• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 15
  • 13
  • 5
  • 5
  • 3
  • 2
  • 1
  • Tagged with
  • 50
  • 15
  • 9
  • 9
  • 8
  • 8
  • 7
  • 6
  • 6
  • 6
  • 6
  • 5
  • 5
  • 5
  • 4
  • 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.
11

Propagação vegetativa de Romãzeira (Punica granatum L.) / Vegetative propagation of pomegranate tree (Punica granatum L.)

Ferreira, Antonio Flávio Arruda 30 January 2017 (has links)
No contexto atual de alimentos nutracêuticos, a romãzeira, frutífera exótica no Brasil, se destaca mundialmente pelo alto poder antioxidante e propriedades anti-inflamatórias, anticancerígenas e antidegenerativas, com pesquisas recentes e produtos disponibilizados no mercado farmacêutico e alimentício. Para aumentar a oferta do produto no mercado consumidor a implantação de cultivos comercias é a primeira etapa do processo. Porém, para o bom desenvolvimento da cultura o uso de mudas de qualidade e com características agronômicas adequadas são primordiais. Almejando essas propriedades, a propagação, é o caminho mais utilizado na fruticultura para a produção de mudas com alto vigor e produtividade. O objetivo deste trabalho foi avaliar os métodos de propagação por estaquia e alporquia para produção de mudas de romãzeira cv. Comum. Avaliou-se o uso de AIB (0, 500, 1000, 1500, 2000 mg L-1) na formação de raízes adventícias em estacas herbáceas, semi-lenhosas e lenhosas de romãzeira, nos períodos de inverno e primavera em ambiente com nebulização. Avaliou-se também, o uso de AIB nas concentrações de (0, 500, 1000, 1500, 2000 mg L-1), no enraizamento de alporques em ramos com 10 e 15 mm de diâmetros, nos períodos de inverno e primavera. Pode-se concluir que, em romãzeira cv. Comum, o método de estaquia é mais eficiente com a utilização de estacas caulinares semi-lenhosas e lenhosas no período de inverno, não necessitando nesta época da aplicação de AIB para estimular a formação de raízes. O método de alporquia proporciona elevadas porcentagens de enraizamento tanto na primavera quanto no inverno. Alporques em ramos com diâmetro de 15,0 mm apresentam maior matéria seca de raízes quando comparados aos ramos de 10,0 mm de diâmetro. O uso de AIB em alporques influencia no comprimento e no número de raízes formadas. Os alporques realizados no inverno apresentam maior matéria seca de raízes. Os materiais usados para a contenção do substrato nos alporques, polietileno e papel alumínio, não interferem no enraizamento da romãzeira. / In the current context of nutraceutical foods, the exotic, fruitful pomegranate in Brazil stands out worldwide for its high antioxidant power and anti-inflammatory, anticancer and antidegenerative properties, with recent research and products available in the pharmaceutical and food market. To increase the supply of the product in the consumer market the implantation of commercial crops is the first stage of the process. However, for the good development of the crop the use of quality seedlings and with suitable agronomic characteristics are primordial. Targeting these properties, propagation, is the most used path in fruit growing for the production of seedlings with high vigor and productivity. The objective of this work was to evaluate the methods of propagation by cuttings and air-layerings for the production of pomegranate seedlings cv. Common. It was evaluated the use of AIB (0, 500, 1000, 1500, 2000 mg L-1) in the formation of adventitious roots in herbaceous, semi-woody and woody piles of pomegranate, during winter and spring periods in the nebulized environment. It was also evaluated the use of AIB in the concentrations of (0, 500, 1000, 1500, 2000 mg L-1), in the rooting of air-layering in branches with 10 and 15 mm of diameter, in the winter and spring periods. It can be concluded that in pomegranate cv. Common, the cutting method is more efficient with the use of semi-woody and woody stem cuttings in the winter period and does not require the application of IBA to stimulate root formation at this time. The weeding method provides high rooting percentages in both spring and winter. Air-layerings in branches with a diameter of 15 mm show a higher dry matter of roots when compared to the branches of 10 mm in diameter. The use of AIB in air-layering influences the length and number of roots formed. The air-layering made in the winter present greater dry matter of roots. The materials used for the containment of the substrate in the air-layering, polyethylene and aluminum foil, do not interfere in the rooting of the pomegranate.
12

Willingness-To-Pay for Pomegranates: Impact of Product and Health Features Using Nonhypothetical Procedures

