**2. Tomato biochemical composition**

Currently, the food industry advocated increasingly in synthetic antioxidants changes by the 'safer natural mixtures'. This option has been made available through the worldwide consumer preference for natural antioxidants, some of which are added intentionally during processing and some exist inherently in foods. Between them, carotenoids comprise the group of the most abundant micronutrients in fruits and vegetable; also, their dietary consumption is related with a lower frequency of some cancer types of as well as reinforces prevention against the cardiovascular diseases [11-13].

**1. Introduction**

46 Plants for the Future

Tomato is one of the most valuable and popular vegetables worldwide. It is desirable that tomatoes are fertile and disease resistant, and each cultivar differs in fruit size, shape, taste, colour, and skin and flesh firmness. Tomatoes must also be resistant to transportation condi‐ tions to meet market requirements and consumer needs, as there is an increased demand for large-fruit salad-type tomato varieties. Tomatoes and tomato-based products are an important agricultural commodity worldwide. More than 80% of tomatoes grown worldwide are processed into products such as tomato juice, paste, puree, catsup, sauce, and salsa. Tomato fruit is rich in organic acids, sugars, dietary fibre, pectic substances, proteins, fats, minerals (potassium, phosphorus, sulphur, magnesium, calcium, iron, copper, and sodium), vitamins (B1, B2, B3, PP, C, provitamin A, I, and H), and carotenoids possessing antioxidant qualities (lycopene, β-carotene, etc.). Due to the importance of vegetables in the human diet, it is recommended to consume 400 -500 grams daily, 140 to 150 kg per year of various vegetables, including 25 to 32 kg of tomatoes for an adult human [1, 2]. The nutritional value, colour, and flavour of tomatoes and their products depend mainly on lycopene, β-carotene, ascorbic acid and sugars, and their ratios in the fruits. The two most important carotenoids in tomato fruits are lycopene, which determines the fruit's red colour, and β-carotene, which accounts for approximately 7% of tomato carotenoids [3]. Therefore, tomato products and their quality can be characterised by the contents of these elements. Humans gets 85% of their lycopene from tomatoes and tomato products [4], which is the reason why tomatoes are used in functional food products [5], and sometimes as functional foods [2, 6]. Epidemiological studies and other studies associated with the consumption of tomato products for the prevention of chronic diseases, such as cancer and cardiovascular disease, confirm that tomato products are func‐ tional foods and show that lycopene and β-carotene act as an antioxidant [7, 8]. In order to increase the amounts of these elements in tomato fruits, it is important to evaluate and investigate the influence of tomato genotypes on carotenoid accumulation. Previous studies have confirmed that the carotenoid content in tomato fruits could be determined by genotypic characteristics [9, 10]. This paper focuses on the biochemical and physical properties of tomatoes of different varieties, their chemical and physical properties, and the functional

properties of supercritical fluid extraction of lycopene from tomato processing.

Currently, the food industry advocated increasingly in synthetic antioxidants changes by the 'safer natural mixtures'. This option has been made available through the worldwide consumer preference for natural antioxidants, some of which are added intentionally during processing and some exist inherently in foods. Between them, carotenoids comprise the group of the most abundant micronutrients in fruits and vegetable; also, their dietary consumption is related with a lower frequency of some cancer types of as well as reinforces prevention against the

**2. Tomato biochemical composition**

cardiovascular diseases [11-13].

