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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Sample Preparation Methods and Pre-harvest Factors Influencing the Contents of Bioactive Compounds and Antioxidant Activity in Peppers

Bae, Hae Jin 2011 December 1900 (has links)
Peppers are a rich source of diverse bioactive compounds with potential health-promoting properties. The levels of bioactive compounds and antioxidant activity can be affected by analytical methods, pre-harvest factors, and the quality of peppers. In order to understand the nutrient composition and antioxidant activity in peppers, determination of factors influencing the contents of bioactive compounds is important. The overall objectives were to determine the efficient conditions of sample preparation and the impact of pre-harvest factors affecting bioactive compounds and antioxidant activity. Optimal extraction procedures were developed, and HPLC methods were validated for bioactive compounds in peppers. The highest flavonoids were extracted in ethanol, while myricetin was extracted using N-N-dimethylformamide. Optimized conditions for flavonoids were obtained during 3 h of extraction time and hydrolysis in M HCl for 60 min at 95 degrees C. Capsaicinoids and ascorbic acid were simultaneously separated and extracted using a solvent mixture consisting of 3% metaphosphoric acid: ethanol (2:8) after 30 min of sonication. To determine the relationship between bioactive compounds and antioxidant activities in pepper extracts from different solvent properties, bioactive compounds were analyzed, and the antioxidant activities were assayed by 2,2,-Diphenyl-1-picryl hydrazyl (DPPH), reducing power, and degradation of deoxyribose. Hexane extracts had the highest levels of capsaicinoids and carotenoids, while methanol extracts had the highest levels of flavonoids. Strong DPPH scavenging activity and reducing power were found in lipophilic extracts, while hydrophilic extracts were appropriate for inhibition of deoxyribose degradation. Variation in content of ascorbic acid, capsaicinoids, and flavonoids was evaluated at immature and mature stages of pepper cultivars in different locations over two years. Mature peppers contained the highest levels of capsaicinoids and ascorbic acid. Flavonoids were variable at different maturity stages. Interactions between pre-harvest factors and bioactive compounds were highly significant. This study demonstrated the efficient sample preparation methods and simultaneous separation of bioactive compounds, which reduces analysis time and leads to reduced cost. The antioxidant properties were strongly associated with the concentration of bioactive compounds based on selective pepper extracts. The pepper quality can be improved by using appropriate pre-harvest conditions that increase the levels of bioactive compounds in peppers.
92

Identification and Antioxidant Properties of Phenolic Compounds during Production of Bread from Purple Wheat Grains and Investigation of Bread Extracts after Simulated Gastrointestinal Digestion

Yu, Lilei 27 October 2014 (has links)
Content of free- (FPC) and bound- phenolics (BPC) significantly (p<0.05) increased during mixing, fermenting and baking. Bread crust and crumb contained the highest FPC and BPC, respectively. Antioxidant activities (AOA) followed the trends of their respective phenolic contents. HPLC analysis demonstrated that different phenolic acids showed various responses to the bread-making process. Total anthocyanin content (TAC) was significantly (p<0.05) reduced through mixing and baking, but fermentation elevated the levels. Anthocyanin extract of purple wheat exerted higher AOA than those of common wheat. Digested purple wheat extracts after in-vitro digestion demonstrated significantly (p<0.05) higher AOA than common wheat. During in-vitro testing, extracts exhibited concentration-dependent effects, while the use of different cell lines exhibited varying levels of cellular antioxidant and pro-oxidant properties. Purple wheat demonstrated higher cytoprotectivity and cellular AOA than those of common wheat. Our findings suggest that purple wheat has the potential to act as functional food in bakery products.
93

Proanthocyanidins, anthocyanins and phenolic acids in food barleys of diverse origin

