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  • Open access
  • 45 Reads
Supercritical fluid extraction and pulsed electric field assisted extraction of Ziziphus lotus fruits, leaves and roots

Currently, the consumption of natural extracts from medicinal plants and fruits present in nature, and the discovery of the many benefits and positive impacts on the human body, connected to their intake have favored and promoted research in the field of extraction. For this purpose, in recent years, the extracts of plant parts (leaves, branches, seeds, stem, roots, fruits, etc.) of the genus of Asteriscus, Atriplex, Haloxylon, Ruta, Ficus, Olea, and Zizyphus have been investigated for their several biological properties and therapeutic activities including those as an antioxidant, antitumoral, antiproliferative, hepatoprotective, and antimicrobial. The shortcoming of using the conventional methods such as maceration, Soxhlet solvent extraction, and pressurized hot water have promoted the development of novel, efficient, economical, and safe extraction techniques to recover the bioactive compounds without losing their quality and properties. Innovative methodologies such as supercritical fluid technology and pulsed electric field-assisted extraction has been proposed as sustainable methodologies to isolate nutraceuticals and pharmaceuticals from natural matrices such as herbs, spices, aromatic and medicinal plants. The study aimed to obtain extracts from fruits, leaves, and roots of Ziziphus lotus by Supercritical Fluid Extraction (SFE) and Pulsed Electric Field (PEF) assisted extraction and characterize the extracts in terms of total antioxidant capacity (ORAC and TEAC), total phenolics, chlorophyll, and carotenoids content. PEF extracts presented an interesting content of phenolic compounds, Fruits: 14.8 ± 0.1; Leaves: 31.1 ± 1.8; Roots: 28.8 ± 1.7 mg GAE/g DW. On the other hand, the concentration of phenolics in SFE extracts was, Fruits: 5.91 ± 0.2; Leaves: 1.184 ± 0.2; Roots:5.72 ±0.8 mg GAE/g DW.

  • Open access
  • 37 Reads
Printability prediction of three gels for 3D food printing

3D food printing is an innovative technique in recent years. This technique has great potential for food customization. It offers great variety of shapes, dimensions, flavours, textures, etc. It has been applied to elaborate different foods such as cookies, mashed potatoes, gels, etc. To obtain new formulations suitable for printing, it is important to carry out printability studies. These studies seek to know the printability and shape stability of formulations and is related to rheological and textural properties. Some authors are correlating printability with rheological and physico-chemical parameters. The objective of this study was to characterize the textural and rheological properties of three gels of different formulation for predict their printability. The gels are composed of 5% porcine gelatin plus 2% carrageenan-i (Gp+I), 4% bovine gelatin with 0.5% carrageenan-k (Gb+K) and 4% methylcellulose (MC). An extrusion test to determine the force required for printing and an oscillatory rheological test to determine their viscoelastic properties were carried out. The results showed that for printing Gp+I and Gb+K a lower maximum force is needed than for MC, being 45, 60 and 83 N, respectively. The average force required to extrude MC varies less than the other samples. The three samples showed a predominantly elastic behaviour. Modules between 100 Pa and 10,000 Pa indicate a zone of good impression, all modules were in that zone except for MC whose viscous modulus was 84 Pa. In terms of stability, the damping factor gave values between 0.14 (Gb+K) and 0.37 (MC), being indicative of weak gels. Observing the ratio rgH/G' for the above damping factors, it was estimated that the maximum height of the samples should be 0.8 cm, 1 cm and 0.008 cm for Gp+I, Gb+K and MC, respectively, to exhibit 5% deformation after 1 hour for a 3 cm diameter cylinder.

