To see the other types of publications on this topic, follow the link: Storage of macadamia nuts.
Dissertations / Theses on the topic 'Storage of macadamia nuts'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 16 dissertations / theses for your research on the topic 'Storage of macadamia nuts.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Chitundu, Elizabeth Malama, of Western Sydney Hawkesbury University, Faculty of Science and Technology, and School of Food Science. "Studies on the shelf life of macadamia nuts." THESIS_FST_SFS_Chitundu_E.xml, 1994. http://handle.uws.edu.au:8081/1959.7/37.
Full textAbstract:
Shelf life studies of raw Macadamia integrifolia nuts were carried out at different storage temperatures, relative humidities and time. An accelerated shelf life test was conducted, and the influence of water activity on kernel texture was studied. The antioxidants naturally present were identified by the use of thin layer chromatography. Accelerated shelf life tests showed that hydrolytic rancidity followed apparent zero order kinetics within the water activity range of 0.3 to 0.5. Oxidative rancidity measured by peroxide value appeared to follow different orders of reaction at different temperatures. At two months of storage rancidity was detected at which the headspace concentration of hexanal was 0.39 ppm and a peroxide value of 0.37 meq/kg. Headspace gas chromatography was done to find a quick and effective method for measuring oxidative rancidity. The presence of natural antioxidants was verified to explain the shelf life of macadamia nuts. In textural study, correlations were found between subjective and objective measurements. The product became unacceptable organoleptically above water activity 0.415 when stored at 20 degrees C. This level was established as the critical water activity. There is a need to establish a water activity at which the consumer is likely to reject the product.<br>Master of Science (Hons) (Food Science and Nutrition)
2
Chitundu, Elizabeth Malama. "Studies on the shelf life of macadamia nuts." Thesis, Richmond, N.S.W. : School of Food Science, Faculty of Science and Technology, University of Western Sydney, Hawkesbury, 1994. http://handle.uws.edu.au:8081/1959.7/37.
Full textAbstract:
Shelf life studies of raw Macadamia integrifolia nuts were carried out at different storage temperatures, relative humidities and time. An accelerated shelf life test was conducted, and the influence of water activity on kernel texture was studied. The antioxidants naturally present were identified by the use of thin layer chromatography. Accelerated shelf life tests showed that hydrolytic rancidity followed apparent zero order kinetics within the water activity range of 0.3 to 0.5. Oxidative rancidity measured by peroxide value appeared to follow different orders of reaction at different temperatures. At two months of storage rancidity was detected at which the headspace concentration of hexanal was 0.39 ppm and a peroxide value of 0.37 meq/kg. Headspace gas chromatography was done to find a quick and effective method for measuring oxidative rancidity. The presence of natural antioxidants was verified to explain the shelf life of macadamia nuts. In textural study, correlations were found between subjective and objective measurements. The product became unacceptable organoleptically above water activity 0.415 when stored at 20 degrees C. This level was established as the critical water activity. There is a need to establish a water activity at which the consumer is likely to reject the product.
3
Du, Preez Alwyn Britz. "Studies on macadamia nut quality." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96929.
Full textAbstract:
Thesis (MSc)--Stellenbosch University, 2015.<br>ENGLISH ABSTRACT: The South African macadamia industry is centred in the sub-tropical regions of South Africa with 40% of the plantings in the Lowveld. Growers receive higher pay-outs for high kernel recovery and unblemished (not discoloured) whole kernels. It is known that the same cultivar in the Lowveld region, produces nuts that differ in kernel recovery, whole kernel recovery and kernel discolouration. Therefore to develop optimal management strategies to maximize productivity and profitability of macadamias, factors that influence kernel recovery, whole kernel recovery and kernel discolouration needed to be investigated.
The fruit structures are formed the first 90 days after anthesis and the fruit continues to grow until 12 to 15 weeks after anthesis until the shell hardens. Climate, soil moisture, cross-pollination and nutrition influence this process which determines the shell thickness and kernel size which in turn both determine kernel recovery.
