Cucurbita moschata Duch. (pumpkin) is an annual plant representing the family of Cucurbitaceae. Alongside with Cucurbita pepo L. and Cucurbita maxima Duch. it belongs to the most economically important species in the genus of Cucurbita. This species have different climatic adaptations and are widely distributed in agricultural regions worldwide (Darrudi et al., 2018).

Pumpkin is a very popular vegetable species, especially in tropical and subtropical countries. Cucurbita moschata is originating in Central America and northern part of South America. However cultivation of Cucurbita moschata, also known as butternut squash, in Slovakia is only at its development stage being cultivated in small areas of the southern parts of Slovak territory (Andrejiová et al., 2016).

Butternut squash is grown mainly for its fruits, but edible parts of the plant include the flowers, leaves, roots and seeds (Kaur, 2017). There are many results showing the beneficial effects of the consumption of butternut squash fruits. This vegetable is considered as a rich source of nutrients and phytochemicals, such as vitamins (vitamin A, vitamin B2, vitamin C and vitamin E), minerals (potassium and calcium), carbohydrates, aminoacids, fiber and the most abundant bioactive compounds – carotenoids and polyphenols (Bouamar et al., 2017). Cucurbita moschata is also popular for its low energetic value and an option of relatively long time of storage. The recent increase in the popularity of Cucurbita species has stimulated the researches in the area of their nutritional composition. Therefore, the main component of the pumpkin pulp is its levels of carotenoids (Provesi and Amante, 2015). Figure 1

Carotenoids are pigments, which naturally occurre in plants, fungi, algae and also in bacteria. There are identified more than 650 different types of these molecules in nature, including around 100 types present in the human diet. Humans can not synthesize carotenoids, we are forced to take it via supplementation (Eggersdorfer and Wyss, 2018). These natural pigments are ususally C40 tetraterpenoids with a long conjugated chain of double bonds, characterized with a range of functions in human health. This particular feature is responsible for both their pigmenting properties and the ability of many of these molecules to interact with free radicals and singlet oxygen and therefore act as an effective antioxidants (Young and Lowe, 2018)..

Although many types of carotenoids have been identified, research focuses on those that are the most prominent in the human diet. Cucurbita moschata is considered to be high in carotenoids, especially β-carotene and lutein. Other carotenoids indentified in this vegetable are α-carotene and minor carotenoids as ζ-carotene, zeaxanthin, violaxanthin, β-carotene-5,6-epoxide, β- cryptoxanthin, taraxanthin, auroxanthin, phytofluene, neurosporene and neoxanthin (Jacobo-Valenzuela et al., 2011). Jaswir et al. (2014) add, that the most important carotenoids in human diet are α-carotene, β-carotene, lutein, zeaxanthin and β -cryptoxanthine. Consumption of carotenoids has been associated with various health benefits, including their great antioxidant activity, reduced risk of age-related macular degeneration, cataract and coronary heart disease. There are further epidemiological evidences about their role in immune response enhancement and reduction of the risk of degenerative diseases such as cancer, cardiovascular diseases and atherosclerosis (Andrejiová et al., 2016; Jacobo- Valenzuela et al., 2011). Figure 2

Bouamar et al. (2017) reports, that it is well known that carotenoids have antioxidant activity and protect against oxidative stress, which can lead to the diseases mentioned above. Cucurbita moschata also contains a large heterogenous group of secondary metabolites called polyphenols, which are as well known to decrease the risk of this defects. Carotenoids and polyphenols are wellknown of capability in cellular redox imbalance modulation, as well as the endothelial and metabolic processes regarding the pathogenesis of inflammatory. One of the causes of neurodegenerative diseases formation is the increased presence of free radicals, which are undesirable for the body. Therefore, antioxidants are important, they can delay the process of oxidation of vital compounds and inhibit the formation of free radicals in the early stages. Natural antioxidants, originating from plants are highly recommended in drug and food forms. It has been proven that, they had therapeutic effects, great nutrition and higher safety, while synthetic antioxidants can cause organ damages , as they can accumulate in the human body. Figure 3

Cucurbita moschata is showing to be a promising plant in terms of its nutritional composition and invites several research teams to examine its premises (Indrianingsih et al., 2019). However, there are many factors which can affect the level of the total carotenoids and its antioixdant activity. The content of these substances in the fruit of the pumpkin differ from one variety to another, and can also be influenced by external factors – climate, nutrition, water availability, habitat, storage conditions, etc.

