The most important bioactive components of cold pressed oil from different pumpkin (Cucurbita pepo L.) seeds

The composition and content of certain bioactive components of the cold pressed oil obtained from six samples of pumpkin seeds (Cucurbita pepo L.) cultivated in Serbia were analyzed by GC and GC/MS. The composition and content of fatty acids, tocopherols and phytosterols, and the total content of squalene were determined. The results indicate oil's excellent quality, with high contents of monounsaturated fatty acids (37.1 ± 0.70–43.6 ± 0.69 g/100 g of total fatty acids), total tocopherols (38.03 ± 0.25–64.11 ± 0.07 mg/100 g of oil), sterols (718.1 ± 6.1–897.8 ± 6.8 mg/100 g of oil) and especially squalene (583.2 ± 23.6–747 ± 16 mg/100 g of oil). High content of squalene, phytosterols and monounsaturated fatty acids recommend the use of this type of the oil in the nutritional and medical purposes.     

Evaluation of water, sucrose and NaCl effective diffusivities during osmotic dehydration of banana (Musa sapientum, shum.)

Osmotic dehydration of banana (Musa sapientum, shum.) was optimized with respect to temperature (25-55 °C), salt (0-10 g/100 g) and sucrose (30-60 g/100 g) concentrations through response surface methodology. The solution of Fick’s law for unsteady-state mass transfer in a cylindrical configuration was used to calculate the effective diffusivities of water, sucrose and NaCl. Analyses were conducted in triplicate for moisture, sugar and salt contents. Peleg’s model was used to predict the equilibrium condition, which was shown to be appropriate for water loss and solute uptake. For the above conditions of osmotic dehydration, the effective diffusivity of water was found to be in the range of 5.19-6.47 × 10⁻¹⁰ m² s⁻¹, the sucrose effective diffusivity between 4.27-6.01 × 10⁻¹⁰ m² s⁻¹ and that of NaCl between 4.32-5.42 × 10⁻¹⁰ m² s⁻¹. The working conditions that simultaneously optimize these 3 variables were the temperature of 25 °C with a solution composed of 30 g/100 g of sucrose and 10 g/100 g of sodium chloride. This condition provided values of 4.80 × 10⁻¹⁰ m² s⁻¹ for effective diffusivity of water, of 3.21 × 10⁻¹⁰ m² s⁻¹ for effective diffusivity of sucrose and 4.49 × 10⁻¹⁰ m² s⁻¹ for effective diffusivity of sodium chloride.     

Analysis of chemical and structural changes in kiwifruit (Actinidia deliciosa cv Hayward) through the osmotic dehydration

Osmotic dehydration experiments of kiwifruit (Actinidia deliciosa cv Hayward) were carried out in order to apply a nonlinear irreversible thermodynamic model. Samples were immersed into 65% (w/w) sucrose aqueous solution at 30 °C during 5, 10, 15, 20, 30, 45, 60, 90, 120, 180, 250, 320, 400, 720, 1440 min. Some physical-chemical parameters were measured in fresh, treated and reposed (24 h at 30 °C) samples. It was possible to apply the enthalpy-entropy compensation coupled to a nonlinear thermodynamic model, obtaining the apparent bulk modulus and explaining the elastic answer of the tissue throughout the osmotic process. The osmotic dehydration also produces losses in the native compounds of kiwifruit such as citric acid and Calcium and Potassium.     

Volatile profile of mango (Mangifera indica L.), as affected by osmotic dehydration

The effect of osmotic dehydration on the volatile fraction of mango fruit was studied. Osmotic treatments were carried out at atmospheric pressure (OD) and by applying a vacuum pulse (PVOD). Sucrose at 35, 45, 55 and 65 °Brix was used as osmotic solution until reaching 20 or 30 °Brix in the liquid phase of dehydrated mango. Volatile compounds of fresh and dehydrated samples were obtained by simultaneous distillation–extraction, and analyzed by GC–MS. In general, osmotic dehydration provoked changes in the concentration of analyzed compounds to different extents, depending on process conditions. The use of highly concentrated osmotic solutions, and the high level of sample osmodehydration, induced losses of volatiles with respect to the fresh samples. On the other hand, more heavily diluted solutions and shorter treatment times (lower osmodehydration level) could give rise to the enhancement of volatile production. In these cases, sample mass loss was reduced during treatment since sugar gain was promoted against water loss.     

