In this thesis, Atomic Force Microscopy (AFM) is used to characterize Micro Fibrillated Cellulose (MFC) produced by two different methods according to their size and shape. For one of these MFC-types, their interaction with the humidity in the atmosphere is investigated and their swelling is calculated. MFC is a relatively new material based on cellulose fibres extracted from wood. This study is performed in co-operation with Stora Enso research centre. Stora Enso is a renewable material company which uses mostly wood based raw materials in their production. The measured swelling is ~ 5 % and depends on the number of elementary fibrils included in the fibre. / Atomkraftsmikroskopi (AFM) har använts för att karakterisera Mikro Fibrillerad Cellulosa (MFC), som är producerad med två olika produktionsmetoder, med avseende på deras storlek och form. För en av dessa MFC-typer så är deras påverkan av en varierande fuktig atmosfär undersökt och deras svällning är uträknad. MFC är ett relativt nytt material baserat på cellulosafibrer från trä. Detta examensarbete är utfört i samarbete med Stora Enso forskningscentrum. Stora Enso är ett företag fokuserat på förnyelsebara material som använder mestadels träbaserade råmaterial i deras prodiktion. Den uppmätta svällningen är ~ 5 % och beror av antalet elementära fibriller som ingår i fibern.

The effects of controlled atmosphere storage vs conventional refrigerated storage on the metabolism of Moorpark and Large Early Montgamet apricot and Elberta peach fruits were studied. The controlled atmospheres studied were 0.0 percent CO2-5.0 percent O2; 2.5 percent CO2-5.0 percent O2; 5.0 percent CO2-2.5 percent O2; 7.5 percent CO2-5.0 percent O2; as compared to conventional refrigerated storage. Nitrogen percent was assumed to be the difference between the total CO2 and O2 content minus 100. Fruits were periodically removed from the storage and analyzed for firmness, fleshy pericarp color, total pectins, pH, titratable acidity, total and free reducing sugars, tannins, organic acids, and amino acids. Controlled atmosphere storage had both beneficial and detrimenta1 effects on stored apricot and peach fruits. The general retardation of the respiration rate and consequent delay of the climateric rise due to controlled atmosphere are important in prolonging the storage life of the fruit. Apricot fruits stored in 2.5 to 5.0 percent CO2 and 2.5 to 5.0 percent O2 maintained superior quality for 15 to 30 days longer than did conventionally refrigerated fruit. Moorpark fruit could be stored longer than Large Early Montgamet fruit, mainly because of mesocarp browning in the latter variety of fruit. The results indicated that the storage life of Elberta peach fruits were not substantially increased in controlled atmosphere storage. Apricot fruit stored in controlled atmosphere treatments ripened at a reduced rate and produced less yellow pigments of the fleshy pericarp tissue than the conventional refrigerated fruit. There was a retardation of the de-greening processes of the fruit stored in CO2 concentrations higher than atmospheric air. It appeared that high concentrations of CO2 had an inhibitory effect on chlorophyll degradation. Succinic acid coupled with high tannin concentrations, induced by CO2, apparently caused browning of the mesocarp tissue of the fruit in controlled atmosphere storage at a more rapid rate than conventional refrigerated stored fruit. The organic and amino acids of peach and apricot fruits had a variable response to control atmosphere treatment. The organic acids, particularly malic acid, were reduced in concentration, while succinic acid accumulated. Succinic acid accumulation was dependent upon the concentration of CO2 in the atmosphere. It was suggested that CO2 had a toxic or inhibitory effect on the succinic oxidase enzyme system which resulted in succinic acid accumulation. The accumulated succinic acid, thereby, may have had a toxic effect on the mesocarp tissue of the fruit and caused part of the browning. Aspartic acid decreased in concentration under higher CO2 treat-ments, while alanine and glutamic acid increased. Total sugar concen-tration was generally not effected by controlled atmosphere storage. The metabolism of free reducing sugars in higher CO2 treatments was markedly reduced in the apricot fruit.The beneficial aspects of controlled atmosphere on stored fruit appeared to be the increased length of the storage period for apricot fruit, as well as a reduced rate of metabolism. The storage life of apricot fruit was extended 15 to 30 days in the appropriate atmosphere. The adverse effects of controlled atmosphere storage of apricot and peach fruit appeared to be: the inhibitory or toxic effect of CO2 on certain enzyme systems; the accumulation of certain metabolites, which may have been toxic to the fruit tissue; the increased rate of tissue browning, the inhibitory effect of CO2 on the de-greening and color development mechanisms.

