streams.
  • Verni, Michela; Wang, Changyin; Montemurro, Marco; De Angelis, Maria; Katina, Kati; Rizzello, Carlo G.; Coda, Rossana (2017)
    This study investigated the metabolic traits of 27 lactic acid bacteria (LAB) strains belonging to different species, previously isolated from faba bean. The activities assayed, related to technological and nutritional improvement of fermented faba bean, included peptidases, beta-glucosidase, phytase, as well as exopolysaccharides synthesis and antimicrobial properties. In addition, the bacteria performance as starter cultures during faba bean fermentation on proteolysis, antioxidant potential, and degradation of condensed tannins were assessed. Fermentative profiling showed that only 7 out of 27 strains were able to metabolize D-raffinose, particularly Leuc. mesenteroides I01 and I57. All strains of Pediococcus pentosaceus exerted high PepN activity and exhibited beta-glucosidase activity higher than the median value of 0.015 U, while phytase activity was largely distributed among the different strains. All the weissellas, and in lower amount leuconostocs, showed ability to produce EPS from sucrose. None of the strains showed antimicrobial activity toward Staphylococcus aureus, while eight strains of P. pentosaceus exhibited a strong inhibitory activity toward Escherichia coli and Listeria monocytogenes. Generally, the doughs fermented with pediococci exhibited high amount of total free amino acids, antioxidant activity, and condensed tannins degradation. These results allowed the identification of LAB biotypes as potential starter cultures for faba bean bioprocessing, aiming at the enhancement of faba bean use in novel food applications.
  • Verni, Michela; Rizzello, Carlo Giuseppe; Coda, Rossana (2019)
    Cereals are one of the major food sources in human diet and a large quantity of by-products is generated throughout their processing chain. These by-products mostly consist of the germ and outer layers (bran), deriving from dry and wet milling of grains, brewers’ spent grain originating from brewing industry, or others originating during bread-making and starch production. Cereal industry by-products are rich in nutrients, but still they end up as feed, fuel, substrates for biorefinery, or waste. The above uses, however, only provide a partial recycle. Although cereal processing industry side streams can potentially provide essential compounds for the diet, their use in food production is limited by their challenging technological properties. For this reason, the development of innovative biotechnologies is essential to upgrade these by-products, potentially leading to the design of novel and commercially competitive functional foods. Fermentation has been proven as a very feasible option to enhance the technological, sensory, and especially nutritional and functional features of the cereal industry by-products. Through the increase of minerals, phenolics and vitamins bioavailability, proteins digestibility, and the degradation of antinutritional compounds as phytic acid, fermentation can lead to improved nutritional quality of the matrix. In some cases, more compelling benefits have been discovered, such as the synthesis of bioactive compounds acting as antimicrobial, antitumoral, antioxidant agents. When used for baked-goods manufacturing, fermented cereal by-products have enhanced their nutritional profile. The key factor of a successful use of cereal by-products in food applications is the use of a proper bioprocessing technology, including fermentation with selected starters. In the journey toward a more efficient food chain, biotechnological approaches for the valorization of agricultural side streams can be considered a very valuable help.
  • Zhang, Yuetuan (Helsingin yliopisto, 2015)
    The literature review described the importance of folate enhancement to human health especially to coeliac patients with an introduction to folate analysis, pseudocereals and possible fortification methods. The aim of this study was to study the natural folate enhancement methods in pseudocereal matrix. Pseudocereal materials consisted of buckwheat, amaranth and quinoa, each of which was subjected to three different treatments: germination, fermentation and combined treatment. Total folate determination was based on an official microbiological assay method (Lactobacillus rhamnosus ATCC 7469). Germination of pseudocereals lasted for 4–5 days. Fermentation was conducted using either baking yeast Saccharomyces cerevisiae ALKO743 or LAB Streptococcus thermophilus ABM5097. All germinated whole grain pseudocereals indeed showed a significant increase in total folate content. Specifically, the increase was 5.4-fold in buckwheat, 5-fold in amaranth and 2.6-fold in quinoa. Fermentation of native pseudocereals also enhanced total folate level. As for the combined treatment, the total folate level of germinated seeds did not further significantly increase or decrease in later fermentation period. Although more studies are needed for processing real pseudocereal foods, our study showed great potential of folate enhancement using germination or fermentation.