A large set of historical data from different regions were used to establish and isolate possible factors involved in kernel recovery, whole kernel recovery and kernel discolouration. These differed between the six regions over two seasons. High kernel recovery was associated with high orchard altitude, good cross-pollination, high crop load (high yield), early season harvesting and processing of nut-in-shell (NIS), high leaf boron concentrations in Nov., water management using deficit irrigation and low daily maximum relative humidity during the nut growth stage (Oct. to middle Jan.). High whole kernel recovery was associated with high kernel recovery, early season harvesting and processing of NIS, Bungay curing system of NIS compared to ambient air, low vapour pressure deficit during the nut maturation period (middle Jan. to harvest), elevated leaf boron and copper concentrations and low manganese leaf concentrations in Nov. High crop load, no cross pollination, low leaf nitrogen and zinc and high leaf potassium concentrations in Nov. were associated with low kernel discolouration.
In order to develop possible orchard practices that increase kernel recovery, whole kernel recovery and decrease kernel discolouration, two irrigation trials and one kaolin trial were conducted.
In the two irrigation trials, water stress was induced over two growing seasons (2011-2013) by applying different levels of irrigation at different phenological stages. Kernel recovery was not affected by any of the treatments, but water stress could not be applied continuously due to frequent high rainfall. Moderate water stress did not influence yield, only trees that were over watered during a drier premature nut drop stage during the 2011/12 season increased yield, although it could not be repeated the following season during a wetter premature nut drop stage.
In the kaolin trial, the efficacy of kaolin foliar application was evaluated to reduce heat stress. Kaolin applications did not affect kernel recovery, nut yield or quality. Temperature during the study was not continuously high (>30 ⁰C), thus heat stress could not be mitigated. We did however establish that up to five layers of foliar applied kaolin did not significantly reduce individual leaf photosynthesis.<br>AFRIKAANSE OPSOMMING: Die makadamia-industrie in Suid-Afrika, is gesentreer in die sub-tropiese streke van die land met 40% van die aanplantings in die Laeveld. Produsente ontvang hoër uitbetalings vir neute wat 'n hoë uitkraak (kernherwinning) persentasie lewer asook ongeskonde (nie verkleurde), heel-kern neute. Daar is gevind dat dieselfde kultivar verskil ten opsigte van kernherwinning, heel-kernherwinning en kernverkleuring in die Laeveld. Om 'n optimale bestuurstrategie te ontwikkel en so maksimale opbrengs en wins te verkry, moes die faktore wat kernherwinning, heel-kernherwinning en kernverkleuring beïnvloed ondersoek word.
Die eerste 90 dae na blom word die vrugstrukture gevorm en vrugte groei tot en met 12 tot 15 weke na volblom totdat die dop verhard. Klimaat, grondvog, kruisbestuiwing en voedingstowwe beïnvloed die prosesse wat dopdikte en kerngrootte beïnvloed en wat beide kernherwinning bepaal.
'n Groot stel historiese data vanaf verskillende streke is gebruik om die moontlike faktore wat kernherwinning, heel-kernherwinning en kernverkleuring beïnvloed te bepaal. Hierdie aspekte het verskil in die ses streke oor twee seisoene. Hoë kernherwinning was geassosieer met hoër liggende boorde (hoogte bo see spieël), goeie kruisbestuiwing, hoë oeslading, vroeë seisoen oes en prosessering van neut-in-dop, hoë boor blaarkonsentrasie in Nov., waterbestuur met onthoudingsbesproeïng en lae daaglikse maksimum relatiewe humiditeit gedurende die neut-groei-stadium (Okt. tot middel Jan.). Hoë heel-kernherwinning was geassosieer met hoë kernherwinning, vroeë seisoen oes en prosessering van neut-in-dop, Bungay droging, lae waterdampdruk tekort gedurende die neut-rypwording stadium (Jan. tot oes), hoë boor en koper blaarkonsentrasies en lae mangaan blaarkonsentrasie in Nov. Hoë oeslading, geen kruisbestuiwing, lae stikstof, sink en hoë kalium blaarkonsentrasies in Nov. was geassosieer met lae kernverkleuring.
Twee besproeïngsproewe en een kaolienproef is uitgevoer om moontlike boord praktyke te ontwikkel wat kernherwinning en heel-kernherwinning verhoog en kernverkleuring verlaag.
In die twee besproeïngsproewe is watertekorte aangewend oor twee seisoene (2011-2013) deur verskillende hoeveelhede te besproei gedurende verskillende fenologiese stadiums. Kernherwinning was nie geaffekteer deur die behandelings nie, maar dit moet ingedagte
gehou word dat watertekorte nie deurlopend toegepas kon word nie as gevolg van hoë reënval. Gematigde watertekorte het nie die opbrengs beïnvloed nie, slegs bome wat oor-besproei was in ’n droeër voor-rypwording-neut-val stadium in die 2011/12 seisoen het 'n verhoging in opbrengs getoon, maar dit kon nie herhaal word die daaropvolgende natter seisoen nie.