Flower and fruit colour is caused by different types of pigments belonging to the terpenoid and phenylpropanoid classes. Carotenoids, chlorophylls, and anthocyanins are the main three groups of pigments. Colour characteristics, in some plants, can be determined by domestica‐ tion of agronomic traits, while in others, the increase of these pigments in tissues can occur naturally. This could be applied to tomato (*Solanum lycopersicum* L.), which has several carotenoids, such as lycopene and β-carotene, among others. The amount of these carotenoids is principally determined by the tomato cultivar and genotype [14, 15]. It has been established that carotene, nitrates, and sugar amounts in fruits and root crop vegetables depend on plant genotype, meteorological conditions, fertilisation, and soil composition [16-19]. The levels of the essential antioxidant vitamins, in contrast with other antioxidative defences, are deter‐ mined mainly by the plant's dietary supply. One major vitamin for enriching human diets is the antioxidant vitamin C (ascorbic acid). This vitamin can counteract the oxidising effects of lipids by scavenging free radicals that have been found to be major promoters of certain diseases. Recently, it has been demonstrated that carotenoids react cooperatively and synerg‐ istically with vitamin C, serving to regenerate a pro-oxidant radical carotenoid following the antioxidant reduction of a radical species [11]. Vitamin C usually found in vegetables and fruits, and it is a natural antioxidant. Ascorbic acid plays an important role in biochemical processes such as the formation of collagen, absorption of iron, and its involvement in the immune response and the synapses. However, a high amount of this antioxidant for human could be painful and cause adverse effect. Thus, the precise determination of ascorbic acid in various plant species or cultivars is very important [21-25]. There seems to be little doubt that acids and sugar not only contribute to the sweetness and sourness of tomatoes but are also major factors in overall flavour intensity. Since the lack of flavour is a common complaint about fresh market tomatoes, increases in sugar and acid contents could make a contribution to improve tomato flavour [16].

Nitrate is very important for plant functions and nutrition. It is a part of the nitrogen cycle and occurs naturally. Human exposure to nitrate is mainly exogenous through the consumption of vegetables, and to a lesser extent through water and other foods. Vegetables are the major vehicles for the entry of nitrate into the human body. Ever-increasing concerns over nitrate toxicity have directed a number of countries to institute maximum allowable threshold concentrations of nitrate-N in vegetables [26].

Tomatoes and tomato products are major sources of lycopene compounds and are also considered an important source of carotenoids and vitamins in the human diet [27, 28]. Therefore, considerable work has been conducted to increase their levels in tomatoes through breeding programmes [29]. The amount of carotenes and their antioxidant activity as well as their biochemical composition are significantly influenced by the tomato variety and maturity [20, 30]. The importance of genotype selection for high nutritional value is outlined first, followed by the optimisation of environmental conditions and agricultural practices [31]. Normalised values for lycopene contents of different tomato cultivars in California ranged from 8.4 to 17.2 mg 100 g-1, representing a 100% difference from the lowest to the highest values [32]. According to Viskelis, the highest amount of lycopene (over 10 mg 100 g-1) was found in the Lithuanian cultivar 'Rutuliai', which was 1.6 times higher than that of the hybrid 'Admiro' and twice as high as the hybrid 'Kassa' [33].

Based on the multiannual data [34] of 10 cultivars ('Viltis', 'Milžinai', 'Skariai', 'Laukiai', 'Vėža', 'Pažar', 'Vilina', 'Ruža', 'Ranij 310', and 'Elbrus') investigated in Lithuania (Fig. 1), the highest level of lycopene was established in cultivars the 'Ranij 310' (13.56 mg 100 g-1) and 'Elbrus' (12.57 mg 100 g-1).

**Figure 1.** The amount of lycopene in tomato fruits.

The least amount of lycopene was found in the fruits of the cultivars 'Skariai' (8.55 mg 100 g-1) and 'Milžinai' (8.75 mg 100 g-1). In other cultivars, the lycopene amount had varied from 9.57 ('Vėža') to 12.08 mg 100 g-1 ('Laukiai'). Lycopene is the most abundant carotene in red tomato fruits and accounts for up to 90% of the total carotenoids. Typical red-pigmented tomato fruits also contain a lesser amount of β-carotene and other carotenoids. β-Carotene occurs in tomato fruits in various amounts from 0.23 to 2.83 mg 100 g-1 [35]. Our studies showed (Fig. 2) that significantly higher amounts of β-carotene were accumulated by two cultivars, 'Ranij 310' and 'Elbrus', with 2.34 and 2.16 mg 100 g-1, respectively. The least amount of β-carotene was found in the cultivar 'Vėža' (1.33 mg 100 g-1). Most of the investigated cultivars had similar amounts of β-carotene, which varied from 1.43 to 1.70 mg 100 g-1.