  • Basnet, Subash (Helsingfors universitet, 2017)
    The literature review of this thesis was focused on the pathway of folate biosynthesis with enzymes involved in it and factors effecting the synthesis of folate by bacteria. The literature was also partly focused on the introduction to propionic acid bacteria (PAB) and the folate production by these bacteria. The aim of the experimental part of the thesis was to screen the folate productivity of selected PAB strains isolated from various dairy and cereal sources after 96-hours anaerobic fermentation and also to see the effect of precursor (para-aminobenzoic acid) of folate biosynthesis on folate production by the strains. Then to further investigate the folate production of some promising PAB strains from screening part either with glucose or lactate as carbon source at four growth phases in aerobic fermentation. The propionic agar medium was used with either glucose or lactate as carbon source in the medium. Optical densities, pH, cell masses were measured after fermentation and folate produced by the strains was determined from biomass and supernatant of the samples using microbiological assay. Carbon consumption and metabolic end-products were analysed with HPLC after fermentation. Some of the screened PAB strains were promising folate producers. Strain 257 produced folate up to 124 µg/l which is even higher than production by some good Lactic acid bacteria (LAB). PAB strains produced intracellular folate upto 28954 ng/g cell biomass and excreted folate into medium upto 107 ng/ml. Strains grew faster with lactate than glucose but cell masses were higher with glucose than lactate even in the low pH. PAB strains showed the highest folate productivity in anaerobic fermentation with lactate as carbon source and aerobic fermentation with lactate as source was observed to be the best for high organic acid production. However, further studies are needed to optimise the cultivation condition of selected PAB strains for their best folate production in different matrices.
  • Mäkelä, Noora (Helsingfors universitet, 2012)
    Folate is a water-soluble vitamin that belongs to the vitamin B group. The most important function of folate is to participate in C1 metabolism, and folate deficiency can lead to megaloblastic anaemia, neural-tube defects or coronary diseases. In Finland the folate fortification of food products is not mandatory and the intake of folate is still too low. Based on previous studies, blue lupin (Lupinus angustifolius) seems to be a good source of folate, especially the Haags Blaue variety, which has shown to be suitable for cultivation under Finnish environmental conditions. The aim of this research was to study if the folate concentration of blue lupin could be increased with germination and fermentation. In addition, the purpose was to examine how these bioprocessing methods would affect vitamer distribution of folates. Three germination experiments were performed, two with seeds that were soaked overnight in water and one with seeds that were soaked in lactic acid solution. The duration was four or five days and the samples were collected daily. The fermentation experiment was performed with kernel flour from non-germinated seeds and kernel flour from seeds that were germinated for two days. The synthesis of folate was studied using two microbes: Streptococcus thermophilus and Saccharomyces cerevisiae. The fermentation with S. cerevisiae yeast was made both with and without glucose addition. Samples were taken at 0 and 24 h. Total folate concentrations of samples were analysed with a microbiological method and the vitamers were analysed with an ultra-high-performance liquid chromatography method (UPLC). The folate concentration of seeds increased 2-fold by germination. The proportion of 5-methyltetrahydrofolate increased significantly during germination, from 60 % in nongerminated kernel flour to 77–88 % in germinated dehulled seeds. S. thermophilus did not produce folates in lupin flours. The folate content of non-germinated flour was increased 1.8-fold by yeast fermentation between 0 and 24 h, and yeast needed the glucose addition. However, glucose addition did not have an impact on folate concentrations of kernel flour from germinated seeds. Germination significantly increased the folate content of lupin seeds, and the greatest proportion of folates were stable vitamers. Stability of vitamers is important for the folates of food products thus germination of lupin seeds appears to be an interesting processing method. On the basis of the fermentation experiment, S. cerevisiae is a promising folate producing microbe when using lupin flour as a matrix. The fermentation experiment should still be repeated and performed using sterilised flour so that the actual production of folate by S. cerevisiae could be studied.
