Non-destructive determination of pre-symptomatic biochemical markers for Peteca spot and evaluation of edible coatings for reducing the incidence of the disorder on ‘Eureka’ lemons

Masters degree. University of KwaZulu-Natal, Pietermaritzburg.International markets that import citrus fruit from South Africa have imposed regulations that involve cold sterilization at low temperatures, which cause physiological disorders such as peteca spot in lemon. The aim of this study was to, non-destructively determine pre-symptomatic biochemical markers for Peteca spot and the evaluation of edible coatings for reducing the incidence of the disorder on ‘Eureka’ lemons. The first chapter is general background which introduces the key words and clearly outlines the aim and objectives of the study. The second chapter is review of literature, which motivated the three research chapters due to the gaps found. Presymptomatic biochemical markers that are related to peteca spot were evaluated in the third chapter. The Principal Component Analysis (PCA) was able to separate fruit harvested from the inside and outside canopy positions based on their susceptibility to the disorder. Fruit harvested in the inside canopy were more susceptible to peteca spot and these were correlated with physic-chemical properties, which were typically low in the inside canopy. The efficacy of carboxymethyl cellulose (CMC) and chitosan (CH) incorporated with moringa leaf extracts (M) edible coatings on reducing the incidence of peteca spot was also evaluated in the fourth chapter. Fruit harvested from inside and outside canopy positions were assigned to five coating treatments: control, M+CMC, CMC, CH and M+CH. The most effective coating treatment in reducing the susceptibility of ‘Eureka’ lemon to peteca spot was M+CMC followed by CMC and CH. The fifth chapter focused on, non-destructively predicting peteca spot using visible to near infrared spectroscopy (vis/NIRS). Presymptomatic biochemical markers that have been related to peteca spot were successfully predicted. Lastly, general discussions and conclusions were made in chapter six as well as recommendations

Strategies for luminiscence analysis of alternaria mycotoxins using molecularly imprinted polymers as recognition elements

Tesis de la Universidad Complutense de Madrid, Facultad de Ciencias Químicas, Departamento de Química Orgánica I, leída el 06-07-2017La contaminación de alimentos por hongos no es únicamente un inconveniente en lo que respecta a su comercialización debido a que provoca su deterioro, –con las consecuentes pérdidas económicas–, sino que también representa una amenaza para la salud animal y humana. Algunos de los metabolitos secundarios producidos por dichos hongos presentan una toxicidad aguda o crónica. Estos metabolitos se conocen como micotoxinas, y normalmente son moléculas de pequeño a mediano tamaño que son bastante estables a las condiciones de cocinado o de congelado. Por esa razón, no son fáciles de eliminar de los alimentos una vez que se han producido. Se requieren por tanto controles de calidad que permitan evitar ominimizar la introducción de estas sustancias tóxicas en la cadena alimentaria. Las toxinasmás comunes en productos de agricultura son producidas por las familias de hongos Aspergillus, Penicillium, Fusarium o Alternaria. La última familia, Alternaria, produce varias micotoxinas de diversos tipos estructurales, de las cuales, las cinco principales son: alternariol, alternariol monometil éter y altenueno como benzopironas; ácido tenuazónico,como ácido tetrámico, y altertoxina-I, que es un derivado de tipo perileno. Estas toxinas pueden encontrarse en cereales, granos, frutas y vegetales, y también en comida procesada como cerveza, vino o derivados de tomate.Food contamination with fungi is not only an inconvenience for food marketing because itcauses food decay, –with the consequent economic losses–, but it also brings about animaland human health hazards. Some of the secondary metabolites produced by fungi have acuteor chronic toxicity. These metabolites are known as mycotoxins and are normally small tomedium size molecules that are rather stable to storage or cooking conditions. For this reason,they are not easy to eliminate from food once they are produced. Food quality controls arerequired in order to avoid or minimize the introduction of these toxic substances in the foodchain. The most common toxins in agricultural goods are produced by the Aspergillus,Penicillium, Fusarium or Alternaria fungi families. The latter family, Alternaria, produces anumber of mycotoxins, belonging to different structural classes, the five major compounds ofwhich are alternariol, alternariol methyl ether and altenuene, as benzopyrone derivatives;tenuazonic acid, which is a tetramic acid derivative, and altertoxin-I, a perylene derivative.These products can be found in cereals, grains, fruits and vegetables, and also in processedfoods such as beer, wine or tomato produces. Recent studies have pointed out that most ofthese substances are mutagenic, teratogenic and/or carcinogenic so that mycotoxins havebecome a major concern for public health. Both alternariol and alternariol monomethyl ether,which are frequently found in combination, were found to be mutagenic. Alternariol is alsoinvolved in the development of squamous cell carcinoma and has been linked to precancerouschanges associated with the oesophagal mucosa in mice.Depto. de Química OrgánicaFac. de Ciencias QuímicasTRUEunpu

Water productivity indices of the soybean grown on silty clay soil under sprinkler irrigation

The objective of this research was to compare the effects of different irrigation treatments on soybean [Glycine max (L.) Merr.] productivity and water use efficiency on experimental fields of the Maize Research Institute of Zemun Polje(Serbia), in 2007 and 2008. Four irrigation levels were investigated: full irrigation (I100), 65% and 40% of I100 (I65 and I40) and a rain-fed (I0) system. The crop water use efficiency (CWUE, also known as crop water productivity –CWP), irrigation water use efficiency (IWUE) and evapotranspiration water use efficiency (ETWUE) were used to assess the water productivity of each studied treatment. The efficiency of the same treatment differed between the years as it depended on seasonal water availability, weather conditions and their impact on seed yields. Maximum and minimum yields were obtained in the I65 and I0 treatments, averaging 3.41 t ha–1 and 2.26 t ha–1, respectively. Water use efficiency values were influenced by the irrigation levels. In general, CWUE values increased with the increased level of irrigation. In both growing seasons, IWUE and ETWUE decreased with increasing the seasonal water consumption and irrigation depth. On average, treatments I40 and I65 resulted in similar or higher CWUE and ETWUE than I100, in both growing seasons. I65 resulted in the highest IWUE, averaged over the two seasons, while I100 had the lowest IWUE. I65 could be proper for the soybean irrigated in Vojvodina when there is no water shortage and I45 could be used as a good basis for reduced sprinkler irrigation strategy development under water shortage

Synthesis of new pyrazolium based tunable aryl alkyl ionic liquids and their use in removal of methylene blue from aqueous solution

In this study, two new pyrazolium based tunable aryl alkyl ionic liquids, 2-ethyl-1-(4-methylphenyl)-3,5- dimethylpyrazolium tetrafluoroborate (3a) and 1-(4-methylphenyl)-2-pentyl-3,5-dimethylpyrazolium tetrafluoroborate (3b), were synthesized via three-step reaction and characterized. The removal of methylene blue (MB) from aqueous solution has been investigated using the synthesized salts as an extractant and methylene chloride as a solvent. The obtained results show that MB was extracted from aqueous solution with high extraction efficiency up to 87 % at room temperature at the natural pH of MB solution. The influence of the alkyl chain length on the properties of the salts and their extraction efficiency of MB was investigated