L-ascorbic Acid Content Research Articles

Low-Cost Electrochemical Determination of L-Ascorbic Acid Using Screen-Printed Electrodes and Development of an Electronic Tongue for Juice Analysis

Low-cost electrochemical methodologies for the determination of L-ascorbic acid (vitamin C) and the analysis of juices are developed based on its electro-oxidation on carbon screen-printed electrodes. A novel chronoamperometric methodology is developed for the quantification of L-ascorbic acid in fruit juices. The proposed method stands out for its simplicity and rapidity, demonstrating its efficacy in determining L-ascorbic acid content in various fruit juices. Notably, the results obtained with this chronoamperometric approach are compared with those yielded by chromatography, with no significant differences between the two methods being found. Additionally, an electronic tongue is developed for the differentiation of juices based on the square wave voltammetric signals.

FOLIAR APPLICATION OF DEPOLYMERISED CHITOSAN ENHANCES THE GROWTH AND CONTENT OF POLYPHENOLS AND L-ASCORBIC ACID IN Eucomis autumnalis, AN ORNAMENTAL AND MEDICINAL PLANT

Chitosan and its derivatives are promising plant biostimulants with potentially broad applications in agriculture and horticulture. In this study, we determined the effect of the application method and dose of depolymerised chitosan on morphological characteristics and metabolite levels in Eucomis autumnalis, a medicinal and ornamental plant. Depolymerised chitosan (molecular weight ~154,500 g/mol, number average molecular weight ~22,800 g/mol and degree of deacetylation ~85%) was used at 50 and 100 mg/l by drenching plants or spraying. In general, depolymerised chitosan increased the length of plant leaves and roots, especially at the dose of 100 mg/l, and also increased the fresh weight of leaves, bulbs and roots, with a more potent effect found when depolymerised chitosan was applied as a foliar spray. In addition, spraying the plants with chitosan solution at 50 and 100 mg/l caused a significant increase in the total chlorophyll content, by 55.4% and 42.0%, respectively, and the total polyphenol content, by 77.7% and 59.0%, respectively, compared with the control. On the other hand, the biosynthesis of carotenoids was most favourably affected by the application of 100 mg/l depolymerised chitosan by drenching and 50 mg/l depolymerised chitosan by spraying. Foliar application of depolymerised chitosan led to an increase in leaf L-ascorbic acid content by an average of 36.4%, regardless of the dose. The results suggest that depolymerised chitosan applied as a foliar spray promoted the growth of E. autumnalis and contributed to increased biosynthesis of polyphenols, which may be a future means of obtaining metabolites in this species.

CHIRAL SWITCHING CONTROL OF PHARMACEUTICAL SUBSTANCES

Objective: The aim of this study was to demonstrate that chiral switching should be recognized as a widespread phenomenon that extends beyond the production of pure enantiomeric drugs. Methods: To investigate the optical activity of substances from various chemical classes, enantiomers of chiral compounds (Sigma-Aldrich, USA) were chosen: valine and its racemic form (D-valine, L-valine, and racemic valine with optical purity ≥ 99%), L-ascorbic acid (content ≥ 99%), carbohydrates (D-glucose, D-galactose, L-galactose, contents ≥ 99.5%). Solutions were prepared using deuterium-depleted water (DDW–"light" water, D/H=4 ppm), natural deionized high-ohmic water (BD, D/H=140 ppm), and heavy water (99.9% D2O; Sigma-Aldrich). Optical activity was measured using the Atago POL-1/2 polarimeter. Results: One of the components in the racemic medication mixture can act as an inert agent, exhibit toxicity, or undergo undesirable biotransformation mechanisms, resulting in the formation of products with unknown properties. It has been established that a change in the deuterium/protium (D/H) ratio in water leads to a change in the equilibrium and kinetic characteristics of optically active compounds across various chemical classes, such as amino acids, carboxylic acids, and carbohydrates. An inequality was observed in the absolute values of the optical rotation of the L-and D-isomers of valine and galactose, depending on the D/H isotope ratio. The impact of chiral water clusters on optical rotation accounts for the sudden shift in the specific rotation of dilute solutions (less than 0.5%) of L-ascorbic acid in water, based on the D/H ratio. The influence of the isotopic composition of water was confirmed by studying the temperature-dependent mutarotation kinetics of D-glucose and L-and D-galactose in Arrhenius coordinates. The mutarotation process in natural high-resistivity water is characterized by an activation energy (Ea) of 40.8±1.4 kJ mol-1, while in deuterium-depleted water, Ea = 63.6±3.5 kJ mol-1. This results in a kinetic isotope effect for deuterium (KIED) of 1.6. Conclusion: Methodological approaches have been developed to control chiral switching based on the isotopic composition of water in vivo and in vitro. The study of changes in the optical activity of hierarchical structures in the human body, the influence of solvent properties on the mechanisms of optical rotation, as well as the use of KIED values, can be utilized to monitor various chiral transitions in vitro and living organisms.

