Determination of Microbiological Properties of Kombucha Produced from Different Plant Sources and Identification of Probiotic Microorganisms Found in the Product

Project no. 22943 · Status: Kapanmış · 2021

Summary

In this study, it was aimed to use Anatolian hawthorn and nettle leaves in the production of Kombucha beverage, and to examine the probiotic properties of the acetic acid bacteria (AAB) and yeasts isolated from Kombucha samples produced. For this aim, twelve different Kombucha beverage was produced by using Anatolian hawthorn (KH), nettle (KN) and black tea (control group-KC) as raw material. Microbiological [AAB, lactic acid bacteria (LAB) and yeast counts] and chemical properties of Kombucha samples were examined during fermentation period, additional physical, chemical and microbiological analyses (color, total phenolic and flavonoid content, antioxidant and antimicrobial activity analyses) and sensory evaluations were also carried out in the final product and during storage at 4ºC for 120 days. In the next stage of the study, AAB and yeast isolation from Kombucha samples were made, the isolates were investigated in terms of biosafety properties (hemolytic activity, resistance to antibiotics), the ability to survive under the harsh conditions (at low pH values and in the presence of bile salts, 0.4% phenol, pepsin and pancreatin), technological properties (protease, amylase and β-Galactosidase enzyme activity, growth at different salt concentrations), antimicrobial and antioxidant activities and in vitro adhesion (autoaggregation, coaggregation and cell surface hydrophobicity) properties, at the final stage, the isolates determined as probiotic were identified at the molecular level.AAB and yeast counts of Kombucha beverages during fermentation period were determined in the range of 3.08-6.15 and 3.30-6.21 log CFU/mL in KH samples, 3.74-6.02 and 3.85-6.85 log CFU/mL in KN samples, and 3.63-6.13 and 3.86-6.70 log CFU/mL in KC samples, respectively. At the end of the storage (at 4℃ for 120 days), AAB and yeast counts of the samples were generally lower than the beginning, while AAB counts of KH and KN samples were found higher than KC samples. During the fermentation period, total acidity, pH and °Brix values of the samples were determined in the range of 0.90-3.82 g acetic acid/L, 2.73-5.38 pH, 2.60-8.85°Brix, respectively, while these values were detected in the range of 0.71-4.43 g acetic acid/L, 2.73-3.73 pH, 2.60-8.85°Brix, respectively, during the storage times. During storage period, it was determined that the values of the samples were changed in the range of 445.00-2602.83 mg GAE/L for total phenolic content, 55.34-255.16 mg catechin/L for total flavonoid content, 62.50-94.84% according to ABTS method and %14.94-93.43 according to DPPH method for antioxidant activity. Also, it was determined that the minimum inhibitory concentration (MIC) values of the samples varied in the range of 15.63 µg/mL and 125.00 µg/mL and when compared to KH and KC samples, KN samples were generally exhibited higher inhibitory effects against the test cultures. The samples were received medium-above acceptance scores for sensory properties during storage period. Depending on the storage time, KK samples were more preferred samples in terms of color properties, while KA samples were more preferred in terms of aroma, clarity, taste, and general acceptance. As a result, within the scope of this study it was determined that Anatolian hawthorn and nettle leaves can be successfully used as raw materials in Kombucha production. Also, the probiotic properties of 170 AAB and 194 yeast isolates obtained from Kombucha samples were examined and isolates with no biosafety risk, high viability in harsh environmental conditions and acceptable in terms of technological properties, antimicrobial/antioxidant activity and in vitro adhesion properties were identified at the molecular level. The results showed that the isolates identified as Gluconobacter sp. A21, Komagataeibacter sp. A33, Komagataeibacter sp. A88, Komagataeibacter sp. A139, Gluconobacter sp. A141, Komagataeibacter sp. A146, Komagataeibacter sp. A190, Komagataeibacter sp. A191, Zygosaccharomyces bailii M36, Z. bailii M40, Brettanomyces anomalus M66, B. anomalus M94, B. anomalus M98, B. anomalus M99, B. anomalus M104, B. anomalus M180 and Pichia kudriavzevii M195 could be evaluated as probiotics.

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