•The change of fatty acid profile of almond kernel oils during roasting is revealed.•Roasting temperature and duration affect phenolic profile in almond kernels.•Antioxidant effects of roasted almond ...kernels correlated well with phenolic contents.•Browning indices of almond kernels increased with roasting temperature and duration.•Maillard reaction products contribute to antioxidant effects of roasted almond kernels.
Roasting treatment increased levels of unsaturated fatty acids (linoleic, oleic and elaidic acids) as well as saturated fatty acids (palmitic and stearic acids) in almond (Prunus dulcis) kernel oils with temperature (150 or 180°C) and duration (5, 10 or 20min). Nonetheless, higher temperature (200°C) and longer duration (10 or 20min) roasting might result in breakdown of fatty acids especially for unsaturated fatty acids. Phenolic components (total phenols, flavonoids, condensed tannins and phenolic acids) of almond kernels substantially lost in the initial phase; afterward these components gradually increased with roasting temperature and duration. Similar results also observed for their antioxidant activities (scavenging DPPH and ABTS+ radicals and ferric reducing power). The changes of phenolic acid and flavonoid compositions were also determined by HPLC. Maillard reaction products (estimated with non-enzymatic browning index) also increased with roasting temperature and duration; they might also contribute to enhancing the antioxidant attributes.
The QuEChERS (quick, easy, cheap, effective, rugged and safe) conditions were optimized for efficient determination of the U.S. Environmental Protection Agency (US EPA) and European Union (EU) ...priority polycyclic aromatic hydrocarbons (PAHs) for the categories of grains, tuber & starchy vegetables, soy beans and products, fish & seafood, and poultry & meat, including raw materials and their corresponding products. The PAHs were analyzed using ultrahigh-performance liquid chromatography with temperature-controlled fluorescence detection and gas chromatography with tandem mass spectrometry. The established conditions had good accuracy, repeatability, and precision. Environmental pollution and processing methods influence the level of PAHs in samples. The low molecular weight PAHs were present in all raw materials, and processing increased high and low molecular weight PAHs in the products. The excess cancer risk for consumption of PAHs in cooked samples was mostly acceptable; a small number of samples might be of slight concern in certain age groups.
•QuEChERS conditions were established to extract 21 HAs from various foods.•The HAs determination conditions had good accuracy, repeatability and precision.•HAs contents of popular food products sold ...in the Taiwan market were determined.•Cooking methods and food consumption affect the dietary intake of HAs.•The intake of HAs in plant-based protein foods also needs attention.
The optimal conditions for QuEChERS (quick, easy, cheap, effective, rugged and safe) with superior performance were established to rapidly extract 21 heterocyclic amines (HAs) from 9 categories of food matrices including meat and poultry, eggs, soy beans and products, composite foods, fish and seafood, grains, beer, dairy foods, and coffee. The QuEChERS conditions and the developed ultra-high performance liquid chromatography-tandem mass spectrometry analysis conditions were then applied to the determination of HAs in popular food products sold in the Taiwan market. The conditions comply with the food chemical analysis specifications of Taiwan Food and Drug Administration. Coffee products and braised products that require a longer cooking time contained relatively high content of HAs (mainly Harman and Norharman), and their consumption is relatively high resulting in relatively high intake of HAs from these products. The dietary intake of HAs in plant-based protein food products should also be of concern.
•Phenolic compositions of the leaves from eight persimmon varieties are determined.•Harvest time and variety of samples affect antioxidant components and activities.•Temperature, solar radiation and ...sunshine duration affect phenolic contents in samples.•Antioxidant activities of samples are significantly correlated with phenolic contents.
The compositions and contents of antioxidant components and antioxidant attributes (scavenging DPPH radicals, TEAC, ferric reducing power and inhibiting Cu2+-induced human LDL oxidation) for the leaves of eight persimmon varieties harvested from Sep. to Nov. were determined. Harvest time and variety were important factors affecting the compositions and contents of phenolic compounds in persimmon leaves; moreover, phenolic contents (polyphenol, flavonoid, condensed tannin and phenolic acid) of the leaves were significantly correlated with their antioxidant activities. For each variety, the leaves harvested in months with higher temperature, solar radiation and sunshine duration had higher phenolic contents contributing to better antioxidant properties (ranking: Sep. > Oct. > Nov.). In addition, the compositions and contents of phenolic components and antioxidant capacities for the leaves from various persimmon varieties were also different. The leaves of persimmon varieties belonging to pollination constant and astringent (PCA) had higher phenolic contents and also presented better antioxidant effects.