Speciation of zinc in pumpkin seeds (Cucurbita pepo) and degradation of its species in the human digestive tract

Pumpkin seeds are one of the foodstuffs recommended in diets which do not contain other Zn-rich sources. The main objectives of this work were to get information on Zn and its species in pumpkin seeds, and their possible degradation in the human gastrointestinal tract, indicative of Zn bioaccessibility. A sequential analytical approach was applied, focusing on total Zn, spatial Zn distribution, extractability, speciation and bioaccessibility of Zn and its species. It was shown that water extracts of pumpkin seeds exhibit a specific Zn species fingerprint with ca. 30% of a low-MW fraction (0.5–2 kDa) and ca. 60% of an intermediate/high-MW fraction (10–20 kDa). Digestion of Zn species under simulated stomach conditions proved that Zn species identified in plant extracts were completely decomposed to Zn²⁺. The subsequent digestion under intestinal conditions showed that Zn becomes less accessible, indicating that antinutrients like naturally present phytate may be responsible for complex formation in the small intestines, thus reducing the potential for Zn bioavailability.     

Infusion of grape phenolics into fruits and vegetables by osmotic treatment: Phenolic stability during air drying

Osmotic treatment (OT) was applied to infuse grape phenolic compounds into plant tissue. The stability of the grape phenolics after a post-treatment, such as convective air drying, was evaluated. A model food made of agar gel and three plant commodities (two fruits, apple and banana, and one vegetable, potato) were osmo-treated and subsequently air-dried (55 °C). In the osmotic solution, sodium chloride (10%, w/w) and sucrose (50%, w/w) were used when treating vegetables and fruits, respectively, while a commercial grape seed extract was the source of phenolics (0.63%, w/w). During OT, total phenolic content and antiradical scavenging capacity of plant foods were significantly increased. The extent of grape phenolic impregnation was controlled by food structure and the kind of osmo-active solute: plant tissue showed a lower grape phenolic infusion than that of the model food. OT, as a pre-treatment, protected against grape phenolic degradation during further convective air drying, even though the mechanisms controlling the phenolic degradation process require further research.     

Cold-induced ethylene in relation to chilling injury and chilling sensitivity in the non-climacteric fruit of zucchini (Cucurbita pepo L.)

Zucchini is a non-climacteric fruit which is harvested immature on reaching about 18 cm in length. In the present paper we compare fruit quality parameters in different zucchini cultivars with the production of ethylene and the expression of two ethylene biosynthesis genes (CpACS1 and CpACO1) throughout postharvest storage at 4, 12 and 20 °C. In fruit stored at 12 or 20° ethylene production and expression of CpACS1 and CpACO1 genes remained very low throughout the whole storage period. Ethylene production was also low at 4 °C, but was induced rapidly upon transfer to 20 °C for a minimum of 4 h. The expression of both CpACS1 and CpACO1 genes was also induced by storage at 4 °C. This cold-induced ethylene is not necessary for triggering chilling injury (CI) symptoms in zucchini, since they were already evident in the cold chambers before rewarming of the fruit and, therefore, before the burst of ethylene. However, the level of the cold-induced ethylene was lower in those cultivars that were more tolerant to CI, and it fell in response to temperature conditioning treatments that alleviate CI symptoms.     

Shrinkage During Convective Drying of Whole Rose Hip (Rosa Rubiginosa L.) Fruits

Volume and area shrinkages occur during food dehydration. The food behaviour must be characterized not only for using in process and equipment simulation models but also to evaluate the final quality of the product. No literature reports were found on the rose hip behaviour. After removing the peduncles, whole fruits were dehydrated in heated air at temperatures of 50, 55, 60, 65, and 75°C, air velocities of 1, 2, 3, 5 m/s, and air relative humidities of 5 and 50%. Volume changes were evaluated by picnometric techniques and with geometric measurements by micrometer and superficial area from geometric measurements. In agreement with previous reports on other foods, volume and area changes do not depend on dehydration operating variables. A linear relationship was found between the dimensionless volume change and the moisture content of the partially dehydrated fruits. The area depended on moisture according to a third-grade polynomial.     