McAdams, Callie 1987- 16 December 2013 (has links)
The use of functional foods by individuals to address health issues has become increasingly common. Pomegranate fruits and other pomegranate products contain phytochemicals, including several antioxidants that may have benefits when consumed as a functional food. The production of pomegranates in the United States is concentrated in California; yet pomegranates can be grown successfully in other regions. The purpose of this study was two-fold: 1) to address the market potential and consumer preferences for pomegranate fruits and other pomegranate products in Texas and 2) to address issues of experimental auction design and estimation in regards to novel products and health benefits of food products. A nonhypothetical experimental procedure was developed that combined preference rankings with a uniform nth-price auction to elicit preferences and willingness-to-pay (WTP) for pomegranate fruit products. Demographic and behavioral characteristics were collected from a representative sample of subjects in the Bryan-College Station area of Texas. Subjects submitted baseline preference rankings and bids on six pomegranate products and a control fruit product, all with the same retail price. Most participants had never purchased or tasted a pomegranate product. Additional information on the pomegranate products was provided in three forms: tasting information, health and nutrition information, and anti-cancer information. Subjects had the greatest WTP for the control product, followed by the juice product, followed by the ready-to-eat products; the whole pomegranate fruits had the lowest WTP. The preference rankings indicated the same order of preferences for the baseline round, but the ranking of the juice product dropped and the ranking of the ready-to-eat and Texas whole fruits rose when additional information was provided. Estimations of the WTP were done using random-effects tobit models and mixed linear models on the full bids and individual changes in bids. Unengaged bidders and bid censoring were addressed. Demographic variables were typically not predictors of WTP with the exception of previous purchases of pomegranates and household size. There were differences in WTP across information treatments, with tasting information having a greater effect than either health and nutrition information or anti-cancer information. Providing a reference price also increased WTP. Preference rankings were estimated using a rank-ordered logit and a mixed rank-ordered logit model. There was an interaction effect of each information treatment with the product characteristics, indicating that studies of effects of information treatments on preferences are not generalizable across products. There was divergence in the results for the preference rankings from the results of the experimental auction; preference rankings and bids gave different results for the same products.
13

Effects of raw materials on vermicompost qualities

A'ali, Rahman, Jafarpour, Mehrdad, Kazemi, Elahe, Pessarakli, Mohammad 11 January 2017 (has links)
Overuse of the chemical compounds and toxic elements leads to problems and transmission of contaminants and pollutants to humans and other living organisms. One of the industries’ byproducts of the agriculture sector is production of various composts from the organic raw materials that the best type of which is so – called Vermicompost. In this study, effects of raw materials on qualitative and quantitative characteristics of Vermicompost are discussed. To do so, sheep manure, pomegranate peels, spent mushroom compost either singly or double, triple or fourfold chopped corn, sugar beet pulp and sawdust were used. This research project was conducted in a completely randomized design experiment with 23 treatments with 3 replications. Results revealed that various bed combinations exert different effects on Vermicompost quality such that, the Vermicomposting process led to a significant decrease in electrical conductivity (EC) and a significant increase in pH in most of the culture (seed) beds. Also, the levels of Nitrogen, Phosphorous and Potassium in most treatments increased following completion of the vermicomposting process. As a result, this process can be introduced as an organic fertilizer with complete nutrients for improving chemical characteristics of agricultural wastes to usable fertilizers.
14

In Vitro and In Vivo Antioxidant Capacity of Synthetic and Natural Polyphenolic Compounds Identified from Strawberry and Fruit Juices