In die kaolienproef, is die gebruik van kaolien blaarbespuiting geëvalueer om hitte stress te verminder. Kaolienbespuitings het geen effek op kernherwinning, neut opbrengs of neutkwaliteit gehad nie. Temperature gedurende die studie was nie deurlopend hoog nie (>30 0C) en dus kon hitte stress nie gemanipuleer word nie. Daar is wel vasgestel dat tot vyf lae kaolien nie enkel-blaar fotosintese verminder het nie.
4
Netiwaranon, Siriwan. "The effect of harvest date on the composition and quality of macadamia nuts /." [St. Lucia, Qld.], 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16323.pdf.
Full text
5
Sithole, Noleen Miriam. "The export potential of South African edible nuts : the special case of macadamia nuts to Germany / Noleen Miriam Sithole." Thesis, North-West University, 2009. http://hdl.handle.net/10394/4984.
Full textAbstract:
One of the top priorities of the South African government is to maintain and enhance economic growth. The South African government is seeking to achieve this by implementing export-led growth policies. In many exporting economies. resources are scarce and often export promotion institutions face the double allocation problem. The double allocation problem implies that export promotion institutions face the difficulty of having to allocate scarce resources efficiently (Cuyvers. De Pelsmaker. Rayp & Roozen. 1995). The apportionment of financial resources is among several export promotion instruments that can be used to attain export success.
In 2005. the Department of Trade and Industry (the dti). as the trade promotion organisation in South Africa. expressed the need for a scientific study on• the realistic export opportunities in products and markets. This would enable decision-makers to scientifically justify the allocation of public resources to promote products with the highest potential earnings. A Decision Support Model (DSM) designed by Cuyvers (1995) was applied to the South African economy (in a study done by Viviers & Pearson (2007)) to identify priority products with high export potential in new and I or existing markets. The DSM identified the product group,. under the Standard International Trade Classification (SITC). SITC 0577 as the twenty-second product with the most realistic export opportunities. SITC 0577 was identified as having thirty-six potential export destinations.
This study evaluated each of the fifteen product categories corresponding to SITC 0577 on an HS level. to determine the product with the most potential for export success for the South African economy. This was achieved by employing a quantitative approach to construct a composite index. The composite export potential index comprised three sub indices: South Africa's export performance index. the world markets index and the production index. Based on an export potential index score of 4.16. macadamia nuts, classified under nuts not else specified (nes). were identified as the product with the highest potential for export success.
Once the product with the highest export potential had been identified. trade and market access statistics were analysed to determine a target market with the highest import potential for South African macadamia nuts. Germany was selected from a group potential target markets as the target market for South African macadamia nuts based on an analysis of market size, growth trends, share in the world market trade, and market accessibility. Thereafter, a survey was conducted through unstructured telephone interviews and from secondary sources of information. The survey determined the market entry requirements, consumption trends and price information for South African exporters of macadamia nuts to Germany. This information was compiled into a market profile to provide exporters of macadamia nuts with essential market information on the German market.<br>Thesis (M.Com. (International Commerce))--North-West University, Potchefstroom Campus, 2010.
6
Silva, Flavio Alves da. "Estudo da aplicação de energia de microondas na secagem da noz macadamia (Macadamia integrifolia Maiden & Betche)." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/255311.
Full textAbstract:
Orientador: Antonio Marsaioli Junior<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos<br>Made available in DSpace on 2018-08-05T01:14:32Z (GMT). No. of bitstreams: 1
Silva_FlavioAlvesda_D.pdf: 2135599 bytes, checksum: 1cb50b2bea2c0d7059788a4f01434a15 (MD5)
Previous issue date: 2005<br>Doutorado<br>Doutor em Engenharia de Alimentos
7
Barbara, Mitchell. "Model and simulation development for the convective, hot-air drying of In-shell macadamia nuts." Thesis, Barbara, Mitchell (2018) Model and simulation development for the convective, hot-air drying of In-shell macadamia nuts. Honours thesis, Murdoch University, 2018. https://researchrepository.murdoch.edu.au/id/eprint/44869/.