Evaluation of the Nutritional Value of Prunus dulcis Blossoms and the Antioxidant Compounds of Their Extracted Oil Using Green Extraction Method

Edible blossoms and extracted oils from various parts of plants have gained the interest of researchers in recent years due to their strong antioxidant activity and their high content of vitamins. In addition, they contain a plethora of polyphenols, and they do not have high caloric content. The blossoms of Prunus dulcis (i.e., almond tree) are edible; however, they have not been examined in terms of nutritional value. The present study aimed to examine the nutritional value of almond blossoms, as well as their extracted oil. The fat content of the blossoms was 1.75 g/100 g dry weight (dw), while the defatted blossoms were found to contain 1.34 g/100 g dw of crude protein and 29.97 g/100 g dw of carbohydrates. In addition, the blossom oil was tested for its composition of fatty acids, polyphenols, and total carotenoids. According to the results, several important fatty acids for human health were identified, such as oleic (25.17%), linoleic (15.64%), and linolenic (10.15%). Simultaneously, a low oxidation index (COX), i.e., 4.05, and many monounsaturated (25.17%) and unsaturated (67.56%) fats were detected, while both polyphenols (51.86 mg GAE/kg) and carotenoids were in abundance. Finally, the combination of simple stirring with ultrasound (a green extraction method) was found to be the most appropriate method to ensure maximum amounts of various antioxidant compounds in the blossom extracts (i.e., polyphenols and L-ascorbic acid). After optimization, the total polyphenol content increased by 23.98% and L-ascorbic acid content by 6.96%. In addition, antioxidant activity was tested by different antioxidant assays and specifically FRAP, DPPH, and H2O2, which showed a corresponding increase (14.46, 17.23, and 8.79%, respectively). Therefore, it can be concluded that Prunus dulcis blossoms, besides being edible, are also highly nutritious, and their oil has nutritional value and deserves further exploration.

Technology development and study of properties of craft marshmallows with raspberry puree

The development of recipes with natural raw materials enriched with bioactive substances is an urgent task for providing the population with a complete and balanced diet. The aim of the study is to develop recipes of craft marshmallows for therapeutic, prophylactic and health-improving purposes. The research was conducted by means of the expert method, sensory analysis, and statistical methods of processing experimental data. Standard and generally accepted methods were used to determine physical and chemical parameters. To achieve this goal, it is proposed to replace part of the apple puree in the recipe with raspberry because of the raspberries’ antibacterial and immunomodulatory properties. Models of marshmallow composition with different proportions of apple and raspberry puree, protein, sugar, glucose syrup and agar-agar were developed. The sensory analysis was carried out and the organoleptic characteristics of model marshmallow compositions (taste, odour, colour, consistency, structure, and surface condition) were determined. A sensory profilogram for model marshmallow compositions was created and the model composition with the best organoleptic characteristics was determined on the basis of the expert evaluation results. The content of pectin substances and L-ascorbic acid in the studied samples was determined. The physical and chemical parameters for the model marshmallow compositions were determined. It was found that due to the increase of raspberry puree content in the marshmallow recipe the moisture content of the marshmallow will increase from 21.3% ± 0.3% in MC1 with 30% raspberry puree content to 22.1% ± 0.3% in MC3 with 40% raspberry puree content. The density, active and titratable acidity of the marshmallow will decrease with the increase of raspberry puree amount in it. The expediency of using vitamin and pectin-containing raw materials (such as raspberry puree) for therapeutic, prophylactic and health-improving purposes in the marshmallow production technology has been experimentally proved. The marshmallow recipes with different proportions of apple and raspberry puree, possessing therapeutic, preventive and health-improving purposes and expanding the range of sugary confectionery products have been developed. The proposed marshmallows contain natural ingredients and are characterised by high organoleptic characteristics. Marshmallows on the developed recipes can be produced on confectionery production line of various capacities and in restaurant establishments