**Figure 2.** The amount of β-carotene in tomato fruits.

Tomatoes are a good dietary source of ascorbic acid (vitamin C); however, the ascorbic acid content in tomatoes varies greatly. Many factors contribute to this variation, and environmen‐ tal growing conditions and cultivar genotype have been reported as having major effects on ascorbic acid composition [21, 22]. There is a wide variation of ascorbic acid content in different cultivars. According to Mathews, the vitamin C values for 41 cultivars ranged from 10.7 to 20.9 mg 100 g-1 (23). Ten years of data presented by a Lithuanian scientist showed that the average amount of ascorbic acid was 16.20 mg 100 g-1 in different tomato cultivars [36]. According to our data (Fig. 3), the cultivar 'Vilina' had a significantly higher amount (15.9 mg 100 g-1) of ascorbic acid compared with the other eight cultivars, except for the value of the cultivar 'Laukiai', which was not significantly different (12.2 mg 100 g-1). The least amount of ascorbic acid was found in the cultivar 'Viltis' (7.8 mg 100 g-1).

**Figure 3.** The amount of ascorbic acid in tomato fruits.

Based on the multiannual data [34] of 10 cultivars ('Viltis', 'Milžinai', 'Skariai', 'Laukiai', 'Vėža', 'Pažar', 'Vilina', 'Ruža', 'Ranij 310', and 'Elbrus') investigated in Lithuania (Fig. 1), the highest level of lycopene was established in cultivars the 'Ranij 310' (13.56 mg 100 g-1) and 'Elbrus'

The least amount of lycopene was found in the fruits of the cultivars 'Skariai' (8.55 mg 100 g-1) and 'Milžinai' (8.75 mg 100 g-1). In other cultivars, the lycopene amount had varied from 9.57 ('Vėža') to 12.08 mg 100 g-1 ('Laukiai'). Lycopene is the most abundant carotene in red tomato fruits and accounts for up to 90% of the total carotenoids. Typical red-pigmented tomato fruits also contain a lesser amount of β-carotene and other carotenoids. β-Carotene occurs in tomato fruits in various amounts from 0.23 to 2.83 mg 100 g-1 [35]. Our studies showed (Fig. 2) that significantly higher amounts of β-carotene were accumulated by two cultivars, 'Ranij 310' and 'Elbrus', with 2.34 and 2.16 mg 100 g-1, respectively. The least amount of β-carotene was found in the cultivar 'Vėža' (1.33 mg 100 g-1). Most of the investigated cultivars had similar amounts

(12.57 mg 100 g-1).

48 Plants for the Future

**Figure 1.** The amount of lycopene in tomato fruits.

**Figure 2.** The amount of β-carotene in tomato fruits.

of β-carotene, which varied from 1.43 to 1.70 mg 100 g-1.

Sugars and acids are particularly important taste constituents of tomatoes. The sugar content of ripe tomatoes averages 3% [37], but in Lithuanian-grown tomatoes, the average amount of total sugar is 4.37% [2]. Other researchers have reported that the amounts of total sugar varied little for different cultivars and ranged from 4.01% to 4.17% [33]. In our research, the total sugar content had a small amount of variation, from 4.32% in cultivar 'Viltis' to 5.03% in cultivar 'Elbrus' (Fig. 4).

The nitrate content in vegetables may range from 1 to 10000 mg kg-1. The various reasons for this wide range are the excessive use of fertilisers, crop variety, types of N-fertilisers, light and temperature conditions, and lack of water [26]. A combination of these factors accounts for the different nitrate values reported for vegetables in different countries. A complicating factor for the nutritional exploitation of vegetables is the presence of nitrate (nitrite), which is antinutritional and toxic in nature. Nitrate content is an important quality characteristic of vegetables [38]. Amr and Hadidi reported that cultivar had a significant effect (*P* ≤ 0.05) on the nitrate content of greenhouse grown tomatoes [39]. Tomatoes accumulate low contents (100 -150 mg kg-1) of nitrates. This was demonstrated in our investigation (Fig. 5); all cultivars had a low content of nitrates compared with other vegetables, and the amount of nitrates ranged from 55 ('Vilina') to 91 mg kg-1 ('Elbrus').

**Figure 4.** The amount of total sugar in tomato fruits.

**Figure 5.** The amount of nitrates in tomato fruits.

#### **2.1. Fruit biochemical composition of organic tomato**

Consumers are becoming more interested in the environmental problems caused by agricul‐ tural activities, and there is an increased focus on the health risks resulting from the use of various chemicals. The growing phytosanitary problems and the unrelenting use of pesticides has led to new challenges in food safety. The sustainability of conventional agriculture is being questioned, and changes are needed in agricultural sciences. Currently, the development of organic growing systems is rapidly emerging as a national priority, and many countries have certified organic agriculture programs. The organic food market is developing dynamically in many countries, and therefore, studies concerning the nutritive value of organically grown products are becoming increasingly important [40, 41].