  • Open access
  • 111 Reads
Optimization of pigments extraction from quinoa flour fermented by Monascus purpureus supplemented with fish hydrolysate and sodium chloride

Monascus purpureus has an important use in Asian gastronomy for producing red color pigments as well as important metabolites. This fungus has been tested with different matrices in solid state fermentation, and has had a different behavior depending on the added nitrogen source. Fish hydrolysate is a rich source of free amino acids, which could lead to an improvement in pigment production. Therefore, the objective of this study is to optimize the ethanol extraction conditions for the fermentate product in order to maximise the yield, by using a response surface design. Quinoa grains were fermented with Monascus purpureus supplemented with 1.0% fish hydrolysate and 0.5% sodium chloride; and incubated for eight days at 30ºC. The extraction parameters evaluated were: ethanol graduation (40, 50, 60º), extraction temperature (50, 55, 60ºC) and ethanol:sample ratio (30:1, 40:1, 50:1 v/w). Under the optimized conditions (ethanol graduation 50.6º, extraction temperature 54.7ºC and ethanol: sample ratio of 38.7 the extraction yield (%) was 34.72 ± 0.1842 In addition, the best equation to predict extract concentration was linear and was attained by adding up absorbances measured at 400, 470 and 500 nm at a dilution of 1:6 (R2=0.966). This study helped determine the optimal conditions for the hydroethanol extraction of pigments from quinoa flour fermented by M. purpureus supplemented with fish hydrolizate. In addition, a very useful equation for future predictions of extract concentrations from that particular fermentate flour was derived.

  • Open access
  • 41 Reads
Study of melanoidins of the Maillard reaction in Dulce de Leche

The “Dulce de leche” (DL) is a dairy product elaborated by milk and sucrose concentrated in favorable conditions for the Maillard Reaction (MR). In this reaction organoleptic properties, as aroma and color are developed. It is a type of non-enzymatic browning which involves the reaction of carbonyl compounds, especially reducing sugars with compounds which possess a free amino group such as amino acids, amines and proteins.

The final stage of the chemical reaction is typified by the production of brown and nitrogen-containing polymers and co-polymers, the melanoidins. Recently research relate this products with antioxidant, antimicrobial, anti-inflammatory, antihypertensive or prebiotic activity.

In foods melanoidins are linked to proteins in a complex structure as melanoproteins which is more difficult to analyze so it is relevant the melanoidins separation and isolation from a complex matrix.

In this study, DL was elaborated in the laboratory with skim milk and sucrose, with initiated pH 7,6. Firstly, separate with dialysis and centrifugation to obtain melanoproteins. Moreover, the insoluble and colored fraction was digested by pronase enzyme. Nextly, the digested enzymatic product was fractionated by gel filtration (BioGel P2 1 a 1,8kDa). Finally, the melanoidins were separated by solid phase extraction (SPE) using a C18 cartridge with different mixtures of methanol and water. The fractions obtained were monitored by TLC and analyzed by mass spectrometry (LC-ESI-IT-MS2).

The TLC reveal with orcinol and ninhydrin, using phenylalanine, alanine and glucose as standards, indicate the presence of carbohydrates and amino acids. In addition, some compounds were fluorescent (detection at 365 nm), in agreement with reported compounds obtained in models of the MR. Mass spectrometry analysis shows compounds with typical structural motifs of melanoidins in a complex mixture with m/z less than 1200.

  • Open access
  • 73 Reads
Characterization of spray dried co-microcapsules containing probiotic culture Lactococcus lactis SKL 13 and γ-aminobutyric acid (GABA) entrapped in a ternary wall matrix

In the present study, the probiotic strain Lactococcus lactis SKL 13 and γ-aminobutyric acid (GABA), a major inhibitory neurotransmitter were co-encapsulated by spray drying technique in a ternary wall matrix (maltodextrin, inulin, and dextran). The physicochemical properties such as moisture content, water activity, probiotic survivability, GABA encapsulation efficiency, flowability (Hausner Ratio and Carr’s Index) of produced microcapsules were evaluated. The spray dried powder exhibited a higher probiotic and GABA encapsulation efficiencies of 93.12 and 83.46%, respectively. The spray drying resulted in a stable microcapsules containing a lower moisture content of 4.15%, and water activity of 0.37 and having a good flow characteristics with a product yield of 57.5%. SEM images of spray dried microcapsules revealed that spray dried powder had a smooth surface with some cavities that might be due to the rapid loss of moisture during spray drying. The x-ray diffraction patterns showed a broad background pattern which indicates the amorphous metastable state of dried powders. The synbiotic powder can be effectively incorporated in different food formulations for the development of probiotic enriched food products.

