Enhanced extraction of flavanones hesperidin and narirutin from Citrus unshiu peel using subcritical water

Flavanones including hesperidin and narirutin constitute the majority of the flavonoids that occur naturally in citrus fruits. The main purpose of this study was to extract valuable natural flavanones from agricultural by-products such as citrus peels using subcritical water extraction (SWE). Thus, the application of SWE to extraction of flavanones hesperidin and narirutin from Citrus unshiu peel was evaluated, and the effect of key operating conditions was determined by varying the extraction temperature (110–200 °C) and time (5–20 min) under high pressure (100 ± 10 atm). The maximum yields of hesperidin (72 ± 5 mg/g C. unshiu peel) and narirutin (11.7 ± 0.8 mg/g C. unshiu peel) were obtained at an extraction temperature of 160 °C for an extraction time of only 10 min. These yields accounted for approximately 99% of the total amount of these flavanones in the original material. The SWE was compared with three conventional extraction methods in terms of the extraction time and recovery yields for hesperidin and narirutin. The hesperidin yield by SWE was more than 1.9-, 3.2-, and 34.2-fold higher than those obtained by extraction methods using ethanol, methanol, or hot water, respectively, and the narirutin yield was more than 1.2-, 1.5-, and 3.7-fold higher.     

Thermal decomposition and oxidation of β-caryophyllene in black pepper during subcritical water extraction

Subcritical water extraction is an efficient technique for extracting components from various plants by changing the polarity of water. β-caryophyllene is a natural bicyclic sesquiterpene with the highest content found among black pepper essential oils. In this study, the efficiency of extraction and yield of β-caryophyllene from black pepper were investigated using a subcritical water extraction technique. The optimal conditions of β-caryophyllene (1.19 ± 0.38 mg/g), and caryophyllene oxide (0.82 ± 0.38 mg/g) were obtained from black pepper under extraction conditions of 170 °C/10 min, and 200 °C/15 min, respectively. As the extraction temperature was increased, β-caryophyllene oxidation proceeded and the extraction content of caryophyllene oxide increased. It is anticipated that both β-caryophyllene and caryophyllene oxide with high biological activity can be used to selectively extract compounds using subcritical water extraction, which will be helpful in industrial applications.     

LC–MS/MS characterization,antidiabetic, antioxidative,and antibacterial effects of different solvent extracts of Anamur banana (Musa Cavendishii)

The main objective of this study was to examine the phenolic compounds and the antibacterial, antioxidant, anti-α-glucosidase and anti-α-amylase activities of the different extracts (methanol, ethanol and hexane) of Musa cavendishii collected from the Anamur district in Turkey. LC–MS/MS was used to identify phenolic compounds. Quinic acid, acotinic acid, hesperidin and amentoflavone were identified in methanol extract. These phenolic compounds, excluding hesperidin, were also identified in the ethanol extract. Methanolic extract appeared the most active in all enzyme inhibition, antibacterial and antioxidative activity assays which is mainly due to its rich phenolic content. The methanol extract of banana showed the highest anti-α-glucosidase and anti-α-amylase activities with IC50 values of 5.45 ± 0.39 mg/mL, 9.70 ± 0.29 mg/mL, respectively. This study showed that methanol and ethanol extract, especially the methanol extract, have potential for use in the development of functional foods for reducing the diabetes and bacterial risks.     

Isolation of hesperidin from peels of thinned Citrus unshiu fruits by microwave-assisted extraction

Simultaneous extraction by microwave-irradiation and crystallisation were performed in the same pot of solvent of 70% (v/v) aqueous ethanol for isolation of hesperidin from thinned immature fruit peels of Citrus unshiu as refining of Citrus waste biomass. The hesperidin content in immature fruits peels was about 3.2-fold higher than that of mature fruit. After microwave-assisted extraction (MAE), the yield of hesperidin reached 58.6 mg/g, which was comparable to the amount obtained after extraction using DMSO:methanol (1:1, v/v) as a solvent for 30 min at room temperature. Heating temperature and time for isolation of hesperidin crystallites were optimised as 140 °C and 8 min by using response surface methodology. Under this optimal condition, 86.8% (47.7 mg/g) of total hesperidin was isolable by MAE and low-temperature storage (5 °C, 24 h).     

