Sirvi Autor "Andreson, Helena" järgi
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Kirje Effect of simultaneous inoculation of commercial yeast starter cultures on Kombucha fermentation(2020) Abel, Maarja; Andreson, Helena; Estonian University of Life Sciences. Institute of Veterinary Medicine and Animal Sciences. Chair of Food Science and TechnologyKombucha – a spontaneously fermented tea beverage, produced by SCOBY (a symbiont of bacteria and yeasts), has become popular in recent years. Its functional properties and features for industrial production and treatment remain largely unknown, however. Our aim of using additional yeast cultures during the primary fermentation was to modify and ultimately improve the sensory properties of the kombucha beverage. During five fermentation experiments the total viable count (TVC) of microbes was determined both in Kombucha and SCOBY samples. The first four fermentation experiments were conducted to stabilize the growth of SCOBYs that were initially of different origin. The last (5th) fermentation contained the simultaneous inoculation of three different active S. cerevisiae cultures into the sweetened black tea together with the SCOBY and was followed by a sensory analysis. Two samples remained as control samples without additional yeast starter culture. The yeast starter cultures affected the microbial counts of Kombucha, but the effect on the microbial count of SCOBY was not statistically significant (p >0.05). The Kombucha containing wine yeast culture had the lowest sensory quality, while Kombucha containing brewer's yeast had the most pleasant flavour and aroma. In conclusion, the simultaneous fermentation with commercial yeast cultures had a minor effect on the microbial counts in SCOBY when compared to the fermentation time, but all added cultures clearly modified the taste and aroma properties of the Kombucha drinks.Kirje Exopolysaccharides production by Lactiplantibacillus plantarum strains isolated from industrial rye bread sourdoughs : [presentation](Estonian University of Life Sciences, 2026) Lutter, Liis; Pikkel, Naatan; Ben Othman, Sana; Andreson, HelenaExopolysaccharides (EPS) are high-molecular-weight polysaccharides synthesized by microorganisms, including lactic acid bacteria (LAB), and are recognized for their impact on both technological and functional attributes of fermented foods. EPS contribute to improved texture, viscosity, water retention, and emulsion stability, while reducing syneresis, and may also exert bioactive effects such as antioxidant, immunomodulatory, anti-cancer, and modulatory activities on gastrointestinal and lipid metabolism. Within LAB, Lactiplantibacillus plantarum is of particular interest owing to its ability to produce EPS with both technological and functional significance. In sourdoughs, preserving microbial diversity in traditional starters is crucial, as these ecosystems harbor unique LAB strains with functional traits that are increasingly lost to uniform commercial cultures. The aim of this study was to characterize the EPS-producing capacity of L. plantarum strains isolated from decades-old, continuously propagated rye sourdoughs and to compare them with a commercial reference strain, thereby assessing their potential as technologically and functionally valuable starter culture candidates. A total of ten strains from an Estonian industrial sourdough, along with one commercial strain, L. plantarum TAK59 (Nordwise Biotech OÜ, Estonia), were included. EPS production by the strains was evaluated after cultivation in MRS broth with 2% sucrose, followed by isolation and quantification using gravimetric and phenol–sulfuric acid assays. The EPS produced exhibited glucose-equivalent sugar contents ranging from 278.3 to 362.8 µg/mg and yields of 131.4–225.2 mg/L. The highest sugar content was observed in L. plantarum strain A44, whereas the greatest EPS yield was recorded for strain A37. The commercial strain TAK59 yielded the lowest EPS dry mass and productivity. No statistically significant differences were detected in sugar content or yield among individual strains or between genotypes (p > 0.05). Notably, differences were observed in the dry mass of lyophilized EPS. L. plantarum isolates A52 and A45, belonging to genotype G5, displayed significantly lower dry mass compared to other genotypes (p < 0.05), except for G6 (L. plantarum isolates A51 and A44), for which differences were not statistically significant. Similarly, no linear correlation was observed between sugar content and dry matter (R²=0.0177), suggesting that these two quantification methods are not directly comparable and likely capture different characteristics of the EPSs, such as purity, composition, or structural variability of the polysaccharides. In conclusion, all L. plantarum strains assessed in this study demonstrated substantial EPS-producing capacity. The results contribute to valorizing sourdough biodiversity and support the development of tailored starter cultures for enhancing bread quality and functional potential. The long-term propagation of these sourdoughs has likely driven strain-specific adaptations, making them valuable sources of technologically and functionally distinct EPS producers compared to commercial starters. Future research should focus on optimizing cultivation conditions (medium composition, pH, temperature, incubation time, nutrient availability) to maximize EPS yield and enable targeted applications in improving the texture, stability, and functionality of fermented foods.Kirje The impact of lactic acid bacteria and yeasts ratio on fermentation and taste