  • Sorvali, Päivi (Helsingin yliopisto, 2019)
    Partial replacement of wheat flour with faba bean flour enhances the nutritional quality of wheat bread, but simultaneously weakens the gluten network, decreases the bread volume and increases bread hardness. The flour can be fermented with lactic acid bacteria, capable of producing exopolysaccharides (EPS), to improve the technological properties for baking. The aim of the research was to produce a bread rich in protein by replacing 30 % of the wheat flour with faba bean flour, which was fermented by EPS-producing Weissella confusa or Leuconostoc pseudomesenteroides -lactic acid bacteria to improve the baking quality. The effect of native and fermented faba bean flour to the properties of dough and bread was studied. Water absorption and rheology of the dough was analyzed with farinograph and Kieffer test of Texture Analyser. The volume of the breads was measured by rapeseed replacement method, and the texture of the breads by using TPA-test of Texture Analyser. The protein content of the total energy value of the bread was determined by calculations. As expected, native faba bean flour decreased the stability and elasticity of the dough compared to the 100 % wheat dough. The volume of wheat - faba bean bread decreased 11 % and the crumb texture was 38 % harder compared to the wheat bread. Fermentation of faba bean flour increased the water absorption and decreased the extensibility of the dough compared to the dough with native faba bean. Fermentation with W. confusa increased the bread volume by 21 % and decreased the bread hardness by 12 % compared to the breads with native faba bean. The volume of the breads with W. confusa-fermented faba bean was increased by 8 % even compared to the 100 % wheat bread. Yet the breads fermented with L. pseudomesenteroides had considerably decreased volume (-15 %) and increased hardness (+116 %) compared to the breads with native faba bean. The difference was hypothesized being caused by more intense acidification and possibly the different structure and amount of EPS. In this study 30 % of wheat flour was successfully replaced with faba bean, resulting a bread rich in protein and with a texture similar to 100 % wheat bread, as the faba bean flour was fermented with EPS-producing W. confusa -lactic acid bacteria. New methods for analyzing the rheology of EPS-containing dough would be beneficial for estimating the baking quality.
  • Coda, Rossana; Varis, Jutta; Verni, Michela; Rizzello, Carlo G.; Katina, Kati (2017)
    The effects of the substitution of wheat flour with faba bean flour and faba bean sourdough on the properties of composite bread were investigated. Bread was prepared by replacing wheat flour with 30% of faba bean flour, native or after sourdough fermentation. The addition of faba bean flour influenced the structure of the breads, causing a slight decrease of volume and higher hardness compared to wheat bread. However, when fermented faba bean flour was added, the crumb porosity of the bread was not affected. The addition of 30% of faba bean flour increased wheat bread protein content from 11.6 up to 16.5% of dry matter. The addition of native faba bean flour did not affect the in vitro protein digestibility, resulting similar to wheat bread (64%). On the contrary, faba bean sourdough bread showed higher protein digestibility (73%). Generally, the addition of native faba bean flour caused an improvement of the nutritional indexes of the composite bread, further enhanced when fermentation was carried out. The free amino acid profile, protein chemical score, and biological value index were the highest in faba bean sourdough bread. In addition, the predicted glycemic index was the lowest in faba bean sourdough bread. (C) 2017 Elsevier Ltd. All rights reserved.
  • Chamlagain, Bhawani; Sugito, Tessa Ayuningtyas; Deptula, Paulina; Edelmann, Minnamari; Kariluoto, Susanna; Varmanen, Pekka; Piironen, Vieno (2018)
    The in situ production of active vitamin B12 was investigated in aqueous cereal-based matrices with three strains of food-grade Propionibacterium freudenreichii. Matrices prepared from malted barley flour (33% w/v; BM), barley flour (6%; BF), and wheat aleurone (15%; AM) were fermented. The effect of cobalt and the lower ligand 5,6-dimethylbenzimidazole (DMBI) or its natural precursors (riboflavin and nicotinamide) on active B12 production was evaluated. Active B12 production was confirmed by UHPLC-UV-MS analysis. A B12 content of 12-37 mu was produced in BM; this content increased 10-fold with cobalt and reached 940-1,480 mu with both cobalt and DMBI. With riboflavin and nicotinamide, B12 production in cobalt-supplemented BM increased to 712 mu Approximately, 10 mu was achieved in BF and AM and was increased to 80 mu in BF and 260 mu in AM with cobalt and DMBI. The UHPLC and microbiological assay (MBA) results agreed when both cobalt and DMBI or riboflavin and nicotinamide were supplemented. However, MBA gave ca. 20%-40% higher results in BM and AM supplemented with cobalt, indicating the presence of human inactive analogues, such as pseudovitamin B12. This study demonstrates that cereal products can be naturally fortified with active B12 to a nutritionally relevant level by fermenting with P. freudenreichii.