Effects of soaking treatment on the acrylamide and inulin contents of Jerusalem artichoke tea and its antioxidant activity

There are several studies that show that large amounts of acrylamide are detected in Jerusalem artichoke (Helianthus tuberosus L.) tea. This study examined acrylamide, inulin content and antioxidant properties of Jerusalem artichoke tea brewed in different conditions. Uniformly sliced Jerusalem artichokes were soaked in different salt and acidic solutions for 60 min at 20 °C and extracted with hot or cold water. The acrylamide content was analyzed by high-performance liquid chromatography–tandem mass spectrometry. The Inulin content and antioxidant activity were analyzed by spectrophotometer. Soaking significantly reduced acrylamide levels (p < 0.05) with the largest decrease observed for acetic acid, whereas the effects of all soaking treatments on inulin content were similar. Teas brewed using small-particle-size samples and hot water exhibited the highest acrylamide/inulin levels and antioxidant activity. Consequently, The most suitable treatment for Jerusalem Artichoke tea preparation was 1-h soaking in 1% acetic acid at 20 °C.     

Novel inactivation methods of Doenjang (fermented soybean paste) by high pressure and ohmic heating

The changes of the total cell number in doenjang (Korean traditional fermented soybean paste) by conventional conduction heating, high pressure non-thermal treatment, and ohmic heating were compared. A total of (10¹–10²) CFU/g cells were decreased by heating at (100–105) °C for 10 min. The inactivation rate was improved when heated to a temperature higher than 110 °C, but the taste, color of doenjang were severely changed. Inactivation by high pressure at (200–800) MPa was not achieved, because the total cell did not reach a reduction of 10¹ CFU/g. The total bacterial counts of 10³ CFU/g were decreased during ohmic heating at 15 V and 60 Hz for 10 min, and showed the most effective inactivation. Therefore, application of the ohmic heating in doenjang with high viscosity can kill target microorganisms related to quality deterioration, and rapid and uniform ohmic heating leads to reduction in sensory quality damage.     

Antimicrobial activity of acid-hydrolyzed Citrus unshiu peel extract in milk

Citrus fruit (Citrus unshiu) peels were extracted with hot water and then acid-hydrolyzed using hydrochloric acid. Antimicrobial activities of acid-hydrolyzed Citrus unshiu peel extract were evaluated against pathogenic bacteria, including Bacillus cereus, Staphylococcus aureus, and Listeria monocytogenes. Antilisterial effect was also determined by adding extracts at 1, 2, and 4% to whole, low-fat, and skim milk. The cell numbers of B. cereus, Staph. aureus, and L. monocytogenes cultures treated with acid-hydrolyzed extract for 12 h at 35°C were reduced from about 8 log cfu/mL to <1 log cfu/mL. Bacillus cereus was more sensitive to acid-hydrolyzed Citrus unshiu peel extract than were the other bacteria. The addition of 4% acid-hydrolyzed Citrus unshiu extracts to all types of milk inhibited the growth of L. monocytogenes within 1 d of storage at 4°C. The results indicated that Citrus unshiu peel extracts, after acid hydrolysis, effectively inhibited the growth of pathogenic bacteria. These findings indicate that acid hydrolysis of Citrus unshiu peel facilitates its use as a natural antimicrobial agent for food products.     

Improving the pressing extraction of polyphenols of orange peel by pulsed electric fields

