Ultrasound-assisted hydrolysis and gas chromatography–mass spectrometric determination of phenolic compounds in cranberry products

An ultrasound-assisted hydrolysis and gas chromatography–mass spectrometric (GC–MS) method has been developed for determination of phenolics in cranberry products. Prior to GC–MS separation and characterisation, the phenolics in samples were hydrolysed by hydrochloric acid with ultrasound-assistance, extracted with ethyl acetate, and derivatised with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) + 1% trimethylchlorosilane (TMCS) reagents. The application of ultrasonication significantly accelerated the acidic hydrolysation of the conjugated phenolics. A baseline separation of the 20 phenolics and internal standard was achieved in 25 min. Standard calibration curves were linear over the concentration range of 0.0–50 μg/mL and detection limits were 0.06–0.70 μg/mL. Twenty phenolics were identified in cranberry samples and all of them occurred mainly in conjugated forms. Of those, the benzoic acid, quercetin, and myricetin were most abundant phenolics. The total phenolics were 12.4 mg/g in cranberry fruits, 9.1 mg/mL in 100% cranberry juice, and 11.1 mg/g in cranberry sauces, respectively.     

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.     

Investigation of α-glucosidase inhibitory activity of wheat bran and germ

Postprandial hyperglycaemia is a primary risk factor in the development of Type 2 diabetes. α-Glucosidase inhibitors that reduce postprandial hyperglycaemia have a key role in the treatment of Type 2 pre-diabetic states and also have the potential to reduce the progression to complications of diabetes. Epidemiological studies showed that risk for Type 2 diabetes mellitus was decreased with consumption of whole grains. The bran and germ of whole wheat are major components of whole grain consumption and are widely accepted as important ingredients in many low glycaemic index (GI) foods. In this study, the α-glucosidase inhibitory activity of wheat bran and germ was investigated. The active compounds were screened using an in vitro enzyme-inhibitory assay guided fractionation. Potent α-glucosidase inhibitory compounds from wheat germ were identified as phosphatidic acids, 1,2-dilinoleoylglycero-3-phosphate and 1-palmitoyl-2-linoleoyl-glycero-3-phosphate. The low GI property of whole grain wheat could be attributed to these α-glucosidase inhibitory phosphatidic acids, which have the potential to prevent or treat Type 2 diabetes.     

Can plant phenolic compounds reduce Fusarium growth and mycotoxin production in cereals?

ABSTRACT

To assess the in vitro activity of three phenolic acids (ferulic acid, p-hydroxybenzoic acid, vanillic acid) and two flavonols (quercetin, rutin) on mycelial growth and mycotoxin accumulation of Fusarium graminearum (FG), F. langsethiae (FL) and F. poae (FP), two different approaches were chosen. First, grains from oat varieties were inoculated with a suspension of three FL isolates to determine the influence of phenolic compounds on the accumulation of mycotoxins. The oat variety Zorro showed a tendency for lower accumulation of T-2/HT-2, diacetoxyscirpenol and neosolaniol. Second, a mycelium growth assay was conducted to follow FG, FL and FP growth on cereal based media supplemented with phenolic compounds. Increasing concentrations of ferulic acid substantially inhibited growth of FG and FL, while FP growth was reduced to 57%. In contrast, p-hydroxybenzoic acid, vanillic acid, quercetin, and rutin slightly stimulated mycelium growth. Results about mycotoxin production in cereal based media were less conclusive.     

Functional implications of bound phenolic compounds and phenolics–food interaction: A review

Sizeable scientific evidence indicates the health benefits related to phenolic compounds and dietary fiber. Various phenolic compounds-rich foods or ingredients are also rich in dietary fiber, and these two health components may interrelate via noncovalent (reversible) and covalent (mostly irreversible) interactions. Notwithstanding, these interactions are responsible for the carrier effect ascribed to fiber toward the digestive system and can modulate the bioaccessibility of phenolics, thus shaping health-promoting effects in vivo. On this basis, the present review focuses on the nature, occurrence, and implications of the interactions between phenolics and food components. Covalent and noncovalent interactions are presented, their occurrence discussed, and the effect of food processing introduced. Once reaching the large intestine, fiber-bound phenolics undergo an intense transformation by the microbial community therein, encompassing reactions such as deglycosylation, dehydroxylation, α- and β-oxidation, dehydrogenation, demethylation, decarboxylation, C-ring fission, and cleavage to lower molecular weight phenolics. Comparatively less information is still available on the consequences on gut microbiota. So far, the very most of the information on the ability of bound phenolics to modulate gut microbiota relates to in vitro models and single strains in culture medium. Despite offering promising information, such models provide limited information about the effect on gut microbes, and future research is deemed in this field.     

