Essential Oils of Five Syzygium Species Growing Wild in Vietnam: Chemical Compositions and Antimicrobial and Mosquito Larvicidal Potentials.

The essential oils of five Vietnamese Syzygium species (Syzygium levinei, S. acuminatissimum, S. vestitum, S. cumini, and S. buxifolium) were first hydro-distilled and analyzed using GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry). Monoterpene hydrocarbons, sesquiterpene hydrocarbons, and oxygenated sesquiterpenoids were the main chemical classes in these oils. All these essential oils showed good-excellent antimicrobial activities against Gram-positive bacteria Enterococcus faecalis, Staphylococcus aureus, and Bacillus cereus, and the yeast Candida albicans. S. levinei leaf essential oil, rich in bicyclogermacrene (25.3%), (E)-ß-elemene (12.2%), (E)-caryophyllene (8.2%), and ß-selinene (7.4%), as well as S. acuminatissimum fruit essential oil containing (E)-caryophyllene (14.2%), α-pinene (12.1%), caryophyllene oxide (10.9%), ß-selinene (10.8%), α-selinene (8.0%), and α-humulene (5.7%), established the same MIC value of 8 µg/mL against E. faecalis and B. cereus, which were much better than the positive control streptomycin (MIC 128-256 µg/mL). The studied essential oils showed the potential to defend against mosquitoes since they caused the 24 and 48 h LC50 values of less than 50 µg/mL against the growth of Culex quinquefasciatus and Aedes aegypti larvae. Especially, S. buxifolium leaf essential oil strongly inhibited Ae. aegypti larvae with 24 and 48 h LC50 values of 6.73 and 6.73 µg/mL, respectively, and 24 and 48 h LC90 values of 13.37 and 10.83 µg/mL, respectively. These findings imply that Vietnamese Syzygium essential oils might have potential for use as supplemental antibacterial agents or as "green" alternatives for the control of mosquitoes.

Juice Powders from Rosehip (Rosa canina L.): Physical, Chemical, and Antiglycation Properties.

Fruits from rosehip (Rosa canina L.) are gaining popularity due to their content and profile of bioactive components. Rosehip is distinct for its antioxidant, immunomodulatory, and anticancer properties. However, the abundance of these bioactives led to a tart taste, resulting in its consumption mainly in processed form. Due to microbiological safety, pasteurization is the preferred way of processing, which affects the chemical properties of the juice. A promising approach to improve acceptability of rosehip's physical properties, while preserving its bioactive compounds and adding health-promoting benefits, is to enrich the rosehip juice with functional carriers before drying. The influence of the carrier type (maltodextrin, inulin, trehalose, palatinose) and drying technique (spray- and freeze-drying) on the physical, chemical, and antioxidant properties of pasteurized, and non-pasteurized juice powders was examined in this study. In addition, the ability of powders with functional carriers to inhibit protein glycation was evaluated. Spray drying led to products with improved physical properties in relation to freeze-drying. The addition of carrier substances significantly influenced the antioxidant capacity determined by TEAC ABTS and FRAP methods, whereby the application of inulin and palatinose retained antioxidant capacity better than the frequently used maltodextrin. Moreover, rosehip juice powders showed a promising ability to inhibit protein glycation.

Fermentative Liberation of Ellagic Acid from Walnut Press Cake Ellagitannins.

Oil is extracted from walnut leaves behind large quantities of defatted press cake that is still rich in valuable nutrients. Aspergillus oryzae and Rhizopus oligosporus, two molds traditionally used in Asia, have the necessary enzymes to use the nutrients in the walnut press cake. Walnuts and the press cake contain ellagitannins, known as precursors for ellagic acid and urolithins. In this study, experiments to optimize the solid-state fermentation of walnut press cake were performed in order to liberate ellagic acid from ellagitannins. Extracts of fermented products were then analyzed with an HPLC-DAD to measure the liberation of ellagic acid from ellagitannins. Good growth of R. oligosporus and A. oryzae mycelia on the walnut press cake was observed. A single mold culture was subjected to a hydration of 0.8 mL/g, an addition of 37.5 mmol/kg acetic acid (AA) and 1% NaCl, and an incubation temperature of 25 °C; these were observed to be good conditions for solid-state fermentation for walnut press cake. The highest ellagic acid concentration was obtained at 48 h. At 72 h, degradation dominated the liberation of ellagic acid.

The effect of dechitinization on iron absorption from mealworm larvae (Tenebrio molitor) flour added to maize meals: stable-isotope studies in young females with low iron stores.

