Volatile phenols like phenylpropanoid and benzoid compounds originate from the aromatic amino acid phenylalanine, which is biosynthesized via the shikimate/arogenate pathway. These volatile compounds ...contribute to the aroma of a number of economically important plant-derived foods like herbs, spices and fruits. The sequestration of numerous phenylpropanoid and benzoid compounds as glycosides occurs widely in fruits, and this pool represents an important source of flavor that can be released during storage and processing. Therefore, this review will provide an overview of the biosynthesis of free and glycosylated phenylpropanoid and benzoid compounds and their reactions during food processing, which both lead to the generation of odor-active volatile phenols in plant-derived foods.
Anthocyanins or anthocyanin rich extracts from several fruits are frequently applied as food colorants. One major drawback of these natural pigments is their poor stability and the rapid loss of ...coloring properties. Spray drying of anthocyanin extracts is a suitable approach for encapsulating and stabilizing them. In this study the effects of added copigments (rutin and ferulic acid) on the storage stability of spray-dried anthocyanins from blackberry were investigated. Degradation of anthocyanins during storage under light and different temperatures showed first order kinetics. Light had a higher impact on anthocyanin stability than elevated temperatures. The addition of copigments led to significantly lower anthocyanin losses compared to samples without copigments and to increased half-life values of the obtained powders. This stabilizing effect may be attributed to the antioxidative properties of the copigments and the prevention of the hydration of the anthocyanins. The observed color changes did not correlate with the anthocyanin loss. Degradation of anthocyanin might led to the formation of colored derivatives and polymers during storage.
•Copigments prevented degradation during spray drying of blackberry anthocyanins.•Color change was less pronounced when copigments were present.•Copigments enhanced shelf-life of obtained powders by up to one half.
Berry pomace, rich in polyphenols, especially anthocyanins, accumulates during the production of red juices. Pomace from chokeberry (Aronia melanocarpa Michx.), bilberry (Vaccinium myrtillus L.), and ...elderberry (Sambucus nigra L.) represent good sources of coloring foodstuffs. Pomace powders (PP) were prepared by milling the seedless fractions of the three dried berry pomaces (50 °C, 8 h). Techno-functional properties of the powders such as particle size distribution, bulk density, sedimentation velocity, and swelling capacity were determined to evaluate the powders for possible food applications. Total anthocyanin content was quantified by UHPLC-DAD before and during a storage experiment to monitor the degradation of anthocyanins in the PP and in a yogurt model application. The high content of phenolic compounds and the still intact cell structure ensured high stability of anthocyanins over 28 days of storage. In the model application, color saturation was stable over the whole storage time of 14 days. Regarding the techno-functional properties, only a few differences between the three PP were observed. The particle size of elderberry PP was larger, resulting in lowest bulk density (0.45 g/mL), high cold-water solubility (16.42%), and a swelling capacity of 10.16 mL/g dw. Sedimentation velocity of the three PP was fast (0.02 mL/min) due to cluster formation of the particles caused by electrostatic and hydrophobic properties. Compared to other high-intensity coloring foodstuffs, the use of PP, showing acceptable color stability with potential health-promoting effects, represents a wide applicability in different food applications and especially in products with a longer shelf-life.
Oxidation of plant phenolics leads to quinones, which are unstable intermediates that may react with nucleophiles. Quinones play an important role in the enzymatic browning of fruits and vegetables ...and may form covalent adducts with amino acids, peptides, and proteins. These reactions may alter both the physicochemical and immunological properties of food proteins. Quinones trap odoriferous compounds and contribute to the formation of aroma compounds through Strecker degradation of amino acids. Oxidative dimerization of chlorogenic acids in the presence of amino acids leads to the formation of green benzacridines, which are a promising alternative to chlorophylls as food colorants.
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•Ultrasound-assisted enzyme maceration enhanced pectin degradation.•Ultrasound creates simpler oligomers that were easier hydrolyzable by pectinases.•Synergistic effects enhanced ...pectin lyase and polygalacturonase activities.•Continuous system equipped with an ultrasound probe revealed a considerable total process output at reduced temperature (30 °C).
Ultrasound-assisted enzymatic maceration (UAEM) has gained considerable interest in the fruit juice industry, owing to its potential to increase juice yield and content of polyphenols while simultaneously saving time and energy. In this study, the effects of UAEM (ultrasonic probe, 20 kHz, 21 W*cm−2 and 33 W*cm−2) on pectin degradation in a continuous circulation system were investigated over 60 and 90 min. Main pectinolytic enzymes activities of (polygalacturonase, pectin lyase and pectin methylesterase) of a commercial enzyme preparation were examined for individual synergistic effects with US. Pectin hydrolysis by UAEM differed significantly compared to treatment with ultrasound or enzymes alone regarding the profile of degradation products compared to treatment with ultrasound or enzymes alone. Ultrasound fragmented pectin to less branched oligomers of medium molecular weight (Mp approx. 150 kDa), which were further degraded by pectinolytic activities. The low molecular weight fraction (<30 kDa), which is known to be beneficial for juice-quality by adding nutritional value and stabilizing polyphenols, was enriched in small oligomers of homogalacturonan-derived, rhamnogalacturonan I-derived, and rhamnogalacturonan II-derived residues. Synergistic effects of ultrasound application enhanced the effective activities of polygalacturonase and pectin lyase and even prolonged their performance over 90 min, whereas the effective activity of pectin methylesterase was not affected. Final marker concentrations determined by each enzyme assay revealed a considerable higher total process output after UAEM treatment at reduced temperature (30 °C) comparable to the output after conventional batch maceration at 50 °C. The obtained results demonstrate the high potential of UAEM to produce high-quality juice by controlling pectin degradation while reducing process temperature and equally highlight the matrix and enzyme specific effects of a simultaneous US treatment.
