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

Využití LED pro zlepšení spektra vnitřních svítidel (zvaný příspěvek)

Not so far ago the two most important characteristics of a light source to be used in indoor lighting were lighting efficiency and colour rendering index. First characteristic allow us to make lighting installation also energy efficient and second one assures that the lighting will be well accepted by the users or at least that the premises will look natural. Although both depend on light source spectra, it was very difficult to adapt spectra of the classical light sources to the needs of users. These changes with the introduction of power LEDs to the interior lighting. Today with use of white and monochromatic LEDs we can tailor spectra of luminaires to our needs. This approach can be used not only to obtain better energy efficiency and colour rendering index but also to adapt the spectra to the "non-visual needs" of users. The paper will show some approaches for the selection of the appropriate LEDs for tuning of spectra and the obtained results with different number of used LEDs in luminaire

Využití LED pro zlepšení spektra vnitřních svítidel (zvaný příspěvek)

Not so far ago the two most important characteristics of a light source to be used in indoor lighting were lighting efficiency and colour rendering index. First characteristic allow us to make lighting installation also energy efficient and second one assures that the lighting will be well accepted by the users or at least that the premises will look natural. Although both depend on light source spectra, it was very difficult to adapt spectra of the classical light sources to the needs of users. These changes with the introduction of power LEDs to the interior lighting. Today with use of white and monochromatic LEDs we can tailor spectra of luminaires to our needs. This approach can be used not only to obtain better energy efficiency and colour rendering index but also to adapt the spectra to the "non-visual needs" of users. The paper will show some approaches for the selection of the appropriate LEDs for tuning of spectra and the obtained results with different number of used LEDs in luminaire

Sustainable exterior lighting for cultural heritage buildings and monuments

The improper illumination of cultural heritage buildings and monuments can be a source of enormous light pollution, which can have a major impact on the overall environment of the illuminated area. Such lighting can be the result of carelessness or a poorly designed lighting system. This paper presents one of the methodologies that can significantly reduce light pollution, especially spilt light out of building façades. The methodology is based on using luminaires with specially made shutters and an appropriate silhouette of the object. The shutters are designed with the help of photos of the object and the location’s sizes measured. The methodology was tested during the renovation of the lighting systems of different churches in Slovenia and is described using the example of the Church of St. Thomas near Ptuj, Slovenia (N 46°28.9554′, E 16°0.7416′). The results show that the methodology is effective and can significantly reduce light pollution that occurs when such buildings are incorrectly lit

Defining the Minimum Density of a Sky Luminance Grid Based on Scale Model Measurements Without the Sun

International audienc

Fastness of dye-based ink-jet printing inks in aqueous solution in the presence and absence of oxygen

Photodegradation of the ink-jet prints is a complex process in which many external and internal factors are involved. Nevertheless, the role of colorants and various accompanying substances in the ink is often overlooked. Our research work aimed to determine the fastness of water-based ink-jet inks in aqueous solutions. A printing ink often contains a complex mixture of colorants to achieve optimal optical properties of color and a suitable fastness of the print. Therefore, we investigated the composition and stability of cyan, magenta, yellow, and black inks under the influence of UVC light in the presence of oxygen as well as in an inert environment based on TLC chromatography and spectrophotometric analysis. The process of photodegradation was evaluated based on ink amount and half-life. According to the results, the majority of inks consist of at least two colorants that differ in color and polarity. The results have shown that the presence of oxygen negatively affects the stability of inkstherefore, the inert atmosphere prolongs the durability of ink in water solution

Developing energy efficient and smart lighting education in Vietnam and Myanmar

Artificial lighting is a basic need for human wellbeing and performance when there is no access to daylight. Large populations, mostly in rural areas, depend on traditional biomass-based lighting techniques whereas in developing countries with electricity supply mostly energy inefficient electric lighting is applied. Implementation of energy efficient and smart lighting products and systems could reduce the annually increasing energy demand and greenhouse gas emissions in developing countries. However, these relatively recent energy efficient and smart lighting solutions are not common in developing countries due to various barriers including a lack of awareness and information, a lack of qualified engineers, and a lack of experience in implementing, testing and maintaining energy efficient and smart lighting design.This article summarizes the education development activities carried out at six universities in Vietnam and Myanmar. In addition to education development, lighting labs were established, teachers and technical staff were adequately trained, and interaction and cooperation between higher education institutions and public bodies and industry were enforced.Peer reviewe

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