•The established UPLC-MSMS condition can simultaneously determine 21 HAs in 15 min.•The established QuEChERS conditions can extract HAs in tofu and soy milk effectively.•This study is the first to ...assess HAs content and their consumption for soy products.•The fried tofu samples had much higher HAs level than the boiled and roasted ones.•The highest HAs level consumed from the soy products was ∼374 ng/day for Whole Group.
A method using UPLC-MS/MS and a core–shell C18 column was developed to simultaneously determine 21 heterocyclic amines (HAs) in 15 min. Appropriate QuEChERS conditions were also established to conveniently extract HAs from soy products cooked with various methods. These conditions presented good analytical performance; limit of detection, limit of quantification, recovery (%), repeatability (coefficient of variation (CV) %) and intermediate precision (CV%) were 0.008 ∼ 0.150 ng/g, 0.025 ∼ 0.500 ng/g, 62 ∼ 91%, ≤ 28% and ≤ 23% for tofu sample, and 0.003 ∼ 0.100 ng/g, 0.010 ∼ 0.350 ng/g, 64 ∼ 93%, ≤ 19% and ≤ 20% for soy milk sample, respectively. HAs contents in the samples increased with cooking temperature and time. The tofu samples cooked by frying had much higher HAs content than those cooked by boiling and roasting. Norharman and Harman mainly contributed HAs content in all samples. For the general population in Taiwan, the highest estimated level of HAs consumed from the samples is 373.67 ng/day.
Antioxidant, anti-proliferative and cyclooxygenase-2 (COX-2) inhibitory activities of ethanolic extracts from freeze (EF) and hot air (EH) dried lemon balm (Melissa officinalis L.) leaves were ...evaluated. Phytochemical contents in the extracts were also determined. Hot air drying significantly lowered phytochemical contents and biological activities of the extract of lemon balm leaves as compared with freeze drying. EF had higher levels of phenols, phenolic acids, flavonoids, proanthocyanidins, ascorbic acid and γ-tocopherol than EH. Rosmarinic acid was the major compound and hesperetin was the highest level of flavonoid in the extracts. EF also presented higher antioxidant (β-carotene bleaching inhibition, scavenging 2, 2-diphenyl-1-picrylhydrazyl radicals, reducing power and Trolox equivalent antioxidant capacity), anti-proliferative (proliferative inhibition for Hep G2, KB and TSGH 9201 human cancer cells) and COX-2 (induced by 12-O-teradecanoylphorbol-13-acetate in KB cells) suppressing activities than EH. The ethanolic extracts of lemon balm leaves, especially EF, may have the potential for cancer chemoprevention.
► Ethanolic extract of lemon balm has good antioxidant activity. ► Ethanolic extract of lemon balm has proliferative inhibition for cancer cells. ► Ethanolic extract of lemon balm has cyclooxygenase-2 inhibitory activity. ► The extract may be beneficial for development of chemotherapeutic agents.
Tyrosinase inhibitors from natural products have applications in the pharmaceutical, food, and cosmetic industries because of the functions of tyrosinase in skin disorders and in the enzymatic ...browning of fruits. Current in vitro inhibitor screening assays are based on the inhibition of the oxidation of l‐3,4‐dihydroxyphenylalanine (l‐DOPA) mediated by a mushroom tyrosinase. However, in these assays, a tyrosinase inhibitor or an antioxidant could inhibit dopaquinone formation. In this study, we aimed to eliminate this ambiguity by using a microplate assay integrating tyrosinase‐immobilized magnetic nanoparticles (TYR‐MNPs) and a homemade magnetic microplate for high‐throughput screening. After incubating extracts of natural products with TYR‐MNPs, the magnetic nanoparticles are attracted to the bottoms of wells, the extracts are rinsed, and TYR‐MNPs react with l‐DOPA. This method can be used to screen compounds that interact with the active sites of the enzyme, or copper chelators that bind more strongly than tyrosinase to copper ions, distinguishing them from antioxidants or tyrosinase substrates. Integration with the homemade magnetic microplate enables high‐throughput inhibitor screening. Aloe vera flowers are crop by‐products, and litchi flowers fall after the blossom. Our work demonstrated that these flowers have tyrosinase inhibitory effects, thus increasing their value.