The metabolism of anthocyanins in humans is still not fully understood, which is partly due to the lack of reference compounds. It is known that sulfation is one way of the complex phase II ...biotransformation mechanism. Therefore, cyanidin-3-
-glucoside and the cyanidin aglycone were chemically converted to their sulfates by reaction with sulfur trioxide-N-triethylamine complex in dimethylformamide. The reaction products were characterized by UHPLC coupled to linear ion trap and IMS-QTOF mass spectrometry. Based on MS data, retention times, and UV-Vis spectra, the compounds could tentatively be assigned to A-, C-, or B-ring sulfates. Analysis of urine samples from two volunteers after ingestion of commercial blackberry nectar demonstrated the presence of two sulfated derivatives of the cyanidin aglycone and one sulfated derivative of the cyanidin-3-
-glucoside. It was found that both the A ring and the B ring are sulfated by human enzymes. This study marks an important step toward a better understanding of anthocyanin metabolism.
► Laying hen eggs contain considerable amount of antioxidants. ► Antioxidants in egg yolks are characterised to be tryptophan and tyrosine. ► Cooking could significantly reduce the antioxidant ...activities and the contents of aromatic amino acids.
Laying hens are known to be able to “bio-convert” health-promoting components from the diet into eggs. Wheat and corn are important sources of antioxidant phenolics in the human diet. Given the fact that wheat and corn are major feed ingredients of laying hens in Canada, the objectives of this study were to characterise the presence of novel phenolic compounds in egg yolk and to determine the effect of cooking methods on their content and activity. The total phenolic content of yolk extracts was 3.83 and 3.49
μmol gallic acid equivalents/g dry yolk for wheat-based and corn-based yolks, respectively. Antioxidant properties of yolk extracts were measured by the ORAC, DPPH and ABTS assays. ORAC values were 151.1
±
26.1 and 155.9
±
9.5
μmol
TE/g for wheat-based and corn-based yolks, respectively. All cooking methods significantly reduced (
p
<
0.05) the antioxidant values. Ferulic acid was detected in trace amounts and no other phenolic compounds were found. However, tryptophan and tyrosine were found to be two main contributors to the antioxidant property of egg yolk. The contents of total free amino acids were 10081.0 and 10009.5
μg/g in wheat-based and corn-based yolks, respectively; cooking methods were found to reduce significantly the amount of free amino acids.
High-performance counter-current chromatography (HPCCC) was used as a tool for the isolation and fractionation of phenolic compounds (PCs) in extracts from wine lees (WL) and grape pomace (GP). The ...biphasic solvent systems applied for HPCCC separation were
-butanol:methyl
-butyl ether:acetonitrile:water (3:1:1:5) with 0.1% trifluoroacetic acid (TFA) and
-hexane:ethyl acetate:methanol:water (1:5:1:5). After refining the ethanol:water extracts of GP and WL by-products by ethyl acetate extraction, the latter system yielded an enriched fraction of the minor family of flavonols. Recoveries of 112.9 and 105.9 mg of purified flavonols (myricetin, quercetin, isorhamnetin, and kaempferol) in GP and WL, respectively, from 500 mg of ethyl acetate extract (equivalent to 10 g of by-product) were obtained. The HPCCC fractionation and concentration capabilities were also exploited for the characterization and tentative identification of constitutive PCs by ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS). In addition to the isolation of the enriched flavonol fraction, a total of 57 PCs in both matrixes were identified, 12 of which were reported for the first time in WL and/or GP. The application of HPCCC to GP and WL extracts may be a powerful approach to isolate large amounts of minor PCs. The composition of the isolated fraction demonstrated quantitative differences in the individual compound composition of GP and WL, supporting the potential exploitation of these matrixes as sources of specific flavonols for technological applications.
Conventional production of spices implicates a number of hygienic problems which can pose tremendous risks for farmers, producers and consumers. Furthermore, food quality may also be adversely ...affected. Only few conventional technologies exist for the sanitation of spices, however, some applications such as the fumigation with ethylene oxide are restricted and even banned by law in the European Union. As a consequence, there is a need for the development of innovative technologies for the production of high quality spices. This contribution summarizes the major problems associated with conventional spice production and provides a review of alternative technologies developed very recently.
Phenolic compounds of 14 pomace samples originating from red and white winemaking were characterized by HPLC-MS. Up to 13 anthocyanins, 11 hydroxybenzoic and hydroxycinnamic acids, and 13 catechins ...and flavonols as well as 2 stilbenes were identified and quantified in the skins and seeds by HPLC-DAD. Large variabilities comprising all individual phenolic compounds were observed, depending on cultivar and vintage. Grape skins proved to be rich sources of anthocyanins, hydroxycinnamic acids, flavanols, and flavonol glycosides, whereas flavanols were mainly present in the seeds. However, besides the lack of anthocyanins in white grape pomace, no principal differences between red and white grape varieties were observed. This is the first study presenting comprehensive data on the contents of individual phenolic compounds comprising all polyphenolic subclasses of grapes including a comparison of several red and white pomaces from nine cultivars. The results obtained in the present study confirm that both skins and seeds of most grape cultivars constitute a promising source of polyphenolics. Keywords: Grape pomace; grape skin; grape seed; screening; HPLC-DAD-MS/MS; anthocyanins; hydroxybenzoic acids; hydroxycinnamic acids; flavanols; flavonols; stilbenes
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