Tomatoes are an excellent plant for the comparison of fruit quality attributes between con‐ ventional and organic systems due to their global value and popularity. Unfortunately, organic cultivation has a markedly negative effect on yield, and organic fruits have more visible defects compared with conventionally grown fruits [42]. However, consumers expect organic food to have a higher nutritional value, to be healthier, or simply to be safer and less risky. Scientists have reported that conventional crops have higher levels of protein and vitamin E, carotenoids, and alkaloids, while organically grown crops tend to have more phytic acid, phenolic com‐ pounds, glucosinolates, and vitamin C. However, studies have shown that the relative impact of adopting organic production methods on food quality and safety may change over time, according to changes of soil characteristics and plant cultivars [43]. Organic foods are perceived by many consumers as safer and healthier compared with conventional ones. Organic farming enhances the long-term natural fertility of the soil, minimises soil pollution, and avoids the use of mineral fertilisers and pesticides, which lead to positive health effects for livestock and humans consuming organic foods. Fruits and vegetables have positive health benefits and contain significant amounts of biologically active compounds that may be responsible for these effects [44].

Tomato fruit quality composition varies due to a wide variety in species, stage of ripeness, year of growth, climatic conditions, light, temperature, soil, fertilisation, irrigation, and other conditions of cultivation. The amount of total and soluble solids in tomato fruits are a major economic parameter for their nutrition value. The average dry matter content of a ripe fresh fruit ranges between 5.0% and 7.5% [45]. Earlier studies noticed statistically significant differences in the content of dry matter in organic tomato fruits. Studies have reported that organic tomatoes contain, on average, 7.86% dry matter in fresh tomato fruits, compared with 5.07% dry matter in conventionally grown tomatoes. An investigation of different cultivars showed that cherry tomato contained the highest levels of dry matter compared with other tomatoes [42].

An investigation of different farming systems was carried out by the Institute of Horticulture Lithuanian Research Centre for Agriculture and Forestry [46]. Tomatoes were grown using two different farming systems (organic and conventional) in unheated greenhouses in natural soil, using the tomato cultivar 'Vilina' and two tomato hybrids, 'Benito' and 'Tolstoi'. Organic tomato plants were sprayed twice (on the 7th and 21th of July) with an organic fertiliser based on seaweed extract (*Ascophyllum*, 15% w/w). Conventional tomatoes were grown under conventional tomato growing technologies adopted by the Institute of Horticulture [46].

**2.1. Fruit biochemical composition of organic tomato**

**Figure 5.** The amount of nitrates in tomato fruits.

**Figure 4.** The amount of total sugar in tomato fruits.

50 Plants for the Future

products are becoming increasingly important [40, 41].

Consumers are becoming more interested in the environmental problems caused by agricul‐ tural activities, and there is an increased focus on the health risks resulting from the use of various chemicals. The growing phytosanitary problems and the unrelenting use of pesticides has led to new challenges in food safety. The sustainability of conventional agriculture is being questioned, and changes are needed in agricultural sciences. Currently, the development of organic growing systems is rapidly emerging as a national priority, and many countries have certified organic agriculture programs. The organic food market is developing dynamically in many countries, and therefore, studies concerning the nutritive value of organically grown

Tomatoes are an excellent plant for the comparison of fruit quality attributes between con‐ ventional and organic systems due to their global value and popularity. Unfortunately, organic cultivation has a markedly negative effect on yield, and organic fruits have more visible defects compared with conventionally grown fruits [42]. However, consumers expect organic food to have a higher nutritional value, to be healthier, or simply to be safer and less risky. Scientists The results of this research agreed with previous data that higher amounts of dry matter and soluble solids were present in the organically grown tomatoes of all investigated cultivars compared with the conventionally grown fruits (Fig. 6) but determined that the differences were not statistically significant. The amount of dry matter varied from 6.64 (cv. 'Vilina') to 9.06% (cv. 'Benito H') in organically grown tomato fruits and from 6.37 (cv. 'Vilina') to 8.44% (cv. 'Benito H') in conventionally grown tomatoes. The highest amount of soluble solids (4.47%) was detected in fruits of the tomato hybrid 'Tolstoi' grown using the organic system. In organic tomatoes, the average amount of dry matter was 7.77%, and the amount of soluble solids was 4.40%, while conventional fruits had 7.30% dry matter and 4.30% soluble solids.