  • Alakotila, Anni (Helsingin yliopisto, 2019)
    The literature section of this Master's Thesis focuses on cheese making process from milk composition to cheese ripening. In addition, the thesis investigates the effect of lactose standardization on lactic acid fermentation, sensory characteristics of the cheese and what biochemical changes the standardization causes during cheese ripening. The aim of the experimental part was to investigate the effect of standardization of the lactose content of cheese milk and how it will affect the ripening and final quality of Swiss -type cheeses. The effect of lactose content of the cheese milk, protein fraction used, pre-ripening time and ripening temperature was studied using statistical design of experiments (DOE). 16 test batches were manufactured according to factorial screening design. Water, cream and protein fraction were used to standardize the lactose content of the cheese milk. In addition, two center point experiments were performed with third protein fraction. The fat and protein content, dry matter, moisture of non-fat substance, fat in dry mater, lactose, lactic acid, acetic acid, propionic acid, butyric acid and the level of volatile organic acids and titrated free amino acids of cheese were analyzed during manufacturing and ripening. The lactose and lactic acid content of the cheese milk can be lowered by standardization of the lactose concentration. If set too low however, it is no longer beneficial for the lactic and propionic acid fermentation processes or to the quality of the cheese, as flaws in the fermentation process will start to occur. With lower levels of lactose content, less lactic acid and more propionic acid will form in the cheese. Pre-ripening creates beneficial environment for propionic acids and that can prevent cracking of the cheese. Cheese that has been ripened for too long in temperatures too high will have flaws in the fermentation process. Moreover, the statistical centre point tests show that the standardization of the protein level in the cheese milk is best to be done by using protein fraction U. Fraction U gave best results on average in the sensory evaluation.
  • Marin, Daniel (Helsingfors universitet, 2006)
    Sekä bakteriosiinit että niitä tuottavat bakteerit pystyvät tietyissä olosuhteissa estämään tautia aiheuttavien bakteerien kasvua, joten niiden käytön ansiosta tuotteen turvallisuus ja säilyvyys paranee. Jos em. bakteriosiinit yhdistetään kemiallisiin aineisiin, joilla on myös kyky parantaa säilyvyyttä, ne voivat yhdessä toimia synergistisesti ja rajoittaa esimerkiksi Listeria sp., Clostridium sp., koliformien ja enterokokkien kasvua. Myös fysikaaliset menetelmät, kuten kevyt lämpö tai sous-vide-valmistustapa parantavat bakteriosiinien hyödyllisiä vaikutuksia. Yhdistettäessä bakteriosiinit kelatoreihin, on todettu, että ne ovat hyödyllisiä jopa ihmisen mahahaavan sekä lehmän utaretulehduksen hoidossa. Yleensä bakteriosiinit lisätään tuotteisiin joko puhdistettuina ja kuivina tai bakteriosiinia tuottavan kannan muodossa. Kuitenkaan "in vivo" tulokset eivät aina täsmää "in vitro" saatujen tulosten kanssa, koska bakteriosiinia tuottavat bakteerit ovat inaktivoituneet tai inhiboitu tai niiden kyky muodostaa bakteriosiineja on heikentynyt kasvuympäristön epäsuotuisien olosuhteiden johdosta. Edellä mainittujen seikkojen lisäksi joitakin bakteriosiineja saatetaan käyttää liian pieninä annoksina, koska ne muuttavat kasvualustan aistinvaraisia ominaisuuksia. Luonteeltaan bakteriosiinit ovat valkuaisaineita tai peptidejä ja siksi herkkiä proteolyyttisten entsyymien vaikutuksille sekä hapettumiselle, joten lihassa niiden jakautuminen ja liukoisuus on joskus heikkoa. Lisäksi joillakin tautia-aiheuttavista bakteereista, kuten Listerialla, on vaihteleva herkkyys bakteriosiineihin ja teollisuusympäristössä ne muodostavat joskus resistenttejä mutantteja. Joskus bakteriosiinien inaktivoituminen johtuu niiden sitoutumisesta kasvualustan