  • Open access
  • 26 Reads
Utilisation of Defined Media Towards Evaluating Brewing Ale Yeast Fermentation in Small Scale Batches

The utilisation of high gravity wort possessing a higher sugar content is frequently used to increase the capacity and efficiency of beer production. In such an environment, osmotic stress, lower nutrient availability, ethanol toxicity and elevated CO2 concentrations may decrease the sustainability of yeast performance and have a negative impact on the desired end product. Traditionally, apparent attenuation has been used as a standard measure of fermentability. Here, we describe a miniature fermentation assay with a defined fermentation media that could be used to assess fermentability on a small scale, including determination of the original gravity and final gravity of the medium for trials using four yeast strains. The results obtained using the defined media were approximately comparable to those obtained using regular wort in terms of their real attenuation limits and specific gravity, although the defined media showed lower final pH values compared to the wort for several strains. With further optimisation, the mini fermentation process applied to a defined medium could provide the foundation for future analytical research into the brewing process, using techniques such as high-performance liquid chromatography (HPLC) and quantitative polymerase chain reaction (qPCR).

  • Open access
  • 25 Reads
Antioxidant and antihypertensive properties from muscle hydrolysates of farm rainbow trout

Aquaculture is an economic activity with worldwide production of 82.1 million tons. A high potential of bioactive peptides from fish sources has been demonstrated but rainbow trout research is scarce and focused mainly on by-products. Thus, the present work aimed to obtain bioactive protein fractions through the enzymatic hydrolysis from the protein muscle of farm rainbow trout. Muscle fillets of trout at the commercial stage (250-300 g) from a local farm were homogenized in a food processor to obtain a uniform paste, which was used for protein content determination by Kjeldahl method. Afterward, trout paste was ultra-frozen at -70°C and freeze-dried at -43°C and 286X10-3 mbar. A lyophilized sample was used to perform suspensions at 5% (p/v) in Tris-HCl buffer (pH= 9), which were hydrolyzed with alcalase, having a mass ratio of 100:10 (soluble protein: enzyme). Enzymatic hydrolysis was carried out at 55°C and sampled at 0, 1, and 2 h, ending it through a boiling water bath for 10 min to inactivate the enzyme. Then, samples were centrifugated and supernatants were used for in vitro determinations of hydrolysis degree, antioxidant capacity, and antihypertensive bioactivity. All last tests were realized by spectrophotometric methodologies, measuring the amine-TNBS complex at 340 nm, DPPH remanent at 515 nm, TPTZ-Fe2+ complex at 595 nm, and hippuric acid presence to determine ACE inhibition at 228 nm. Trout muscle paste exhibited 17.87±0.31% of protein content. The maximum hydrolysis degree was equivalent to 32.64±0.37 mM of glycine. The best time for scavenging and ferric reducing power was at 2 h with 3.69±0.09 µM and 33.98±0.75 mM of Trolox and Fe2+ equivalent, respectively. At the same time, ACE inhibition was only 2.14±0.04%, having the best inhibition (56.43±2.05%) at 1 h. Results showed that antioxidant properties increased with higher hydrolysis time, but antihypertensive bioactivity could be lost.

  • Open access
  • 22 Reads
Production of antibacterial compounds from fermented dairy products using kefir grain microflora


The aim of the study was to evaluate antibacterial properties of active compounds released during the fermentation of goat milk and whey form goat milk by selected bacterial strains form kefir grain microflora (Lactiplantibacillus plantarum, Limosilactobacillus fermentum, Lacticaseibacillus rhamnosus, Lactobacillus acidophilus). Two milk sources were used i.e., goat milk and whey from goat milk from the Organic Farm in Poland. Antibacterial activity was exanimated by the evaluation of the reduction of indicator microorganisms (E. coli, Salmonella, Micorcoccus luteus and Proteus mirabilis) checking by:

- plating on the selective medium (VRBG medium, nutrient agar),

- impedance changes measured by BacTrac 4100 Automatic Microorganism Growth Analyzer,

- optical density changes analysed by Bioscreen C.

Based on the experiments, it was found that during the fermentation of whey and goat's milk, bioactive substances are released, which inhibit the growth of indicator microorganisms by up to 6 logarithmic cycles. Impedance and optical density changes observed correlated with a decrease in the number of cells of indicator microorganisms, which confirms the antibacterial properties of milk and whey fermented by selected strains from kefir grain microflora.