Moreover, the stability of carotenoids is influenced by several factors, such as the storage time and temperature, the availability of oxygen and light, and the type of carotenoid involved (Wibowo et al., 2015). The aim of the work was to determine the content of total carotenoids and antioxidant activity in fruits of 6 selected varieties of Cucurbita moschata Duch. and to record the changes in their dynamics.

This field experiment was founded in 2018 in the experimental fields of the Botanical Garden of Slovak University of Agriculture (SUA) in Nitra. Six different varieties of Cucurbita moschata Duch. – Liscia, Matilda, Orange, Serpentine, UG 205 F1 and Waltham were examined. The growing cycle at the experiment location was initiated on April 2018 and was followed by cultivating routine season. The cultivation area is located in a very warm agro-climatic region, characterized with a very dry subregion, the average annual temperature is 10 °C and the average annual rainfall is 584.5 mm. The soil is characterized as a glue fluvisol, formed on alluvial sediments.

The total carotenoids content in the pulp of the fresh fruits of selected varieties of Cucurbita moschata Duch. after the harvest and after the storage is given in the Table 1. The values ranged from 3.80 to 8.42 mg.100g^-1. In the dry matter the content ranged from 49.66 to 91.32 mg.100g^-1. The highest content was determined in ̔ Orange ̓ variety, which is known for its intensive orange colour of the pulp. Our results are comparable with those, which determined Andrejiová et al. (2016) in the range from 9.33 to 15.10 mg.100g^-1. Other authors examined various genotypes of Cucurbita moschata Duch., while the total carotenoid content in the fresh fruits ranged from 12.46 mg.100g^-1 to 69.9 mg.100g^-1 (Carvalho et al., 2015). Priori et al. (2017) reports the total carotenoid content ranging from 10.8 mg.100g^-1 to 36.7 mg.100g^-1. The stability of carotenoids differs depending on many factors. One of the main factors which has a great impact on the stability and the associated total carotenoids content is the storage. It is important to study the factors related to the loss of colour of foods based on pumpkin since colour retention during storage is one of the parameters of food quality (Gliemmo et al., 2009). On the basis of our results, we can generalize that the period of 60 days of storage had positive influence on total carotenoids content (TCC) in fresh matter. We have recorded an increase of TCC in the case of all observed varieties. A similar result has been reported by Andrejiová et al. (2016), who stated that the 52 days of storage had positive impact on TCC with the exception of one variety. After the period of 120 days of storage we have recorded interesting results. In the case of five observed varieties the TCC decreased, while the values were still slightly higher than after the harvest (Liscia, Matilda, UG 205 F1) and for the ̔Orange ̓ and ̔ Serpentine ̓ lower. On the contrary in case of ̔Waltham v̓ ariety the TCC increased by 35%. Statistically significant differences were found in this variety, both between the 0. day – 60. day and the 0.day – 120. day.