elementteihin. Tästä seuraa, että ennen bakteriosiinien lisäämistä tuotteeseen, sen rakenteen, pH:n, veden aktiivisuuden sekä suolan määrää on syytä arvioida. Jotta elintarvikkeiden aistinvaraiset ominaisuudet eivät muuttuisi tai bakteriosiinit eivät menettäisi suojaavaa kykyään (elintarvikkeen rakenteellisten elementtien kanssa reagoimisen seurauksena), niitä käytetään joskus suojaavaan kalvoon yhdistettyinä. Tällä tavalla bakteriosiinit pystyvät vaikuttamaan paikallisesti ilman, että elintarvikkeen rakenteelliset elementit pystyisivät inaktivoimaan ne. Tämän seurauksena bakteriosiinien ja maitohappobakteerien hyödylliset tai haitalliset vaikutukset ruoissa ovat jollakin tavalla riippuvaisia elintarvikkeen tyypistä, säilytysajasta ja ehkä myös kuluttajan odotuksista. Bakteriosiinit tehoavat pääasiallisesti gram-positiivisia bakteereita vastaan, kun taas gram-negatiivisten bakteereiden herkkyys bakteriosiinin vaikutuksiin riippuu tekijöistä, jotka heikentävät niiden ulkoista kalvoa. Täten yhdistämällä bakteriosiinejä ja erilaisia "hurdle"-menetelmiä, kuten uudenaikaisia pakkaustekniikoita, hyviin hygieenisiin menettelytapoihin, on mahdollista lisätä lihan ja lihanvalmisteiden säilyvyyttä sekä turvallisuutta. Kun otetaan huomioon, että jälkipastörointi voi aiheuttaa Clostridium sp. ja Bacillus sp. lisääntymisen ruokapakkauksissa ja että pilaajabakteerit voivat myös helposti pilata käsitellyt elintarvikkeet, on äärimmäisen tärkeää, että uusia menetelmiä edellä mainittujen ongelmien ratkaisemiseksi löydetään. Lisäksi on huomioitava sekä lakisääteiset että taloudelliset asiat. Geneettisesti muunnellut mikrobit tarjoavat uusia mahdollisuuksia. Geneettisesti muunnelluilla suojakannoilla sekä niiden tuottamilla bakteriosiineillä saattaa olla vielä paremmat mahdollisuudet pidentää elintarvikkeiden säilytysaikoja sekä parantaa niiden turvallisuutta.
  • Nihtilä, Hanna (Helsingin yliopisto, 2019)
    Brewers’ spent grains (BSG) are by-products of the brewing industry. Utilization of BSG in food applications is challenging, due to its poor technological characteristics. Because of their water retaining properties, interactions with matrix components and impact on texture formation, bacterial exopolysaccharides (EPS) represent a promising tool for improvement of BSG properties. Among bacterial exopolysaccharides, dextran produced in situ by lactic acid bacteria (LAB) during fermentation has shown major improvements in technological and sensorial features of products prepared from various types of plant materials. The nutritious composition of BSG may support the growth of LAB and enable in situ dextran production. The aim of this study was to establish and examine the synthesis of dextran by LAB in BSG. Sixteen dextran producing LAB strains were screened for viscosity formation in BSG fermentation. The strains showing the highest viscosity formation were further assessed for fermentation performance. The more suitable fermentation temperature was traced by comparing the viscosifying performance of selected starters at 20 and 25 °C. Dextran amount was determined semi-quantitatively from selected fermented samples showing optimal results, and the presence of oligosaccharides was assessed. Sucrose, glucose, maltose and fructose amounts were analyzed to observe the relation between sugar consumption and dextran and oligosaccharides formation. Weissella confusa strains A16 and 2LABPTO5 and Leuconostoc pseudomesenteroides strain DSM20193 appeared the most promising starters for viscosity formation and thus dextran synthesis in this matrix. From the examined fermentation temperatures, strains showed the highest potential for dextran synthesis at 25 °C. The amount of synthesized dextran ranged from 1.1 to 1.7 % w/w (of the wet weight of the whole sample matrix). The rheological properties of BSG were modified via LAB fermentation and dextran synthesis, resulting in more viscous texture, and its applicability in food systems was thus potentially enhanced.