Deoxynivalenol in wheat,maize, wheat flour and pasta: surveys in Hungary in 2008–2015

Among Fusarium mycotoxins, deoxynivalenol (DON) is the most common contaminant in case of cereals and cereal-based foods in Hungary. In this study, Hungarian wheat (n = 305), maize (n = 108), wheat flour (n = 179) and pasta (n = 226) samples were analysed (N = 818). The samples were collected during 2008–2015 in Hungary. Applied methods of analysis were enzyme-linked immunosorbent assay and liquid-chromatography coupled with a mass spectrometer. Results were compared and evaluated with Hungarian weather data. Among cereal samples, in 2011, wheat was contaminated with DON (overall average ± standard deviation was 2159 ± 2818 µg kg^?1), which was above the maximum limit (ML). In case of wheat flour and pasta, no average values above ML were found during 2008–2015, but higher DON contamination could be observed in 2011 as well (wheat flour: 537 ± 573 µg kg^?1; pasta: 511 ± 175 µg kg^?1).     

Iron binding characteristics of phenolic compounds: some tentative structure–activity relations

Two mechanisms are commonly proposed to explain the antioxidant role of phenolic compounds; these are metal chelation and/or free radical scavenging. However, the structural requirements for each may not be the same. This paper describes the determination of iron-binding efficiencies (in vitro) for a series of pure phenolics of known structure [gallic acid, tannic acid, catechin, epicatechin (EC), epicatechingallate (ECG), epigallocatechin (EGC), epigallocatechingallate (EGCG) and quercetin] and of tea beverages of known flavonoid composition. Iron-binding efficiency was measured as catechin equivalents or tannic acid equivalents using the two wavelength assay. High catechin equivalents require the presence of a 3′,4′ dihydroxy (catechol ) group on flavanoid ring B. In contrast, the presence of a 3′,4′,5′-trihydroxy (galloyl) group of ring B (epigallocatechin) or ring C (epicatechin gallate) was associated with reduced Fe-binding. The extent of Fe-binding was also found to be lower for quercetin than catechin, which is probably due to the presence of conjugation extending from the C4-keto group, via C2-3 to the 3′-OH group (rings B and C). For the polyphenols examined, catechin equivalents were inversely correlated with tannic acid equivalents and with antioxidant activity of flavonoids, as measured by the TEAC assay. Requirements for efficient iron-binding are discussed.     

Extraction of phenolic compounds from grapes and their pomace using β-cyclodextrin

Use of aqueous cyclodextrins (CD) for recovery of selected bioactive phenolic compounds from grapes and their pomace was evaluated. When α, β and γ forms of CD were compared, β-CD was the most effective in recovering stilbenes, flavonols, and flavan-3-ols from grape pomace. The maximum quantified phenolics were obtained from the powder and the slurry of grape pomace when extracted with 2.5% (w/v) aqueous β-CD solutions at 60 °C for 12–24 h. With β-CD, total quantified phenolics obtained from the dry powder were 123 mg/100 g (DW) while from the slurry, they were 35.8 mg/100 g (FW). Incorporation of β-CD to grape mash prior to pressing for juice enhanced the recovery of phenolics in juice. Incorporation of β-CD was more effective in recovering flavan-3-ols than flavonols. Aqueous CD can effectively be used in recovering phenolics from by-products of fruit processing and therefore for functional foods and nutraceutical applications.     

Acrylamide–asparagine relationship in baked/toasted wheat and rye breads

Acrylamide in baked and toasted wheat and rye bread was studied in relation to levels of asparagine in flour, dough, bread and toasts. Asparagine was consumed during bread preparation resulting in reduced acrylamide content in the products. In wheat bread, 12% of the asparagine initially present in the flour (0.14 g kg^?1) remained after yeast fermentation and baking; for rye bread, 82% of asparagine remained after sourdough fermentation and baking. Asparagine present in untoasted wheat bread had totally reacted after hard toasting. Toasted wheat and rye bread slices contained 11–161 and 27–205 µg kg^?1 acrylamide, respectively, compared to untoasted wheat and rye bread with <5 and 7–23 µg kg^?1 acrylamide, respectively. The dietary intake of acrylamide from bread (untoasted) of 2 µg day^?1 is relatively low; however, acrylamide exposure from bread increases several fold for people eating toasted bread.     