Previous studies noted that the lycopene content in organic tomatoes was lower than in conventional ones, but found a significantly higher level of β-carotene in organic fruits [42]. Schulzova and Hajslova [47] investigated the impact of fertilisation systems on biologically active compounds in tomatoes and determined that the amounts of carotenoids varied depending on the farming system and cultivar. In their experiment, levels of β-carotene ranged

**Figure 6.** The influence of farming systems on the amount of dry matter and soluble solids in tomato fruits.

from 5.4 to 9.8 mg kg-1 and levels of lycopene ranged from 137 to 286 mg kg-1. However, Riahi and colleagues [48] investigated the impact of conventional and organic production systems on the quality of field tomatoes and did not find any significant differences in the amount of lycopene for all cultivars.

The data (Fig. 7) from this study show that tomato hybrids, grown organically, accumulated significantly higher amounts of lycopene in their fruits compared with those under conven‐ tional farming, but there were no significant difference in the amount of lycopene in cv. 'Vilina' fruits. The organic fruit of the tomato hybrid 'Tolstoi' had 5.85 mg 100 g-1 of lycopene, while conventional tomato fruits had 4.58 mg 100 g-1 of lycopene. The average amount of lycopene in organic fruits was significant higher compared with conventional tomatoes. A comparison of β-carotene in organic and conventional tomatoes showed that a significant higher amount (0.21 mg 100 g-1) was found only in organic fruits of the hybrid 'Tolstoi'.

**Figure 7.** The influence of farming systems on the amount of carotenoids in tomato fruits.

### **2.2. Tomato ripening impact on fruit biochemical composition**

from 5.4 to 9.8 mg kg-1 and levels of lycopene ranged from 137 to 286 mg kg-1. However, Riahi and colleagues [48] investigated the impact of conventional and organic production systems on the quality of field tomatoes and did not find any significant differences in the amount of

**Figure 6.** The influence of farming systems on the amount of dry matter and soluble solids in tomato fruits.

The data (Fig. 7) from this study show that tomato hybrids, grown organically, accumulated significantly higher amounts of lycopene in their fruits compared with those under conven‐ tional farming, but there were no significant difference in the amount of lycopene in cv. 'Vilina' fruits. The organic fruit of the tomato hybrid 'Tolstoi' had 5.85 mg 100 g-1 of lycopene, while conventional tomato fruits had 4.58 mg 100 g-1 of lycopene. The average amount of lycopene in organic fruits was significant higher compared with conventional tomatoes. A comparison of β-carotene in organic and conventional tomatoes showed that a significant higher amount

(0.21 mg 100 g-1) was found only in organic fruits of the hybrid 'Tolstoi'.

**Figure 7.** The influence of farming systems on the amount of carotenoids in tomato fruits.

lycopene for all cultivars.

52 Plants for the Future

The fruit quality and biochemical composition of tomatoes can be determined by fruit maturity at harvest. That is particularly problematic when tomatoes are picked green because it is difficult to distinguish between mature and immature green tomatoes. Thus, the chosen harvest time determines tomato fruit quality and biochemical composition. Normally, advanced mature green tomatoes will usually achieve much better flavour at the table-ripe stage compared with fruits picked at the immature or partially mature stages, which are more susceptible to physical injuries and water loss because of their thin skin. During ripening on the vine, tomato fruits accumulate sugars, carotenoids, and ascorbic acid [1, 49]. Fruit texture is another very relevant attribute of tomato quality in common with biochemical composition. Tomato firmness is closely related to the susceptibility of fruit to physical damages at harvest time and during storage. In addition, this characteristic can be tested very easy, by human fingers, and that can be the most important factor for consumer [49, 50].

