Tez (Doktora) - Süleyman Demirel Üniversitesi, Fen Bilimleri Enstitüsü, Bahçe Bitkileri Anabilim Dalı, 2008. / Kaynakça var.

Tez (Doktora) - Süleyman Demirel Üniversitesi, Fen Bilimleri Enstitüsü, Bahçe Bitkileri Anabilim Dalı, 2009. / Kaynakça var.

No description available.

No description available.

The application of pulsed electric fields (PEF) in food processing is a novel technique that requires careful study. In addition, improved understanding of the effect of PEF parameters on both physical and qualitative attributes of agrifood products is a requirement for the application and control of this emerging technology. PEF parameters investigated were pulse widths of 100, 200, and 300 mus, with electric field strengths of 0.75 and 1.5 kV/cm. The amount of pulses used for apples was up to 60, whereas up to 120 pulses were used for potatoes. Initially, apple and potato slices were exposed to various combinations of PEF parameters in order to evaluate the change in their electrical conductivities as an indicator of the disruption of the cell membrane. Subsequently, the impact of PEF on color and texture attributes was studied. In the final set of experiments, PEF was applied as a pre-treatment in order to accelerate the diffusion of moisture in a convective air-drying process at 70°C. / Results regarding the electrical conductivity and the changes in color revealed the similar effect of applying pulses with 100, 200 and 300 mus of duration. Increasing the number of pulses and/or the electric field strength resulted in increased electrical conductivity and discoloration rates of samples. PEF reduced the compressive strength of apple tissues between 21 to 47%. However, the compressive strength of potato tissues did not seem to be affected by the application of PEF. When PEF was applied as a pre-treatment, it caused an increase of up to 30% in the moisture diffusion coefficients of potatoes. In the case of apples, PEF pre-treated samples did not show any increase in drying rates.

No description available.

No description available.

The distribution of total phenolics, antioxidant capacity, monomeric anthocyanin, and ascorbic acid contents in the peel and flesh of Red Delicious, Granny Smith, and Fuji apples during a six-month storage period were determined. In addition, the effect of 1-MCP (1-Methyl cyclopropene) on these parameters of the edible portion of apples during storage was also investigated. Two different assays were employed to determine antioxidant activities: the spectrofluorometric-based Oxygen Radical absorbing Capacity (ORAC) and the spectrophotometric-based Ferric Reducing Antioxidant Power (FRAP). Total phenolics were measured using the Folin-Ciocalteau method. A determination of monomeric anthocyanin content was also performed using the pH-differential method for Red Delicious and Fuji apples. Antioxidant activity was predominantly observed in the aqueous fraction and was attributed to polyphenolics. Antioxidant activities were highest in the peel, with Red Delicious peel having the highest values, presumably due to anthocyanin pigments. At zero time month storage, the ORAC, FRAP, total phenolics, and total monomeric anthocyanin contents of Red Delicious peel were: 37.7 μmol T.E./g, 62.7 μmol T.E./g, 6.63 mg/g GAE, and 26.4 mg/100g, respectively. The three tested cultivars were significantly different with respect to ORAC, FRAP, total phenolics, and monomeric anthocyanin contents. 1-MCP treatment did not have a significant influence on antioxidant activities and monomeric anthocyanin contents of the three cultivars during storage. Storage did not have significant influence on ORAC values of the edible portion of apple, however it had significant influence on the FRAP values. The contribution of ascorbic acid to the total antioxidant capacity was small. / Graduation date: 2003

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Made available in DSpace on 2014-06-11T19:23:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-11-24Bitstream added on 2014-06-13T20:50:29Z : No. of bitstreams: 1 jorge_pcs_me_arafcf.pdf: 737046 bytes, checksum: dec84c3ab28e6bf448b4986f93072480 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os filmes e revestimentos biodegradáveis são usados para revestir os alimentos, agindo como barreira à umidade e a gases, reduzindo a respiração e as perdas de água por transpiração e desidratação, além do escurecimento enzimático, e mantendo as características do alimento, com aumento da vida de prateleira. Este trabalho teve como objetivos reunir informações sobre o uso da quitosana como revestimento de frutas e vegetais, visando dar suporte ao trabalho experimental; avaliar maçãs revestidas com quitosana comercial, durante o armazenamento à temperatura ambiente, simulando as condições de comercialização das frutas para o mercado interno; avaliar maçãs revestidas com quitosana comercial durante 6 meses de armazenamento sob atmosfera controlada e baixa temperatura, condições de estocagem das frutas para o mercado externo, seguido de armazenamento por 30 dias em atmosfera ambiente e baixa temperatura, visando simular o transporte das frutas para o mercado consumidor no exterior, e posteriormente estocadas à temperatura ambiente, simulando as condições de comercialização; e avaliar maçãs revestidas com quitosana modificada, quando submetidas à temperatura ambiente, visando prolongar a vida de prateleira durante a comercialização, após 6 meses de armazenamento sob atmosfera controlada e baixa temperatura, seguidos de armazenamento por 30 dias em atmosfera ambiente e baixa temperatura. Maçãs ‘Royal Gala’ foram produzidas na safra de 2009, e após a colheita foram separadas em 3 lotes, sendo as frutas do 1o lote revestidas com quitosana comercial; as do 2o lote imersas em solução de ácido acético, que foram usadas como branco e as maçãs do 3o lote não receberam tratamento e foram usadas como controle. Após 6 meses de armazenamento sob atmosfera controlada e baixa temperatura, seguido de mais 30 dias de armazenamento em atmosfera ambiente... / The films and biodegradable coatings are used to coat the food, acting as a barrier to moisture and gases, reducing the respiration and water loss by transpiration and dehydration in addition to the enzymatic browning, maintaining the characteristics of food, with increased of shelf life. This study aimed to gather information about the use of chitosan as a coating for fruits and vegetables, aiming to support the experimental work; evaluate apples coated with commercial chitosan coating during storage at ambient temperature, simulating the real conditions of sale of the fruit for the domestic market; evaluate apples coated with commercial chitosan during 6 months of storage under controlled atmosphere and low temperature, storage conditions of fruit for the export market, followed by 30 days storage under at ambient and low temperature, in order to simulate the transport of fruit to the consumer market abroad, and subsequently stored at ambient temperature, simulating the conditions of marketing; and evaluate apples coated with modified chitosan, at ambient temperature, in order to prolong the shelf life during marketing after six months storaged under controlled atmosphere and low temperature, followed by another 30 days storage under at ambient atmosphere and low temperature. ‘Royal Gala’ apples were produced in 2009 crop and after the harvest they were separated into 3 lots, the first batch of fruit coated with commercial chitosan, those from second lot were immersed in an acetic acid solution and used as blank and the third lot of apples used as controls received no treatment. After 6 storage months under controlled atmosphere and low temperature, followed by another 30 days storage under at ambient atmosphere and low temperature apples without any treatment were separated in 2 lots, being the first batch of fruit coated with modified chitosan, and the second batch used as controls... (Complete abstract click electronic access below)