Full textAbstract:
The drying of agricultural food crops is an essential process in ensuring the safe and reliable delivery of produce to consumers. This is no less true for cultivated nuts, grains and seeds, which have a certain vulnerability to degradation under moist conditions. The macadamia nut is particularly susceptible to this issue, due to its high oil content and markedly slow drying characteristics, providing rancidity and disease with an opportunity to spoil the produce. In recent decades, the design of efficient industrial drying schemes has become a large focus for researchers, with many studies aiming to better describe the underlying physical processes in food drying. This dissertation details the design and implementation of a fundamental model and accompanying simulation for the drying of nut-in-shell macadamias, intended to aid a future control system design study.
Research is given toward the macadamia industry, as well as some of the relevant physical properties of the nut. An extensive review is given on modelling, with particular importance placed on techniques used for the deep-bed drying of nuts, grains and seeds. Control system architecture is briefly discussed, but is not the primary focus of this report. Verification of work done by prior researchers is carried out, before then deriving a comprehensive deep-bed drying model for macadamias. Crucial aspects toward how such a model is adapted into a MATLAB simulation is given, without intending to become an extensive review on software design. A robust and thorough model verification procedure is conducted, to prove that the final simulation does indeed successfully suit the purposes of control system design.
8
Chitundu, Elizabeth Malama. "Studies on the shelf life of macadamia nuts : thesis submitted in partial fulfilment of the requirements for the Degree of Master of Science (Honours) in Food Science and Nutrition /." Richmond, N.S.W. : School of Food Science, Faculty of Science and Technology, University of Western Sydney, Hawkesbury, 1994. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20030530.112709/index.html.
Full text
9
Saunders, Thomas Philip. "Inactivation Of Salmonella And Surrogate Bacteria On Cashews And Macadamia Nuts Exposed To Saturated Steam And Propylene Oxide Treatments." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/86138.
Full textAbstract:
Saturated steam (SS) and propylene oxide (PPO) fumigation are two common methods to improve microbiological quality and safety of tree nuts. Validation of these processes is needed to ensure adequate control of bacterial pathogens. Since pathogens cannot be studied in food processing environments, surrogates with resistance comparable to the pathogens needed to be identified. The objective was to investigate the suitability of Enterococcus faecium, Pediococcus acidilactici, and Staphylococcus carnosus as surrogate bacteria for Salmonella spp. on whole cashews and macadamia nuts, processed with SS or PPO.
Whole cashews and macadamia nuts were co-inoculated with a cocktail of Salmonella enterica and one of the three potential surrogates. Nuts were dried to original aw, packaged in poly-woven bags (2.3 kg) and commercially processed using vacuum assisted steam at 80 ͦ C or PPO fumigation. Salmonella and the potential surrogates were enumerated by serial dilution, and plated onto TSA with overlay of XLT-4 (Salmonella) or media selective for the potential surrogates.
Mean log reductions (CFU/g) of Salmonella and each potential surrogate were compared using a paired T-test. SS results: reduction of Salmonella (6.0 ± 0.14) was significantly larger than E. faecium (4.3± 0.12), or P. acidilactici (3.7± 0.14) on whole cashews. Salmonella (5.9 ± 0.18) was significantly larger than P. acidilactici (4.4± 0.18) on whole macadamia nuts.
PPO results: reduction of Salmonella (7.3 ± 0.19) was significantly greater than E. faecium (6.4± 0.31), or P. acidilactici (6.3± 0.33) on whole macadamia nuts. Reduction of Salmonella was significantly greater than E. faecium and P. acidilactici reduction on cashews.
P. acidilactici may be considered a surrogate for Salmonella reduction on whole macadamia nuts and whole cashews processed using SS at 80 ͦ C. E. faecium and P. acidilactici may be considered surrogates for Salmonella reduction on whole macadamia nuts and whole cashews processed using PPO. Reduction of St. carnosus exceeded that of Salmonella indicating it is not a suitable surrogate for Salmonella using either processing intervention.<br>Master of Science in Life Sciences
10
Rábago, Panduro Lourdes Melisa. "Evaluation of compositional changes in pecan nuts during storage and the use of pulsed electric fields as an aid to enhance oil extraction yield." Doctoral thesis, Universitat de Lleida, 2021. http://hdl.handle.net/10803/671793.