Lettuce heads (Cultivar "Great Lakes") were stored in different concentrations of O2 and CO2, including l percent O2 and l percent CO2, 2.5 percent O2 and 2.5 percent CO2, 5 percent O2 and 0 percent CO2, and 5 percent O2 and 5 percent CO2; temperatures of 35 and 70 F; and with or without microbe- and senescence-inhibiting chemicals and packaging. The samples were taken on the twentieth and fortieth days in the first series of experiments; and in the subsequent experiments, on the fifteenth, thirtieth, forty-fifth, sixtieth, and seventy-fifth days of storage for quality evaluation, determination of rate of respiration, and chemical analyses. The results indicated that lettuce could be stored at 35 F for at least 2 to 3 weeks. At this temperature, lettuce heads were still field fresh and bright green, without apparent sign of quality deterioration. At 70 F, none of the treatments could prolong the shelf-life of the lettuce more than l week. Lettuce heads maintained the best marketing quality when stored in atmospheres of 2.5 percent O2 and 2.5 percent CO2 at 35 F for 60 days. Microbe- and senescence-inhibiting chemicals (Captan, Phaltan, Mycostatin, and N6-benzyladenine) had detrimental effects on the quality of lettuce stored in controlled atmosphere. The reduction in russet spotting was the major benefit in controlled atmosphere storage at 35 F. In addition, the incidence of pink rib and butt discoloration was less than for those lettuce heads held in the conventional refrigerator. However, the hearts of the lettuce were sensitive to low O2 injury in controlled atmospheres consisting of 1 percent O2 and l percent CO2. Controlled atmosphere (2.5 percent O2, 2.5 percent CO2) and controlled atmosphere combined with polyethylene packaging reduced the CO2 production, degradation of chlorophyll, loss of total sugar, and starch. Phaltan (microbe inhibitor, 1,000 ppm) or Phaltan in combination with polyethylene packaging under controlled atmosphere storage had an adverse effect on the lettuce held in the conventional refrigerator. In every case, the rate of respiration was in direct correlation with the sugar retention data.

Tomatoes are widely produced and consumed due to their nutritional content and versatility. However, the tomato is a soft fruit liable to damage and flavour deterioration. Hence, the main challenge for the tomato producing industry is to prevent the high loss incurred during harvest, handling and transportation of the crops. The objective of this study was to investigate the overall nutritional implication of controlled storage of tomatoes using ozone on the ripening process and the basic nutritional components of tomatoes. This investigation was also designed to focus on the effect of different ozone doses on the basic components and properties (carotenoids, ascorbic acid, total antioxidant activity and soluble sugars content) of the quality and dynamic maturity of tomatoes. Green tomatoes (Rio Grande) were treated in glass chambers with ozone enriched air [(air + 2, 7 and 21 mg O3/g tomato) and control (air only)] under humidity and temperature of 90-95% and 14-17 oC respectively. Tomatoes were sampled after 14 days of ozone treatment in the storage chamber and analyzed for different quality parameters (appearance, weight loss, Total Soluble Solids (TSS), titratable acidity, total ascorbic acid and carotene) of the ripening. The variety Elegance tomatoes were selected and the fruits were graded by colour and subjected to treatment with ozone (in doses 0 (clean air), 0.25, 0.50, and1.00 mg O3/g tomatoes) during storage for 6 days under the same humidity and temperature conditions. The fruits were analysed for carotenoids, ascorbic acid content, total antioxidant activity and soluble sugars. Analysis of the fruits clearly showed that ozone significantly delayed the development of colour on the surface, particularly in the low doses, and caused black spots on the surface of the tomatoes, particularly in higher ozone doses. Ozone did not affect the ascorbic acid and titratable acidity content. However ozone did reduce the Total Soluble Solids (TSS) by about 10% at the lowest ozone dose. A high inhibition of accumulation of carotenoids, particularly at low dose, of the tomatoes (Rio Grande) was also observed. Tomatoes (Elegance) under ozone treatments contained higher ß-carotene than those under the control treatment and lycopene content increased during storage in the red stage of tomato fruits. Ascorbic acid (AsA), dehydroascorbic acid (DHA) and the total of AsA and DHA concentrations, and ratios of redox (ASA/ (ASA + DHA) and DHA/AsA in pericarp and pulp of tomatoes tissue, did not show clear differences between the different treatments. The concentrations of the glucose and fructose increased in the tomatoes which were subjected to ozone treatments. Results from this study show that controlled atmosphere storage of tomatoes using ozone is a viable technique which warrants further study.