The influence of pulsed electric field (PEF) treatment on the extraction by pressing of total polyphenols and flavonoids (naringin and hesperin) from orange peel was investigated. A treatment time of 60 μs (20 pulses of 3 μs) achieved the highest cell disintegration index (Zp) at the different electric field strengths tested. After 30 min of pressurization at 5 bars, the total polyphenol extraction yield (TPEY) increased 20%, 129%, 153% and 159% for orange peel PEF treated at 1, 3, 5 and 7 kV/cm, respectively. A PEF treatment of 5 kV/cm to the orange peels increased the quantity of naringin and hesperidin in the extract of 100 g of orange peels from 1 to 3.1 mg/100 g of fresh weigh (fw) orange peel and from 1.3 to 4.6 mg100 g fw orange peel respectively. Compared to the untreated sample, PEF treatments of 1, 3, 5 and 7 kV/cm increased the antioxidant activity of the extract 51%, 94%, 148% and 192%, respectively.The results of this investigation demonstrate the potential of PEF as a gentle technology to improve the extraction by pressing of polyphenols from fresh orange peel. This procedure enhances the antioxidant capacity of the extracts, reduces extraction times and does not require using organic solvents.Industrial relevanceProcessing of orange fruits to obtain fresh juice or citrus-based drinks generates very large amounts of byproduct wastes, such as peels that are a rich source of polyphenols mainly flavonoids. Extraction of these compounds from orange peels is a crucial step for use of these compounds in the food and pharmaceutical industries as antioxidants. PEF-assisted extraction by pressing of polyphenols from fresh orange peels stands as an economical and environmentally friendly alternative to conventional extraction methods which require the product to be dried, use large amounts of organic solvents and need long extraction times.     

Influences of extrusion parameters on physicochemical properties of textured vegetable proteins and its meatless burger patty

Isolated soy protein, wheat gluten, and starch at ratio 5:4:1 were texturized under different moisture contents (40 and 50%) and die temperature (130 and 150 °C) by the twin-screw extruder. Physicochemical properties were firstly studied. These textured vegetable proteins (TVPs) were used to form 100% plant-based burger patties. Cooking and textural features were secondly investigated. TVP at 50% moisture content and 130 °C die temperature represented the highest water absorption capacity and integrity index but the lowest solubility among TVPs. Cooking loss and shrinkage in diameter and thickness, cohesiveness, chewiness, hardness, and cutting strength of TVP meatless burger patties were significantly lower than that commercial meat patty, while moisture retention and springiness of TVP meatless burger patties were higher (p < 0.05). Our results found that the texture of patty made with TVP at 50% moisture content and 130 °C die temperature was the most similarity to commercial meat patty.     

Brewing of glucuronic acid-enriched apple cider with enhanced antioxidant activities through the co-fermentation of yeast (Saccharomyces cerevisiae and Pichia kudriavzevii) and bacteria (Lactobacillus plantarum)

Co-fermentation using yeast (Saccharomyces cerevisiae and Pichia kudriavzevii) and the bacteria (Lactobacillus plantarum) as starters isolated from spontaneous sourdough was conducted for the brewing of glucuronic acid (GlcA)-enriched apple cider. The concentration of GlcA in the apple cider co-fermented for 14 d with commercial S. cerevisiae and L. plantarum was 37.7 ± 1.7 mg/mL while a concentration of 62.8 ± 3.1 mg/mL was recorded for fermentation with P. kudriavzevii and L. plantarum, which was higher than the corresponding single yeast fermentation. The co-fermented apple cider revealed higher 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of 171.67 ± 0.79 µg trolox equivalents (TE)/mL using P. kudriavzevii and L. plantarum, compared to the control (143.89 ± 7.07 µg TE/mL) just using S. cerevisiae. Thus, the co-fermentation of S. cerevisiae and L. plantarum and P. kudriavzevii and L. plantarum provided a new strategy for the development of GlcA-enriched apple cider with enhanced antioxidant capacity.     

Quantification of main phenolic compounds in sweet and bitter orange peel using CE–MS/MS

The food and agricultural products processing industries generate substantial quantities of phenolics-rich subproducts, which could be valuable natural sources of polyphenols. In oranges, the peel represents roughly 30% of the fruit mass and the highest concentrations of flavonoids in citrus fruit occur in peel. In this work we have carried out the characterisation and quantification of citrus flavonoids in methanolic extracts of bitter and sweet orange peels using CE–ESI–IT–MS. Naringin (m/z 579.2) and neohesperidin (m/z 609.2) are the major polyphenols in bitter orange peels and narirutin (m/z 579.2) and hesperidin (m/z 609.2) in sweet orange peels. The proposed method allowed the unmistakable identification, using MS/MS experiments, and also the quantification of naringin (5.1 ± 0.4 mg/g), neohesperidin (7.9 ± 0.8 mg/g), narirutin (26.9 ± 2.1 mg/g) and hesperidin (35.2 ± 3.6 mg/g) in bitter and sweet orange peels. CE coupled to MS detection can provides structure-selective information about the analytes. In this work we have developed a CE–ESI–IT–MS method for the analysis and quantification of main phenolic compounds in orange peels.     