  • Kianjam, Maryam (Helsingfors universitet, 2016)
    The literature review deals with faba bean and the important effects of lactic acid bacteria (LAB) fermentation on legumes. Particularly, the information about sourdough and LAB microbiota together with the main factors affecting sourdough microbial community is presented. A brief introduction regarding the methods used for LAB identification is also given. The main aim of the experimental study was to identify LAB microbiota in faba bean sourdoughs of two different varieties during backslopping procedure. Doughs from Italian (I) and Finnish (F) faba bean flours were spontaneously fermented and propagated daily through backslopping on a laboratory scale for 14 days. Samples were taken from selected propagation times (0, 1, 2, 5, 7, and 14) for microbiological and biochemical analyses. The pH values and total titratable acidity (TTA) were monitored throughout the process. Analyses of organic acids and oligosaccharides of selected samples were carried out with HPLC methods at University of Bari, Italy. The identity of the LAB isolates was revealed by sequence analysis of 16S rDNA and the differentiation of LAB strains was analyzed by randomly amplified polymorphic DNA (RAPD)-PCR. Minor changes occurred between I and F sourdoughs based on microbiological and biochemical analyses. However, several differences were found in LAB diversity between these two sourdoughs. More variety of LAB species and higher strains diversity were found in F faba bean sourdough. Besides Pediococcus pentosaceus, Leuconostoc mesenteroides, and Weissella koreensis identified in both sourdoughs, Enterococcus casseliflavus, Enterococcus faecium, Lactobacillus sakei, Lactococcus lactis, and Weissella cibaria were only detected in F sourdough. In both sourdoughs, Pediococcus pentosaceus was predominant and persistent. Also, Leuconostoc mesenteroides was found as second frequent species in both sourdoughs. According to all analyses, the maturity of sourdoughs was achieved during 5 days of propagation. This study demonstrated the importance of flour type and composition on establishing microbial ecology of sourdough. The research study encourages exploring the potential of faba bean flour in sourdough-type fermentation and encourages further investigations on the identified isolates as starter cultures for fermented faba beans and faba bean-cereal products.
  • Tamene, Aynadis; Baye, Kaleab; Kariluoto, Susanna; Edelmann, Minnamari; Bationo, Fabrice; Leconte, Nicolas; Humblot, Christele (2019)
    Folate deficiencies are widespread around the world. Promoting consumption of folate-rich foods could be a sustainable option to alleviate this problem. However, these foods are not always available. Cereals, being a staple food, could contribute to folate intake. They are fermented prior to consumption in many African countries, and fermentation can modify the folate content. In Ethiopia, injera is a widely consumed fermented flat bread. The main drivers of its fermentation are lactic acid bacteria (LAB). The aim of this work was to isolate and identify folate-producing LAB from injera fermented dough and to evaluate their ability to increase folate status after depletion in a rat model. Among the 162 strains isolated from 60 different fermentations, 19 were able to grow on a folate-free culture medium and produced 1 to 43 mu g/L (24 h, 30 degrees C incubation). The four highest folate producers belonged to the Lactobacillus plantarum species. The most productive strain was able to enhance folate status after depletion in a rat model, despite the relatively low folate content of the feed supplemented with the strain. Folate-producing L. plantarum strain has potential use as a commercial starter in injera production.
  • Pirttiniemi, Juho (Helsingin yliopisto, 2020)
    The objective was to evaluate how different silage additives can manipulate the ensiling process and the profile of bacterial communities of grass silages under varying management conditions. Silages were made from mixed timothy (Phleum pratense) and meadow fescue (Festuca pratensis) grass to laboratory scale silos using two compaction levels. The tightly compacted grass was also contaminated with soil and dairy cow faeces. Four additive treatments were used including control without additive (CONT), formic acid based additive (FA), homofermentative strains of lactic acid bacteria (LAB) and salt based additive (SALT). Tight compaction resulted on average in lower pH and ethanol concentration in silages than loose compaction mostly caused by changes in CONT silages. Soil contamination clearly affected CONT and SALT silages by stimulating extensive fermentation and thus decreasing pH and amount of residual water-soluble carbohydrates (WSC) compared to non-contaminated silages. In all conditions, FA restricted fermentation resulting in silages with high WSC and reduced total fermentation products concentration. Soil contamination improved aerobic stability of silages compared to non-contaminated ones because of higher acetic acid concentration in contaminated silages. Abundance of selected 16 bacteria in raw material was low, with Sphingomonas and Stenotrophomonas genera being the most abundant. After fermentation both Lactobacillaceae family and as part of it Lactobacillus genus were dominant with Sphingomonas genus in most of the silages. FA decreased the abundance of Lactobacillaceae family whereas LAB increased it. Soil contamination reduced the amount of other Lactobacillaceae family but boosted the growth of Lactobacillus genus. Lactobacillus presented negative correlations with Mycoplana, Devosia and Sphingomonas. Five bacteria were connected to desirable fermentation pattern and they all were part of same phylum Firmicute. All other selected bacteria had negative correlation with low pH and amount of lactic and total fermentation acids in silage. Use of additives improved fermentation quality of silages ensiled under different management conditions. Different types of additives resulted in varied bacterial profiles. Results confirmed the importance of tight compaction and good hygiene for stable fermentation. Strong correlations between bacterial communities and fermentation quality parameters provided clear insight of the role of the most abundant populations on the fermentation process of grass silage.