BACKGROUND: Edible insects have a low ecological footprint and could serve as an alternative dietary iron source. However, chitin, a major component of insects, avidly binds iron and might inhibit iron absorption. OBJECTIVES: We aimed to measure fractional iron absorption (FIA) from Tenebrio molitor-based test meals with and without dechitinization, and to assess the effect of native and low chitin T. molitor on FIA from iron-fortified maize porridge. METHODS: We measured iron absorption in young females with low iron stores (n = 21) from 1) labeled (54FeSO4) fortified maize porridge (maize alone); 2) intrinsically labeled (57Fe added during rearing) T. molitor larvae with native chitin content (NC) added to maize alone; and 3) dechitinized intrinsically labeled (57Fe) T. molitor larvae with low chitin content (LC) added to maize alone. We determined FIA using erythrocyte isotope incorporation and measured in vitro iron dialyzability from the 3 meals. RESULTS: NC and LC T. molitor had similar mean ± SD iron content (12.0 ± 0.1 mg/100 g). Geometric mean (95% CI) FIAs from the 3 test meals were 1) maize alone: 5.8% (3.2%, 10.8%); 2) maize + NC T. molitor: 5.3% (2.5%, 11.3%) and 4.1% (1.9%, 8.7%); and 3) maize + LC T. molitor: 4.6% (2.0%, 10.3%) and 4.0% (1.8%, 9.2%), for extrinsic and intrinsic labels, respectively. FIA from NC and LC T. molitor did not significantly differ, and both were lower (P < 0.005) than FIA from the labeled maize porridge in the 3 meals, which did not significantly differ. The slopes of the relations between FIA and serum ferritin in the different meals and from the intrinsic and extrinsic labels did not significantly differ. CONCLUSIONS: T. molitor biomass does not strongly affect iron absorption when added to maize porridge. Our data suggest T. molitor iron is absorbed from the common nonheme iron pool. Native T. molitor is high in iron which is moderately well absorbed, suggesting it could be a valuable dietary iron source.This trial was registered at clinicaltrials.gov as NCT04510831.

Dietary Modulation of the Human Gut Microbiota and Metabolome with Flaxseed Preparations.

Flaxseeds are typically consumed either as whole flaxseed, ground flaxseed, flaxseed oil, partially defatted flaxseed meal, or as a milk alternative. They are considered a rich source of vitamins, minerals, proteins and peptides, lipids, carbohydrates, lignans, and dietary fiber, which have shown hypolipidemic, antiatherogenic, anticholesterolemic, and anti-inflammatory property activity. Here, an in vitro batch culture model was used to investigate the influence of whole milled flaxseed and partially defatted milled flaxseed press cake on the gut microbiota and the liberation of flaxseed bioactives. Microbial communities were profiled using 16S rRNA gene-based high-throughput sequencing with targeted mass spectrometry measuring lignan, cyclolinopeptide, and bile acid content and HPLC for short-chain fatty acid profiles. Flaxseed supplementation decreased gut microbiota richness with Firmicutes, Proteobacteria, and Bacteroidetes becoming the predominant phyla. Secoisolariciresinol, enterodiol, and enterolactone were rapidly produced with acetic acid, butyric acid, and propionic acid being the predominant acids after 24 h of fermentation. The flaxseed press cake and whole flaxseed were equivalent in microbiota changes and functionality. However, press cake may be superior as a functional additive in a variety of foods in terms of consumer acceptance as it would be more resistant to oxidative changes.

1H NMR spectrometry for methanol quantification in apple wines and ciders as optimised by comparison to SIDA-HS-GC-MS.

Methanol, a hepato- and neurotoxic compound, is present in apple-based beverages as a by-product of the enzymatic degradation of pectin. Stable isotope dilution assay (SIDA) employing gas chromatography-mass spectrometry (GC-MS) is the state-of-the-art method for methanol determination in beverages. Despite higher initial investment costs, quantitative 1H NMR spectroscopy (qNMR) is a simpler and faster analytical technique to quantify numerous analytes in liquid foods. Beyond targeted analyses, qNMR spectral fingerprints in the product might be used for non-targeted analytical goals, such as adulteration and contamination detections. Here, an existing 1H-qNMR method used for wine profiling was optimised for methanol quantification in apple-based products, including cross-validation against a SIDA-HS-GC-MS method and reference values from interlaboratory trials. The optimisation involved a pivotally important estimation of a correction factor by an external calibration approach, making qNMR results comparable to SIDA-HS-GC-MS. The optimised qNMR method is suggested to be an alternative for methanol quantification in beverages.

The Vitamin C Analogue 2-O-ß-D-Glucopyranosyl-L-ascorbic Acid in Rhizomes, Stems and Leaves of Lycium barbarum.