Full textAbstract:
Les nous pacanes són una font important d’àcids grassos mono- i poliinsaturats, fitosterols, tocoferols i compostos fenòlics. La tecnologia de polsos elèctrics (PE) s’està aplicant com a pretractament per millorar l’extracció d’oli de diferents llavors augmentant el rendiment d’extracció d’oli (REO). Aquesta tesi va demostrar que compostos fenòlics i capacitat antioxidant de les nous pacanes tenen molta relació amb l'assecat i temps d'emmagatzematge, evidenciant el seu impacte en les seves propietats funcionals. Pel que fa al tractament amb PE, la immersió de les nous en aigua per a l'aplicació de PE va disminuir el contingut inicial d'oli tant en les nous fresques com seques, demostrant que cal tenir en compte l'oli extret en l'aigua de remull. A més, l'efectivitat de la tecnologia de PE va ser depenent de la nou pacana utilitzada incrementant el REATOTAL a nou fresca però no en nou seca.<br>La almendra de nuez pecanera es una fuente importante de ácidos grasos mono- y poliinsaturados, fitoesteroles, tocoferoles y compuestos fenólicos. Una alternativa para mejorar el rendimiento de extracción de aceite total (REATOTAL) del aceite de nuez es la tecnología de campos eléctricos pulsados (CEP). En esta tesis doctoral se evidenció que tanto el contenido de compuestos fenólicos como la capacidad antioxidante de la nuez pecanera son alterados por el proceso de secado y el tiempo de almacenamiento lo que podría repercutir en las propiedades funcionales de este alimento. Respecto a la aplicación de CEP, es necesario considerar la recuperación del aceite extraído en el agua de remojo. Además, la efectividad de la tecnología de CEP fue dependiente de la nuez pecanera utilizada incrementando el REATOTAL en nuez fresca pero no en nuez seca.<br>Pecan nut kernels have been identified as an important source of mono- and polyunsaturated fatty acids, phytosterols, tocopherols, and phenolic compounds. Pulsed electric fields (PEF) are being applied as a pretreatment to improve oil extraction from different seeds increasing the oil extraction yield (OEY). This dissertation proved that phenolic compounds and antioxidant capacity of kernels are highly susceptible to drying and storage time, evidencing their impact on the functional properties of pecan nuts. Concerning pretreatment with PEF, it was demonstrated that it is necessary to take into consideration the recovery of the oil retained into the soaking water. Furthermore, the effectiveness of PEF to improve OEYTOTAL depended on whether the pretreatment was applied to fresh or dry pecan nuts, improving OEYTOTAL of fresh kernels but with no effect on OEYTOTAL of dry kernels.
11
Verjux, Christian. "Les structures en creux du site mésolithique d'Auneau "le Parc du Château" (Eure-et-Loir) : nouveau bilan et implications concernant le mode de vie des dernières populations de chasseurs-collecteurs en Europe." Thesis, Paris 1, 2015. http://www.theses.fr/2015PA010715/document.
Full textAbstract:
Ce travail s'appuie sur un nouveau bilan concernant les 70 structures en creux mésolithiques du site du « Parc du Château » à Auneau (Eure-et-Loir), datées entre 8 000 et 5 500 ans avant J.-C. Leurs fonctions variées — sépultures, dépôts intentionnels de restes animaux, foyers en fosse, calages de poteau, extraction, stockage, dépotoirs — évoquent des installations d'une certaine durée. Une enquête étendue à une bonne partie de l'Europe permet de recenser plus d'une centaine d'autres sites mésolithiques livrant des structures analogues, parfois en grand nombre. Il en ressort une image très éloignée de la vision traditionnelle de ces sociétés (cf. chasseurs-collecteurs très mobiles aux campements temporaires sommairement aménagés). Deux types de structures retiennent particulièrement l'attention : les fosses destinées au stockage alimentaire enterré (cf. silos) laissent envisager une consommation différée de fruits à coque (noisettes, glands) permettant de s'affranchir des cycles saisonniers ; les fosses-dépotoirs attestent, quant à elles, une gestion des déchets évoquant des installations durables. On en déduit que le développement de stratégies de subsistance adaptées à un riche environnement post-glaciaire a pu favoriser la sédentarisation de certains groupes de chasseurs-collecteurs stockeurs dès le Mésolithique moyen — bien avant donc les premiers contacts avec les populations néolithiques. L'apparition des premiers cimetières en Europe constitue un autre indice très évocateur d'une restriction de la mobilité, également perceptible à travers certains impacts anthropiques sur le milieu et divers types d'équipement (outillage lourd, vannerie, pirogues, pêcheries)<br>Our research leans on new analysis about the