Plant genotype, growing conditions, and fruit ripeness can have a major influence on carote‐ noids content in tomato fruits [2, 34, 51]. On the basis of scientific data, the lycopene amount can vary widely in fully ripened tomatoes. For example, Heinonen and colleagues [52] detected 3.1 mg 100 g-1 lycopene, while others reported that the average amount of lycopene was 9.27 mg 100 g-1 [7], or varied from 3.1 to7.7 mg 100 g-1 in fresh tomato fruits [3]. The investigation of the impact of tomato ripening on fruit biochemical composition was carried out at the Lithuanian Research Centre for Agriculture and Forestry [53]. To evaluate the impact of fruit ripening on tomato quality, tomatoes were picked at different ripening stages: I—100% green tomato fruits, II—early stage of ripeness (10% -30% coloured tomato fruits), III—tomato fruits gained colour specific to the cultivar (60% -90% coloured tomato fruits), and IV—fully ripened (over 90% coloured tomato fruits). The research was conducted on 5 tomato (*Lycopersicon esculentum* Mill.) varieties: 'Aušriai', 'Skariai', 'Milžinai', 'Vilina', and 'Vėža'. It was found that the highest amount of accumulated lycopene was detected in fully ripened fruits and varied from 9.21 ('Milžinai') to 12.69 mg per 100 g-1 ('Vilina') (Fig. 8). In the green tomato fruits detected, lycopene levels were the lowest ones and varied from 0.25 ('Milžinai') to 0.72 mg 100 g-1 ('Vėža').

The similar tendencies were observed with β-carotene content (Fig. 9). In the green tomato fruits detected, β-carotene amount was lowest and ranged from 0.20 ('Milžinai') to 0.47 mg 100 g-1 ('Vėža'), while in fully ripened tomatoes, detected β-carotene levels were highest and varied from 1.40 ('Vėža') to 1.69 mg 100 g-1 ('Vilina'). According to these experiment, it is possible to make conclusion that levels of lycopene and β-carotene increase sequentially in tomato fruits during their ripening, except in varieties 'Vilina' (between II and III stages) and 'Milžinai' (between III and IV stages) fruits where a small increase in lycopene and β-carotene was detected, but these values were not statistically insignificant.

Fruit flavour of tomato is mainly determined by acids and sugars quantity and the ratio of the two. The flavour is more enjoyable with more sugars and less acids [54, 55]. Tomato quality changes during the fruit ripening time. There are less ascorbic acid and more organic acids in the tomatoes at the beginning of the fruit ripening, and there are the high levels of total sugar and dry matter in fruits at the end of tomato ripening. However, data regarding total sugar and ascorbic acid amount in tomatoes within their ripening vary greatly; some authors say that tomato ascorbic acid levels increase rapidly throughout ripening [33], while others report that there were no significant differences [56].

**Figure 8.** Amount of lycopene in different cultivars at different tomato ripening stages.

**Figure 9.** Amount of β-carotene in different cultivars at different tomato ripening stages.

Studies have shown that amounts of ascorbic acid (Fig. 10) and total sugars (Fig. 11) throughout tomato ripening increased in some investigated cultivars, while in others decreased. In fully ripened tomato fruits, the average amount of ascorbic acid varies from 10 to 20 mg 100 g-1. However, some scientists note that the average amount of ascorbic acid is 25 mg 100 g-1 in fresh tomatoes [57]. According to this study, it was found that ascorbic acid increased rapidly within tomato ripening only in cv. 'Vilina' fruits and the highest amount of ascorbic acid was accumulated in fully ripe tomatoes and reached 20.4 mg 100 g-1. Throughout the ripening period of tomatoes, there were no trends found of ascorbic acid accumulation in other cultivars. The lowest levels of ascorbic (in all ripening stages) were found in cv. 'Milžinai and varied from 3.8 to 4.2 mg 100 g-1. It is possible to make a conclusion that the amount of ascorbic acid mainly depends on tomato genotype and lees influenced by fruit ripening stage. Thus, the amount of total sugar varied independently of the tomato ripening stage. The highest levels of total sugar were detected in fully ripe tomatoes in three of the five investigated cultivars, and the established amount varied from 4.71% to 5.14%.

**Figure 10.** Ascorbic acid content in different tomato cultivars at different ripening stages.

**Figure 11.** Total sugar content in different tomato cultivars at different ripening stages.