Drying kinetics of nopal (Opuntia ficus-indica) using three different methods and their effect on their mechanical properties

Nopal (Opuntia ficus-indica) is an endemic plant of the arid and semiarid lands of America. Preservation problems are associated with nopal utilization and processing, so a practical alternative is dehydration. This work deals with the drying of nopal correlated with the textural properties of the dried product. Convective drying studies were performed and the most representative experimental results at two air flow rates (3 and 5 m/s) and two air temperatures (45 and 65 °C) are displayed here. Experiments of osmotic drying with glucose at 40 and 60 °Brix, and drying temperatures of 25 and 45 °C were tested. A combination of both drying processes was also performed. Results have shown forced convection drying with a mostly decreasing trend at the constant rate period. In the osmotic drying, moisture loss was associated to glucose concentration. Texture profile analysis of dehydrated nopal suggested that samples undergoing convective drying have more cohesiveness than samples treated solely by osmotic drying. On the other hand, samples treated by osmotic drying became more elastic. Between the two drying methods studied, the convective drying has shown the best results at the experimental conditions assayed.     

Effect of candying on microstructure and texture of plums (Prunus domestica L.)

The plums (Prunus domestica L.) of a specific ‘Green Gage’ variety, “Rainha Cláudia Verde”, are used to produce the candied product “Ameixa d’Elvas”. The candying process consists in boiling the intact plums in water and further immersion in sucrose syrup until 75 °Brix. Scanning electron microscopy of unprocessed plums revealed perfectly turgid parenchyma isodiametric cells with few intercellular spaces and the boiled plums showed a loss of intercellular adhesion of parenchyma cells and ruptures on the vascular strand structure. However, candied plums showed recovery of the turgidity and cell-to-cell adhesion of parenchyma cells. Texture analysis showed that the unprocessed plums had a fairly hard texture, improved by the presence of the skin. Firmness, rigidity, and deformation work had a sharp decrease upon boiling. However, after candying, an increase of firmness and deformation work was observed, also improved by the skin. Microstructure and texture recovery of the candying product suggests the formation of a jam-like structure in the middle lamella region promoted by the syrup. Nevertheless, cell adhesion recovery is limited by the extent of the disruption of the tissues during the boiling process. This is the first report concerning texture and microstructure changes of plums occurring during the candying process.     

Evolution of porosity, shrinkage and density of pasta fortified with pea protein concentrate during drying

The aim of this work was to study the impact of fortification with commercial pea protein concentrate on the evolution of the moisture content, density, shrinkage and porosity of pasta made from durum wheat semolina during drying. Pasta were processed from durum wheat semolina enriched with pea protein concentrate at 0, 5, 10 and 15 g 100-g-dry matter⁻¹ and dried at low (40 °C) and high (80 °C) temperature. Moisture content, density, shrinkage and porosity and effective moisture diffusivity coefficients were linked through theoretical development. It enabled to study the behaviour of the properties as a function of drying time. The results showed that drying temperature has a greater effect on the studied properties than enrichment with pea protein concentrate. Drying at 80 °C increased radial and total shrinkage compared to drying at 40 °C, but no differences were observed for longitudinal shrinkage. Pasta dried at 80 °C were denser and overall less porous, but had greater internal porosity. The volumetric percentage of water lost during drying replaced by air within the pasta matrix was lower at 80 °C. Scanning electron microscopy analysis showed that the gluten network of pasta dried at 80 °C seems denser and more continuous. Effective moisture diffusivity coefficients of pasta dried at 80 °C were higher at 5 and 10 g 100-g-dry matter⁻¹ enrichment level compared to the control.     