Mesolithic pits discovered during the excavation at "le Parc du Château" in Auneau (Eure-et-Loir; France). These 70 pits date between 8.000 and 5.500 cal. BC. Their various functions — i.e. graves, faunal hoards, pit-hearths, post-holes, extraction, storage, rubbish dumps — evocate long duration settlements. A European survey links to record more than 100 sites With such features, sometimes very numerous. These new data provide an original pattern, quite different from the traditional models of very mobile hunter-gatherer and short time encampment. Two kinds of features seem to be especially significant: food storage pits (similar to silos) may have allowed a delayed consumption of nuts (hazelnut or acorn) providing the bulk of food during the season of scarcity; rubbish pits indicate waste management linked to long term dwellings. From our point of view new subsistence strategies related with rich post-glacial environmental resources may allow some storing hunter-gatherer groups to adopt a sedentary way of life Since the middle Mesolithic — i.e. several millennia before the first interactions with Neolithic populations. The emergence of actual cemeteries in Euro e at the same period reveals also decreasing mobility evidence likewise some anthropogenic impacts on the environment and various equipment such as heavy lithic tools, basketry, pirogue, fishery, and so on
12
"Elemental distribution in selected edible nuts and the impact of soil quality on the chemical characteristics of macadamia (Macadamia integrifolia) nuts." Thesis, 2007. http://hdl.handle.net/10413/425.
Full text
13
Mphethe, Vusani. "Activity patterns, species composition and dietary analysis of bats on two macadamia farms in Levubu, South Africa." Diss., 2017. http://hdl.handle.net/11602/978.
Full text
14
Jelassi, Arij. "Technological processes for reduction of fungal and mycotoxin contamination of nuts." Master's thesis, 2019. http://hdl.handle.net/10198/23589.
Full textAbstract:
Almond and hazelnut production in Portugal are of great importance for the economy of their main producing areas. However, the contamination of these nut fruits with fungi and mycotoxins poses a significant risk to food security. Mycotoxins are secondary metabolites produced by filamentous fungi that frequently contaminate these commodities. This work intended to evaluate the influence of storage conditions on the microbial and mycotoxin stability and safety of nuts throughout long-term storage. For that, almond and hazelnut samples were stored under different relative humidity (RH) conditions (60, 70 and 80%) at 25°C for up to 6 months. The storage of two almond varieties – Lauranne and Guara - under 60% and 70% RH at 25°C were further compared with storage at 4 ºC for 9 months. Microbial loads (aerobic mesophiles and yeasts and molds) were determined at post-harvest stage and after being submitted to preservation, and molds were identified morphologically and molecularly. Nuts were also subjected to multi- mycotoxin analysis by LC-MS/MS to determine their mycotoxin contamination level and profile. For hazelnuts, five fungal species were identified belonging to four fungal genera commonly associated with mycotoxin production: Alternaria, Aspergillus, Fusarium, and Penicillium. For hazelnuts, an important range of mycotoxin was detected after 6 months of storage with a remarkable cumulative amount in 80% RH at 25°C, when compared to 60% and 70% RH at 25°C. For almonds, 26 species were identified belonging to seven genera: Alternaria, Aspergillus, Cladosporium, Fusarium, Penicillium, Paecilomyces, Talaromyces. For the variety Guara, mycotoxins related to Aspergillus sect. Flavi such as Aflatoxin B1, B2, G1, G2, Averufin, Versicolorin C, Norsolorinic acid were detected only after nine months of storage at 70 and 60% RH at 25°C. Penicillium sp. mycotoxins as Quinolactacin A, Roquefortine C and Flavoglaucin were also detected. Flavoglaucin was present in all time-points and conditions of storage in important amounts. For the variety Lauranne, Penicillium sp. mycotoxins were detected such as Citrinin, Quinolactacins A and B, Roquefortines Cand D, Cyclopenin, Cyclopenol, Penitrem A, Viridicatin and Viridicatol. Mycotoxins related to Aspergillus sp. such as Aspulvinone E, Flavoglaucin, Paspalin, Asperglaucide, Asperphenamate, cyclo(L-Pro-L-Tyr) and cyclo(L-Pro-L-Val) were also detected.