  • Open access
  • 54 Reads
Evaluation of Antioxidant Activity of Alcoholic Beverage Mead Produced from Greek Chestnut Honey

Mead is a yeast-derived alcoholic beverage made from the fermentation of honey, also called “honey wine” or traditionally “hydromeli”. Mead has never received the reputation it deserves, although it is a product derived from the most famous natural sweetener. However, it seems to have been in extremely high demand in recent years as it incorporates organoleptic characteristics like wine. Mead contains many biologically active substances, including phenolic compounds, derived from honey. The aim of this study was to evaluate and correlate the antioxidant activity of mead with the chestnut honey from which it is derived. For this purpose, a fermentation of chestnut honey was performed with the Belgian yeast strain M12 Saccharomyces cerevisiae var. diastaticus for 30 days at 19 ℃. Antioxidant activity was estimated using the DPPH assay, and results were expressed as mmol Trolox equivalents kg-1. In chestnut honey the scavenging effect of the DPPH radicals was 6.80±0.04 mmol Trolox kg-1, while mead was slightly better in eradicating radicals with inhibition of 7.67±0.05 mmol Trolox kg-1. Even though honey was diluted in a 1:2 ratio with water before fermentation, the final product showed a higher rate of antioxidant activity than honey. This paradoxical effect is probably because, during fermentation, compounds which can react with the radicals of the DPPH assay are probably formed. Our results demonstrate that mead has a particular scientific interest due to its antioxidant properties. Further research is needed on the effect of the yeast strain and fermentation conditions as an effort fora deeper investigation of the understudied topic of Greek mead.

  • Open access
  • 101 Reads

Honey is a natural substance produced by bees of the genus Apis. Depending on the raw material used for its production, honey can be classified into two large groups. Blossom honey, which results from the metabolization of nectar extracted from flowers, and honeydew honey, in which bees use plant or insect secretions for its production. Physicochemical characteristics are different between these two types of honey. For example, honeydew honey is darker and is characterized by high content of phenolic acids. On the contrary, blossom honey stands out for its abundance of flavonoids. Blossom honey can be also classified based on the pollen origin. Thus, honeys with more than 45% of the pollen coming from the same species can be considered monofloral, otherwise, they are considered multifloral.

Honey is one of the food products with the highest fraudulent practices. Most of the adulterations consist of ingredient dilution, adding sweet substances, such as syrups, sugar cane, or corn syrup, among others. In the market, this was reflected in the dubious drop in prices for this product. In the last few years, several honey frauds have come to light.

This work aimed to develop a non-targeted ultra-high-performance liquid chromatography – high-resolution mass spectrometry (UHPLC-HRMS) fingerprinting method to address the characterization, classification, and authentication of Spanish honey samples considering their botanical and geographical origin. A total of 136 honeys from different Spanish production regions belonging to different botanical varieties were analyzed, including: blossom honey (orange blossom, rosemary, thyme, eucalyptus, and heather) and honeydew honey (holm oak, forest, and mountain). A simple sample treatment was carried out, consisting of dissolving 1 g of honey in 10 mL of water, followed by a 1:1 dilution with methanol. The chromatographic separation of the obtained extracts was performed using a Kinetex® C-18 core-shell column (100 x 4.6 mm I.D., 2.6 μm), working under gradient elution, using an aqueous solution of 0.1% formic acid and acetonitrile as the mobile phase components. HRMS acquisition was performed using electrospray in negative ionization mode (-2500 V) in an LTQ-Orbitrap working in full scan MS (m/z 100 – 1000) at a resolution of 50,000 full-width at half maximum (FWHM). The obtained non-targeted UHPLC-HRMS fingerprints (peak signals as a function of retention time and m/z) were considered as chemical descriptors of the analyzed honey samples for principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA). PLS-DA revealed a good discrimination between blossom and honeydew honeys. Furthermore, the obtained chemometric models allowed to achieve a very good classification among the different botanical varieties under study for both blossom and honeydew honeys. The discrimination of honey regarding the different Spanish climate production regions was more limited, although some trends were observed. Thus, the non-targeted UHPLC-HRMS fingerprinting approach showed to be an appropriate methodology to address honey characterization, classification, and authentication based on their different botanical origin.