Hambira, Chipo 11 January 2010 (has links)
Phytochemicals found in grains complement those found in fruits and vegetables. These phytochemicals, though minor compounds, contribute to the antioxidant properties which are related to the health benefits associated with the consumption of whole grain. In this thesis project, nine barley genotypes of diverse origin namely CI2230 from Nepal, CI1248 from Israel, 3 Peruvian genotypes; Peru 3, Peru 16 and Peru 35, Hokuto Hadaka from Japan, EX116; a cross between Moroccan and Canadian genotype, EX83; a cross between two Canadian genotypes and EX127; a cross between Canadian and German genotypes were studied. The genotypes were categorized based on appearance into purple, black and yellow grains. Phenolic acids and flavonoids were identified and quantified in these diverse genotypes using HPLC-ESI-MS analysis. The main classes of dietary flavonoids studied in the barleys were anthocyanins and flavan-3-ols. Phenolic acids were identified and quantified (p-coumaric, ferulic, sinapic, caffeic, vanillic). Three ferulic acid dehydrodimers (8-0-4’ DFA, 8-5’ benzofuran form and 5-5’ DFA) were also identified. The most abundant dimeric flavan-3-ols were procyanidins B3 and prodelphinidin B3. The monomeric unit, (+)-catechin, was the most abundant while catechin glucoside (m/z 451) was also identified. Among the Peruvian genotypes, Peru 16 and Peru 35 exhibited relatively high levels of total PA content. Total phenolic content and antioxidant activities of methanolic, acetone and alkali hydrolyzed extracts of the nine barley genotypes was determined by the Folin- Ciocalteau assay, DPPH radical scavenging assay and oxygen radical absorbance capacity (ORAC assay).The acetone extract exhibited the highest antioxidant capacity using all the methods of analysis. Furthermore, dark colored grains were found to exhibit higher contents of phenolic compounds. The phenolic acids, PAs and anthocyanins identified and quantified had significant contribution to the overall antioxidant capacity of the barley whole grain. Four hull-less genotypes namely CI2230, EX127, CI1248 and Peru 35 were further partially sprouted to establish the effects of sprouting on phenolic acid composition. Partial sprouting was observed to significantly increase the soluble conjugated phenolic acids. The barley genotypes studied were found to contain different quantities of phytochemicals and had high proanthocyanidin content thereby rendering them as alternative sources of antioxidants. Barley sprouts present a possible novel food ingredient with improved properties such as phenolic acid composition and other benefits such as easier incorporation into food products under development.
94

Antioxidant properties of spaghetti and infant cereals and characterization of major phenolic compounds by LC/MS analysis

Hirawan, Rhanissa 08 April 2011 (has links)
The present study investigated the antioxidant properties of commercial regular- and whole- wheat spaghetti. The antioxidant properties comprise the total phenolic content, DPPH radical scavenging activity, oxygen radical absorbance capacity. The contents of ferulic acid, C-glycosyl flavones and SDG were measured by using LC/MS techniques. Whole wheat spaghetti showed significantly higher TPC and ORAC. The contents of ferulic acid, C-glycosyl flavones and SDG were significantly higher in whole wheat spaghetti. The TPC was found to decrease 48 – 78% after cooking. The results showed that consumption of whole grain is strongly recommended. The present study also compared the antioxidant properties of commercial infant cereals. Purple wheat and red rice were used in making home-made and lab-made infant cereals. Pigmented infant cereals showed higher TPC, total anthocyanin content (TAC) and ORAC then brown rice and commercial ones. Anthocyanins were found only in purple wheat while a C-glycosyl flavone was found at higher levels in purple wheat than in red rice samples. Home-made samples did not show significant differences in TPC, TAC and ORAC with lab-made ones; however, the contents of anthocyanins and C-glycosyl flavones were significantly different. Home-made purple wheat infant cereals showed higher cellular antioxidant activity (CAA) than lab-made purple wheat, red rice and commercial ones. Whole purple wheat holds potential to improve the antioxidant properties of infant cereals.
95

Effects of in vitro gastrointestinal digestion on extractability of nutrient and bioactive compounds from wheat bran