<br>A produção de amêndoa e avelã em Portugal é de grande importância para a economia das regiões produtoras. No entanto, a contaminação destes frutos com fungos e micotoxinas apresenta um elevado risco para a segurança alimentar. Micotoxinas são metabolitos secundários dos fungos frequentemente produzidos nestes frutos. O presente trabalho teve como objetivo avaliar a influência das condições de armazenamento de longo prazo na sua estabilidade e segurança microbiana. Para o efeito, amostras de amêndoas e de avelãs foram armazenadas sob diferentes condições de humidade relativa (HR) – 60, 70 e 80%, a 25 ºC durante 6 meses. O armazenamento de duas variedades de amêndoa – Lauranne and Guara – a 60% e 70% HR (25 ºC) foi também comparado com o armazenamento a 4 ºC durante 9 meses. A carga microbiana (aeróbios mesófilos) e fúngica (bolores e leveduras) foi determinada após a colheita e após preservação. Os bolores foram identificados morfológica e molecularmente. Os frutos foram também submetidos a análise multi-micotoxina por LC-MS/MS para determinação do nível e perfil de contaminação com micotoxinas. Nas avelãs foram identificados quatro géneros de fungos potencialmente produtores de toxinas: Alternaria, Aspergillus, Fusarium e Penicillium. Várias micotoxinas foram detetadas após 6 meses de armazenamento, com níveis cumulativos elevados a 80% HR. No caso das amêndoas, foram identificadas 26 espécies pertencentes a sete géneros: Alternaria, Aspergillus, Cladosporium, Fusarium, Penicillium, Paecilomyces, Talaromyces. Para a variedade Guara, foram detetadas várias toxinas relacionadas com Aspergillus sect. Flavi como Aflatoxinas B1, B2, G1, G2, averufina, versicolorina C e ácido norsolorinico após nove meses de armazenamento a 70 e 60% HR. Foram ainda detetadas várias micotoxinas de Penicillium sp. (quinolactacina A, roquefortina C e flavoglaucina). Para a variedade Lauranne, foram detetadas as micotoxinas de Penicillium sp. citrinina, quinolactacinas, roquefortinas, ciclopenina, ciclopenol, penitrem A, viridicatina e viridicatol, e as micotoxinas de Aspergillus sp. aspulvinona E, flavoglaucina, paspalina, asperglaucide, asperfenamate, ciclo(L-Pro-L-Tyr) e ciclo(L- Pro-L-Val).<br>Work financed by ValNuts Project (PDR2020-101-030756), as part of a community initiative promoted by PDR2020 and co-financed by FEADER, within the Portugal 2020. This work was also partially financed by CIMO (UID/AGR/00690/2019) through the FEDER under PT2020.
15
Steyn, Jakobus Nicolaas. "Alternative practices for optimising soil quality and crop protection for macadamia orchards, Limpopo Province, South Africa." Thesis, 2019. http://hdl.handle.net/11602/1409.
Full textAbstract:
Department of Ecology and Resource Management<br>PhDENV<br>The main aim of the research was to contribute means for converting conventional, high-input
production systems to more sustainable ecological systems, thereby improving the sustainability
of macadamia production and ultimately contributing to food security. This was achieved by a)
investigating the potential use of cover crops and compost to enhance soil quality in macadamia
orchards and b) investigating the potential use of use of cover crops and orchard heterogeneity to
control stinkbug pests that target macadamia crops.
Field experiments were conducted in three phases: phase one tested the potential of six cover
crops for crop protection (as trap crops) and simultaneously for soil restoration or fertility
enhancement purposes in macadamia orchards. Phase two repeated the trials of phase one (both
soil restoration and trap crops) but with modifications to both categories. Soil restoration
treatments were conducted with trees which were growing in what appeared to be healthy soils,
and then repeated with trees in the same orchard where the topsoil had been degraded (totally
removed) by agricultural operations. The third phase repeated the trap crop trials only, but this
time on three different study areas (all commercial farms) with the single cover crop which
performed the best as a trap crop during phase two. Trials were modified from the first to the last
phase to overcome practical implementation problems encountered along the way and to adapt to
local conditions experienced in the commercial macadamia farming systems which served as
research sites. Diversity of natural orchard vegetation was enhanced in phase three to improve
conditions for natural predators as part of the trap crop treatments in the last phase and cover
crops were finally first composted and then returned to the root zones of the macadamia trees as
part of the soil quality enhancement treatments in the second phase.
The results from the trap crop trials shows a significant effect of trap crops combined with
increased orchard diversity in reducing unsound kernel percentages caused by stinkbug pests and
demonstrate that trap crops combined with an increase in orchard diversity could be utilized in
macadamia orchards as a more sustainable alternative to inorganic pesticides against the stinkbug
complex.