Impact of Different Solvents and Temperatures on the Extraction of Bioactive Compounds from Rose Fruits (Rosa rugosa) Pomace

The use of waste brings many environmental and economic benefits to the country. One of the by-products of the fruit industry in Poland is rose fruits pomace. Rose fruit has great nutritional value and is a rich source of beneficial bioactive compounds. The aim of this study was to investigate the effects of temperature (25, 45, and 65 °C), time extraction (15, 30, 45, and 60 min), and different solvents on the recovery of total phenolic compounds (measured by Folin–Ciocalteu) and L-ascorbic acid (measured by the HPLC method) of rose fruits (Rosa rugosa) pomace. Higher temperatures (45 °C and 65 °C) showed a higher content of L-ascorbic acid but also faster degradation of this acid after 30 min of extraction. The highest content of polyphenolic compounds was obtained using 50% acetone at 65 °C (average 37.28 mg gallic acid equivalents/g of freeze-dried pomace) and the lowest using 100% acetone at 25 °C (average 12.46 mg gallic acid equivalents/g of freeze-dried pomace). The highest yield of L-ascorbic acid from pomace was obtained using water as a solvent (average 33.64 mg L-ascorbic acid/g of freeze-dried pomace). Rose fruits pomace extracts could therefore be used as natural bioactive molecules for many industrial applications.

Influence of Rheum taxa and harvesting date on the content of L-ascorbic acid and oxalic acid in the climatic conditions of South Moravia (Czech Republic)

ABSTRACT Rhubarb (Rheum L.) is a well-known medicinal and culinary plant. Apart from its rich nutritional value, rhubarb contains a higher concentration of oxalates. In this study, the content of L-ascorbic acid (AA) and oxalic acid (OA) within three rhubarb species (Rheum rhabarbarum, R. rhaponticum and R. palmatum × wittrockii) differentiated to 16 accessions in a gene bank rhubarb collection (Lednice, Czech Republic) in the condition of conventional production in the South Moravia region during the harvesting period was evaluated. While L-ascorbic acid is essential in human nutrition, oxalic acid is considered toxic, and high doses may cause serious health issues. AA and OA content, the morphology evaluation and ISSR (inter simple sequence repeats)-based genetic analysis were performed. The results of this study confirm the significant influence of taxonomy and harvesting time on the content of AA in Rheum accessions. The content of AA was determined from 6 mg · 100 g-1 to 10 g · 100 g-1 fresh weight (FW) at the beginning of the harvesting season (May) up to 25 mg · 100 g-1 FW at the end of the harvesting period. The content of OA strongly varied from 300 mg · 100 g-1 to 1800 mg · 100 g-1 FW. Regarding the antinutrient character of oxalate, the optimal harvest period of this region was estimated to be from May to early June, when the OA content was the lowest. The role of AA as a precursor of oxalate formation in rhubarb was not affirmed by the results of this study.

Effect of natural fertilization on the yield, biological value, and qualitative and quantitative composition of essential oil in common basil (<i>Ocimum basilicum</i> L.)

Basil (<i>Ocimum basilicum</i> L.) is one of the most popular herbal plants used globally in the food and pharmaceutical industries and as an ornamental plant. It is highly valued for the rich content of active substances, whose amount depends on environmental and anthropogenic factors. The type of fertilizer used is an important determinant of the yield and quality of the herb and the soil environment. The aim of the study was to assess the effect of natural fertilizers (granulated cattle manure and granulated chicken manure) applied at different doses (50, 100, 150, 200 g m<sup>−2</sup>) on the quantity and quality of the yield of common basil (<i>Ocimum basilicum</i> L.) cultivated in the temperate climate of Lublin Upland. The applied doses of manure had a significant effect on the fresh weight of <i>O. basilicum</i> L. A significant effect of the type and dose of manure on the content of L-ascorbic acid was found. Additionally, the fertilizer dose had a significant effect on the extract content in the analyzed plants. Significantly higher basil yields were achieved in the fertilization variant with 50 g m<sup>−2</sup> and 100 g m<sup>−2</sup> of the manure. The concentration of essential oil in the plants did not change under the influence of the applied manure dose. The experimental factors did not exert an effect on the content of essential oil with its main component (linalool), total nitrogen, and protein in basil plants. The highest content of linalool (78.22%) in the <i>O. basilicum</i> L. herb was determined in the variant with chicken manure fertilization at the dose of 150 g m<sup>2</sup>.