Golom, Sirak Tsegai 06 January 2012 (has links)
A static in vitro digestion method was developed as a strategy to understand the effects of modelled digestion on the solubility of nutrients and selected bioactive compounds of autoclaved and untreated wheat bran. Brans from common soft, hard, and durum wheats were evaluated. Results indicated that the in vitro digestion protocol was suitable and effective. Effects of gastrointestinal simulation were considerably larger than gastric digestion alone. Digestibility of the brans ranged from 28.1 to 47.9%. Digestibility of bran minerals, starch and protein was substantial compared to lesser, but still significant, effects on fibre. Fibre solubility was significantly enhanced due to autoclaving. Total phenolic content, free radical scavenging and metal chelation activity were all substantially increased in soluble digests. Yields of these factors indicated that digestion of wheat bran releases ample levels of antioxidants that would be available for absorption in the small intestine to promote beneficial health effects.
96

Antioxidant properties of alkaline extracts from insoluble and soluble dietary fibre derived from selected whole-grain cereals

Guo, Weiwei 23 August 2012 (has links)
The extraction yields of insoluble dietary fibre (IDF) and soluble dietary fibre (SDF) from seven whole-grain cereals (WG) ranged from 11.73% to 23.71% and 2.28% to 5.15%, respectively. Eight monomeric phenolic acids and four diferulic acids were identified and quantified in cereal alkaline extracts by reversed phase high performance liquid chromatography coupled with quadrupole - time of flight mass spectrometry. IDF alkaline extracts had significantly (p < 0.05) higher levels of total phenolic content (TPC) and DPPH radical scavenging activity than WG and SDF extracts. Corn IDF (C-IDF) extracts exhibited the highest TPC and DPPH, followed by red rice. MTT cell viability assay indicated that 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) or xanthine-xanthine oxidase (X-XO) induced cell loss can be effectively reduced by pre-incubating Caco-2BBe or FHs 74 Int cells with certain levels of C-IDF extracts. This effect was speculated to be associated with the antioxidant activity of C-IDF linked phenolic compounds.
97

Kvapiojo rozmarino etanolinių ištraukų technologijos ir kokybės vertinimas / Evaluation of technology and quality of ethanol tinctures of Rosmarinus officinalis