Kinetics of quality changes of pumpkin (Curcurbita maxima L.) stored under isothermal and non-isothermal frozen conditions

The effects of freezing process and frozen storage at isothermal (−7, −15 and −25 °C) and non-isothermal (accelerated life testing with step-stress methodology; temperature range from −30 to −5 °C) conditions on pumpkin quality were investigated. Storage temperature conditions were selected to embrace the limits practiced in the cold chain. Quality changes, such as texture, colour CIE Lab and vitamin C (ascorbic acid) content, were evaluated for both frozen storage regimes. The freezing process (that included a pre-blanching step) and subsequent frozen storage had significant impacts on all quality parameters analysed.A fractional conversion kinetic model was adequate in colour, texture and vitamin C data fits. The storage temperature effect was successfully described by the Arrhenius law.This study shows that non-isothermal frozen storage has a marked effect on pumpkin quality.     

Flavonoids of Zizyphus jujuba L. and Zizyphus spina-christi (L.) Willd (Rhamnaceae) fruits

The ripe edible fruits of jujube, Zizyphus jujuba Miller (syn. Z. sativa Gaertner, Z. vulgaris Lam.) and Christ’s thorn jujube Zizyphus spina-christi (L.) Willd (Rhamnaceae family) were phytochemically investigated, comparing their quali-quantitative flavonoids profile. Twelve compounds from both methanol extracts have been recognized as quercetin, kaempferol, and phloretin derivatives by means of HPLC/ESI-MS analyses. Six major compounds have been purified by Sephadex LH-20 column chromatography followed by HPLC and were characterized using NMR spectroscopy. One C-glycoside, 3′,5′-di-C-β-d-glucosylphloretin, was detected in Z. spina-christi. The quantitative analysis of all compounds was also reported showing a higher content of flavonoids in Z. jujuba.     

Phenolic compounds in strawberry (Fragaria x ananassa Duch.) fruits: Composition in 27 cultivars and changes during ripening

Phenolic compounds in fruits of 27 cultivars of strawberry (Fragaria x ananassa Duch.) grown in Norway were characterised and quantified by HPLC-DAD-MSⁿ. Total phenolic content, calculated as the sum of the individual compounds, varied 2.3-fold among cultivars, i.e., from 57 to 133 mg/100 g of fw. There were significant differences among cultivars in concentration of all phenolic compounds. The highest variation between cultivars was found for cinnamoyl glucose (0.6-24.9 mg/100 g of fw). Concentration of anthocyanins, the most abundant class of phenolic compounds in the majority of the cultivars, varied from 8.5 to 65.9 mg/100 g of fw. Flavan-3-ols (11-45 mg/100 g of fw) and ellagitannins (7.7-18.2 mg/100 g of fw) contributed on average 28% and 14% to total phenolic contents in the strawberry cultivars, respectively. In three cultivars harvested at three stages of ripeness, anthocyanins and cinnamic acid conjugates were the compounds most affected by ripening. The anthocyanin profile for the individual cultivars was only slightly affected by ripening and growing conditions.     

Changes on essential oil composition of coriander (Coriandrum sativum L.) fruits during three stages of maturity

The essential oils composition of coriander (Coriandrum sativum L.) fruits obtained by hydrodistillation was studied at three stages of maturity by GC–FID and GC–MS. Essential oil yields showed marked increase during maturation process and forty one compounds were identified. Geranyl acetate (46.27%), linalool (10.96%), nerol (1.53%) and neral (1.42%) were the main compounds at the first stage of maturity (immature fruits). At the middle stage, linalool (76.33%), cis-dihydrocarvone (3.21%) and geranyl acetate (2.85%) were reported as the main constituents. Essential oils at the final stage of maturity (mature fruits) consist mainly on linalool (87.54%) and cis-dihydrocarvone (2.36%). Additionally, accumulation of monoterpene alcohols and ketones was observed during maturation process of coriander fruit.     

A review of the chemistry and pharmacology of the date fruits (Phoenix dactylifera L.)