Chemical composition of Dracocephalum kotschyi and Origanum majorana hydrosols and their effect as a natural preservative on the quality of fresh-cut broccoli during storage

Dracocephalum kotschyi and Origanum majorana hydrosols, as a beneficial by-product of steamed-distilled essential oil (EO), are consumed for treating fresh-cut broccoli. The effect of two independent variables, the concentration of hydrosols (50-100%) and the portion of Origanum majorana hydrosol to the sum of Dracocephalum kotschyi and Origanum majorana hydrosol (0-100%) on maintaining the quality of fresh-cut broccoli (content of moisture, L-ascorbic acid, and total phenolic components, antioxidant activity, textural and color features, and microbiological properties) after 14 days of storage at 4°C was assessed and modeled through response surface methodology. Origanum majorana hydrosol was effective in preserving the firmness, color, and ascorbic acid content of fresh-cut broccoli. Origanum majorana hydrosol was more efficient at reducing the mesophilic and fungal populations, while Dracocephalum kotschyi hydrosol was effective in controlling the psychrophilic and lactobacillus count. Increasing the concentration of hydrosols decreased the mesophilic count; however, it had no considerable effect on the psychrophilic, lactobacillus, and fungal populations of the product. Optimum levels of independent variables considering the microbial and physicochemical properties of the product were 47.9% portion of Origanum majorana hydrosol, 52.1% portion of Dracocephalum kotschyi hydrosol, and 73.93% concentration of hydrosols. A comparison of the optimal and control samples’ characteristics revealed that treatment of fresh-cut broccoli with appropriate concentration and the portion of the hydrosols postponed the microbial spoilage and textural, colorimetric, and nutritional changes of fresh-cut broccoli during 20 days of storage.

Enzymatic tissue browning caused by biological membrane degradation in the young immature fruit of ‘Moriya’ persimmon (Diospyros kaki Thunb.)

Determining the mechanism of fruit tissue browning is important to prevent fruit quality degradation and reduce fruit loss at the postharvest stage in persimmons. We aimed to provide a fundamental understanding of the mechanism of browning of mature persimmon fruit and contribute to develop a method for its prevention over the course of the marketing supply chain by analyzing the browning of young immature persimmon fruit. Tissue browning was first observed seven days after harvest (DAH), and spontaneous ethylene production was initiated at five DAH. The activities of the browning enzymes polyphenol oxidase (PPO) and peroxidase (POD) were sufficiently high to induce fruit tissue browning. As these enzymes are normally sequestered by biological membranes in cells, we hypothesized that biological membrane degradation occurs prior to browning. Electrolyte leakage and the increase in malondialdehyde content occurred during storage. An increase in malondialdehyde content provided evidence of progressive membrane degradation. The increased expression of phospholipase relative DkPLD alpha1, DkPLD beta/gamma1, and lipoxygenase relative DkLOX3 genes, probably induced by ethylene, indicated their significant roles in membrane degradation. The ascorbic acid may play a role in inhibiting the oxidation of phenolic substrates by PPO and POD owing to its antioxidant activity. The results of our study suggest that the hydrolysis of phospholipids by DkPLD alpha1 and DkPLD beta/gamma1 and peroxidation by DkLOX3 promote biological membrane degradation in both persimmon skin and flesh. Additionally, we hypothesized that the decrease in L-ascorbic acid content could induce browning, as a result of PPO and POD leaked from the biological membrane could react with phenolic substrates.

THE EFFECTS OF APPLYING CHITOSAN OF DIFFERENT MOLECULAR WEIGHTS ON THE QUALITY OF KAMCHATKA BERRIES (LONICERA CAERULEA L.): PART 2

We evaluated the effects of chitosan of different molecular weights on the quality of Kamchatka berries after harvest and storage. Chitosan with lower molecular weights (from 3 to 21 kDa) positively influenced the soluble solid content after harvest. However, chitosan had no significant effect on titratable acidity after harvest. Regardless of the chitosan molecular weight, the berries contained from 7.4% to 30% more total polyphenols compared with the control (162 mg per 100 g) after harvest. After storage, the total phenolic content decreased slightly and depended on the storage conditions. The L-ascorbic acid content was the highest after harvest and storage after treatment with the highest molecular weight of chitosan (950k kDa). Chitosan 50 kDa positively influenced the firmness and puncture resistance of the berries after harvest (146% of control) and storage (135% of control).