Subcritical water extraction of flavonol quercetin from onion skin

Subcritical water could be an excellent alternative to organic solvent as a medium for extracting flavonol quercetin, due to its temperature-dependent selectivity, safety, efficiency of recovery, and lower cost. This study investigated the application of subcritical water extraction (SWE) of quercetin from onion skin and evaluated the effect of key operation conditions by varying the temperature (100-190 °C), extraction time (5-30 min), and mixture ratio of onion skin and diatomaceous earth (DE) (0.5:3.5-2:2) under high pressure (90-131 bar). The maximum yield of quercetin (16.29 ± 0.75 mg/g onion skin) was obtained at extraction temperature of 165 °C, extraction time of 15 min, mixture ratio of 1.5:2.5 for onion skin and DE. The SWE was compared with three conventional extraction methods in terms of the efficiency. The quercetin yield by SWE was over eight-, six-, and fourfold greater than those obtained using the ethanol, methanol, and water-at-boiling-point extraction methods, respectively.     

Subcritical water extraction of phenolic compounds from potato peel

Potato peel, a waste generated from potato processing, is a disposal problem. But, potato peel is a good source of functional ingredients such as phenolic compounds. This study investigated the extraction of eight phenolic compounds (Gallic acid, GAC; Chlorogenic acid, CGA; Caffeic acid, CFA; Protocatechuic acid, PCA; Syringic acid, SGA; p-hydroxyl benzoic acid, PBA; Ferulic acid, FRA and Coumaric acid, CMA) from potato peel using subcritical water.Experiments were performed in a batch stainless steel reactor at 6 MPa, 2 mL/min and temperatures ranging from 100 to 240 °C at residence time of 30 to 120 min. High recoveries of phenolic compounds (81.83 mg/100 g; wet basis wb) were obtained at 180 °C and extraction time of 30 min compared to 3 h extraction with methanol (46.59 mg/100 g wb). CGA (14.59 mg/100 g wb) and GAC (29.56 mg/100 g wb) were the main phenolic compounds obtained from potato peel at 180 °C. Subcritical water at 160 to 180 °C, 6 MPa and 60 min might be a good substitute to organic solvents such as methanol and ethanol to obtain phenolic compounds from potato peel.     

Antimicrobial activity of 405 nm light-emitting diode (LED) in the presence of riboflavin against Listeria monocytogenes on the surface of smoked salmon

This study investigated the antimicrobial activity of 405 nm light-emitting diode (LED) with and without riboflavin against Listeria monocytogenes in phosphate buffered saline (PBS) and on smoked salmon at different storage temperatures and evaluated its impact on food quality. The results show that riboflavin-mediated LED illumination in PBS 25 °C significantly inactivated L. monocytogenes cells by 6.2 log CFU/mL at 19.2 J/cm², while illumination alone reduced 1.9 log CFU/mL of L. monocytogenes populations at 57.6 J/cm². L. monocytogenes populations on illuminated smoked salmon decreased by 1.0–2.2 log CFU/cm² at 1.27–2.76 kJ/cm² at 4, 12, and 25 °C, regardless of the presence of riboflavin. Although illumination with and without riboflavin caused the lipid peroxidation and color change in smoked salmon, this study demonstrates the potential of a 405 nm LED to preserve the smoked salmon products, reducing the risk of listeriosis.     