Abountiolas, Marvin 20 March 2016 (has links)
Strawberries can be considered a functional food because their consumption has been associated with several health benefits. They are important sources of bioactive compounds, such as vitamins and polyphenolic compounds, with recognized antioxidant capacity (AOC). However, strawberry overall quality and bioactive content are greatly affected by environmental conditions during pre- and post-harvest and, little is known about the stability of its bioactive compounds, specifically ascorbic acid (AA) and polyphenolics compounds. Furthermore, additional research that addresses the impact of polyphenolic compounds on in vitro and in vivo models is needed to understand the mechanisms behind their potential health benefits. Therefore, the objectives of the work presented in this thesis were to: 1) evaluate the impact of different disease control treatments on strawberry bioactive compounds and AOC; 2) understand the relationship between bioactive compounds and AOC in strawberries and fruit juices; 3) investigate the origin of AOC in strawberries by identifying their major polyphenolic compounds and, 4) explore the effects of polyphenol-rich fruits and fruit juices on the proliferation of cancer cells and lifespan of Caenorhabditis elegans. Conscientious consumers are aware of the health benefits of substantial fruit and vegetable consumption but are also concerned about the amount of pesticide residues that can be found in conventionally grown produce, with pesticide-free produce (i.e., organic) becoming more popular. However, the market price for organic strawberries can be more than twice that of conventionally grown fruit which discourages the average American from purchasing this fruit on a regular basis. Therefore, in the first study presented in this thesis, we hypothesized that reducing pesticide usage would provide the consumer with a “sustainable strawberry” that would have better or similar quality at a lower cost than organic fruit while it would also reduce environmental impact and risk to pesticide applicators. Results from this study showed that strawberries from a reduced fungicide treatment, had better or similar bioactive content and AOC than fruit from the conventional disease control treatment. After cold storage, strawberries from the reduced or conventional disease control treatments showed comparable amounts of bioactive compounds and AOC. These results indicate that growing strawberries with a reduced number of fungicide applications can be an alternative to the conventional disease control or organic practices as it may reduce residual fungicides in the fruit, decrease production costs while still retaining important bioactive compounds. In order to understand the relationship between bioactive compounds and AOC in strawberries and fruit juices, 56 different types of commercial beverages were chosen for the second study presented in this thesis. Overall, results showed that the higher the total phenolic contents (TPC) in the beverage the higher their AOC. Amongst all beverages studied, aronia, blackcurrant, and pomegranate juices contained the highest amount of TPC and AOC. Furthermore, after opening the bottles, these juices were maintained for 14 days at 4 °C, to test the stability of their TPC which was in general relatively stable throughout storage. Further investigation on individual polyphenolic compounds and their possible contribution to the overall AOC of fruits and fruit juices, led to a third study. Overall, results showed that the AOC of major individual polyphenolic compounds found in strawberries (i.e., pelargonidin, cyanidin, ellagic acid, quercetin, kaempferol, catechin, epicatechin, caffeic acid, p-coumaric acid, ferulic acid) was significantly higher than that of mixtures of the same compounds. In addition, the AOC of strawberries correlated with its major bioactive compounds (i.e., polyphenolic compounds and ascorbic acid) in a form of a synthetic bioactive strawberry model (“Powerberry”) composed of major strawberry polyphenolic compounds, vitamin C, fructose and glucose in the same ratios found in a real strawberry. These results suggest that even though strawberries contain many different polyphenolic compounds and vitamins, their AOC might only depend on few compounds that are found in significant quantities in the fruit. Finally, using cell and worm models we were able to demonstrate that conventional and organic strawberry, raspberry and blueberry fruits, and aronia, blackcurrant and pomegranate juices successfully inhibited the proliferation of HeLa cervical cancer cell lines. In addition, when introduced in low doses (0.75 mg ml-1 or lower) to the C. elegans diet, aronia, blackcurrant and pomegranate juices promoted longevity. Overall, results suggest that using whole fruit or fruit juices might constitute an alternative of treating cancer cells in vivo and that polyphenolic compounds contained in fruits and fruit juices displayed significant bioactivity in a worm model.
15

Quality Management Model Focusing on Good Agricultural Practices to Increase Productivity of Pomegranate Producing SMEs in Peru

Cárdenas, Mayra, Rodriguez, Mayra, Ramos, Edgar, Carvallo, Edgardo, Raymundo, Carlos 01 January 2020 (has links)
El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Peru’s pomegranate productivity is 10.3 tons, which is almost a third of that produced by Turkey (27.5 tons) and almost half of that produced by Spain (20 tons). In this sense, it is necessary that the organizations know the importance of quality management to monitor and maintain product quality. It is important to consider the appropriate methods to adopt and implement quality management so that MSEs may develop a better understanding of how quality management systems should be implemented and the significant, positive impact they generate. This document proposes a model based on quality management and good practices, which frames a series of activities and criteria to provide an objective diagnosis. This model was developed based on information gathered from SMEs in the district of Santiago de Ica.
16

The impact of different storage temperatures and storage period on the antioxidant activity of pomegranate

Gule, Aphiwe Angela January 2021 (has links)
>Magister Scientiae - MSc / Fruit storage at cold temperatures is normally used to delay decay while maintaining the fruit’s quality. However, storage at low temperatures for a prolonged period causes some important metabolic functions within the fruit to stop functioning properly. This phenomenon is even more critical and complex in chilling-sensitive fruits. Fruits that originated in the tropical and sub-tropical regions are known to be chilling sensitive; their storage at low but non-freezing temperatures causes them to experience chilling injury (CI). Chilling injury causes irreversible damage to the external and internal attributes of the fruits. Pomegranate, which is investigated in this study, is consumed as fresh arils in many regions of the world. / 2023
17

Postharvest physiology and effects of modified atmosphere packaging and anti-browning treatment on quality of pomegranate arils and aril-sac (CV. Bhagwa)