Technological Processing of Dried Powdered Rosehips to Tablets Through Wet Granulation

Abstract The pseudo-fruits of Dog Rose are a rich source of L-ascorbic acid and several other active substances, which means their high supportive therapeutic potential. The study aimed to examine the impact of the chosen technological procedure for the preparation of tablets containing rosehip powder on the amount of L-ascorbic acid in the final pharmaceutical form. Drying of the plant drug was performed at room temperature to avoid possible thermal degradation of this heat-sensitive compound. Similarly, drying of the granules after wet granulation in the oven was replaced by natural drying at room temperature. The composition of two types of prepared granule formulations differed in the filler – lactose (LAC) or microcrystalline cellulose (MCC). Apart from the disintegration test, they meet the technological requirements for granules or tablets. Lactose was confirmed as a more suitable filler, which despite the unsuccessful disintegration of the granules, ensures the disintegration of tablets within 15 minutes even without the addition of a special excipient acting as a disintegrant. The content of L-ascorbic acid detected using isotachophoresis – capillary zone electrophoresis was 87.16 ± 5.06 µg in LAC tablets and 63.33 ± 2.83 µg in MCC tablets.

In vitro anticholinergic and antiglycaemic properties of frost-hardy Actinidia fruit extracts and their polyphenol profile, L-ascorbic acid content and antioxidant capacity

The aim of this study was to investigate the inhibitory effects of Actinidia arguta (‘Weiki’, ‘Skarlet September Kiwi’) and Actinidia kolomikta (‘Lande’) fruit extracts against advanced glycation end-products (AGEs) formation and acetylcholinesterase (AChE) activity. The extracts were also tested regarding polyphenol profile and Lascorbic acid content (UHPLC-DAD-MS), and antioxidant capacity (DPPH, ABTS). ‘Scarlet September Kiwi’ showed the strongest anti-AGEs activity studied with BSAGLU (IC50 = 2.68) and BSA-MGO (IC50 = 18.06) models. The highest anti-AChE activity was found for the ‘Lande’ extract (IC50 = 4.56). ‘Lande’ showed the highest L-ascorbic acid content (8271.96 µg/g dw), ABTS (312.42 µmol TE/g dw) and DPPH (282.01 µmol TE/g dw) values. 'Scarlet September Kiwi' revealed the highest individual phenolics concentration (2321.43 µg/g dw). The contents of (+)-catechin and L-ascorbic acid were significantly correlated with anti-AChE activity. This research sheds new light on the bioactivity of Actinidia arguta and Actinidia kolomikta fruit elucidating the role of (+)-catechin and L-ascorbic acid in prevention of Alzheimer’s disease.

Mineral and phytochemical profiles of selected garlic (Allium sativum L.) cultivars

Garlic (Allium sativum L.) is a versatile horticultural commodity with multiple medicinal properties. In this study, we determined the content of macroelements (K, Na, Ca, Mg, P) and microelements (Cu, Zn, Mn, Fe, Cr, Ni, Co, Pb and Cd), the content of phenolic acids (gallic acid, chlorogenic acid, ferulic acid, p-hydroxybenzoic acid, caffeic acid) and L-ascorbic acid in selected cultivars of garlic (Bjetin, Eden Rose, Garpel, Havran, Mojmir, Novozamocky). Statistical analysis indicated, that the Bjetin is characterized mainly by a high content of minerals (Mn, Fe, Ca Co), while Garpel and Mojmir are characterized by higher levels of ferulic acid, gallic acid, and p-hydroxybenzoic acid. Novozamocky is characterized by a high content of chlorogenic acid. Positive correlations between Pb content and gallic acid, ferulic acid, and p-hydroxybenzoic acid content, and negative correlation between Pb content and chlorogenic acid content were determined.