Awareness of health benefits of goji berries coming from their bioactive compounds, mostly antioxidants like ascorbic acid, has grown. Recently, an ascorbic acid analogue from goji berries, the 2-O-ß-D-glucopyranosyl-L-ascorbic acid has been reported. In rats, the analogue is absorbed intact and in the form of free vitamin C and consequently has been proposed as a provitamin C. Synthesis of the analogue is demanding and laborious and therefore reliable natural sources are searched. Knowledge concerning the analogue's occurrence in other parts of goji plant is lacking. The aim of this study was to evaluate the contents of 2-O-ß-D-glucopyranosyl-L-ascorbic acid in rhizomes, stems and leaves from Lycium barbarum. Rhizomes, stems and leaveswere extracted and the content of 2-O-ß-D-glucopyranosyl-L-ascorbic acid and non glucosylated, free ascorbic acid was determined by HPLC-DAD. 2-O-ß-D-glucopyranosyl-L-ascorbic acid was found in all goji plant tissues investigated. Based on dry weight, 3.34 mg/100 g were found in the leaves, 4.05 mg/100 g in the stems and up to 12.6 mg/100 g in the rhizomes. Nevertheless, the analogue content in goji berries is much higher (40 to 280 mg/100 g dry weight). The present study confirmed the presence of 2-O-ß-D-glucopyranosyl-L-ascorbic acid in rhizomes, stems and leaves of Lycium barbarum. However, their content compared to goji berries is considerably lower.

Phenolic compounds of grape stems and their capacity to precipitate proteins from model wine.

Reintegration of grape stem, a by-product from wine production, into the food chain is of high interest from an economic and environmental perspective. Therefore, an investigation of stems was undertaken and is described here. It is known that quality of stems is of high variability. In this study the stems from four grapevine varieties (Syrah, Cabernet Sauvignon, Merlot and Chasselas) cultivated in Switzerland were treated in following ways: drying, cutting and separation into fractions based on particle size. All fractions were then characterised for their phenolic compounds content. It was found that Chasselas fractions contained most phenolic compounds. The addition of grape stems of the four different varieties allowed reduction of the protein content of a model wine. The extent of protein precipitation was highly correlated with the amount of phenolic compounds in stems added. Among the examined varieties, Chasselas brought most promising results, with the high reduction of the protein at low level of stem addition.

Bioactive Compounds of Juice and Peels of Yuzu Fruits Cultivated in Switzerland.

Yuzu is a citrus fruit cultivated mainly in northeast Asia. Due to the huge gastronomic interest emerging in recent years, some attempts to grow yuzu in Europe are being made. Juice and peel of yuzu cultivated in Switzerland have been characterised in this study. Peel constituted the major part of yuzu fruit followed by flesh, juice and seeds. The fruit degree of maturity was investigated by measuring pH, total titratable acidity and total soluble solids of the juice. The analyses were pursued by determining the content of vitamin C, malic and citric acids amounting to 0.560, 6.18 and 44.7 g/L, respectively. Four flavanones: naringin, hesperidin, naringenin, and hesperetin were identified and quantified in both juice and peel. The most abundant flavanone was hesperidin with 47 µg/mL and 640 µg/g dry matter (DM) in juice and peel, respectively. For the first time yuzu grown in Switzerland have been analysed and the obtained values have been compared with literature for other citrus fruits. Yuzu juice showed higher contents of citric and malic acid. Yuzu cultivated in Switzerland contained nearly twice as much vitamin C as yuzu juices from different regions of Japan. The content of vitamin C of yuzu was as high or higher than in most other citrus fruits. Large differences in the content of flavanones in yuzu juice from different regions of Japan were reported, in general the values noted were lower than those in the present study.

Drying-induced physico-chemical changes in cranberry products.

Sugar-free cranberry juice (XAD) and juice with 15% of maltodextrin were dried by freeze-, vacuum and spray drying methods. Total phenolics (589-6435mg/kg dry matter) including 5 flavonols, 3 phenolic acids, 2 procyanidins and 5 anthocyanins were stronger affected by juice formulation than by drying methods. Spray drying of juice, regardless of its formulation, was competitive to freeze drying in terms of polyphenols' retention. Increase in temperature up to 100°C during vacuum drying of XAD extracts resulted in degradation of polyphenolics (down to 4%), except chlorogenic acid. Its content increased with rise in temperature and accelerated hydroxymethylfurfural formation. The stronger the impact of drying, the more chlorogenic acid is present in cranberry products. In all powders analysed, formation of furoylmethyl amino acids was noted. Antioxidant capacity of cranberry products was influenced by juice formulation and was linked to content of polyphenols.

