Influence of UV-B Light Emitting Diodes on Colour Development and Accumulation of Polyphenols and Antioxidants in Apple Skin

UV light provoked stress can evoke antioxidant defence system and consequently induces the synthesis of several phytochemical compounds. The aim of the present study was to investigate the influence of UV-B light irradiation on surface colour and synthesis of some bioactive compounds in apples skin of cultivars ‘Elstar’ and ‘Jonagold’. Half of each apple was shaded with aluminium foil to compare irradiated and non-irradiated parts of skin. Apple fruits were exposed to constant UV-B light at 310 nm in chamber for 13 days at 8.5 °C. The UV-B light emitting diodes were positioned ca. 13 cm above the apple fruit and the average irradiance fruit received was 4.6 μW/cm2. Measurements of colour parameters (L*, a*, b*) were performed on the same spots of irradiated and non-irradiated surface of each apple fruit before and after 7, 10 and 13 days of storage constant UV-B light irradiation. All apple fruits started to develop red colour on the irradiated surface. The antioxidant potential, ascorbic acid content, total phenolic compounds, six flavonols and anthocyanin cyanidin-3-galactoside were quantitatively evaluated. Apple skins exposed to UV-B light irradiation contained significantly more total phenolic compounds and had higher antioxidant potential as compared to non-irradiated. UV light treated apple skin contained more cyanidin-3-galactoside and flavonols

Utjecaj žute svjetlosti valne duljine od 590 nm, emitirane pomoću LED svjetiljki, na skladištenje plodova jabuke, rajčice i paprike babure

The objective of this study is to investigate the eff ects of irradiation from light-emitting diodes (LEDs) on several fruits during storage. To improve storage and increase the contents of some bioactive compounds, apple, tomato and red bell pepper fruits were exposed to yellow light emitted from the diodes at 590 nm. The contents of ascorbic acid, total phenolics, total flavonoids and several pigments were investigated, along with the antioxidant potential. The colour parameters (L*, a* and b*) and firmness of the fruit were also determined. After 7 days of LED light irradiation, there was significantly higher total phenolic content and antioxidant potential in apple peel extracts. The irradiated fruit of tomato had significantly higher levels of total phenolic compounds, and the fruit of red bell pepper had significantly higher antioxidant potential. LED light had no effects on the colour parameters, although there was a tendency to accelerate colour development. Apple fruit irradiated with LED light was significantly less firm. Among twelve analysed pigments, significantly more β-carotene was detected in LED light-irradiated apple and bell pepper fruit, more α-tocopherol and γ-tocopherol in bell pepper fruit, and more lutein in apple peel and bell pepper fruit. The applied LED light slightly accelerated the ripening of the studied fruit, and affected the synthesis of some of the secondary metabolites.Svrha je ovoga rada bila ispitati utjecaj svjetlosti koje emitiraju LED svjetiljke na skladištenje nekoliko vrsta plodova. Jabuka, rajčica i paprika babura izlagane su žutoj svjetlosti valne duljine od 590 nm radi poboljšanja trajnosti plodova i povećanja udjela nekih bioaktivnih sastojaka. Određene su sljedeće vrijednosti: udjeli askorbinske kiseline, ukupnih fenola, ukupnih flavonoida i nekoliko pigmenata, te antioksidacijski potencijal plodova. Nakon sedam dana izlaganja plodova LED svjetlosti došlo je do znatnog povećanja udjela ukupnih fenola i antioksidacijskog potencijala u ekstraktima kore jabuke, povećanja udjela ukupnih fenola u plodu rajčice, te do povećanja antioksidacijskog potencijala ploda paprike babure. LED svjetlost nije utjecala na karakteristike boje, iako je donekle ubrzala razvoj boje plodova. Izlaganje jabuke LED svjetlosti uzrokovalo je mekšanje ploda. Ispitani su udjeli dvanaest pigmenata u plodovima, te je pronađeno znatno više β-karotena u jabuci i paprici baburi, više α- i γ-tokoferola u paprici, te više luteina u kori jabuke i plodu paprike babure nego u kontrolnim uzorcima. LED svjetlost je donekle ubrzala sazrijevanje plodova i utjecala je na sintezu nekih sekundarnih metabolita

Vegetable of Slovene origin and consumers

Production of vegetable is decreasing constantly in Slovenia. From health point of view locally produced food is more recommendable, because it contains fewer residues of pesticides, more vitamins and has high quality. In my dissertation I presented state of agriculture in Slovenia. Above all I was interested in state and production of vegetables. I described different types of production of vegetable, from conventional to biological dynamic. I was interested in rules, laws and regulations, which are defining individual type of agriculture. I introduced national declarations of crops, registered trademarks and brands. I made an analysis of executions of inspection controls at sellers and then I presented results of completed reviews. I completed interviews with ten sellers on central Ljubljana marketplace and with ten sellers on marketplace BTC City. I also completed interviews with ten costumers on each marketplace. They decide for purchases especially because of high quality of Slovene vegetable and shorter delivery on point of sale. As factor that obstructs the purchase of Slovene vegetable on market place, buyers oftenest listed price. I found out that the majority of buyers don’t trust sellers