Aindongo, Wilhelmina Vulikeni 04 1900 (has links)
Thesis (MScFoodSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Knowledge of postharvest quality attributes of minimally processed packaged fruit is essential in order to establish the optimum shelf life period. The aim of this study was to investigate the effects of Passive-modified atmosphere packaging (MAP) on the quality of minimally processed pomegranate (cv. Bhagwa) arils and aril-sacs. These began by understanding the physiological processes i.e. respiration and transpiration rates of the whole fruit, arils and aril-sacs. The respiration rates (RR) of whole fruit, aril-sacs and arils were studied at 5, 10, 15 and 22°C, and comparisons were made among these fruit fractions. A high RR was observed in aril-sacs compared to whole fruit and arils across all storage temperatures. A 74.5% decrease in RR was observed when storage temperature was reduced from 22°C to 5°C. A significant increase in RR occurred from day 3 of storage across all fruit fractions and storage temperatures. The transpiration rates (TR) of arils and aril-sacs were studied at storage conditions of 5, 10 and 15°C and 76, 86 and 96% relative humidity (RH), and was found to increase with increase in temperature and decrease in relative humidity, with lowest TR occurring in fruit fractions stored at 5°C and 96% RH showing lower TR. Arils had high TR compared to aril-sacs, and this may be related to high surface area to volume ratio of exposed arils. The effects of modified atmosphere packaging and application of anti-browning agents on quality of arils and aril-sacs stored at 5°C were studied. Compared to clamshell packaging, Passive-MAP using POLYLID® 107 polyethylene (PE) polymeric film showed greater positive effects in maintaining the quality and extends the shelf life of the arils and aril-sacs. Furthermore, the anti-browning agents used controlled browning on the cut-surfaces of the peel of the aril-sacs and reduced microbial growth in both arils and aril-sacs. When the effects of MAP and anti-browning were combined, aril-sacs stored better than arils. These treatments extended the shelf life of aril-sacs to 12 days while arils lasted up to 9 days. The water vapour transmission rate (WVTR) of pomegranate fruit membrane was evaluated at cold storage (5°C, 90% RH) and room condition (18.7°C, 70% RH). A high WVTR occurred in membranes stored at room condition, compared to those stored at cold storage. Further studies are warranted to improve our understanding of the biophysical properties of pomegranate membranes in relation to possible exchange of water vapour and gases between the aril-sacs. In summary, the use of MAP in combination with anti-browning agents showed a high potential in maintaining the quality of pomegranate arils and aril-sacs and consequently increase their shelf-life. / AFRIKAANSE OPSOMMING: Kennis van naoes- gehalte-eienskappe van minimaal geprosesseerde verpakte vrugte is essensieel ten einde optimum rakleeftyd te bepaal. Die doel van hierdie studie was om die gevolge van passiewe gemodifiseerde atmosfeerverpakking (GAV) op die gehalte van arils en arilsakkies van minimaal geprosesseerde granaat (kv. Bhagwa) te ondersoek. ʼn Aanvang is gemaak deur die fisiologiese prosesse, m.a.w. respirasie- en transpirasietempo’s van die hele vrugte, arils en arilsakkies, te begryp. Die respirasietempo’s (RT) van hele vrugte, arilsakkies en arils is by 5, 10, 15 en 22°C bestudeer, en vergelykings is getref tussen hierdie vrugdele. ʼn Hoë RT is waargeneem by arilsakkies in vergelyking met hele vrugte en arils oor alle bergingstemperature heen. ʼn Afname van 74.5% RT is waargeneem toe bergingstemperatuur van 22°C na 5°C verminder is. ʼn Beduidende toename in RT het van dag 3 van berging af oor alle vrugdele en bergingstemperature heen voorgekom. Die transpirasietempo’s (TR) van arils en arilsakkies is by bergingstoestande van 5, 10 en 15°C en 76, 86 en 96% relatiewe humiditeit (RH) bestudeer, en daar is bevind dat dit verhoog met ’n toename in temperatuur en ʼn afname in relatiewe humiditeit, met die laagste TR wat voorkom by vrugdele geberg by 5°C en 96% RH wat dus laer TR toon. Arils het hoë TR gehad in vergelyking met arilsakkies, en dit kan verband hou met die verhouding van hoë oppervlakarea tot volume blootgestelde arils. Die gevolge van gemodifiseerde atmosfeerverpakking en aanwending van middels vir die voorkoming van verbruining op gehalte van arils en arilsakkies geberg teen 5°C is bestudeer. In vergelyking met verpakking in toeknipbakkies (clamshell packaging), het passiewe GAV waarby POLYLID® 107 poliëtileen- (PE) polimeriese film gebruik is, groter positiewe gevolge by die behoud van gehalte getoon, en die rakleeftyd van die arils en arilsakkies is verleng. Daarbenewens het die middels vir die voorkoming van verbruining beheerde verbruining op die sny-oppervlakke van die skil van die arilsakkies gebruik en mikrobiese groei in beide arils en arilsakkies verminder. Toe die gevolge van GAV en die voorkoming van verbruining gekombineer is, het arilsakkies beter as arils geberg. Hierdie behandelings het die rakleeftyd van arilsakkies tot 12 dae verleng terwyl arils tot 9 dae gehou het. Die waterdamptransmissiespoed (WDTS) van granaatvrugtemembraan is geëvalueer by koel berging (5°C, 90% RH) en kamertoestande (18.7°C, 70% RH). ʼn Hoë WDTS het voorgekom by membrane wat by kamertoestande geberg is in vergelyking met dié wat in koelbewaring geberg is. Verdere studies is geregverdig vir verbetering van ons begrip van die biofisiese eienskappe van granaatmembrane in verhouding met moontlike uitruiling van waterdamp en atmosfere tussen die arilsakkies.
18