The post-harvest physiology of sugarbeet (Beta vulgaris) roots was studied during controlled atmosphere (CA) storage at 35° and 50°F. Zero, 3, 6 and 10% carbon dioxide and 5% oxygen concentrations were employed to investigate the most beneficial concentrations of gases. Under the experimental conditions beets were stored successfully for 200 days. The maximum beneficial effects of CA were observed under 6% carbon dioxide and 5% oxygen at 35°F. Regardless of storage temperatures , sucrose retention was highest in the beets stored under CA, compared to conventional refrigeration (CR). Other beneficial effects include less hydrolysis of sucrose to reducing sugars and a decrease in raffinose accumulation. Fungal growth and sprouting were also inhibited significantly, under CA. In the second phase of the studies, investigations were conducted on sugarbeets to study the effects of different levels of nitrogen fertilizer on the optimum CA storage at 40°F. Regardless of the level of nitrogen fertilization, the beets stored under CA demonstrated beneficial effects as described earlier. In addition, respiration, measured on the whole beets, and amino nitrogen content of the beets were lower in the CA-stored beets than those stored under CR. Accumulation of citric acid and succinic acid was significant in the CA-stored beets.

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniv., 2006. / Härtill 4 uppsatser.

Orientadores : Benedito Carlos Benedetti, Celso Luiz Moretti / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-04T02:42:20Z (GMT). No. of bitstreams: 1 Rinaldi_MariaMadalena_D.pdf: 1659013 bytes, checksum: 7766fb7599482e92590b5b1e9b1c4c30 (MD5) Previous issue date: 2005 / Resumo: Este trabalho teve como objetivo avaliar a vida útil do repolho minimamente processado sob diferentes condições de atmosfera modificada. O mesmo foi dividido em três etapas seqüenciais, sendo adotado em cada uma delas a mesma metodologia para o processamento mínimo do repolho, que consistiu em seleção, lavagem, retirada do talo central, corte em tiras, enxágüe 1, sanitização, enxágüe 2 e centrifugação. Na primeira etapa avaliou-se o comportamento respiratório e produção de etileno do repolho inteiro e minimamente processado, em sistema fechado, nas temperaturas de 5ºC e 10ºC por 6 horas. Na segunda, a influência da atmosfera controlada sobre o repolho minimamente processado. O produto foi submetido a um fluxo contínuo de nove misturas gasosas ternárias, previamente umidificadas, com diferentes concentrações de O2 e CO2, complementadas com N2, sendo utilizado como controle o ar atmosférico. O experimento foi realizado na temperatura de 5ºC por 10 dias. Nesta fase foram realizadas análises de cor (L*, a*, b*), incremento no escurecimento, ácido ascórbico, pH, acidez titulável e sólidos solúveis. Na terceira etapa determinou-se a vida útil do repolho minimamente processado acondicionado em embalagens de polietileno de baixa densidade (PEBD), 32µm de espessura, com atmosfera modificada ativa (2% O2; 6,5% CO2) e passiva, e em bandejas de poliestireno expandido revestidas com filme de policloreto de vinila (PVC), 20µm de espessura. O produto foi armazenado por 16 dias em câmara frigorífica na temperatura de 5ºC e em um balcão refrigerado conveniência, com o intuito de representar os locais de comercialização a varejo. Analisou-se a concentração gasosa (O2 e CO2) no interior das embalagens, cor (L*, a*, b*), incremento no escurecimento, atividade da polifenoloxidase e peroxidase, ácido ascórbico, pH, acidez titulável, sólidos solúveis, perda de massa fresca, coliformes totais e fecais, contagem total de microrganismos aeróbios mesófilos, bolores e leveduras, Salmonella sp, Listeria monocytogenes e análise sensorial (Análise Descritiva Quantitativa -ADQ Modificado) no repolho minimamente processado. Observou-se que o repolho inteiro e minimamente processado, armazenado na temperatura de 5ºC, apresentou atividade respiratória significativamente menor que o armazenado a 10ºC, e nas duas temperaturas o repolho minimamente processado apresentou atividade respiratória significativamente maior que o repolho inteiro. Não foi detectada produção de etileno. Em atmosfera controlada, para a maioria das variáveis analisadas, as misturas utilizadas não apresentaram variação significativa em relação ao tratamento controle. No entanto, as misturas M1 (2% O2; 3% CO2) e M5 (2% O2; 6,5% CO2) não apresentaram diferença significativa entre si, porém apresentaram-se como as mais adequadas para o armazenamento do repolho minimamente processado, por não ter ocorrido redução significativa nos valores de L*, menor incremento no escurecimento, menor redução de vitamina C, sólidos solúveis e estabilidade nos valores de pH e acidez titulável. A atmosfera modificada ativa não foi efetiva no aumento da vida útil do repolho minimamente processado, quando comparada aos demais tratamentos. A embalagem de PEBD é mais adequada ao acondicionamento do repolho minimamente processado, no entanto, a embalagem de PVC também apresenta resultados satisfatórios no acondicionamento do repolho minimamente processado. Houve uma grande variação na