# Changes in Selected Quality Indices in Microbially Fermented Commercial Almond and Oat Drinks
## 3 Results and Discussion  
### Out and Almond Drinks as Mediums for the Growth of the LAB and Yeast Strains Used  
The main nutritive component of both plant drinks was carbohydrates (9.7 g/100 mL in oat and 5.0 g/100 mL in almond), with a predominance of sugars (4.2 and 6.1 g/100 mL for almond and oat drinks, respectively). This was a positive premise for fermentation since simple sugars can be easily used as a carbon source. However, the analyzed drinks differed in their fat and protein contents. The contents of both of these components were extremely low in the oat drink (only 0.4 g of protein and 0.5 g of lipids in 100 mL of the oat drink) while the composition of the almond drink (4.1 g and 1.7 g/100 mL for fat and protein contents, respectively) was more similar to non-skimmed cow milk, which usually contains ca 3.6, and 3.2 g/100 mL of fat and protein, respectively [31]. After inoculation by the LAB strains, the initial count was 1.0-2.2 \(\times\) 10\({}^{4}\) CFU/mL of the prepared beverages (Table 1). After 48 h of fermentation, a significant increase was observed in all LAB strains, resulting in a final concentration of 1.0-4.8 \(\times\) 10\({}^{9}\) CFU/mL. Almond beverages were characterized by a slightly higher density of LAB counts. _L. plantarum_ strains have been isolated from many food products, including cheese, meat, fish, fermented vegetables, and fruits, and selected strains are used as probiotics. _L. bulgarcicus_, together with _Streptococcus thermophilus_, is a typical yoghurt microbiota [32]. In accordance with the requirements of the FAO/WHO Codex Alimentarius standard [33], the number of characteristic microflorae in classical yoghurt must be at least 10\({}^{7}\) CFU in 1 g of the product throughout the shelf life. The LAB count density in the prepared plant beverages was similar to that found in freshly prepared, fermented milk-based products [34]. In general, in a variety of retail fermented foods, the amount of live LAB ranges between 10\({}^{5}\) and 10\({}^{9}\) CFU/g or mL [34]. This shows that both plant matrices were valuable nutrient sources for bacteria growth and multiplication. After inoculation by the yeast strains, their initial concentration ranged from 9.8 \(\times\) 10\({}^{2}\) to 6.5 \(\times\) 10\({}^{3}\) CFU/mL of prepared beverages (Table 1). In the fermented beverages, a significant increase was noted in all strains, reaching a final density that ranged from 8.9 \(\times\) 10\({}^{5}\) (almond drink fermented by _C. lipolytica_) to 1.2 \(\times\) 10\({}^{8}\) CFU/mL (an oat drink fermented by _K. marxianus_). Generally, _K. marxianus_ showed the highest count increase(close to 5 log CFU/mL) while _C. lipolytica_ showed the lowest (close to 2 log CFU/mL). For the other yeast strains, the observed increase was close to 4 log CFU/mL. _Kluyveromyces_ species are components of the yeast content of kefir and kefir grains ([PERSON] cheese, 2017) and of Serro Minas cheese (2018). These strains possess the unique ability (for yeasts) to ferment lactose into lactic acid ([PERSON], 2017), but _K. marxianus_ also utilizes other sugar substrates (i.e., hemicellulose hydrolyses, xylose, l-arabinose, d-mannose, galactose, maltose, sugar syrup molasses, and cellobiose) ([PERSON], 2017) and can grow in olive oil as a carbon source ([PERSON], 2017). In contrast, the low level of multiplication of _C. lipolytica_ and _Y. lipolytica_ in both used plant beverages is difficult to explain. _Y. lipolytica_ and _C. lipolytica_ are the teleomorph and anamorph names of the same species ([PERSON], 2017). These species are widespread in nature and can be found in a number of foods, such as sites contaminated with oil, plants, brief, feta, cheddar, and meat ([PERSON], 2017). It was recently shown that when cassava residues with a low lipid content were used as a carbon source, _Y. lipolytica_ QU69 produced 22.3% of protein and 9.4% of lipids in dry biomass, respectively.