Modified atmosphere packaging of pomegranate arils

Caleb, Oluwafemi James 03 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Modified atmosphere packaging (MAP) is a dynamic process of altering gaseous composition inside a package. It relies on the interaction between the respiration rate (RR) of the produce, and the transfer of gases through the packaging material. These two processes are dependent on numerous factors such as storage temperature, film thickness and surface area, produce weight as well as free headspace within the pack. Therefore, in order to achieve the desired modified atmosphere in a given package, it is important to understand the three basic disciplines of MAP, namely produce physiology, polymer engineering, and converting technology. In this study the effects of storage conditions and duration on physiological responses i.e. respiration (RR) and transpiration rate (TR) of two pomegranate cultivars ‘Acco’ and ‘Herskawitz’, were investigated and mathematical models were developed to predict these physiological responses at given time and storage conditions. The result of this study showed that RR of whole pomegranate fruit was significantly higher than that of fresh arils, and that temperature had a significant impact on the RR of both whole fruit and fresh arils. The influence of time, and the interaction between temperature and time also had significant influences on RR of fresh pomegranate arils. These findings highlight the significance of maintaining optimal cold-storage condition for packaged arils or whole fruit along the supply chain. In addition, mathematical models based on the Arrhenius-type equation and the power function equation coupled with Arrhenius-type equation accurately predicted the effect of temperature and the influence of time and temperature on the RR of fresh pomegranate arils for both cultivars. Furthermore, the results of experimental and model prediction studies showed that both relative humidity (RH) and storage temperature had significant effects on TR. RH was the variable with the greatest influence on TR, and it was observed that arils were best kept at 5°C and 96% RH to maintain quality for 8 days. The applicability of the transpiration model developed was validated based on prediction of TR of pomegranate arils under different combinations of storage conditions. The model adequately predicted TR and provides a useful tool towards understanding the rate of water loss in fresh pomegranate arils as affected by storage conditions and duration. The effect of passive-MAP engineering design parameters as a function of produce weight contained, storage temperature and duration on fresh pomegranate arils was investigated. The result showed that produce weight of aril content, temperature and the interaction between temperature and time had slight but insignificant effects on measured physicochemical quality attributes. However, headspace gas concentration was significantly influenced by produce weight and storage temperature. Oxygen (O2) composition decline below 2% after day 3 and 5 at 15 and 10 ºC, respectively, while samples at 5 °C did not reach below 2% throughout the study. On the other hand, CO2 levels increased significantly during storage for all packaging conditions. This study showed the importance of a systematic approach to the design of optimal MAP systems. At lowest storage temperature the inability to achieve desired modified atmosphere (MA) required for optimal storage of arils despite the increase in produce weight, suggests that the use of active gas modification (gas flushing with recommended atmosphere) would be necessary. However, the present results show that at higher temperature macro/micro perforations would be required on the polymeric films used in the present study in order to avoid critical levels of O2 and CO2. The influence of passive MAP, storage temperature and duration on volatile composition and evolution of packaged pomegranate arils was investigated. The results showed that changes in aroma compounds were dependent on cultivar differences, storage condition and duration. Using GC-MS analysis of pomegranate juice HS-SPME extracts, a total of 18 and 17 volatiles were detected for ‘Herskerwitz’ and ‘Acco’, respectively. Furthermore, flavour life (7 days) was shorter than the postharvest life (10 days) for both cultivars. There was a decrease in volatile composition during the storage period (aldehydes < alcohols < esters) while the concentration (%) and composition of ethyl esters increased with storage time. These results highlight the need for a more precise definition of flavour shelf life for MApackaged pomegranate arils and other packaged fresh produce. The importance of maintaining optimal cold storage condition, selection of appropriate packaging materials and a systematic approach to the design and application of MAP systems has also been shown. / AFRIKAANSE OPSOMMING: Gemodifiseerde atmosfeer-verpakking (GAV) is ’n dinamiese proses