Conti et al. (2015) indicate in his research an intensifying in colour in the pulp of the fruit of Cucurbita moschata Duch. after 60 days of storage and similary a very slight decrease after 180 days of storage. The incongruitties of these results suggest that the post harvest dynamics of TCC in the fruits of Cucurbita moschata Duch. may result from the interaction of various factors, affecting the metabolism of these important compounds. Biosynthesis of carotenoids continue in fruits even during the postharvest period, until the plant material is not treated in the way, which could inactive the carotenogenesis responsible enzymes. Obviously, the high storage temperature and conditions supporting wilting may cause carotenoids degradation as well (Rodriguez- Amaya, 1997). Antioxidants are a heterogeneous category of molecules, which play an important role in human health such as preventing cancer and cardiovascular diseases, and lowering the incidence of many different diseases. The beneficial influence of many foodstuffs and beverages, including fruits, vegetables, tea, coffee and cacao, on human health has been recently recognized to originate from their antioxidant activity. Antioxidants are compounds or systems that can safely interact with free radicals and terminate the chain reaction before vital molecules are damaged. They can use several mechanisms: (I) scavenging species that initiate peroxidation, (II) chelating metal ions so that they are unable to generate reactive species or decompose peroxides, (III) quenching superoxide, preventing formation of peroxides, (IV) breaking the auto-oxidative chain reaction, or (V) reducing localized oxygen concentrations (Oroian and Escriche, 2015; Gülçin, 2012). The evolution of antioxidant activity (AOA) in the fruits of Cucurbita moschata Duch. is presented in the Table 2. The values of AOA in fresh pulp of the fruits ranged from 2.76% to 10.31%. The highest rate was recorded for the ̔Matilda ̓variety. After the 60 days of storage changes have occurred. In the case of ̔Liscia, Serpentine, Waltham ̓ variety we have recorded an increase, while in the ̔Matilda, Orange, UG 205 F1 ̓ we have observed an decrement of AOA. On the basis of our results, we can declare during the following 60 days of storage an increase of AOA in all the observed varieties.

Significant differences were found for all the varieties in all observed variants (storage period), except for the ̔

The evolution of antioxidant activity (AOA) in the fruits of Cucurbita moschata Duch. is presented in the Table 2. The values of AOA in fresh pulp of the fruits ranged from 2.76% to 10.31%. The highest rate was recorded for the ̔Matilda ̓variety. After the 60 days of storage changes have occurred. In the case of ̔ Liscia, Serpentine, Waltham ̓ variety we have recorded an increase, while in the ̔Matilda, Orange, UG 205 F1 ̓ we have observed an decrement of AOA. On the basis of our results, we can declare during the following 60 days of storage an increase of AOA in all the observed varieties. Figure 4

Significant differences were found for all the varieties in all observed variants (storage period), except for the ̔Matilda ̓ variety for the storage period variant 60 to 120 days of storage. The antioxidant activitiy in general is affected both by physical and chemical factors.

Li et al. (2012) reports, that the postharvest storage may affect the composition of some phytochemicals in plants; however, the degree of the effect depends more on the storage conditions. Metabolism of the phytochemicals begins right after harvest, and it can involve complex biochemical reactions during transportation and postharvest storage. These reactions can lead to significant changes in plant attributes (taste, smell, appearance and texture), and the health promoting phytochemicals, such as those with strong antioxidant activities. Storage temperature, atmosphere gas composition and use of chemicals are major factors that influence the quantity and quality of phytochemicals and so AOA.

The Figure 5 is showing the dynamics of changes in the dry matter of the fruit for each variety after the harvest and the storage period. As we can see, in each case there is an increasing tendency in TCC after the 60 days of storage. However, after this period a decrement appears. Despite, we recorded an exception as well at the ̔Waltham ̓ variety, characterized by 12% increment during the next 60 days of storage. The biggest abundance of TCC in DM was recorded in the ̔Orange ̓variety, by 28% during the 120 days of storage.

Bonina-Noseworthy et al. (2016) also indicate an increment of TCC in DM after 60 days of storage in the ranges from 4.2 mg.100g^-1 to 14.5 mg.100g^-1 (harvest) to 8.4 mg.100g^-1 to 23.9 mg.100g^-1 (60 days of storage).