The most notable changes in the soil that took place with soil quality enhancement treatments
were the significant increases in soil phosphorous content and pH which resulted not in an
improvement in soil quality in terms of these two indicators but revealed an important issue about
the use of compost containing animal manure originating from dairies or feedlots. In summary
however, it was clear that although not all the soil quality indicators that were employed to assess
changes in the soil with compost treatments improved significantly, a holistic consideration of all
indicators portrays an overall improvement which was particularly significant in the degraded soil
plots where the topsoil had been removed by prior agricultural activities.<br>NRF
16
Pereira, Cátia Liliana Morais. "Characterization of allergens from several tree nuts and their role in plant food allergy." Master's thesis, 2013. http://hdl.handle.net/10451/11516.
Full textAbstract:
Tese de mestrado, Controlo da Qualidade e Toxicologia dos Alimentos, Universidade de Lisboa, Faculdade de Farmácia, 2014<br>Food allergies are a common issue in western countries. In the last decade, these diseases has increased significantly, and nowadays it is estimated that affects 2-8% of the population. Within the food allergies, plant food is the most frequent in adult population and the most part of the plant food allergens belong to protein families with defense or storage functions.
Among plant food allergies there is a special interest in tree nut allergy. In the course of history, nuts have been part of the diet around the world. Tree nuts have a high nutritional value and they are very important in the human diet. However, in the developed world, the allergic reactions caused by tree nuts represent one of the first causes of food allergies in children and the first in adults.
Understanding the mechanism by which a harmless protein to the organism is capable of inducing an allergic response is the basis to prevent and treat this type of disease.
Until now, in food allergy, the only possible treatment is avoiding the consumption of the culprit food. Although, the existence of cross-reactivity between allergens and the specific sensitization profiles of each patient, makes it difficult to know which foods are related and which ones the patient should avoid.
In order to develop safe and effective immunotherapy, it is necessary to characterize the allergens involved both at molecular and immunological level.
The major allergens described in tree nuts are 7S vicilins, 11S legumins, 2S albumins, lipid transfer proteins (LTPs) and thaumatin-like proteins (TLPs).
In this thesis, the allergenic molecular basis of these proteins was studied in order to try to understand the possible mechanisms that are mediating sensitization and cross-reactivity and the prevalence of these proteins in a Spanish population, with the use of protein microarrays.<br>As alergias alimentares são um problema comum nos países ocidentais. Na última década, estas doenças têm aumentado significativamente e actualmente é estimado que afectem 2-8% da população. Nas alergias alimentares, a alergia a alimentos vegetais é a mais frequente na população adulta e a maioria dos alergenos de alimentos vegetais pertencem a famílias de proteínas com funções de defesa e armazenamento.
Entre as alergias a alimentos vegetais, há um interesse especial na alergia a frutos secos. No decurso da história, os frutos secos têm feito parte da dieta em todo o mundo. Os frutos secos têm um elevado valor nutricional e são muito importantes na dieta humana. Contudo, no mundo desenvolvido, as reacções alérgicas causadas pelos frutos secos, representam uma das primeiras causas de alergia alimentar em crianças e a primeira em adultos.
Conhecer o mecanismo pelo qual uma proteína inofensiva ao organismo é capaz de induzir uma resposta alérgica, é a base para prevenir e tratar este tipo de doença.
Até agora, na alergia alimentar, o único tratamento possível é evitar o consumo do alimento culpado pela alergia. Todavia, a existência de reactividade-cruzada entre alergenos e os perfis especifícos de sensibilização dos patientes, torna difícil saber que alimentos estão relacionados e quais os alimentos que o paciente deve evitar.
De modo a desenvolver imunoterapia segura e eficaz é necessário caracterizar os alergenos envolvidos, tanto a nível molecular como a nível imunológico.
Os alergenos maioritários descritos nos frutos secos são vicilinas 7S, leguminas 11S, albuminas 2S, proteínas de transferência de lípidos (LTPs) e proteínas similares a taumatinas (TLPs).
Nesta tese, a base molecular alergénica destas proteínas foi estudada de modo a perceber os possíveis mecanismos que medeiam a sensibilização e a reactividade-cruzada e a prevalência destas proteínas numa população Espanhola, com a utilização de microarrays de proteínas