of kvass(Estonian University of Life Sciences, 2024) Pisponen, Anna; Andreson, Helena; Estonian University of Life Sciences. Institute of Veterinary Medicine and Animal Sciences. Chair of Food Science and TechnologyKvass, a non-alcoholic beverage derived from rye malt or special rye bread through natural fermentation, traditionally involves yeast in the production process. However, the introduction of various lactic acid bacteria (LAB) accelerates fermentation and imparts a distinctive taste and aroma to the kvass. This research aimed to optimize the ratios of LAB to baker’s yeast in kvass to enhance its fermentation, sensory qualities, and physicochemical properties, thereby improving its acidic flavour and overall acceptability. Baker's yeast and three commercial LAB strains were used for fermenting the kvass wort made of dried rye bread. The experimental design focused on four distinct inoculation ratios: 100% LAB, 50% LAB:50% yeast, 80% LAB:20% yeast, and 100% yeast. Key parameters such as pH, dry matter content, and titratable acidity were monitored over 12, 14, and 16 hours of fermentation, with a detailed sensory analysis conducted on the 80:20 LAB to yeast ratio kvass samples that were fermented for 14 hours and then cooled. It was found that varying the ratios of LAB and yeast significantly affected the fermentation process. Extended fermentation times, particularly with higher LAB ratios, led to more pronounced acidity and sensory characteristics. Optimal microbial balances, notably the 80% LAB to 20% yeast ratio, enhanced kvass's flavour profile and physicochemical properties, suggesting a tailored approach to fermentation can improve kvass's quality and consumer acceptance. These variations, alongside significant strain- and species-related differences, highlight the importance of microbial balance in enhancing kvass's acidic flavour and overall acceptability.Kirje Toiduainete tehnoloogia(Audiomeister, 2017) Poikalainen, Väino; Laikoja, Katrin; Traksmaa, Anna; Laos, Katrin; Lepasalu, Lembit; Soidla, Riina; Andreson, Helena; Veri, Kristiina; Mahla, Tauno; Tatar, Vilma; Tatar, Vilma (koostaja); Tatar, Vilma (koostaja)Toiduainetööstus annab suure osa Eesti rahvuslikust koguproduktist ja on toidu tooteahelas (toore-töötlemine-turustus) kõige olulisemaks lisandväärtuse loojaks. Sellele vaatamata puudub senini eestikeelne toiduainete tehnoloogia kõrgkooliõpik, mis sisaldaks süsteemselt esitatud baasteadmisi: • loomse- ja taimse toorme omadustest, koostisest jms, • toidutoorme töötlemise füüsikalis-keemilistest ja bioloogilistest põhiprotsessidest, • olulisemate toiduainete tehnoloogiatest. Eestikeelne toiduainete tehnoloogia õppekirjandus on senini lünklik, käsitleb eraldi kitsaid teemasid ega moodusta ühtset tervikut. See asjaolu raskendab üliõpilaste õppetööd, spetsialistide täiendkoolitust ja üldiste töötlemispõhimõtete tutvustamist ka laiemalt toidu tooteahelas. Koostatud õpik on mõeldud eelkõige toiduainete tehnoloogia alaste baasteadmiste omandamiseks bakalaureuseõppes ja edaspidi jääb aluseks praktiliste õppevormide (labortööd, praktikumid) ning erinevate e-õppe materjalide, õppevideote jms süsteemsel väljatöötamisel. Õpiku olemasolu võimaldab suurendada toiduainete tehnoloogia bakalaureuseõppe üliõpilaste iseseisva töö mahtu ja muuta kogu õppeprotsessi efektiivsemaks. Selleks, et toiduainete valmistamine toimuks efektiivselt, on vajalik tunda nii toidutoorme koostist ja omadusi kui võimalikke töötlemise meetodeid ja tehnilisi lahendusi. Koostatav õpik on vajalik infoallikas ka toiduainete tööstustele, kuna toiduainete töötlemine (tehnoloogia) on suhteliselt keeruline, mitmekülgseid baasteadmisi eeldav valdkond. Peale selle soodustab õpik ühtse eestikeelse erialaterminoloogia juurdumist ning on kasulik infoallikas vastavatele hobirühmadele ja toiduainete tarbijatele kui toidu tooteahela sihtgrupile.Kirje Volatile organic compounds and their generation in sourdough(Estonian University of Life Sciences, 2023) Lutter, Liis; Jõudu, Ivi; Andreson, Helena; Estonian University of Life Sciences. Institute of Veterinary Medicine and Animal Sciences. Chair of Food Science and TechnologySourdough technology is involved in bread making process for improving the sensory, rheological, nutritional and shelf life characteristics of bakery products. More than 540 volatile organic compounds (VOCs) and other flavour precursors belonging to the chemical classes, such as aldehydes, ketones, esters, acids, alcohols, terpenes and others, have been identified in sourdoughs and sourdough breads. The synthesis of VOCs is microbial species-specific, originating mainly from fermentation process. VOCs can be used as indicators to characterize microbial processes. Other additional sources of VOCs in sourdoughs are lipid oxidation and browning reactions, the latter of which occurs during the production of dried starter cultures. The purpose of this article is to provide an overview of the composition of VOCs and their effect on the sensory properties of sourdough bread, and to describe the most common extraction methods of VOCs used in the studies of sourdough and bread aroma profile. Long-term propagated sourdough VOCs have been less studied compared to volatiles found in bread crust and crumb or sourdoughs started with defined starter culture(s) due to their complexity and diversity in metabolic pathways, including sophistication of the analytical methodology of VOCs. The relation between sourdough microbiota and its volatile profile is not fully understood and therefore, their variability and precise role as a bread flavour enhancer is not yet known in detail.