Stability of goji bioactives during extrusion cooking process.

Due to the increasing popularity of goji berries, efforts are made to enlarge the offer of goji containing foods. In this study, rice flour based extrudates enriched with goji berries were investigated. The extrusion was performed using a twin screw extruder with constant feed moisture and screw speed. Raw mixtures as well as extruded products obtained were analysed in order to determine antioxidant activity and contents of rutin, zeaxanthin dipalmitate and 2-O-ß-d-glucopyranosyl-l-ascorbic acid. The antioxidant activity of goji extrudates was boosted up to 20times compared to the extrudates without any addition. The process of extrusion increased the antioxidant activity despite of decrease in rutin content. Regardless of extrusion conditions rutin retention in the extrudates was not lower than 60% compared to the respective raw mixtures. In the case of zeaxanthin dipalmitate the retention level was around 40%. 2-O-ß-d-glucopyranosyl-l-ascorbic acid was stable at the conditions applied.

Amber ale beer enriched with goji berries - The effect on bioactive compound content and sensorial properties.

Goji berries, traditionally used in Chinese medicine, are nowadays gaining popularity in the Western world. Efforts are made to enlarge the offer of goji containing foods. In this study, goji berries were added to ale type beer at different stages of the production process in order to develop a beverage with desirable sensory characteristic and high antioxidant capacity. The obtained beers differed significantly in terms of appearance, taste and antioxidant activity. Consumers preferred beers to which goji berries were added at the beginning of the brewing process. These beers were also characterized by lower turbidity, high color intensity, caramel- and coffee-like taste, high antioxidant activity and high content of bioactives such as rutin and 2-O-ß-d-glucopyranosyl-l-ascorbic acid. To conclude, an addition of goji berries to traditional brewing process creates a perspective to enlarge the range of goji containing foods.

Bioactives of coffee cherry pulp and its utilisation for production of Cascara beverage.

Coffee cherry pulp is a by-product obtained during coffee production. Coffee cherry pulp contains considerable amounts of phenolic compounds and caffeine. An attempt to produce Cascara, a refreshing beverage, has been made. Six dried coffee pulp samples and a beverage called Cascara produced in Switzerland out of one of those samples were investigated. Aqueous extraction of coffee pulps revealed a content of total polyphenols between 4.9 and 9.2mg gallic acid equivalents (GAE)/gDM. The antioxidant capacity was between 51 and 92µmol Trolox equivalents (TE)/gDM as measured by the assay with ABTS radical. Bourbon variety from Congo and maragogype variety showed highest caffeine contents with 6.5 and 6.8mg/gDM. In all samples chlorogenic acid, protocatechuic acid, gallic acid and rutin were present. The beverage Cascara contained 226mg/L of caffeine and 283mgGAE/L of total polyphenols whereas antioxidant capacity amounted to 8.9mmol TE/L.

Effect of theanine and polyphenols enriched fractions from decaffeinated tea dust on the formation of Maillard reaction products and sensory attributes of breads.

The antiglycoxidative properties of theanine (TEF) and polyphenols enriched fractions (PEF) prepared from tea dust were tested in a model system composed of bovine serum albumin (BSA) and methylglyoxal (MGO). PEF caused a decrease in available free amino groups of BSA in presence and absence of MGO, suggesting the simultaneous occurrence of glycoxidation reaction and phenols-protein interaction. The presence of PEF and TEF inhibited formation of fluorescent advanced glycation end-products (AGEs). Moreover, theanine (TB) and polyphenol-enriched bread (PB) were formulated. A significant increase in free amino groups was observed in TBs with a dose-response effect, while addition of PEF in bread produced a significant decrease (p<0.05). PEF efficiently reduced fluorescent AGE formation in breads compared with TEF. The results are in line with the simplified model systems. PEF used as food ingredient allows obtaining a tasty food possessing health promoting properties and lower content of potential harmful compounds (AGEs).

Identification of bioaccessible and uptaken phenolic compounds from strawberry fruits in in vitro digestion/Caco-2 absorption model.

Strawberry fruits are highly valued for their taste and nutritional value. However, results describing the bioaccessibility and intestinal absorption of phenolic compounds from strawberries are still scarce. In our study, a combined in vitro digestion/Caco-2 absorption model was used to mimic physiological conditions in the gastrointestinal track and identify compounds transported across intestinal epithelium. In the course of digestion, the loss of anthocyanins was noted whilst pelargonidin-3-glucoside remained the most abundant compound, amounting to nearly 12 mg per 100 g of digested strawberries. Digestion increased the amount of ellagic acid available by nearly 50%, probably due to decomposition of ellagitannins. Only trace amounts of pelargonidin-3-glucoside were found to be absorbed in the intestine model. Dihydrocoumaric acid sulphate and p-coumaric acid were identified as metabolites formed in enterocytes and released at the serosal side of the model.