waartydens die gassamestelling binne-in ’n verpakking gewysig word. Dit berus op die wisselwerking tussen die respirasietempo (RT) van die produkte en die oordrag van gasse deur die verpakkingsmateriaal. Hierdie twee prosesse is van verskeie faktore soos bergingstemperatuur, dikte van die film en oppervlakte, gewig van die produkte asook vry boruimte binne-in die pakkie afhanklik. Om dus die gewenste gemodifiseerde atmosfeer in ’n gegewe verpakking te verkry, is dit belangrik om die drie fundamentele dissiplines van GAV te begryp, naamlik produkfisiologie, polimeerontwerp, en omsettingstegnologie. In hierdie studie is die gevolge van bergingstoestande en -duur op fisiologiese reaksie, met ander woorde, respirasie- (RT) en transpirasietempo (TT) van twee geselekteerde granaatkultivars ‘Acco’ en ‘Herskawitz’, ondersoek en wiskundige modelle is ontwikkel om ons in staat te stel om hierdie fisiologiese reaksies by gegewe tyd- en bergingstoestande te voorspel. Die resultaat van hierdie studie het aangetoon dat die respirasietempo (RT) van heel granaatvrugte aansienlik hoër was as die RT van vars arils, en temperatuur het beduidende uitwerking op RT van beide heel vrugte en vars arils gehad. Die invloed van tyd, en die wisselwerking tussen temperatuur en tyd het ook ’n beduidende invloed op die RT van vars granaatarils gehad. Hierdie bevinding beklemtoon die belang van die handhawing van optimale koelbewaringstoestande vir verpakte arils of heel vrugte met die aanvoerketting langs. Daarbenewens wiskundige modelle wat gebaseer op die Arrhenius-tipe vergelyking en die magsfunksie-vergelyking gepaard met Arrhenius-tipe vergelyking, die uitwerking van temperatuur en die invloed van tyd en temperatuur op die RT van vars granaatarils vir beide kultivars onderskeidelik voldoende en akkuraat voorspel. Afgesien die resultate van eksperimentele en modelvoorspellings die studies aangetoon dat beide relatiewe humiditeit (RH) en bergingstemperatuur ’n beduidende uitwerking op TT het. RH was die veranderlike met die grootste invloed op TT, en it was waargeneem dat dit die beste was om arils teen 5°C en 96% RH te bewaar (8 dae). Die toepaslikheid van die transpirasiemodel wat ontwikkel is, is bevestig op grond van voorspelling van TT van granaatarils onder verskillende kombinasies van bergingstoestande. Die model het TT voldoende voorspel en sou ’n bruikbare instrument wees ten einde die waterverliestempo in vars granaatarils en ander vars produkte, soos deur bergingstoestande en duur beïnvloed, te begryp. Die uitwerking van passiewe-GAV ontwerpparameters as ’n funksie van gewig van die produkte, bergingstemperatuur en duur op vars granaatarils is ondersoek. Dit het aan die lig gebring dat gewig van die produkte, temperatuur en die wisselwerking tussen temperatuur en tyd ’n geringe maar onbeduidende uitwerking op gemete fisikochemiese gehalteeienskappe gehad het. Die gaskonsentrasie in die boruimte is betekenisvol beïnvloed deur gewig van die produkte en bergingstemperatuur. Die O2-samestelling het tot benede 2% gedaal na 3 en 5 dae by 15 en 10 ºC, onderskeidelik, terwyl monsters by 5 °C deur die studie heen nooit laer as 2% was nie. Aan die ander kant, CO2-vlakke het gedurende berging betekenisvol verhoog wat betref alle verpakkingstoestande. Hierdie studie het die belangrikheid van ’n sistematiese benadering by die ontwerp van ’n optimale GAV-stelsel aangetoon. By die laagste bergingstemperatuur dui die onvermoë om die gewenste gemodifiseerde atmosfeer (GA) wat vir optimale berging van arils benodig word, te verkry – ondanks die toename in die gewig van die produkte – daarop dat die gebruik van aktiewe gasmodifisering (gasspoeling met aanbevole atmosfeer) nodig sou wees. Egter die huidige uitslae aangetoon dat by hoër temperatuur, sou makro/mikroperforasies op die polimeerfilms wat gebruik word in die onderhawige studie egter nodig wees ten einde kritiese vlakke van O2 en CO2 te verhoed. Die invloed van passiewe GAV, bergingstemperatuur en duur op onstabiele samestelling en evolusie van verpakte granaatarils is ondersoek. Die resultate aangetoon dat veranderinge in aromaverbindings afhanklik was van kultivarverskille, bergingstoestande en duur. Met behulp van GC-MS-analise van granaatsap HS-SPME-ekstrakte, het ons ’n totaal van 18 en 17 vlugtige stowwe vir ‘Herskawitz’ en ‘Acco’, onderskeidelik bespeur. Verder het ons waargeneem dat die smaakleeftyd (7 dae) korter was as die na-oesleeftyd (10 dae) vir beide kultivar. Daar was ’n afname in vlugtige samestelling (aldehiede < alkohole < esters) terwyl die konsentrasie (%) en samestelling van etielesters het met bergingstyd verhoog. Hierdie resultate het die aandag gevestig op die behoefte aan ’n meer presiese definisie van geur-raklewe vir GA-verpakte granaatarils en ander verpakte vars produkte. Die belang van die handhawing van die optimale koelbewaringstoestand, seleksie van geskikte verpakkingsmateriaal en ’n sistematiese benadering tot die ontwerp van ’n optimale GAVstelsel, is ook beskryf.
19

