Percorrer por autor "Chaski, Christina"
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- Chemical composition and bioactive properties of pumpkin seeds and seed cakesPublication . Polyzos, Nikolaos; Fernandes, Ângela; Chaski, Christina; Petropoulos, Spyridon Α.; Ferreira, Isabel C.F.R.; Barros, LillianPumpkin, (Cucurbita pepo L.) is one of the most important vegetables of the Cucurbitaceae family which is widely used for its edible fleshy fruit, especially fruit pulp. However, other fruit parts such as seeds are a good source of phytochemical and usually consumed in raw or processed form. ln the present work, the chemical composition and bioactive properties of pumpkin seeds and seed cakes were evaluated. Plants from local landrace ''Nychaki" were cultivated at the experimental farm of the University of Thessaly during the summer-autumn growing period of2020 and fruit were collected at marketable maturity. Seeds were removed from 15 randomly selected after cutting each :fruit at the equatorial axis. Then seeds were air-dried at room temperature and pressed with a cold-press to obtain the seed oils and seed cakes, while whole air-dried seeds were ground to fine powder. The ground seeds were rich in fat and proteins (42.7 g/100 g dw and 37.7 g/100 g dw, respectively) while carbohydrates and ash content were 16.1 g/100 dw and 3.5 g/100 g dw. On the other hand, seed cakes contained a high amount ofprotein (58.6 g/100 g dw) and carbohydrates (28.4 g/1 00 g dw ). Ground seeds and seed cakes contained ali the four vitamin E isoforms (a-, p-, y- and S-tocopherols) with y-tocopherol being the most abundant isomer in both samples (6.59 mg/100 g dw and 1.07 mg/100 g dw, respectively). The main detected free sugar in ground seeds and seed cakes were sucrose, followed by trehalose, fructose and glucose, while seed cakes contained a higher amount of sucrose and total free sugars than ground seeds. Regarding the organic acids content, oxalic acid content was the only detected compound in seed cakes, whereas no organic acids were detected in ground seeds. The main detected fatty acids were linoleic acid (43.9% and 41.5% in ground seeds and seed cakes, respectively) and oleie acid (37.0% and 36.3% in ground seeds and seed cakes, respectively), followed by stearic acid (4.83% and 5.46% in ground seeds and seed cakes, respectively). Polyunsaturated and unsaturated fatty acids were the main fatty acids class and accounted for 81.9% and 79.0% oftotal fatty acids in ground seeds and seed cakes, respectively. Finally, both materiais showed no toxic effects against non-tumor PLP2 cell lines indicating that they are safe for human consumption. ln, conclusion, the presented results highlighted the nutritional value of the tested materiais which could be considered a rich source of protein. Moreover, the high content in polyunsaturated fatty acids and tocopherols could be further valorized for pharmaceutical and nutraceutical purposes and increase the added value of pumpkin crop.
- Enhancing Tomato Growth and Quality Under Deficit Irrigation with Silicon ApplicationPublication . Añibarro-Ortega, Mikel; Pereira, Alexis; Pinela, José; Liava, Vasiliki; Chaski, Christina; Alexopoulos, Alexios A.; Barros, Lillian; Petropoulos, Spyridon A.This study aimed to evaluate the effect of two irrigation systems (deficit irrigation (DI)—70% of field capacity—and full irrigation (FI)—100% of field capacity) and a biostimulant formulation (silicon (Si) and calcium (Ca) at four different rates) on the chemical composition and fruit quality of greenhouse-grown tomatoes. Deficit irrigation and biostimulant application influenced the proximate composition of tomato fruits. Fructose and glucose were the main soluble sugars, while malic and citric acids were the predominant organic acids. Free sugar and organic acid content increased under DI and biostimulant applications. In contrast, deficit irrigation combined with biostimulant application decreased α-tocopherol levels. In terms of carotenoids, lycopene and β-carotene concentrations were higher under full irrigation. The main fatty acids were palmitic (C16:0) and linoleic (C18:2n6) acids, with saturated (SFA) and polyunsaturated (PUFA) fatty acids being the main classes. Moreover, biostimulant applications reduced the total phenolic content regardless of the irrigation regime, whereas the flavonoid content increased when biostimulants were applied under FI conditions. Regarding antioxidant activity (assessed by TBARS and OxHLIA assays), a variable response to irrigation and biostimulant application was observed. In conclusion, the application of Si and Ca under DI showed promising results in terms of yield and quality of tomato fruit and it could be considered a sustainable strategy to mitigate adverse effects of climate change on horticultural crops.
- Food industry by-products applied as pumpkin-based foodstuff preservativesPublication . Leichtweis, Maria Gabriela; Molina, Adriana K.; Pereira, Carla; Chaski, Christina; Polyzos, Nikolaos; Petropoulos, Spyridon Α.; Ferreira, Isabel C.F.R.; Barros, LillianPumpkin is traditionally cultivated and consumed worldwide, being the fruit and its by-products recognized by their nutritional and health benefits. In the current pandemic scenario and towards a circular economy, the development of a healthy and green technological food product was proposed using pumpkin pulp enriched with bioactive compounds obtained from pumpkin by-products.