temperatura do balcão refrigerado conveniência em comercialização simulada, não influenciando significativamente na vida útil do produto, quando comparado ao submetido na temperatura de 5ºC. Considerando-se a análise sensorial, a vida útil do repolho minimamente processado foi de 11 dias para todos os tratamentos, com exceção do submetido a comercialização simulada na embalagem de PEBDativa e PEBDpassiva, que apresentaram vida útil de 16 dias. No entanto, todos os tratamentos apresentaram contagem alta de coliformes totais, aeróbios mesófilos e bolores e leveduras, limitando a vida útil do produto em 7 dias. De acordo com as análises microbiológicas o repolho minimamente processado apresentou ausência de Salmonella sp e L. monocytogenes e coliformes fecais abaixo de 10 UFC g-1 / Abstract: The objective of this work was to evaluates the shelf life of the minimally processed cabbage under different conditions of modified atmosphere. The same was divided in three stages sequences, being adopted in each one of them the same methodology for the minimally processed of the cabbage, that consisted of selection, wash, retreat of the central shaft, cut in ribbons, rinse 1, sanitation, rinse 2 and centrifugation. In the first stage it was evaluated the breathing behavior and ethylene production of the whole cabbage and minimally processed, in closed system, in the temperatures of the 5ºC and 10ºC for 6 hours. In the second stage, the influence of the controlled atmosphere on the minimally processed cabbage. The product was submitted to a continuous flow of nine ternary gaseous mixtures, previously humidified, with different concentrations of O2 and CO2, complemented with N2, being used as control the atmospheric air. The experiment was accomplished in the temperature of 5ºC by 10 days. In this phase color analyses were accomplished (L*, a*, b*), increase in the darkening, ascorbic acid, pH, titratable acidity and soluble solids. In the third stage was determined the shelf life of the minimally processed cabbage conditioned in packed in low density polyethylene (PEBD), 32 µm of thickness, with modified atmosphere active (2% O2; 6,5% CO2) and passive, and in trays of expanded polystyrene covered with film of 20 µm of thickness polyvinyl choride (PVC). The product was stored by 16 days in refrigerating chamber in the temperature of 5ºC and in a counter refrigerated convenience, with the intention of representing the commercialization places to retail. The gaseous concentration was analyzed (O2 and CO2) inside the packed, color (L*, a*, b*), increase in the darkening, activity of the polyfhenoloxidase and peroxidase, ascorbic acid, pH, titratable acidity, soluble solids, loss of fresh mass, total and fecal coliforms, total count of microorganisms mesophily aerobics, mould and yeasts, Salmonellae sp, Listeria monocytogenes and sensory analysis (Quantitative Descriptive Analysis Modified - ADQ) in the minimally processed cabbage. It was observed that the whole cabbage and minimally processed, stored in the temperature of 5ºC, they presented breathing activity significantly smaller than stored them to 10ºC, and in the two temperatures the minimally processed cabbage presented breathing activity significantly larger than the whole cabbage. No ethylene production was detected. In controlled atmosphere, for most of the analyzed variables, the used mixtures did not present significant variation of the treatment it controls. However, the mixtures M1 (2% O2; 3% CO2) and M5 (2% O2; 6,5% CO2) they did not present significant difference to each other, however they came as the most appropriate for the storage of the minimally processed cabbage, for not having happened significant reduction in the values of L*, smaller increment in the darkening, smaller vitamin reduction C, soluble solids and stability in the pH values and titratable acidity. Modified atmosphere active was not effective in the increase of the useful life of the minimally processed cabbage, when compared to the other treatments. The packing of PEBD is more appropriate to the conditioned of the minimally processed cabbage, however, the packing of PVC also presents satisfactory results in the conditioned of the minimally processed cabbage. There was a great variation in the temperature of the counter refrigerated convenience in simulate commercialization, not influencing significantly in the useful life of the product, when compared to the submitted in the temperature of 5ºC. Being considered the sensorial analysis, useful life of the minimally processed cabbage went of 11 days to all the treatments, except for submitted him the simulate commercialization in the packing of PEBD active and PEBD passive, that presented useful life of 16 days. However, all the treatments presented high count of total coliforms, mesophily aerobics and mould and yeasts, limiting the useful life of the product in 7 days. In agreement with the analyses microbiological the minimally processed cabbage presented absence of Salmonellae sp and L. monocytogenes and fecal coliforms below 10 UFC g-1 / Doutorado / Tecnologia Pós-Colheita / Doutor em Engenharia Agrícola