This study represents the first reported use of tyrosinase‐immobilized magnetic nanoparticles and 96‐well microplates for quickly screening tyrosinase inhibitors. The core technology is the homemade magnetic microplate. With our novel method, only true inhibitors are identified without interference from antioxidants, and with additional steps, we can identify whether the inhibitor is a copper ion chelator or a specific enzyme binder.
Bag teas, packed 3
g of ground black, green, oolong, paochoung and pu-erh tea leaves (the particle size used was 1–2
mm), were steeped in 150
mL of 70, 85 or 100
°C hot water to study the effects of ...the number of steeping (the same bag tea was steeped repeatedly eight times, 30
s each time, as done in China for making ceremonial tea) and varied steeping durations (0.5–4
min) on caffeine, catechins and gallic acid in tea infusions. The changes in tea infusions during storage at 4 or 25
°C for 0–48
h and the variations in these compounds of bag tea infused with 150
mL of 4 or 25
°C cold water for 0.5–16
h were also investigated. A HPLC method with a C18 column and a step gradient solvent system consisting of acetonitrile and 0.9% acetic acid in deionized water was used for analysis. Results for all kinds of tea samples showed that the second tea infusion contained the highest contents of caffeine, catechins and gallic acid when bag teas were steeped in 70
°C water. It was different from that steeped at 85 and 100
°C, the highest contents existed in the first infusion. These compounds decreased gradually in later infusions. Higher amounts of caffeine, catechins and gallic acid could be released from bag teas as hotter water was used. As steeping duration prolonged, these ingredients increased progressively, however, their levels were lower than that cumulated from the infusions with the identical bag tea prepared recurrently at the same temperature and time points. (−)-Gallocatechin gallate and (+)-catechin existed in these tea infusions rarely and could not be detected until a certain amount of them infusing. Except gallic acid that showed a significant increase and caffeine that exhibited no significant change, all kinds of catechins decreased appreciably after tea infusions were stored at 25
°C for 36
h; nevertheless, all of them showed no evident changes at 4
°C storage. The caffeine, catechins and gallic acid in tea infused with cold water also increased with increasing duration. Their contents in 25
°C steeped tea were higher than that made at 4
°C; moreover, their infusion rates from bag teas to cold water were markedly lower than that steeped in hot water. Infusing efficiencies of non-gallated catechins were higher than gallated catechins under cold water steeping.
The antioxidant capacities of the acetone, methanol and water extracts of hot-air dried lychee (
Litchi chinenesis Sonn.) flowers were estimated with Trolox equivalent antioxidant capacity (TEAC) ...assay, reducing power and 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) radical-scavenging assay. The contents of antioxidant components in these extracts were also determined. Results showed that the highest and lowest contents of these components including phenols, flavonoids and condensed tannins were found in acetone and water extracts, respectively. The antioxidant activities of the lychee flower extracts for all assays were in the order: acetone extract
>
methanol extract
>
water extract. The contents of antioxidant components in these extracts were correlated with antioxidant activities.
Antioxidant activities of ethanolic extract from dill flower and its various fractions were evaluated with 2,2-diphenyl-1-picrylhydrazyl radical scavenging, Trolox equivalent antioxidant capacity, ...reducing power, chelating power, and β-carotene bleaching assays. The flower extract was successively separated into
n-hexane, ethyl acetate and ethanol soluble fractions by liquid–liquid partition. Dill leaf and seed extracts were used for comparison. In all assays, the flower extract showed higher antioxidant activity than the leaf and seed extracts. With regard to various fractions of the flower extract, the sequence for antioxidant activity was ethyl acetate fraction
>
ethanol fraction
>
original flower extract
>
n-hexane fraction. Phenols including flavonoids and proanthocyanidins should be responsible for antioxidant abilities of the flower extract. Chlorogenic acid, myricetin, and 3,3’,4′,5,7-pentahydoxyflavan (4
→
8)-3,3′,4′,5,7-pentahydoxyflavan were the major phenolic acid, flavonoid, and proanthocyanidin, respectively, in the dill flower extract.
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