  • Montemurro, Marco; Coda, Rossana; Rizzello, Carlo Giuseppe (2019)
    The growing consumers' request for foods with well-balanced nutritional profile and functional properties promotes research on innovation in pasta making. As a staple food and a common component of diet, pasta can be considered as a vector of dietary fiber, vegetable proteins, vitamins, minerals, and functional compounds. The conventional process for pasta production does not include a fermentation step. However, novel recipes including sourdough-fermented ingredients have been recently proposed, aiming at enhancing the nutritional and functional properties of this product and at enriching commercial offerings with products with new sensorial profiles. The use of sourdough for pasta fortification has been investigated under several aspects, including fortification in vitamin B, the reduction of starch digestibility, and gluten content. Sourdough fermentation has also been successfully applied to non-conventional flours, (e.g., from pseudocereals and legumes), in which an overall increase of the nutritional value and health-promoting compounds, such as a significant decrease of antinutritional factors, were observed. Fermented non-conventional flours, obtained through spontaneous fermentation or using selected starters, have been proposed as pasta ingredients. As the result of wheat replacement, modification in textural properties of pasta may occur. Nonetheless, fermentation represents an efficient tool in improving, besides nutritional and functional profile, the sensory and technological features of fortified pasta.
  • Koskela, Salla (Helsingfors universitet, 2016)
    Fungal ferulic acid esterases (FAEs) are important accessory enzymes that participate in degradation of plant cell wall hemicellulose in grasses, including cereals and many energy crops. They could be used to convert agricultural wastes into a variety of value-added products such as biofuel, feed and paper. In non-aqueous media, they have been shown to act as catalysts for enantioselective reactions. Putative faes are widespread in genomes of plant pathogenic and saprotrophic fungi. However, only few FAEs have been characterized in detail. Additionally, despite of their diverse biotechnological potential, fungal FAEs have not been produced recombinantly on a bioreactor scale, which is a necessary step for their commercial applications. The aim of the present study was recombinant production on a bioreactor scale and biochemical characterization of a putative FAE from Aspergillus terreus. The enzyme demonstrated a broad substrate profile and an excellent storage stability. Its catalytic activity was highest against methyl 3,4-dimethoxycinnamate, but the enzyme was also active against methyl ferulate. It preferred methoxy groups to hydroxyl groups on the substrate’s phenyl ring, while shortening of the aliphatic side chain diminished the activity. The enzyme was observed to be fully stable at 37 °C for 1 h, and it demonstrated thermal activation at the same temperature. At 45 ˚C, it retained 75 % of its initial activity for 1 h. McIlvaine’s buffer was observed to increase the activity by 85 % compared to the standardly used MOPS buffer. The results of this study have contributed to the biochemical knowledge of fungal FAEs and elucidated their substrate preferences.
  • Seppänen, Siri (Helsingin yliopisto, 2021)
    Legume consumption and cultivation is recommended due to several health and environmental benefits. However, legumes naturally lack vitamin B12 and contain non-digestible, fermentable raffinose family oligosaccharides (RFOs) which are found to cause abdominal symptoms. Propionibacterium freudenreichii was earlier found to produce significant B12 contents into plant-based matrices by fermentation. Moreover, many of lactic acid bacteria used in food fermentation are found to produce the enzyme α-galactosidase which degrades the RFO compounds. This study aimed investigating the use of fermentation for a simultaneous B12 production and RFO reduction. The study examined direct fermentation with P. freudenreichii and co-fermentation with starters. In relation to B12, the study examined if B12 content and RFO reduction positively correlated after the fermentation process. The state of RFO breakdown was explored by detecting the RFO levels with high performance anion exchange chromatography combined with a pulse amperometric detector (HPAEC-PAD) after every 24 h during the 72 h of fermentation. Several fermentation schemes showed either efficient or complete RFO degradation and produced active B12 at significant level with some minor differences between them. Generally, direct fermentation led to superior RFO reduction compared to co-fermentation in the studied matrices. The study concluded the inversely proportional relation between RFO reduction and B12 formation when co-fermented with a commercial starter.