Vpliv valovne dolžine emitirane svetlobe svetlečih diod na vsebnost bioaktivnih spojin v plodovih sadja in zelenjave med skladiščenjem

Kokalj, Doris (author), Vidrih, Rajko (mentor), Cigić, Blaž (co-mentor)

V doktorski disertaciji smo preučili vpliv emitirane svetlobe svetlečih diod na vsebnosti bioaktivnih spojin, predvsem fenolov, v izbranih plodovih sadja in zelenjave po obiranju. Določili smo aktivnosti dveh encimov fenilpropanoidne/flavonoidne sintezne poti, tj. fenilalanin amonijak liazo (PAL) in flavonoid 3'-hidroksilazo. Odzivi plodov na obsevanje so bili odvisni od izbrane valovne dolžine svetlečih diod, trajanja obsevanja ter od vrste in sorte. Največje spremembe v vsebnostih bioaktivnih snovi smo določili pri antocianih. Modra svetloba z valovno dolžino 444 nm je značilno vplivala na povišano akumulacijo antocianov v češnjah in kožicah jabolk. Pri češnjah nismo določili razlik v vsebnostih ostalih fenolnih spojin, medtem ko so se pri jabolkih povišale vsebnosti klorogenske kisline in treh od šestih kvercetin glikozidov. Obsevanje z modro svetlobo z valovno dolžino 444 nm ni povzročilo sinteze peonidin 3-O-galaktozida, ki je bil prisoten v naravno obarvanih rdečih jabolkih. Določili smo visoke pozitivne korelacije med posameznimi antociani in aktivnostmi encima PAL. Prav tako smo določili visoko korelacijo med barvnimi parametri hue, C* in ΔE ter vsebnostjo antocianov. Rdeča svetloba ni vplivala na vsebnosti antocianov, flavonolov in flavanolov v kožici jabolk. Obsevanje s svetlobo valovnih dolžin 420, 444, 620 in 740 nm je vplivalo na znižanje vsebnosti klorofila a in b ter β-karotena, neoksantina in violaksantina. Rdeča svetloba z valovno dolžino 740 nm je rezultirala v povišanju vsebnosti zeaksantina.

• Language: Slovenian
• Keywords: sadje, zelenjava, skladiščenje, valovna dolžina svetlobe, spekter svetlobe, obsevanje s svetlobo, poobiralno tretiranje, svetleče diode, bioaktivne spojine, barva, skupne fenolne spojine, flavonoidi, pigmenti, antociani, fenilalanin amonijak liaza, antioksidativni potencial, vsebnost askorbinske kisline
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: BF - Biotechnical Faculty
• Publisher: [D. Kokalj]
• Year: 2019
• PID: 20.500.12556/RUL-113423
• UDC: 664.8.03:641.1:577.1
• COBISS.SI-ID: 5144184
• Publication date in RUL: 02.01.2020

Secondary language

• Language: English
• Title: The influence of light-emitting diode wavelength on the content of bioactive compounds in fruits and vegetables during storage

Abstract

Within the scope of the doctoral dissertation, the influence of light emitted by light emitting diodes on bioactive compounds in fruit and vegetables during storage was examined. Additionally, activities of two enzymes of the phenylpropanoid/flavonoid pathway, namely phenylalanine ammonia lyase (PAL) and flavonoid 3’-hydroxylase were determined. The fruits' responses to irradiation were LEDs wavelength, treatment duration and fruit species and cultivar dependent. In general, the major changes in bioactive compounds were determined in the content of anthocyanins. Blue light at 444 nm significantly increased their accumulation in cherries and apple peel. No changes of other phenolic contents were observed in cherries while in apples chlorogenic acid and three out of six studied quercetin glycosides increased in all cultivars studied. Contrary to natural light conditions, LED irradiation of ‘Idared’ apples at 444 nm did not induce the accumulation of peonidin 3-O-galactoside. High positive correlations between individual anthocyanins and PAL activities were determined in cherries and apples. Moreover, highly significant correlations were found between anthocyanins and colour parameters hue, C* and ΔE. In apples, red light did not significantly affect the contents of anthocyanins, flavonols, and flavanols. Irradiation with LEDs at 420, 444, 620 and 740 nm decreased the chlorophyll a and b contents as well as β-carotene, neoxanthin, and violaxanthin. Zeaxanthin accumulation was induced by a red LED light at 740 nm.

• Keywords: fruits, vegetables, storage, light wavelength, light spectrum, light irradiation, postharvest treatment, light emitting diodes, bioactive compounds, colour, total phenolic compounds, flavonoids, pigments, anthocyans, phenylalanine ammonia lyase, antioxidant potential, ascorbic acid content