Valodkaitė, Orinta 28 June 2011 (has links)
Šio darbo tikslas - pagaminti kvapiųjų rozmarinų etanolines ištraukas (tinktūras, skystuosius ekstraktus) ir įvertinti jų kokybę. Darbo uždaviniai:  Remiantis literatūros duomenimis parinkti žaliavos ir ekstrahento santykį bei ištraukų gamybos metodus.  Įvertinti pagamintų ištraukų kokybę, nustatant sauso likučio ir fenolinių junginių kiekį.  Įvertinti technologinių parametrų daromą įtaką veikliųjų medžiagų išsiskyrimui iš žaliavos.  Įvertinti ištraukų antioksidacinį aktyvumą. Bendras fenolinių junginių kiekis rozmarinų tinktūrose ir ekstraktuose nustatytas spektrofotometriniu metodu (spektrofotometras UNICAM Helios α UV, Didžioji Britanija) pagal rozmarino rūgšties standartą. Antioksidacinis aktyvumas nustatytas spektrofotometriškai, panaudojant DPPH• laisvojo radikalo sujungimo metodą. Sausasis rozmarinų etanolinių ištraukų likutis nustatytas drėgnomačiu MLS 50-3HA160. Maišymo įtaka išsiekstrahavusių fenolinių junginių kiekybei nustatyta, naudojant magnetinę maišyklę. Tiriant etanolio koncentracijos įtaką išsiekstrahavusių veikliųjų junginių kiekybei, nustatyta, kad optimalus ekstrahentas yra 50 % etanolis. Tačiau antioksidacinio aktyvumo priklausomybė nuo etanolio koncentracijos yra nežymi. Rezultatai parodė, kad rozmarinų tinktūrų ir skystųjų ekstraktų antioksidacinis aktyvumas nepriklauso nuo vaisto formos. Ištirta, kad sauso likučio ir fenolinių junginių kiekis yra didesni skystuose ekstraktuose lyginant su rozmarinų tinktūromis. Nustatyta, kad brinkinimo laikas... [toliau žr. visą tekstą] / The aim of this research is to make ethanol extracts (tinctures and liquid extracts) of Rosmarinus officinalis and evaluate their quality. The tasks of this research are:  According to the literature, to select proportion of the substance and extractive solvent and select the method of production of ethanol extracts.  To evaluate the quality of produced extracts by fixing the dry residual and phenol compounds.  To evaluate an impact of technologic parameters for the quantity of active compounds.  To evaluate an antioxidative activity of ethanol extracts. The total amount of phenol compounds in tinctures and extracts of Rosmarinus officinalis is estimated spectrophotometrically (spektrophotometer UNICAM Helios α UV, Great Britain). Rosmarinic acid was used as a standart. Antioxidative activity (AA) was determined spectrophotometrically by free radical DPPH• method. The dry residual of ethanol extracts was determined by hygrometer MLS 50-3HA160. The impact of stirring on the quantity of seperated phenol compounds was evaluated by magnetic stirrer. Searching the impact of ethanol concentration on the quantity of seperated active compounds, it‘s evaluated that optimal extractive solvent is 50 % ethanol. However AA dependence on ethanol concentration is low. The findings confirm that AA of tinctures and extracts of Rosmarinus officinalis doesn‘t depend on drug form. It‘s evaluated that the quantity of dry residual and phenol compounds in liquid extracts is more than in... [to full text]
98

PREPARATŲ SU ROZMARINO RŪGŠTIMI PALYGINAMOJI ANALIZĖ / Comparative analysis of products with rosmarinic acid

Savickaja, Eleonora 18 June 2014 (has links)
Darbo tikslas: atlikti preparatų, turinčių augalinių žaliavų kaupiančių rozmarino rūgštį, sudėčių palyginamąją analizę, nustatyti bendrą fenolinių junginių kiekį, rozmarino rūgšties kiekį ir antioksidacinį aktyvumą. Darbo uždaviniai:  Išrinkti preparatus su rozmarino rūgštimi;  Atlikti šių preparatų sudėčių palyginamąją analizę;  Nustatyti ir palyginti bendrą fenolinių junginių kiekį preparatuose;  Nustatyti ir palyginti rozmarino rūgšties kiekį ESC metodu;  Nustatyti ir palyginti antioksidacinį aktyvumą. Tyrimo objektai ir metodai: preparatai, turintys augalines žaliavas, kaupiančias rozmarino rūgštį ir kvapiųjų rozmarinų skystasis ekstraktas. Bendras fenolinių junginių kiekio nustatymas atliktas spektrofotometriniu būdu, naudojant standartinį Folin – Ciocalteu reagentą. Rozmarino rūgšties kiekis preparatuose nustatytas ESC metodu. Antioksidacinis aktyvumas nustatytas DPPH radikalo sujungimo metodu. Literatūros analizės metodu atlikta rozmarino rūgšties preparatų sudėčių analizė. Išvados: Tyrimams išrinkti 3 kompleksiniai preparatai su kvapiųjų rozmarinų augaline žaliava ir skystasis rozmarinų ekstraktas. Daugiausia kvapiųjų rozmarinų žaliavos ir RR kiekio RPD buvo keturkomponentiniame Verdin. Žaliavos dalis sudaro 50,68 % preparato. Atlikus bendro fenolinių junginių kiekio tyrimą, nustatyta, kad didžiausias fenolinių junginių kiekis yra skystajame rozmarinų ekstrakte (160,34 RRE mg/ml) (P<0.05). Didžiausias rozmarino rūgšties kiekis rastas skystajame rozmarinų... [toliau žr. visą tekstą] / Aim: to make comparable analysis of preparations containing plant materials accumulating rosmarinic acid, determine the total phenolic compound content, rosmarinic acid content and compare antioxidant activity. Objective:  Elect the preparations with rosmarinic acid;  Make the comparative analysis of compositions of these preparations;  Determine and compare the total phenolic compound content;  Determine and compare the rosmarinic acid content using HPLC method;  Determine and compare their antioxidant activity. Objects and methods: products with plant materials accumulating rosmarinic acid and rosemary leaf liquid extract. Total content of phenolic compounds was carried out spectrophotometrically using a standart Folin- Ciocalteu reagent. Rosmarinic acid content was determined by HPLC method. Antioxidant activity determined by DPPH radical scavenging method. The comparable analysis of products composition performed by literary analysis method. Conclusion: For research were selected 3 complex preparations with rosemary plant material and liquid rosemary extract. The highest quantity of raw rosemary material and RR quantity in RDD had Verdin, the preparation containing 4 components. Rosemary plant material makes 50,68 % in the preparation. Total phenolic compounds study showed that the highest amount of phenolic coumpounds had liquid rosemary extract (160,34 RAE mg/ml). The biggest quantity of rosmarinic acid was found in liquid rosemary extract (0.03 mg/ml). Combined... [to full text]
99

