Review Received: 24 April 2017 Revised: 15 June 2017 Accepted article published: 20 June 2017 Published online in Wiley Online Library: (wileyonlinelibrary.com) DOI 10.1002/jsfa.8492 Targeted use of LEDs in improvement of production efficiency through phytochemical enrichment Erja Taulavuori, a* Kari Taulavuori, a Jarmo K Holopainen, b Riitta Julkunen-Tiitto, b Canan Acar c and Ibrahim Dincer d Abstract Based on available literature, ecology and economy of light emitting diode (LED) lights in plant foods production were assessed and compared to high pressure sodium (HPS) and compact fluorescent light (CFL) lamps. The assessment summarises that LEDs are superior compared to other lamp types. LEDs are ideal in luminous efficiency, life span and electricity usage. Mercury, carbon dioxide and heat emissions are also lowest in comparison to HPS and CFL lamps. This indicates that LEDs are indeed economic and eco-friendly lighting devices. The present review indicates also that LEDs have many practical benefits compared to other lamp types. In addition, they are applicable in many purposes in plant foods production. The main focus of the review is the targeted use of LEDs in order to enrich phytochemicals in plants. This is an expedient to massive improvement in production efficiency, since it diminishes the number of plants per phytochemical unit. Consequently, any other production costs (e.g. growing space, water, nutrient and transport) may be reduced markedly. Finally, 24 research articles published between 2013 and 2017 were reviewed for targeted use of LEDs in the specific, i.e. blue range (400–500 nm) of spectrum. The articles indicate that blue light is efficient in enhancing the accumulation of health beneficial phytochemicals in various species. The finding is important for global food production. © 2017 Society of Chemical Industry Keywords: blue light; efficient food production; light emitting diodes; phytochemicals; sustainable development INTRODUCTION Due to their superior properties, light emitting diodes (LEDs) are more often replacing traditional lighting systems, for example in household lighting, electronics and street lamps. 1,2 In addition, LED lamps used for lighting in plant production in greenhouses and indoor growing systems challenges conventional lamp types. The properties of LEDs are described in the next paragraphs in more detail. Energy conservation is a major concern for indoor food produc- tion, especially during winter months in the north. Future gener- ation LED fixtures could achieve even higher levels of efficiency while offering other new benefits to crop growers using multi-tier growing systems. 3 LED lamps have high luminous efficiency, and thus they are capable of producing a significant amount of visi- ble light energy, which is expressed as lumens per unit input of electrical power (lm W -1 ).The rationale of LEDs in food production (and any other purpose) is to support sustainable development, and to reduce carbon footprint. We started the review by assess- ing the environmental aspects related to the use of LED lighting in food production. We assessed the sustainability of LEDs by taking the following properties into consideration: average luminous effi- ciencies (lm W -1 ), photon efficiencies (μmol J -1 ), life spans (hours), mercury emissions (mg per lamp), CO 2 emissions (kg kWh -1 ), heat emissions (W per lamp), and electricity usages (equivalent to 60 W incandescent light bulb). Average values for these properties were taken from the literature, and are presented in Table 1. In order to analyse strengths and weaknesses of each lamp type, the data given in Table 1 are normalised and ranked based on two equations. When normalising, each property was scored in values from 0 (lowest performance) to 5 (best performance). However, the three uppermost properties in Table 1 are aimed to be maximised, whereas the rest of them should be minimised from the sustainable development point of view. Therefore, two different equations were used to normalise and rank the data. The ranking and normalisation calculations were carried out based on the procedure that has been previously described 9,10 as follows. For data that is desired to be maximised (i.e. luminous and photon efficiencies, and life spans), the following equation is used: rank (i)= data (i)- minimum maximum - minimum × 5 (1) ∗ Correspondence to: E Taulavuori, Department of Ecology and Genetics, Univer- sity of Oulu, P.O. Box 3000, 90014 Oulu, Finland. E-mail: erja.taulavuori@oulu.fi a Department of Ecology and Genetics, University of Oulu, Oulu, Finland b Department of Environmental and Biological Sciences, University of Eastern Finland, Finland c Faculty of Engineering and Natural Sciences, Bahcesehir University, Be¸ sikta¸ s, Istanbul, Turkey d Clean Energy Research Laboratory (CERL), Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, Canada J Sci Food Agric (2017) www.soci.org © 2017 Society of Chemical Industry