Fermenteeritud kaerajoogi väljatöötamine keefiri starterkultuuri abil
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Kuupäev
2025
Kättesaadav alates
04.09.2025
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Eesti Maaülikool
Abstrakt
Taimsed piimatoodete alternatiivid koguvad järjest rohkem populaarsust, sest need sobivad suuremale tarbijaskonnale. Fermentatsiooni järgselt võivad need joogid omandada probiootilise toime, mis tugevdab seedesüsteemi mikrofloorat. Tootmisprotsessis keeruline saavutada taimsest toorainest toodet, mis sarnaneks sensoorsete omaduste poolest keefirile. Üheks põhjuseks on taimses joogis leiduvate valkude ja rasvade väiksem sisaldus, mis mõjutab tekstuuri, maitse tasakaalu ja fermenteerimisvõimet.
Bakalaureusetöö eesmärk oli uurida keefiriseene ja starterkultuuriga fermenteeritud kaerajoogi omadusi. Töö raames fermenteeriti kuus proovi, mille suhkrusisaldus oli 2%, 3% ja 4%. Lisati vastavalt starterkultuur või keefiriseen. Fermentatsioon toimus 18 tundi temperatuuril 37 °C. Enne fermenteerimist määrati kaerajoogi tiitritav happesus, pH ja lahustunud kuivaine sisaldus (Brix). Pärast katsete lõppu määrati samuti tiitritav happesus, pH, Brix ning lisaks viidi läbi sensoorne analüüs, kus hinnati välimust, lõhna, maitset, konsistentsi, magusust ja happesust.
Töö tulemustest selgus, et kõikide proovide pH langes algtasemelt 7,49±0,046 vahemikku 4,59–4,95. Madalaima pH oli proov KJ 2% (4,59±0,49), millel oli ka kõrgeim tiitritav happesus (43,87±2,57 °Th). Statistiliselt oluline erinevus tiitritavas happesuses ilmnes proovide KJ 3% ja KS 3% vahel (p = 0,0014). Brix langus viitas sellele, et fermentatsiooni käigus tarbisid mikroorganismid aktiivselt suhkrut. Sensoorse analüüsi tulemuste põhjal selgus, et starterkultuur ja suhkru kontsentratsioon mõjutas enim magususe ja happesuse tajumist. Parima lõhnahinnangu sai proov KJ 3%. Välimuse ja konsistentsi hinnangud ei erinenud märgatavalt. Keefiriseenega katse teise korduse proovid jäeti sensoorsest hindamisest välja, kuna jook oli visuaalselt ja lõhna poolest riknenud – jook eraldus tugevalt, muutus tükiliseks ja lõhnas alkohoolselt.
Käesoleva bakalaureusetöö tulemused näitavad, et stabiilsema tulemuse annab fermentatsioonil starterkultuuride kasutamine. Lisaks mõjutab starterkultuuri ja suhkru kontsentratsiooni kooslus keemilisi ja sensoorseid omadusi. Kokkuvõttes saab kaerajoogist valmistada taimset keefiri alternatiivi, mille organoleptilised omadused vajavad veel optimeerimist.
Plant-based dairy alternatives are gaining popularity, as they are suitable for a wider range of consumers. After fermentation, these drinks may acquire probiotic properties that support the gut microbiota. However, achieving a product from plant-based raw materials that resembles kefir in its sensory characteristics is challenging in the production process. One of the reasons is that plant-based drinks compared to milk have a lower level of proteins and fats that affect fermentation capacity, texture and flavour balance. The aim of this bachelor’s thesis was to study properties of oat-based drinks fermented with kefir grains and starter culture. Six oat drink samples with varying sugar contents (2%, 3% and 4%) were fermented with both kefir grains and starter culture for 18 hours at 37 °C. Before fermentation, the titratable acidity, pH and soluble dry matter content (Brix) of the oat drink were measured. After the fermentation process, the same parameters were measured again, and a sensory evaluation was conducted to assess appearance, aroma, taste, texture, sweetness and acidity. The results of the study revealed that the pH of all samples decreased from the initial level of 7.49±0.046 to a range of 4.59–4.95. The lowest pH was observed in sample KJ 2% (4.59±0.49), which also had the highest titratable acidity (43.87±2.57 °Th). A statistically significant difference in titratable acidity was found between samples KJ 3% and KS 3% (p = 0.0014). The decrease in Brix indicated that microorganisms actively consumed sugar during fermentation. Based on the sensory analysis results, it was found that the starter culture and sugar concentration most strongly influenced the perception of sweetness and acidity. Sample KJ 3% received the highest aroma rating. There were no significant differences in appearance and consistency ratings. The second replicate samples of the kefir grain test were excluded from the sensory evaluation, as the beverage was spoiled in terms of appearance and smell – it had separated strongly, became lumpy, and had an alcoholic odor The results of this bachelor’s thesis indicate that using starter cultures provides a more stable fermentation outcome. Additionally, the combination of starter culture and sugar concentration affects both chemical and sensory properties. In conclusion, it is possible to create a plant-based kefir alternative from oat drink, though its organoleptic properties still require optimization.
Plant-based dairy alternatives are gaining popularity, as they are suitable for a wider range of consumers. After fermentation, these drinks may acquire probiotic properties that support the gut microbiota. However, achieving a product from plant-based raw materials that resembles kefir in its sensory characteristics is challenging in the production process. One of the reasons is that plant-based drinks compared to milk have a lower level of proteins and fats that affect fermentation capacity, texture and flavour balance. The aim of this bachelor’s thesis was to study properties of oat-based drinks fermented with kefir grains and starter culture. Six oat drink samples with varying sugar contents (2%, 3% and 4%) were fermented with both kefir grains and starter culture for 18 hours at 37 °C. Before fermentation, the titratable acidity, pH and soluble dry matter content (Brix) of the oat drink were measured. After the fermentation process, the same parameters were measured again, and a sensory evaluation was conducted to assess appearance, aroma, taste, texture, sweetness and acidity. The results of the study revealed that the pH of all samples decreased from the initial level of 7.49±0.046 to a range of 4.59–4.95. The lowest pH was observed in sample KJ 2% (4.59±0.49), which also had the highest titratable acidity (43.87±2.57 °Th). A statistically significant difference in titratable acidity was found between samples KJ 3% and KS 3% (p = 0.0014). The decrease in Brix indicated that microorganisms actively consumed sugar during fermentation. Based on the sensory analysis results, it was found that the starter culture and sugar concentration most strongly influenced the perception of sweetness and acidity. Sample KJ 3% received the highest aroma rating. There were no significant differences in appearance and consistency ratings. The second replicate samples of the kefir grain test were excluded from the sensory evaluation, as the beverage was spoiled in terms of appearance and smell – it had separated strongly, became lumpy, and had an alcoholic odor The results of this bachelor’s thesis indicate that using starter cultures provides a more stable fermentation outcome. Additionally, the combination of starter culture and sugar concentration affects both chemical and sensory properties. In conclusion, it is possible to create a plant-based kefir alternative from oat drink, though its organoleptic properties still require optimization.
Kirjeldus
Bakalaureusetöö
Toiduainete tehnoloogia õppekaval
Märksõnad
bakalaureusetööd, fermenteeritud joogid, kaerajook, piimhappebakterid, pärmid