Biologiškai aktyvių junginių ir antioksidacinio aktyvumo natūraliose ir komercinėse vynuogių sultyse tyrimas / Bioactive compounds and antioxidant activity of natural and commercial grape juices study

Kazlauskaitė, Sandra 18 June 2014 (has links)
Tyrimais įrodyta, kad vynuogių sultys turi teigiamą poveikį mažinant rizikos veiksnius, susijusius su širdies ir kraujagyslių ligomis, dėl vynuogių sultyse esančių fenolinių junginių. Vynuogių sultyse esantys biologiškai aktyvūs junginiai yra stiprūs antioksidantai, kurie slopina kai kurių rūšių vėžio vystymąsi. Darbo tikslas — nustatyti ir palyginti natūralių sulčių, pagamintų iš skirtingų Lietuvoje augančių vynuogių veislių (Vitis vinifera L.) uogų, ir komercinių vynuogių sulčių kokybinius ir kiekybinius rodiklius, įvertinti antioksidacinį aktyvumą. Pasterizuotose vynuogių sultyse nustatytas statistiškai reikšmingai didesnis tankis (p<0,05) nei komercinėse vynuogių sultyse. Komercinėse vynuogių sultyse nustatyti didesni pH reikšmės ir sauso likučio kiekiai. Komercinėse mėlynų vynuogių sultyse spektrofotometriškai nustatytas didžiausias bendras fenolinių junginių ir antocianinų kiekis (p<0,05). Antioksidacinis aktyvumas tiesiogiai koreliavo su biologiškai aktyviais junginiais, bet statistiškai reikšmingai didesnė priklausomybė nustatyta nuo bendro fenolinių junginių kiekio (p<0,01, r = 0,684). / Grape juices have been shown in the study to have beneficial effect on reducing cardiovascular risks, possibly due to the high quantity of phenolics compounds. Bioactive compounds in grape juices are powerful antioxidants, which inhibit the development of some types of cancer. The aim of this research is to determine and compare quality indicators and antioxidant activity of natural grapes juices produced from the different grape species (Vitis vinifera L.) and commercial grapes juices. In pasteurized grape juices were determined statistically significantly higher density (p<0,05) than in commercial grape juices. In commercial grape juices were determined bigger pH value and dry residue levels. Commercial grape juice from blue berries have the biggest content of phenolics compounds and anthocyanins (p<0,05). Antioxidant activity directly correlated with bioactive compounds but statistically higher dependence is from totol phenolics compounds (p<0,01, r = 0,684).
100