Physicochemical Properties of Starches from Different Lotus Cultivars in Japan: Shinashirobana cultivar and Kanasumi-line No. 20

Abstract: We investigated the physicochemical properties of starches from rhizomes of two lotus (Nelumbo nucifera Gaertn.) cultivars, Shinashirobana cultivar and Kanasumi-line No. 20, harvested at the same farm in Japan. A rapid visco analyser analysis indicated that pasting temperatures of the starches from Shinashirobana cultivar and Kanasumi-line No. 20 were 62.1 and 66.5 °C, respectively, and the peak viscosities of the starch of both lotuses were similar 244 and 240 RVU, respectively. The starch from the Kanasumi-line No. 20 at 60 °C had low viscosity, 16.2 mPa∙s, but the starch from Shinashirobana cultivar had higher viscosity, 2,720 mPa∙s, at 60 °C. The onset and peak temperatures of the differential scanning calorimetry (DSC) curve of the starch from Shinashirobana cultivar were 4–5 °C lower than those of the starch from Kanasumi-line No. 20, although both exhibited similar ΔH values (13.4 and 11.6 J/g). The distribution patterns of the branched chain lengths of amylopectin in the two starches indicated that the rate of low-degree of polymerization (DP 5–12) of all branched chains was higher for the starch from Shinashirobana cultivar than that for the starch from Kanasumi-line No. 20. These results suggest that the increased rate of DP 5−12 in the starch from Shinashirobana cultivar is related to the higher viscosity of the starch.     

Thermomechanical process intensification for oil extraction from orange peels

The study investigated the intensification and improvement of oil extraction from orange peel through a thermomechanical process: the instantaneous controlled pressure drop (briefly D.I.C. process). This process involves subjecting orange peel for a short time to steam pressure, followed by an instantaneous decompression to a vacuum at 50 mbar. Central composite design was used to study the combined effects of processing steam pressure (1–7 bar; which corresponds to a temperature ranging between 100 °C and 162 °C respectively), processing time (0.3–3.7 min) and initial moisture content of orange peel before thermomechanical oil extraction (9.8–60.2% on dry material basis). The quantitative analysis, have been undertaken on oil present in orange peels, after processing. Correlation analysis of the mathematical regression model indicated that quadratic polynomial model could be employed to optimize the extraction of oil from orange peel. From response surface plots, the three variables exhibited a linear effect with the strongest effect for the processing pressure. The optimum reaction conditions selected with response surface analysis were as follows: steam processing pressure: 6.6 bar, processing time: 3.68 min, initial moisture content: 53.6% d.m. basis. Under these conditions, experimental yield of orange peel oil was close to predicted value (99%) calculated from the polynomial response surface model equation. A kinetic study indicated that extraction performed by D.I.C. process is clearly quicker than conventional steam distillation method.

Industrial relevance

World production of citrus fruit has experienced continuous growth in the last decades of the XX century. Total annual citrus production was estimated at over 105 million tons in the period 2000–2004 (http://www.unctad.org/infocomm/anglais/orange/market.htm). Oranges constitute the bulk of citrus fruit production, accounting for more than half of global citrus production in 2004. Thus, the quantities of generated by-products are very important. In this study, extraction of oil from orange peel was performed through a thermomechanical process developed in our laboratory. We report on some results obtained using this process as well as others comparing extraction kinetics when using a conventional steam distillation process and the proposed extraction process. One of the advantages of the described method is the short contact of extracted oil with the heated zones in the apparatus resulting in a lower heating period of the product compared to steam distillation. At industrial scale, this is interesting regarding oil quality and energy saving.     

Characterization of gluten-free rice bread prepared using a combination of potato tuber and ramie leaf enzymes

A combination of freeze-dried powder of disproportionating enzyme (D-enzyme)-containing potato tuber and β-amylase-containing ramie leaf was used to improve the gluten-free (GF) bread, and its physicochemical properties were characterized. The presence of D-enzyme and β amylase in the potato tuber and ramie leaf was confirmed. Sixty five percent of partially gelatinized rice flour and 20% corn starch was combined with 10% freeze-dried potato tuber and 1% ramie leaf powder, and baked. The specific volume increased by 23% compared to the control with improved internal characteristics. Texture profile analysis revealed that retrogradation of the bread was retarded when stored for 90 h at 4 °C. The bread crumb amylose content was reduced from 14 to 9% and amylopectin branch chain-length distribution was rearranged, whereby the proportions of the branch chains with Degree of polymerization (DP) < 9 and DP > 19 decreased. The results suggest that D-enzyme and β-amylase cooperatively altered amylose/amylopectin ratio and amylopectin structure.     