Based on the data from our research displayed in the Figure 6, we can conclude that there are significant differences between individual varieties of the observed varieties. Significant differences were found between ̔Liscia ,̓ ̔Matilda ̓ variety and other evaluated varieties. The greatest contrast was shown between the ̔Matilda ̓ and ̔Serpentine ̓ variety. The effect of the variety on the antioxidant activity was statistically proven.

Šlosár et al. (2018) also report that, the variety of the used plant material is a major factor, which can affect the antioxidant activity.

Antioxidant activity significantly decreased after 60 days of storage (by 15%), but it was followed by statstically significant increase (by 25%) after 120 days of storage (Figure 7). The increase of the antioxidant activity during the whole period of storage was by 6.5%, but this change was not statistically significant.

Conti et al. (2015) report the data of the single antioxidants content in the fruit of Cucurbita moschata Duch., separately for ascorbic acid, α-carotene, β-carotene and lutein. The results of their study indicate a significant intital increase in α-carotene after 120 days of storage, but this was followed by its gradual reduction until the end of the storage period (another 120 days). Lutein dropped below the limit detection within the first 120 days, both ascorbic acid and β-carotene increased during the storage.

On the basis of our results showed in the Figure 8, we can state that there are significant differences between the examined varieties of Cucurbita moschata Duch. in terms of TCC. These differences were found mainly between the Serpentine ̓variety and the other varieties. The highest contrast was examined between the L̓ iscia ̓ and Serpentine variety.

The effect of the variety on the total carotenoids content was statistically proven. Andrejiová et al. (2016) also confirm the influence of the variety on the TCC.

Total carotenoids content significantly increased after 60 days of storage (by 17%). This increment was followed by 2% decrease after the next 120 days of storage (Figure 9). The increase of the total carotenoids content during the whole period of storage was by 15% and was statistically significant. Provesi et al. (2011) declare that storage period of 180 days did not significantly influenced the TCC in the brazil variety of Cucurbita moschata Duch. the ̔Menina Brasileira ̓ variety.

Cucurbita moschata Duch. is a less-known vegetable in Slovak republic, which is consumed here just a little. This cultivar is more spread in the northern part of South America and the Central America. Among the cucurbitaceous vegetables, Cucurbita moschata Duch. has always been very appreciated for its high yield, good storage period, longer periods of consumption, high nutritive value, and has numerous traditional medicinal uses. The aim of this study was to assess the dynamics of changes of total carotenoids content and antioxidant activity in the pulp of the fruit of Cucurbita moschata Duch. after the harvest and during the storage, as well as the effect of the variety on total carotenoids content and antioxidant activity. Total carotenoids content after the harvest ranged from 3.80 to 8.42 mg.100g^-1 FM. In the DM the content ranged from 49.66 to 91.32 mg.100g^-1 , while the highest content was determined in ̔ Orange ̓ variety. The period of 60 days of storage had positive influence on total carotenoids content in FM, as we have recorded an increase of TCC in the case of all observed varieties. After the period of 120 days of storage we have recorded both increase and decrease, depending on the variety. The increase of the total carotenoids content during the whole period of storage was by 15% and was statistically significant. The values of the antioxidant activity after the harvest ranged from 2.76% to 10.31%, while the highest rate was recorded for the ̔Matilda ̓ variety. After the 60 days of storage, we have recorded both increase in ̔ Liscia, Serpentine, Waltham ̓ and decrease in the ̔Matilda ̓, Orange, UG 205 F1 ̓ variety. During the following 60 days of storage an increase occurred in all of the observed varieties. Significant differences were found for all the varieties in all observed variants (storage period), except for the ̔ Matilda ̓ variety for the storage period variant 60 to 120 days of storage. Antioxidant activity significantly decreased after 60 days of storage (by 15%), but it was followed by statstically significant increase (by 25%) after 120 days of storage. The increase of the antioxidant activity during the whole period of storage was by 6.5%, but this change was not statistically significant. On the basis of our results, .we can equally state that variety of Cucurbita moschata Duch. had stastically proven effect both on the total carotenoids content and the antioxidant actvity.