Melon (Cucumis melo L.) Fruit Yield under Irrigation and Mycorrhiza Conditions

The size and quality of the melon fruit yield depend on the cultivar, climatic and agronomic factors. A three-year field experiment investigated the effect of arbuscular mycorrhizal fungi (AMF) application and irrigation (IR) on the fruit yield of melon (Cucumis melo L. var. saccharinus Naud.) cultivars. The study was conducted on a certified organic farm located in south-eastern Poland (51.36° N, 22.83° E). The factors of the experiment were as follows: cultivar (Melba, Emir F1, Seledyn F1, Oliwin) and cultivation method (AMF and IR; AMF and non-IR; non-AMF and IR; non-AMF and non-IR as control). The dry matter (%), soluble solid (%), total sugar and reducing sugar (% fresh weight, FM), L-ascorbic acid (mg · 100 g−1 FM), and carotenoid (mg · 100 g−1 FM) contents of the fruit were determined. The highest total and marketable fruit yields were obtained using AMF and IR. Fruit from the AMF series (IR and non-IR) had the most carotenoids (respectively: 801.5 and 788.8 µg · 100 g−1 FM). The fruits of the AMF and IR plants contained the most total sugars (5.98%) and reducing sugars (2.91%) compared to the others. The control plants had the lowest number of marketable fruit, total and marketable fruit yield, and accumulated the least L-ascorbic acid, total sugars and reducing sugars. We suggest that AMF and IR can be recommended as a practical agronomic solutions for the field cultivation of melon under temperate climate conditions.

Living Mulch as Sustainable Tool to Improve Leaf Biomass and Phytochemical Yield of Cynara cardunculus var. altilis

Living mulch (LM) provides many beneficial agro-ecological services by reducing soil evaporation, conserving moisture, controlling soil temperature, reducing weed growth, increasing organic matter and nutrient availability, and improving microbial activities. Legumes, commonly used as living mulches, can affect the yield and quality of main crops. We hypothesized that Egyptian clover co-cultivated with Cynara cardunculus var. altilis (cultivated cardoon) can positively affect both leaf biomass and phytochemical yield. The study was performed on two growing seasons of field experiments to evaluate the potential variation in biomass and phytochemical yields of cardoon leaves. In addition, the leaves were collected at 90, 120, and 150 days after transplanting to evaluate the possible effect of the harvest time. LM improved the fresh and air-dried leaves biomass yields, total phenolic, and dry matter content, while it had no effect on the content of crude fibre, total sugars, L-ascorbic acid, total chlorophylls, and antioxidant activity. Except for luteolin-7-O-glucoside content, no negative effect of LM was observed on the polyphenol profile. Behind the cultivation system, the parameters were also affected by both the harvest time and growing season. According to our data, the proposed intercropping of cultivated cardoon with LM could represent an innovative cultivation system to increase both leaf biomass and the health-promoting compounds of cultivated cardoon leaves by sustainable soil management.

Growth and Quality of Leaf and Romaine Lettuce Grown on a Vertical Farm in an Aquaponics System: Results of Farm Research

The integration of indoor vertical cultivation with a recirculating aquaculture system into an aquaponic system has the potential to become one of the most effective sustainable production systems for fish and leafy vegetables. In this study, lettuce was produced on rafts in a coupled recirculation aquaponic system in the plant factory under controlled environmental conditions. The aims of this study were to evaluate the yield, mineral status, and health-promoting bioactive compounds of leaf and romaine lettuce cultivars grown in a recirculating aquaponic system. The yield and biometric parameters and quality parameters of lettuce leaves (nitrate, mineral, L-ascorbic acid, carotenoid, phenolic compound, and total polyphenolic contents) were examined. Monitoring of the water in the aquaponic system showed a low concentration of nitrates, phosphorus (P), potassium (K), and magnesium (Mg), but the proportion of mineral nutrients as well as pH were stable throughout the lettuce cultivation period. The heads of romaine lettuce ‘Yakina’, ‘Pivotal’, and ‘Waygo’ reached a fresh weight of 86 g, on average, 23% higher than the leaf lettuce ‘Nordice’ over a three-week cultivation period. Despite the low nutrient concentration in the aquaponic solution, the nutrient status of the romaine lettuces ‘Yakina’ and ‘Pivotal’ was within the optimal range. The concentrations of chlorophyll a and carotenoids in ‘Yakina’ and ‘Pivotal’ were higher than those in ‘Nordice’ and ‘Waygo’. The nitrate, phosphorus, and potassium contents in the leaves of ‘Nordice’ and ‘Waygo’ were below the optimal range; however, their polyphenol concentrations were the highest. Our results indicate that the effectiveness of aquaponic cultivation of lettuce in terms of biomass production and the nutritional and health-promoting value of lettuce depends on the plant genotype.

