Mikrobiološka obstojnost in protimikrobna aktivnost cvetnega prahu osmukanca pri različnih načinih shranjevanja

Podržaj, Lucija (author), Smole Možina, Sonja (mentor)

Cvetni prah osmukanec je čebelji produkt, ki vsebuje visoko vsebnost hranilnih snovi in vode. Kot tak omogoča ugodne pogoje za rast različnih mikroorganizmov. Ta magistrska naloga raziskuje mikrobiološko obstojnost svežega cvetnega prahu osmukanca pri različnih temperaturah skladiščenja in po sušenju pri uporabi različnih režimov sušenja ter protimikrobno aktivnost izvlečkov cvetnega prahu osmukanca in učinek različnih načinov obdelave in skladiščenja na ohranjanje njegove protimikrobne aktivnosti. V vzorcu svežega cvetnega prahu osmukanca so prevladovale kvasovke (6,2 log CFU/g) in mezofilni aerobni mikroorganizmi (6,0 log CFU/g). Zmanjšano koncentracijo mikroorganizmov smo potrdili po sušenju pri 35 °C ali 30 °C 72 h. 12- mesečno shranjevanje pri 16 °C v temi ni poslabšalo njegove obstojnosti. Na začetku shranjevanja pri sobni temperaturi smo kot glavne mikrobiološke povzročitelje kvarjenja identificirali kvasovke Metschnikowia sp., Lachancea thermotolerans, Meyerozyma guillermondii in Aurebasidium melanogenum, po 5. tednu shranjevanja pa Metschnikowia sp., Papilotrema flavescens in Lachancea thermotolerans. Rast kvasovk smo spremljali v prisotnosti raztopine cvetnega prahu osmukanca v gojišču YPD in bujonu PBS, ter v prisotnosti etanola v gojišču YPD. Določili smo protimikrobno aktivnost izvlečkov različno obdelanega in skladiščenega cvetnega prahu osmukanca proti bakterijam E. coli (MIK 5,9 – 25 mg/mL), C. jejuni (MIK 3,5 – 25 mg/mL) in L. monocytogenes (MIK 6,3 – 12,5 mg/mL). Ugotovili smo, da sušenje protimikrobne aktivnost izvlečkov cvetnega prahu osmukanca ni zmanjšalo, med dolgotrajnim skladiščenjem pa so se povečale razlike med vzorci. Zmanjšala se je protimikrobna aktivnost proti bakteriji L. monocytogenes.

• Language: Slovenian
• Keywords: cvetni prah, osmukanec, shranjevanje, sušenje, mikrobiološka obstojnost, protimikrobna aktivnost
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [L. Podržaj]
• Year: 2019
• PID: 20.500.12556/RUL-109358
• UDC: 638.178.2:579.67:579.24:664.9.03
• COBISS.SI-ID: 5085816
• Publication date in RUL: 31.08.2019

Secondary language

• Language: English
• Title: Microbiological stability and antimicrobial activity of bee pollen stored in different conditions

Abstract

Bee pollen is a bee product with a high concentration of nutrients and water. With this, it offers suitable conditions for the development of different microorganisms. The aim of this Master thesis was to examine the microbiological stability of fresh bee pollen at different storage temperatures and after drying at different drying conditions. High concentrations of yeasts (6,2 log CFU/g) and mesophilic aerobic microorganisms (6,0 log CFU/g) was observed in fresh bee pollen. The decrease in the microbial count was observed after drying at 35 °C and 30 °C for 72 h. During 12-month storage at 16 °C in darkness we did not observe any decrease in the shelf life of bee pollen. Bee pollen samples showed a high population of yeasts, among these the most representative species in fresh bee pollen were Metschnikowia sp., Lachancea thermotolerans, Meyerozyma guillermondii and Aurebasidium melanogenum, and in bee pollen samples after 5 weeks of storage Metschnikowia sp., Papilotrema flavescens and Lachancea thermotolerans. Growth of yeasts was monitored in the presence of bee pollen solution in YPD media and PBS broth as well as in YPD media containing ethanol solution. The antimicrobial activity of differently treated and stored bee pollen extracts was found against E. coli (MIC 5,9 – 25 mg/mL), C. jejuni (MIC 3,5 – 25 mg/mL) and L. monocytogenes (MIC 6,3 – 12,5 mg/mL). Drying has not reduced antimicrobial activity bee pollen extracts, but long-term storage increased differences between samples. Antimicrobial activity against L. monocytogenes has been reduced.

• Keywords: bee pollen, pollen, storage, drying, microbiological stability, antimicrobial activity