Avaliação da atividade antioxidante da romã (Punica granatum, L.) - participação das frações de ácidos fenólicos no processo de inibição da oxidação / Evaluation of the antioxidant activity of the pomegranate (Punica granatum, L.) - participation of the phenolic acids fractions on the inhibition of the oxidation´s process

Jardini, Fernanda Archilla 19 September 2005 (has links)
Os antioxidantes de origem natural têm importância na área de alimentos, pois podem representar uma alternativa de substituição aos antioxidantes sintéticos. Os compostos fenólicos, presentes nos vegetais, desempenham importância na inibição da oxidação, A romã (Punica granatum, L.) é rica em compostos fenólicos como as antocianinas, flavonóides e ácidos fenólicos. Avaliou-se a atividade antioxidante da polpa e semente de romãs plantadas no Brasil (Pernambuco), e foi feita a obtenção dos extratos e frações de ácidos fenólicos da fruta, que foram submetidos aos testes de co-oxidação de substratos &#946;- caroteno e ácido linoléico, em meio emulsionado, e ao método Rancimat, em meio lipídico. Também foi avaliado o comportamento cinético da atividade antioxidante para os extratos e frações de ácidos fenólicos. Verificou-se que os extratos aquosos da polpa e semente apresentaram significativa inibição da oxidação a concentrações baixas, em ambos os testes utilizados, fato atribuído à grande quantidade de compostos fenólicos presentes nestes extratos, em relação aos demais. A avaliação cinética dos extratos aquosos demonstrou que estes também foram mais eficientes ao longo do processo oxidativo, apresentando-se mais estáveis do que o antioxidante sintético BHT. As frações de ácidos fenólicos esterificados a compostos solúveis da polpa foi a fração que apresentou maior inibição da oxidação, e também maior quantidade de compostos fenólicos, apresentando uma atividade cinética bastante eficiente. Entretanto, as frações de ácidos fenólicos livres da polpa e semente apresentaram porcentagens de inibição da oxidação bastante altas a uma concentração menor. A semente da romã apresenta em sua composição de ácidos graxos o ácido graxo punícico. Este ácido é um isômero conjugado do ácido linolênico, e que constitui 58% da composição total de ácidos graxos da semente da fruta, sendo seu principal ácido graxo. / The antioxidants of natural origin have an important role on food science, because they may substitute the synthetic antioxidants. The phenolic compounds of vegetables play an important role as oxidation inhibitors. The pomegranate (Punica granatum, L.) is rich in phenolic compounds as anthocianins, flavonoids and phenolic acids. The antioxidant activity of extracts and acid phenolic fractions obtained from the pulp and seeds of brazilian pomegranate (from Pernambuco) was evaluated, by the co-oxidation of &#946;-carotene and linoleic acid assay and the Rancimat method. The kinetic behavior of the antioxidant activity of the extracts and acid phenolic fractions by the co-oxidation of &#946-carotene and linoleic acid test was evaluated, too. It was noted that the aquous extracts from the pulp and seeds have significant antioxidant activity at slow concentration. It was possible by the high content of phenolic compounds present on those extracts. The kinetic behavior showed that the aquous extracts was the most efficient along the oxidative process, showing larger stability than the antioxidant BHT. The pulp\'s of bound acid phenolic fraction by soluble compounds was the most efficient among the acid phenolic fractions, and it has major amount of phenolic compounds. The pomegranate seed has the punicic acid on its fatty acid composition. The punicic acid is a I conjugated inolenic acid isomer.The punicic acid is present at 58% from the total fatty acids from the fruit, being its principal fatty acid.
20