Ascorbic Acid Content and Antioxidant Activities of White and Brown Teff [Eragrostic tef (Zucc.)Trotter] Grains and Injera.

Teff [Eragrostis tef (Zuccagni) Trotter] is a cereal grain originating in Ethiopia as a staple food for millions of people. Its grain is a gluten-free superfood and got acceptance as a medicinal ingredient. Therefore, it is worthwhile to determine the antioxidative activities and L-ascorbic acid contents of teff grain and its baked food (injera). This study aimed to determine the ascorbic acid contents and antioxidant activities in the aqueous extract of the white and brown teff grains and their injera samples using iodimetric titration and UV-Vis spectrophotometric methods, respectively. The ascorbic acid contents in the white and brown teff ranged from 67.9-112.6 mg/100 g and 69.2-117.2 mg/100 g, respectively, and those in injera of the selected teff samples ranged from 30.5-32.9 mg/100 g and 37.3-43.0 mg/100 g, respectively. The antioxidant activities ranged from 1.26-7.04 μmol AAE/g for the white teff grains, 1.44-6.29 μmol AAE/g for the brown teff grains, 1.81-2.47 μmol AAE/g for white teff injera, and 3.89-4.86 μmol AAE/g for the brown teff injera samples. Findings of the present study have revealed that white teff and brown teff grains and their injera were found to have a higher content of ascorbic acid than commonly consumed grains and vegetables. No significant difference (α = 0.05) has been observed between the two varieties of teff grains with respect to the ascorbic acid content and antioxidant activities. However, there was a statistically significant difference (α = 0.05) in the ascorbic acid content and antioxidant activities between the teff grains and their injera samples. Therefore, this study indicated that teff grains and injera are rich in ascorbic acid content and antioxidant activities as compared to other cereal grains and are very crucial for human nutrition and health.

Effect of Air-Drying and Freeze-Drying Temperature on the Process Kinetics and Physicochemical Characteristics of White Mulberry Fruits (Morus alba L.)

Mulberry fruits (MF) contain many biologically active compounds beneficial for human health. In particular, in the literature, there are no studies on the kinetics of the freeze-drying of MF and the effect of the process temperature on the properties of dried fruits. The objective of this study was to ascertain how freeze-drying (FD) and air-drying temperature affected the kinetics of dehydration and chosen physicochemical parameters of MF. Both temperature and dehydration methods significantly influenced the drying rate and properties of MF. The Midilli model was the best fitted to the experimental data of the course of drying curves and with the lowest values of mean-square error. The highest lightness and yellowness were noted for freeze-dried fruit, whereas air-dried MF were characterized by the highest redness. An increase in drying temperature significantly changed the color of fruits and led to the degradation of L-ascorbic acid content. The highest content of L-ascorbic acid was found in fresh fruits (214 ± 4 mg/100 g dry mass (DM)) and freeze-dried fruits at 30 °C (182 ± 3 mg/100 g DM). Both FD and AD drying significantly reduced the content of this compound. The lowest reduction in L-ascorbic acid was observed for freeze-dried fruits. Fruits freeze-dried at 30 °C showed the highest content of total phenolics and antioxidant capacity.

Nutritional Value and Sensory Quality of New Potatoes in Response to Silicon Application

Since silicon regulates plant physiological and biochemical processes, it was hypothesized that foliar silicon application could contribute to improving the quality of new potatoes. This paper analyzes the effect of silicon (sodium silicate) on the nutritional value and sensory quality of new potatoes. Silicon was applied at the dose of 23.25 g Si·ha−1 or 46.50 g Si·ha−1 once at the leaf development stage (BBCH 14–16) or at the tuber initiation stage (BBCH 40–41) and twice, at the leaf development and tuber initiation stages. Potatoes were harvested 75 days after planting (the end of June). Silicon had no effect on the dry matter, total sugars and monosaccharides, protein, L-ascorbic acid or nitrate content in new potato tubers, but it increased the starch content under water deficit conditions. The most starch was accumulated by tubers following the application of 46.50 g Si·ha−1 at the leaf development stage (BBCH 14–16). Silicon did not affect the color of tuber flesh after cooking.