Antioksidacinio aktyvumo nustatymas preparatuose, turinčiuose omega – 3 riebalų rūgščių / Evaluation of antioxidant activity of preparations containing omega - 3 fatty acid

Kiškytė, Karolina 18 June 2014 (has links)
Darbo tikslas: nustatyti antioksidacinį preparatų, turinčių omega – 3 riebalų rūgščių, aktyvumą, palyginti jį su preparatų sudėtimis, atlikti vaistinės asortimento analizę. Darbo uždaviniai: Atlikti preparatų antioksidacinio aktyvumo tyrimą DPPH metodu. Atlikti preparatų palyginamąją analizę vertinant sudėtis. Išnagrinėti omega – 3 riebalų rūgščių turinčių preparatų pasiūlą vaistinėse. Metodai: antioksidacinis aliejų aktyvumas tirtas spektrofotometriškai naudojant 2,2-difenil-1-pikrilhidrazilo (DPPH) laisvojo radikalo sujungimo metodą. Pasirinktų linų sėmenų, kanapių sėklų, judros, rapsų, kviečių gemalų, graikinių riešutų aliejų bei žuvų taukų sudėtys vertintos ir lygintos literatūros analizės metodu. Tyrime naudotų aliejų paplitimas vaistinės asortimente nustatytas renkant duomenis vaistinėse bei elektroninėse vaistinių parduotuvėse. Rezultatai: nustatytas antioksidacinis aktyvumas (išreikštas inaktyvuoto DPPH % ±SD) kviečių gemalų aliejaus 53,59 ± 9,45, žuvų taukų 22,58 ± 5,38, judros aliejaus 22,40 ± 4,74, linų sėmenų aliejaus 22,17 ± 2,64, kanapių sėklų aliejaus 19,05 ± 1,54, graikinių riešutų aliejaus 18,66 ± 4,10, rapsų aliejaus 17,04 ± 2,68. Palyginus rezultatus ir literatūroje pateiktus duomenis nustatyta, kad nėra ryšio tarp aliejuje esančio omega – 3 riebalų rūgščių kiekio ir antioksidacinio aktyvumo, tačiau yra statistiškai patikimas ryšys tarp antioksidacinio aktyvumo ir sudėtyje esančio vit.E kiekio. Įvertinus vaistinės asortimentą nustatyti 75 žuvų taukų... [toliau žr. visą tekstą] / Objective of work: To estimate the antioxidant activity of preparations containing omega - 3 fatty acids; compare it with constitution of preparations; to execute the analysis of pharmacy range. Main tasks: to estimate the antioxidant activity by using DPPH method. To compare preparations by evaluating their constitutions. To execute the analysis of pharmacy range. Methods: antioxidant activity determined by using 2,2 – diphenyl-1-picrylhidrazyl free radical scavenging method. The constituents of flax seed, hemp seed, camelina, rapeseed, wheat germ, walnut and fish oil were evaluated by literature analysis. The data of prevalence of selected oils in pharmacy range was collected in the pharmacies and their online-shops. Results: antioxidant activity of wheat germ oil was 53,59 ± 9,45%, fish oil 22,58 ± 5,38%, camelina oil 22,40 ± 4,74%, flax seed oil 22,17 ± 2,64%, hemp seed oil 19,05 ± 1,54%, walnut oil 18,66 ± 4,10%, rapeseed oil 17,04 ± 2,68%. A comparison of the results showed that there is no significant relationship between amount of omega – 3 fatty acids and the antioxidant activity of the oil, but there is a statistically significant relationship between the amount of tocopherols and the antioxidant activity. The evaluation of the pharmacy range showed 75 fish oil products, 10 products containing flax seed oil, 9 wheat germ oil, 6 hemp seed oil, 3 products with camelina oil, 2 rapeseed oil, and only one product containing walnut oil. Conclusions: The highest... [to full text]

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