Atividade dos compostos fenólicos antioxidantes da romã (Púnica granatum, L.) -- avaliação in vivo e em culturas de células / Activity of the antioxidant phenolic compounds of pomegranate (Punica granatum, L.) -- in vivo and cell cutlure evaluation

Jardini, Fernanda Archilla 07 May 2010 (has links)
Os radicais livres são formados constantemente em nosso organismo, e em quantidades controladas desempenham alguns papéis fisiológicos. Entretanto, sua presença em quantidades acima daquelas aceitáveis passa a ser um fator de risco para funcionamento adequado do organismo. Muitas doenças crônicas degenerativas têm sua origem no desequilíbrio do estado redox. Apesar de possuir um sistema de proteção antioxidante endógeno, o organismo pode ser beneficiado pela presença de compostos antioxidantes exógenos, como os compostos fenólicos encontrados em alguns alimentos. A romã (Punica granatum, L) é uma fruta que apresenta elevados conteúdos destes compostos. Foram obtidos os extratos e as frações de ácidos fenólicos da polpa e das sementes da fruta, e avaliou-se a capacidade antioxidante através de três métodos in vitro: o de co-oxidação de substratos (&#946;- caroteno e ácido linoléico), o do radical DPPH&#8226; e o ORAC. Em todos os testes foram obtidos resultados que indicaram uma elevada atividade antioxidante, principalmente para a fração de ácidos fenólicos livres (AFL) da polpa. Frente a estes dados, a fração foi submetida a um ensaio de transporte celular, o qual foi possível verificar que os diferentes ácidos fenólicos ali encontrados foram capazes de atravessar a membrana celular. A fração AFL da polpa propiciou uma redução na produção de espécies reativas intracelulares e efeitos sobre a proliferação e a viabilidade em células das linhagens Caco-2, HeLa e MDCK. Por fim, o ensaio in vivo avaliou, sob condições fisiológicas normais, o efeito do extrato aquoso e da fração AFL sobre a oxidação lipídica e na atividade do sistema enzimático de defesa antioxidante. O tecido cerebral apresentou uma redução significativa nos níveis de lipoperoxidação. A atividade das enzimas superóxido dismutase, catalase e glutationa peroxidase apresentou resultados bastante díspares e sugerem que as respostas não seguem um padrão único e podem variar de acordo com o órgão analisado, respondendo com o aumento ou a diminuição da atividade enzimática de acordo com suas funções fisiológicas. / Free radicals are continuosly formed in our organism, and under suitable amounts they play physiological roles. However, when there´s a higher presence in their levels than the acceptable ones, they turn into a risk factor to the adequate work of the organism. Most of the degenerative illness are originated from the redox state desequilibrium. Although the organism has an endogenous antioxidant defence system, it may be beneficiated by the presence of antioxidant compounds of exogenous origen, as the phenolic compounds that are found in some kinds of food. The pomegranate (Punica grantum, L.) is a high phenolic compound fruit. The extracts and phenolic fractions both from the pulp and seeds of the fruit were obtained and their antioxidant activity was obtained using three in vitro methods: the co-oxidation of substrates (&#946;-carotene and linoleic acid), the DPPH&#8226; radical and the ORAC. For all of them the results have showed a great antioxidant activity, higher than those of the free phenolics acids´fraction (FPA) of the pulp. Face to these data, the fraction was taken to a cellular transport assay, which was possible to verify that the different phenolic acids present at FPA were able to cross the cellular membrane. The FPA pulp´s fraction provocated a down in production of the the intracelular reactive species and had effects into the cellular proliferation and viability of the Caco-2, HeLa and MDCK cells. Finally, the in vivo tryout was made using rats submitted to normal physiologic conditions and the effects of the aquous extract and FPA fraction over the lipidic oxidation and the activity of the enzymatic system of antioxidant defence were avaliated. The brain tissue showed a significant reduction about the lipoperoxidation levels. The results about the activity of the enzymes superoxide dismutase, catalase and glutathione peroxidase were so different between themselves, which suggests that the enzymes don´t follow an only standard of response, and the reply can vary in accordance with the analyzed organ. The increase or the reduction of the enzymatic activity can occur by the physiologic conditions that the organ is able to do.

Page generated in 0.0965 seconds