Jabolka so sadje, razširjeno in zelo priljubljeno po celem svetu. Bogata so s fenolnimi spojinami, med katerimi so glavne katehin, klorogenska kislina in kvercetin. Vsebnost fenolov v jabolku se razlikuje glede na sorto jabolk, okoljske razmere in razmere skladiščenja. Zanimalo nas je, ali svetloba uporabljena pri optimalnih razmerah skladiščenja jabolk, vpliva na vsebnost fenolnih spojin v jabolku in če imajo le-te vpliv na bakterijsko rast, adhezijo, agregacijo in tvorbo zunajceličnih polimernih snovi (EPS) pri bakterijah vrste Escherichia coli. Ugotovili smo, da imajo jabolčni ekstrakti pred in po 18-dnevnem shranjevanju jabolk pri 10 °C pri svetlobi valovnih dolžin 420 nm in 450 nm ter v temi na bakterije vrste E. coli enako protibakterijsko aktivnost, če je le ta določena kot minimalna inhibitorna koncentracija (MIC, 6,25 % vol. jabolčnega ekstrakta oz. 1,13-1,91 mg galne kisline/ml jabolčnega ekstrakta). Po 18-dnevnem shranjevanju jabolk pri 10 °C pri svetlobi valovne dolžine 450 nm in v temi, jabolčna ekstrakta (Ekstrakt 450 3,13 % vol. in 0,78 % vol. oz. ekstrakt tema v koncentracijah 3,13 % vol., 1,56 % vol. in 0,78 % vol.) zmanjšata adhezijo bakterij vrste E. coli skoraj za polovico. Po 18-dnevnem shranjevanju jabolk pri 10 °C pri svetlobi valovnih dolžin 420 nm in 450 nm ter v temi, v koncentraciji 3,13 % vol., jabolčni ekstrakti ne vplivajo na agregacijo bakterij vrste E. coli, vplivajo pa v koncentraciji 1,56 % vol. in 0,78 % vol. Pri tem se je koncentracija sladkorjev zmanjšala iz 120 µg/ml na 50,7 µg/ml, ob dodatku Ekstrakta 420 v koncentraciji 3,13 % vol. in za polovico pri dodatku Ekstrakta 450 v koncentracijah 1,56 % vol. in 0,78 % vol. Zaključimo lahko, da jabolčni ekstrakti imajo vpliv na različne bakterijske strukture in procese vendar bi za podrobnejše poznavanje potrebovali več raziskav in analiz s katerimi bi dobili vpogled v njihovo delovanje in mehanizme. Apples are a fruit widespread and very popular all over the world. They are rich in phenolic compounds, the main ones being catechin, chlorogenic acid and quercetin. The phenol content of an apple varies according to the apple variety, environmental conditions and storage conditions. We were interested in whether the light used under optimal storage conditions of apples affects the content of phenolic compounds in the apple and if they have an effect on bacterial growth, adhesion, aggregation and formation of extracellular polymeric substances (EPS) of Escherichia coli. We found out that the apple extracts before and after 18 days of storage of apples at 10 ° C in the light of wavelengths of 420 nm and 450 nm and in the dark have the same antibacterial activity determined by MIC (6. 25% by volume of apple extract or 1.13-1.91 mg of gallic acid / ml of apple extract) on E. coli. After 18 days of storage of apples at 10 ° C in the light of wavelength 450 nm (in concentrations of 3.13% vol. and 0.78% vol.) and in the dark (in concentrations of 3.13% vol., 1.56% vol. and 0.78% vol.) reduce the adhesion of E. coli by almost half. After 18 days of storage of apples at 10 ° C in the light of wavelengths of 420 nm and 450 nm and in the dark, at a concentration of 3.13% vol. do not affect the aggregation of E. coli, but affect aggregation in the concentration of 1.56% vol. and 0.78% vol. The concentration of sugars in EPS decreased from 120 µg/ml to 50.7 µg/ml with the addition of Extract 420 at a concentration of 3.13% vol. and by half with the addition of Extract 450 in concentrations of 1.56 % vol. and 0.78 % vol. We can conclude that apple extracts have an impact on various bacterial structures and processes, but for more detailed knowledge we would need more research and analysis to get an insight into their functioning and mechanisms.