RP-HPLC–DAD analysis of phenolic compounds in pomace extracts from five grape cultivars: Evaluation of their antioxidant,antiradical and antifungal activities in orange and apple juices

Phenolic compounds, related to antioxidative and antifungal properties of ethanolic extracts from five commercial grape cultivars (three red and two white) grown in Turkey were determined. A reversed-phase high performance liquid chromatography (RP-HPLC) procedure was developed, and a total 18 different phenolic compounds were identified. Total phenolic contents of the extracts were determined using Folin–Ciocalteau method. Antioxidant activities of the extracts were evaluated by using DPPH radical scavenging and phosphomolybdenum methods. All extracts exhibited strong antioxidant and antiradical activity. Phenolic compounds and antioxidant activities of the extracts were variety dependent. Antifungal activities of the pomaces and extracts were screened by both in vitro agar-well diffusion assay and antifungal activity in apple and orange juices in situ using Zygosaccharomyces rouxii and Z. bailii. Antifungal activities revealed that the pomaces and extracts of Gamay and Kalecik karasi could be more effective antifungal agents than those of Emir, Narince and Okuzgozu grape cultivars.     

Determination of phenolic compounds in olive oil: New method based on liquid–liquid micro extraction and ultra high performance liquid chromatography-triple–quadrupole mass spectrometry

A novel analytical approach has been performed and evaluated for the identification and quantification of phenolic compounds (phenolic alcohols, secoiridoid derivates, lignans, flavonoids, phenolic acids and aldehydes) which can be found in both virgin olive oil (VOO) and extra virgin olive oil (EVOO). An improved liquid–liquid micro extraction (LLME) method combining with ultra high performance liquid chromatography (UHPLC) coupled to electrospray ionization source (ESI) and tandem mass spectrometry (MS/MS) in Dynamic Multiple Reaction Monitoring (DMRM) mode has been developed, reducing the amount of sample, reagents and time consumed. The proposed methodology was applied to standard solutions, and the quality control parameters obtained were compared with those achieved in spiked refined olive oil (SROO). Generally, these parameters showed lower values in SROO than in standard solutions. Matrix effect, recovery and process efficiency have been studied using SROO. The recoveries were around 90% and the process efficiency of the whole method was higher than 80% for most of the phenolic compounds studied. Examination of these parameters revealed that work straight in the olive oil matrix, which is closer to behave as a real sample, provides better results. The applicability and reliability of this methodology have been confirmed using real samples.     

Extraction of phenolic compounds from oregano using high voltage electrical discharges–sustainable perspective

The aim of the study was to observe the sustainability parameters of high voltage electrical discharge (HVED) as a novel technology for extraction of phenolic compounds from oregano. The life cycle assessment (LCA) of HVED was evaluated and compared with conventional extraction methods–infusion and maceration. The results showed that HVED extraction with nitrogen gave 2.19%–34.04% higher yield of phenolic compounds compared to infusion and 6.13%–90.95% higher yield compared to maceration, depending on the voltage and treatment time used for HVED. The environmental pillar of LCA, assessed by global warming potential, ranged from 1.130 to 4.635 kg CO₂e for HVED samples treated with nitrogen and from 1.207 to 4.487 kg CO₂e for samples treated with argon, which was mainly related to the duration of treatment. Other pillars of sustainability, namely society, economy, food safety and quality, were discussed. HVED was found to be the more sustainable technology (based on the results from LCA), with prospects for future scale-up for the food industry.     

Polyols’ effect on thermal stability of lipase and its application in cotton fabrics’ enzymatic treatment

In this paper, the effect of polyols on thermal stability of lipase was investigated. Lipase, with or without polyols was heated at 75°C for different periods of time. Half-life (t_1/2, min) of lipase at 75°C was prolonged from 8.74 to 12.62, 11.66, 9.45, and 8.95 with the addition of d-sorbierite, d-fructose, mannite, and maltose, respectively. Conformational changes of lipase after the heat treatment were studied by both Fluorescence spectra test and UV spectra test. The UV values (as the unfolding ratios of lipase) calculated from UV spectra were related to the proportion of inactivated lipase. Residual activity^UV (originated from UV values) reflected residual lipase activity from the experimental data accurately. Compared with cotton fabrics treated by the crude lipase at 75°C, the appearance of polyols enhanced the capillary effect and weight loss of cotton fabrics to some extent.     

Characteristics of wheat starch–pectin hydrolysate complexes by dry heat treatment

Food Science and Biotechnology - The objective of this study was to characterize dry heat-induced wheat starch–pectin hydrolysate (WST/PH) complexes to develop the retrogradation-retarded...