Phoenix dactylifera L., commonly known as the date palm is a primeval plant and has been cultivated for its edible fruit in the desert oasis of the Arab world for centuries. The fruits are a rich source of carbohydrates, dietary fibers, certain essential vitamins and minerals. The date pits are also an excellent source of dietary fiber and contain considerable amounts of minerals, lipids and protein. In addition to its dietary use the dates are of medicinal use and are used to treat a variety of ailments in the various traditional systems of medicine. Phytochemical investigations have revealed that the fruits contain anthocyanins, phenolics, sterols, carotenoids, procyanidins and flavonoids, compounds known to possess multiple beneficial effects. Preclinical studies have shown that the date fruits possess free radical scavenging, antioxidant, antimutagenic, antimicrobial, anti-inflammatory, gastroprotective, hepatoprotective, nephroprotective, anticancer and immunostimulant activities. This review presents a comprehensive analysis of the phytochemistry and validated pharmacological properties of date fruits and the seeds.     

Chemical changes of three native Turkish hazelnut varieties (Corylus avellana L.) during fruit development

Three native hazelnut varieties from Turkey, namely, Tombul, Palaz, and Badem, were examined for their proximate composition, minerals, and fatty acid profiles, as well as polyphenol oxidase (PPO), peroxidase (POD), and lipase activities during fruit development stages (early stage: ES, middle stage: MS, and harvest stage: HS). Proximate composition varied considerably (dry weight basis) from ES to MS. Fat was the predominant component at all stages and showed increasing trends. Six essential minerals (calcium, iron, magnesium, phosphorus, potassium, and zinc) were analysed (dry weight basis). Consuming recommended daily amount of 42.5 g hazelnut at HS supplies 23.3–25.0% of phosphorus, 11.6–18.1% of magnesium, 7.0–18.9% of iron, 4.9–8.9% of zinc, 5.1–5.7% of calcium, and 5.1–5.3% of potassium for recommended dietary allowances or adequate intake for adults. Significant (P < 0.05) decreasing trends were found in all mineral contents from early development to maturity, with some exceptions. Sixteen fatty acids were identified, among which 18:1ω9 was by far the most predominant one, followed by 18:2ω6, 16:0, and 18:0. As expected, total monounsaturated fatty acids constituted the main group of fatty acids ranging from 75.51 to 81.07% in Tombul, from 78.21 to 82.71% in Palaz, and from 73.69 to 81.65% in Badem through the maturation stages. In contrast, total polyunsaturated fatty acids showed decreasing trends from ES to HS. No significant changes (P > 0.05) were observed in total saturated fatty acids at different maturation stages. Tombul variety had the lowest PPO activity compared to those of Palaz and Badem. Badem showed highest POD activity compared to Tombul and Palaz at three stages of maturation and significant decreases (P < 0.05) in all hazelnut samples were observed in POD activity from ES to HS. No lipase activity was detected in any hazelnut samples at ES and MS, except in Badem at MS. In contrast, lipase activity was detected in all hazelnut samples at HS. These results suggest that some proximate compositions, minerals, and fatty acids gave good indications during fruit development stages, whereas enzymatic activities of PPO, POD, and lipase behaved differently among varieties and fruit development stages.     

Color stability of pumpkin (Cucurbita moschata, Duchesne ex Poiret) puree during storage at room temperature: Effect of pH, potassium sorbate, ascorbic acid and packaging material

The color stability of pumpkin (Cucurbita moschata, Duchesne ex Poiret) puree of pH 4.00 and 5.00 containing potassium sorbate (KS), ascorbic acid (AA) or their mixture, packaged in polyethylene and in polyvinyl chloride-polyvinylidene chloride copolymer (PCPC) bags, was analyzed throughout the storage at 25 °C. Color changes were measured through lightness (L), redness (a), yellowness (b). Changes in a and b were mathematically modeled. In general, lightness, redness and yellowness diminished with storage time. The presence of KS diminished color loss of purees packed in PCPC bags and increased the discoloration of purees contained in polyethylene suggesting, in the first case, that KS oxidation diminished the available oxygen protecting carotenoids oxidation, and in the second case, the existence of a coupled oxidation between KS and carotenoids helped by the oxygen presence. Addition of AA to a puree of pH 4.00 containing KS and packed in polyethylene minimized the losses of redness and yellowness; probably as a consequence of the antioxidant action of AA. The increase in pH from 4.00 to 5.00 in the presence of KS significantly minimized color degradation of puree packed in PCPC. From the point of view of improving color stability, a convenient formulation could be a puree of pH 5.00 preserved with KS and packed in PCPC.