Characterisation of Aronia powders obtained by different drying processes.

Nowadays, food industry is facing challenges connected with the preservation of the highest possible quality of fruit products obtained after processing. Attention has been drawn to Aronia fruits due to numerous health promoting properties of their products. However, processing of Aronia, like other berries, leads to difficulties that stem from the preparation process, as well as changes in the composition of bioactive compounds. Consequently, in this study, Aronia commercial juice was subjected to different drying techniques: spray drying, freeze drying and vacuum drying with the temperature range of 40-80 °C. All powders obtained had a high content of total polyphenols. Powders gained by spray drying had the highest values which corresponded to a high content of total flavonoids, total monomeric anthocyanins, cyaniding-3-glucoside and total proanthocyanidins. Analysis of the results exhibited a correlation between selected bioactive compounds and their antioxidant capacity. In conclusion, drying techniques have an impact on selected quality parameters, and different drying techniques cause changes in the content of bioactives analysed. Spray drying can be recommended for preservation of bioactives in Aronia products. Powder quality depends mainly on the process applied and parameters chosen. Therefore, Aronia powders production should be adapted to the requirements and design of the final product.

Innovative microwave-assisted hydrolysis of ellagitannins and quantification as ellagic acid equivalents.

The health-promoting effects of ellagic acid and its intestinal degradation products are well-known. In plants, ellagic acid mainly appears in the form of its precursors, the so-called ellagitannins. Therefore, determination of total ellagic acid content has been accomplished by cleaving ellagitannins with high temperatures and strong acids. Microwave-assisted extraction (MAE) has been shown to be a very effective and quick extraction technique. The aim of the present study was to establish an MAE-based method for a rapid hydrolysis of ellagitannins and to compare this method with a conventional acid hydrolysis. For this purpose, strawberries (Fragaria x ananassa), which have been identified as a major source of ellagitannins in human diet, were used as a model. The newly developed MAE method was quicker, less chemical-consuming and more effective in hydrolysing ellagitannins.

Cocoa polyphenols are absorbed in Caco-2 cell model of intestinal epithelium.

Cocoa is an abundant source of polyphenols, mainly flavan-3-ol monomers and polymers. In the literature, there are contradictory data on the absorption limit of procyanidins in humans. In our study, the Caco-2 cell model of intestinal epithelium was used to determine the absorption and secretion of cocoa flavan-3-ols. Three compounds: (+)-catechin, (-)-epicatechin and procyanidin B2 were detected and quantified at the receiver side of Caco-2 monolayer after 2h transport experiment. The obtained results of apparent permeability coefficient suggest paracellular route of transport of investigated compounds. Additionally, the results suggest that compounds of cocoa powder purified extract are able to affect tight junction functioning.

Determination of catechins and flavonol glycosides in Chinese tea varieties.

A standardised profiling method based on high performance liquid chromatography combined with ultraviolet (UV) and mass spectrometric detection (MS) was established to analyse the phenolic compounds of selected tea varieties used for manufacturing of green, black and oolong teas. The composition and content of 24 tea constituents were analysed, including catechins, flavonol and flavones glycosides, phenolic acids and purine alkaloids. Each tea variety had a unique chemical profile. The compositions of catechins were lower in the tea varieties for green tea manufacturing, while the content of myricetin glycosides was the lowest in the tea variety for oolong tea manufacturing. The content of individual phenolic compounds in the selected tea varieties is highly variable. However, the content of total catechins is proposed to be helpful to classify tea according to the future application as non fermented green and fermented oolong or black tea.

Fluorometric Method to Assess Lipase Inhibition Activity.

Obesity and excess weight have become serious health problems in our developed societies today. Increased blood pressure, blood glucose levels and abnormal blood lipids are frequent consequences. Inhibition of digestive enzymes by pharmacological or nutritional intervention are one avenue to be considered to treat this population. In the present study a robust assay to screen biologically active materials for their ability to inhibit pancreatic lipase, the most important enzyme in fat digestion, has been developed. Methyl-umbelliferyl butyrate was used as an artificial substrate, enabling assessment of lipase activity via specific fluorescence emission. Applicability of the assay was shown by assessment of lipase inhibition activity of wild plants from Switzerland and France. Testing showed some plants to have a high inhibition rate of about 70%. In further projects, this lipase inhibition assay could be used for a scientific proof of biological activity of raw materials with the intention to develop functional foods for weight reduction.