Changes in microflora of tea fungus during storage of fermented dairy beverages

Abstract

The tea fungus is being increasingly used in the production of innovative food products, both in Serbia and in other countries. This trend can be primarily ascribed to potential therapeutic characteristics of the fungus. The mechanism of this effect is still being researched, but it is quite certain that the tea fungus contains a symbiosis of acetic acid bacteria and yeasts, which can vary to a great degree depending on the origin and geographic region. The consummation of kombucha tea has a very long tradition; however, the use of the tea fungus in the production of fermented milk beverages is a new technology which can most certainly find its perspective in the dairy industry. Bearing in mind that the technology has been determined to a great extent, the question remains as to the sustainability of the product and its quality during the storage period. In this sense, this paper looks into the changes in the microbiological image of kombucha bacteria and yeasts present in the product, during a ten day storage period. In order to get a fermented dairy beverage, fermented tea inoculum was prepared, in milk with a varied milk fat content (0.9 %, 2.2 %) to the concentration of 10 %. The growth ability of acetic acid bacteria, lactic acid bacteria and yeasts was examined. It was determined that the examined microflora was very active, with the number of lactococci on day 0 amounting to 105 cfu/ml, of acetic acid bacteria to 104 cfu/mL and of yeasts and lactobacillus to 103 cfu/ml. After ten days of storing the fermented dairy product at 4°C, the viability of acetic acid bacteria was the highest and stood at 108 cfu/ml, of lactococci and yeasts at 104 cfu/mL and of lactobacillus at 103 cfu/ml. The changes in the examined microflora indicate good activity during the storage of the fermented dairy beverage; however, other characteristics of this product must also be looked into, including sensory characteristics, the chemical and nutritional composition.

Čajna gljiva nalazi sve veću primenu u proizvodnji inovativnih prehrambenih proizvoda, kako kod nas tako i u svetu. Ovakav trend se pripisuje pre svega njenim potencijalnim terapeutskim svojstvima. Hemizam ovakvog dejstva je još uvek predmet istraživanja, ali sasvim je sigurno da čajnu gljivu čini simbioza sirćetnih bakterija i kvasaca, koje mogu biti veoma raznovrsne, zavisno od porekla i geografskog regiona. Konzumiranje čajnog napitka ima veoma dugu tradiciju, ali primena čajne gljive u proizvodnji fermentisanih mlečnih napitaka predstavlja novu tehnologiju, koja svakako može naći svoju perspektivu u industriji mleka. S obzirom da je sama tehnologija velikim delom determinisana, postavlja se pitanje održivosti proizvoda i njegovog kvaliteta tokom skladištenja. U tom smislu, u radu je izvršeno ispitivanje promene mikrobiološke slike prisutnih bakterija i kvasaca čajne gljive tokom skladištenja od 10 dana. Za dobijanje fermentisanog mlečnog napitka, primenjen je inokulum čajnog napitka, u mleku sa različitim sadržajem mlečne masti (0,9% i 2,2%) u koncentraciji od 10%. Ispitana je sposobnost rasta sirćetnih bakterija, bakterija mlečne kiseline i kvasaca. Utvrđeno je da je ispitivana mikroflora bila veoma aktivna, pa je u 0-om danu broj laktokoka bio na nivou 105 ćelija/mL, sirćetnih bakterija 104 ćelija/mL i kvasaca i laktobacila 103 ćelija/mL. Nakon 10 dana skladištenja fermentisanog mlečnog napitka na 4°C vijabilnost sirćetnih bakterija je bila najveća i iznosila 108 ćelija/mL, laktokoka i kvasaca 104 ćelija/mL i laktobacila 103 ćelija/mL. Promena ispitivane mikroflore ukazuje na njenu dobru aktivnost u toku čuvanja fermentisanog mlečnog napitka. Međutim, veoma je važno ispitati i druga svojstva ovog proizvoda, kao što su senzorna svojstva, hemijski i nutritivni sastav.