- Food industry by-products applied as pumpkin-based foodstuff preservativesPublication . Leichtweis, Maria Gabriela; Molina, Adriana K.; Pereira, Carla; Chaski, Christina; Polyzos, Nikolaos; Petropoulos, Spyridon Α.; Ferreira, Isabel C.F.R.; Barros, LillianPumpkin is traditionally cultivated and consumed worldwide, being the fruit and its by-products recognized by their nutritional and health benefits. In the current pandemic scenario and towards a circular economy, the development of a healthy and green technological food product was proposed using pumpkin pulp enriched with bioactive compounds obtained from pumpkin by-products. The seeds, rinds, and fibrous placenta of seventeen different pumpkin genotypes from Greece were assessed for their antioxidant properties (TBARS), while the pulp was evaluated in terms of ash, protein, fat, and carbohydrate contents by AOAC methods¹. The free sugars profiles were obtained by HPLC-RI. All pumpkin by-products revealed great antioxidant properties, demonstrating their ability to inhibit lipid peroxidation and suggesting their potential application as sources of preservative compounds. All pulp samples recorded carbohydrates as the major compounds, with contents of about 67-86%, followed by protein (about 8-21%) and fat (about 0,4-1,1%). The ash content ranged from about 3,5 to 11%. Regarding free sugars, two predominant profiles were traced: one rich in fructose and glucose and low in sucrose, and another one with opposite prevalence (Figure 1). These results corroborate the great nutritional value of pumpkin genotypes from Greece and reveal the potential use of pumpkin by-products in the development of preservative solutions to maintain the pulp quality and safety over storage time, through the development of pumpkin-based food products.
- The effect of biostimulants on fruit quality of processing tomato grown under deficit irrigationPublication . Liava, Vasiliki; Chaski, Christina; Añibarro-Ortega, Mikel; Pereira, Alexis; Pinela, José; Barros, Lillian; Petropoulos, Spyridon Α.Water shortage can be a restrictive factor for the growth and quality of vegetable crops. Considering the alleviating effects of biostimulant application against water stress, this study aimed to investigate the effect of four biostimulant products (protein and amino acids with carboxylic acids (Tr1); protein and amino acids with seaweed extracts (Tr2); humic and fulvic acids with seaweed extracts (Tr3); SiO2 (Tr4); and control (no biostimulants added)) and two irrigation systems (regulated deficit irrigation (RDI)—65% of field capacity and regular irrigation (RI)—100% of field capacity) on quality parameters of processing tomato fruit. Regulated deficit irrigation and biostimulant application increased the energetic value, carbohydrates, and free sugars content, while organic acids showed a variable response to biostimulant use. In terms of tocopherols (α-, β-, γ-, δ-) and carotenoids (lycopene and β-carotene), regular irrigation and biostimulant application negatively affected their content, while Tr3 treatment had a beneficial impact on these lipophilic compounds under RDI conditions. The main fatty acids were palmitic (C16:0) and linoleic (C18:2n6) acids, which increased when plants were treated with Tr3 and Tr1 biostimulants under a deficit regime. Antioxidant activity (assessed by TBARS and OxHLIA assays) and total phenolic and flavonoids content also showed a variable response to the studied factors. In particular, the application of Tr3 and the control treatment under RDI increased the total phenolic content, while the control and Tr3 treatments under the same irrigation regime recorded the highest antioxidant activity. In conclusion, our results indicate that the adoption of eco-friendly strategies such as regulated deficit irrigation and biostimulant application can beneficially affect the quality traits of processing tomatoes.
- Water stress alleviation effects of biostimulants on greenhouse-grown tomato fruitPublication . Fernandes, Ângela; Chaski, Christina; Pereira, Carla; Kostić, Marina; Rouphael, Youssef; Soković, Marina; Barros, LillianThe aim of the present study was to evaluate the effects of three biostimulant products (Nomoren (N), Twin Antistress (TW), x-Stress (XS) and control treatment (C: no biostimulants added)) on the nutritional value, chemical composition and bioactive properties of greenhouse tomato fruit grown under full (W+: 100% of field capacity) and deficit irrigation (W–: 70% of field capacity) conditions. Fat content was the highest for the fully irrigated plants that received no biostimulants (CW+), while proteins and carbohydrates and energetic value were the highest in the XSW+ treatment. The content of the main detected sugars (fructose, glucose and trehalose) varied depending on the irrigation and biostimulant treatment. The highest amounts of individual and total organic acids and tocopherols were recorded in fully irrigated plants treated with Twin Antistress (TW), whereas the lowest overall values were observed under deficit irrigation for plants that received the XS treatment. The most abundant fatty acids were palmitic (27.5–36.0%) and linoleic acid (27.4–35.4%), followed by oleic (9.2–21.2%), linolenic (5.4–13.1%) and stearic acid (5.3–6.8%). Moreover, the highest values of -carotene and lycopene were recorded for the CW- and NW+ treatments, respectively. The TWW+ showed the highest antioxidant activity for both assays tested (TBARS and OxHLIA). Most of the tested extracts showed lower antibacterial activity against the tested bacteria compared to the positive controls. On the other hand, CW+, XSW+ and XSW- treatments showed higher antifungal activity (MIC values) than positive controls. In conclusion, each biostimulant product had a different effect on the determined characteristics depending on the level of irrigation. Therefore, more research is needed to better identify the mechanisms of action and the physiological processes, after which the tested biostimulants may be used to standardize the application of such products in tomato cultivation.