Antioxidative and anti-inflammatory properties of Citrus sulcata extracts

Citrus sulcata was subjected to ultrasound, high-pressure, and Soxhlet extractions. The antioxidant and anti-inflammatory activities of the extracts were evaluated qualitatively and quantitatively. The antioxidant content of the peel extract was twice that of the fruit extract. The quantitative analysis showed that the narirutin and hesperidin contents in the peel extracts were 8.8 and 7.5 mg/100 g, respectively. These extracts had a total phenolic content of 112.22 ± 2.89 gallic acid equivalent (GAE) mg/100 g, a total flavonoid content of 54.09 ± 1.01 rutin equivalent (RE) mg/100 g, DPPH radical scavenging activity of 46%, and antioxidant activity of 213.25 ± 2.82 μM of Trolox equivalents (TEAC). C. sulcata extracts could prevent hydrogen peroxide (H₂O₂)-induced oxidative stress, reduce expression of the inflammatory markers nuclear Factor kappa B (NFκB) and phosphorylated IκBα (p-IκBα) in A549 human lung carcinoma cells, and inhibit Lipopolysaccharide (LPS)-induced THP-1 monocyte differentiation to an extent of 85%.     

Pilot study of countercurrent cold and mild heat extraction of sugar from sugar beets, assisted by pulsed electric fields

This study describes experiments on pulsed electric field (PEF)-assisted water extraction of sugar from sugar beet using a pilot countercurrent extractor with 14 extraction sections. Cossettes were prepared from sugar beet by industrial knives and PEF treatment of the cossettes was done with electric field strength E varied between 100 and 600 V/cm. The total time of PEF treatment was t_PEF = 50 ms. The effects of the main extraction parameters (temperature of extracting water and draft) on the extraction kinetics, as well as on the juice and cossette (pulp) characteristics, were investigated. The temperature of extraction from PEF-treated cossettes was varied from 30 to 70 °C; the draft was varied from 120 to 90%. The principal possibility of cold (at 30 °C) and moderate thermal (50-60 °C) extraction of sucrose from sugar beet cossettes treated by PEF was confirmed on the pilot countercurrent extractor. The purity of the juice obtained by cold and moderate thermal extraction was not lower than the purity of juice obtained by conventional hot water diffusion at 70 °C. The sugar beet pulp can be well exhausted by cold or mild thermal extraction of cossettes treated by PEF. Decrease of draft to 100-90% permitted increasing of the extracted juice concentration, but the cossettes were worse exhausted. The pulp obtained by cold extraction of PEF-treated cossettes had dryness >30%, which was noticeably higher than dryness of the pulp obtained by conventional hot water extraction technique.     

Effect of pulsed electric fields and high pressure on improved recovery of high-added-value compounds from olive pomace

Olive pomace is considered a solid by-product and a rich source of valuable compounds such as polyphenols, flavonoids with antioxidant properties, and proteins. Nonthermal technologies, which cause alterations to cell permeability, are being explored to assist conventional recovery techniques. The aim of this study was to assess the effect of pulsed electric fields (PEF) and high pressure (HP) on improved recovery yield of the high-added-value compounds or to shorten the extraction time of these compounds. Olive pomace (Tsounati cv) was pretreated with PEF (1.0 to 6.5 kV/cm, 0.9 to 51.1 kJ/kg, and 15 µs pulse width) or HP (200 to 600 MPa and 0 to 40 min). Evaluation of the intracellular compounds extracted via solid–liquid extraction (50% ethanol–water solution) was performed. More intense PEF and HP conditions resulted in a significant increase of the phenolic concentration up to 91.6% and 71.8%, respectively. The increased antioxidant capacity of each extract was correlated to phenolic compound concentration. The protein concentration that was achieved with PEF pretreatment was doubled; however, HP-pretreated extracts reached 88.1% higher yield than untreated for pressures up to 200 MPa. HP and PEF pretreatment decreased extraction completion time t₉₈ (needed time to recover the equal amount of phenolics and proteins of untreated after 60 min of conventional extraction) to 12 min and lower than 1 min, respectively. To conclude, both pretreatments are effective in improving the conventional extraction process for increased yield recovery of high-added-value compounds from olive pomace.