The influence of light-emitting diode wavelength on the content of bioactive compounds in fruits and vegetables during storage

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\u27-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.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\u27 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

Yield and nutritional quality of soil‐cultivated crisphead lettuce (Lactuca sativa L. var. capitata) and corn salad (Valerianella spp.) harvested at different growing periods

Abstract Crisphead lettuce and corn salad varieties were grown during different growing seasons in the greenhouse or in the field under intensive tillage. They were evaluated for agronomic and nutritional quality to determine the influence of growing period, variety, and in the case of lettuce, leaf position (inner, middle, and outer leaf) on total and marketable yield, color parameters, relative chlorophyll, total sugars, isovaleric acid, total phenolic content (TPC), and multielement composition. Significant differences were found among total yield, color parameters (L*, b*, c*, and hue), and relative chlorophyll for crisphead lettuce, and color parameters (L*, a*, b*, c*, and hue) and relative chlorophyll for corn salad varieties. Relative chlorophyll was strongly correlated with most color parameters. The growing period affected yield, relative chlorophyll, TPC, total sugars, isovaleric acid, and multielement composition for corn salad, and the color parameter a* and relative chlorophyll for crisphead lettuce. The position of lettuce leaves had a significant effect on TPC, total sugars, and multielement composition. In addition, this study confirmed that farmers and consumers should pay attention to nutritional quality when selecting different lettuce and corn salad varieties

Nuclear magnetic resonance as a tool for the assessment of postharvest changes in the metabolome of the skin of sweet cherry ( Prunus avium L.)

A metabolomics approach based on nuclear magnetic resonance (NMR) spectroscopy, a rapid and simple technique, was used for the assessment of chemical changes of ‘Van’ sweet cherries during their storage. This approach affords a holistic analysis since NMR spectroscopy allows the simultaneous detection of diverse groups of secondary and primary metabolites, and reflects the real molar levels of the metabolites. Additionally, color parameters L*, a* and b*, total phenolic content (TPC), total flavonoid content (TFC), anthocyanidins and total antioxidant potential (AOP) were measured. After harvest, cherries were stored at 1°C and sampling was done after 0, 2, 4, 7 and 10 days. Cherry skin was removed, freeze dried and stored at -80°C till analyses. For NMR analyses, freeze dried cherry skins have been extracted with methanol-d4/trifluoroacetic acid-d solvent mixture. For other analyses, samples were extracted in 70% ethanol with 1% of formic acid. The 1D and 2D NMR spectral analysis confirmed that sugars (glucose, fructose, sucrose), organic acids (malic and citric acid), and phenolic compounds (neochlorogenic acid, cyanidin 3-O-rutinoside, and cyanidin 3-O-glucoside) are the main compounds in the cherry skin extracts. The 1H NMR spectral data have been subjected to multivariate analysis. Orthogonal projections to latent structures (OPLS) were applied to correlate the NMR data with the storage time. The changes in chemical composition among the samples with different storage time were clearly visible on the score plot. According to the goodness of fit of the model (R2=0.954), and its predictive ability (Q2=0.634), cherry skin extracts were well-correlated with the storage time. A positive correlation of the signals corresponding to glucose, neochlorogenic acid, cyanidin 3-O-rutinoside, and cyanidin 3-O-glucoside with the storage time of cherries has been observed on the loading plot. According to the loading plot, the increase in the content of glucose, neochlorogenic acid, cyanidin 3-O-rutinoside, and cyanidin 3-O-glucoside has been correlated with the storage time of cherries. Since polyphenolic compounds were found to correlate well with the storage time, the content of redox active compounds was further assessed with AOP, TPC and TFC. All these parameters were increasing for 7 days after harvest then started to decline slightly. The content of all three anthocyanidins increased 2 days after harvest then remained stable till the end of sampling period.VIII International Cherry Symposiu

Influence of Yellow Light-Emitting Diodes at 590 nm on Storage of Apple, Tomato and Bell Pepper Fruit

The objective of this study is to investigate the eff ects of irradiation from light-emitting diodes (LEDs) on several fruits during storage. To improve storage and increase the contents of some bioactive compounds, apple, tomato and red bell pepper fruits were exposed to yellow light emitted from the diodes at 590 nm. The contents of ascorbic acid, total phenolics, total flavonoids and several pigments were investigated, along with the antioxidant potential. The colour parameters (L*, a* and b*) and firmness of the fruit were also determined. After 7 days of LED light irradiation, there was significantly higher total phenolic content and antioxidant potential in apple peel extracts. The irradiated fruit of tomato had significantly higher levels of total phenolic compounds, and the fruit of red bell pepper had significantly higher antioxidant potential. LED light had no effects on the colour parameters, although there was a tendency to accelerate colour development. Apple fruit irradiated with LED light was significantly less firm. Among twelve analysed pigments, significantly more β-carotene was detected in LED light-irradiated apple and bell pepper fruit, more α-tocopherol and γ-tocopherol in bell pepper fruit, and more lutein in apple peel and bell pepper fruit. The applied LED light slightly accelerated the ripening of the studied fruit, and affected the synthesis of some of the secondary metabolites