# Aromatic Profile of Hydroponically and Conventionally Grown Tomatoes
## 1 Introduction  
Today's market offers us a wide choice of fruit and vegetables throughout the whole year. Consumers are increasingly paying attention to the quality of their food and sensory quality is becoming more and more important for consumer decision making when choosing a product. It is certainly an important factor when purchasing the same product again, where consumers mainly consider whether the product was of the required aroma and taste characteristics for them [1]. The flavor is a combined sensation of taste and aroma; sugars, acids, and volatile compounds are their main determinants [1]. A large number of volatile compounds have been identified and the volatile profile of tomato has been investigated closely in many studies [2, 3, 4, 5]. The resulting flavor characteristic of tomato is the result of complex interactions between organic acids, sugars, and more than 400 volatile compounds. Ofthe volatile compounds identified, less than 10% are present at significant concentrations and at thresholds that are likely to affect the odor and taste of tomatoes. Several studies have shown that only 16 of the total aromatic volatiles are present in sufficient quantities to be detected by the olfactory system. Therefore, the following selected descriptors are recognized as carriers of tomato taste and are present in significant quantities in the fruit. However, minor volatiles with negative odor units should not be neglected as they may still contribute to the overall aroma as adjuvarants [6; 7]. The individual interactions between volatiles, also those involving the gustatory and olfactory systems are significant. These complicate the aroma because specific volatile aromas perceived by the retronasal olfactory system can influence the perception of sweetness or sourness and vice versa [8; 9]. Tomato fruit aroma is important in determining consumer perception and acceptability of fruit products [1]. The aroma of fresh ripe tomato is mainly attributable to cis-3-hexenal, cis-3-hexenal, hexanal, 1-penten-3-one, methyl salicate, 2-isobutylthiazol and \(\upbeta\)-ionone in appropriate concentrations. These compounds are biosynthetically derived from the degradation of compounds such as fatty acids, amino acids, carotenoids, and are also formed by other biosynthetic pathways [10]. In recent decades, the selection of tomato cultivars has emphasized parameters such as yield, fruit size, firmness, product flawlessness, disease resistance, ease of handling and longer shelf life, rather than sensory aspects of fruit quality. As a result, consumers started to complain about the poor tomato flavor [11; 12; 13]. Tomato flavor is now commonly referred to as \"classic tomato flavor\" or \"old-fashioned tomato flavor\", which indicate the deterioration of the sensory quality of commercial tomato fruits. However, it is unclear how, why and whether the quality of the fruit has actually changed, but consumers associate recent varieties with a lack of aroma, although such an association has not been scientifically proven. The fact is that there is now an increasing number of consumers who demand freshly grown products with a higher quality of aroma, flavor, and taste [1]. It is this recent problem, but also the demand for higher quality products, and the need of the market for year-round availability of tomatoes that stimulates the search for new ways of their growing. Hydroonic growing systems offer an opportunity to at least augment the traditional in global food production. The advantages of hydroponic growing systems include the reduction of water wastage (recirculation), the ability to manipulate conditions to maximize production (according to [14], NaCl treatment which increases sweetness, sourness, umami (i.e., flavor deliciousness) and overall preference) in a limited space (vertical gardens), and the fact that crops are grown in a controlled environment (control of pests, nutrients, and attributes necessary for optimal plant growth).