No description available.

This study was undertaken to determine the effect of four different combinations of treatments and storage; i.e., controlled atmosphere (2.5 percent O2 and 2.5 percent CO2), controlled atmosphere in combination with phaltan (1,000 ppm), controlled atmosphere with packaging in polyethylene bags, controlled atmosphere with phaltan and packaging in polyethylene bags, as well as conventional refrigeration, on the chemical composition of lettuce heads (Cultivar "Great Lakes") during 75 days of storage. Analyses of total sugars, starch, reducing sugars, total organic acids, free amino acids, soluble proteins, pH, titratable acidity, and total carotenes were made on the fifteenth, thirtieth, forty-fifth, sixtieth, and seventy-fifth days of storage at 35 F. There were no significant differences in total organic acids and free amino acids between the conventional refrigeration (35 F) and other treatments during the early stage of storage. They were, however, higher after 45 days of storage with phaltan treatments, although still not changed in controlled atmosphere and controlled atmosphere in combination with packaging. The soluble proteins and the reducing sugars were lower in the controlled atmosphere lettuce than in the conventional refrigeration lettuce. The lettuce treated with phaltan or phaltan in combination with polyethylene packaging had higher amounts of soluble proteins. Although pH of the lettuce heads was not changed throughout 75 days of storage, the titratable acidity was higher in all treatments during the storage.

Tomatoes are widely produced and consumed due to their nutritional content and versatility. However, the tomato is a soft fruit liable to damage and flavour deterioration. Hence, the main challenge for the tomato producing industry is to prevent the high loss incurred during harvest, handling and transportation of the crops. The objective of this study was to investigate the overall nutritional implication of controlled storage of tomatoes using ozone on the ripening process and the basic nutritional components of tomatoes. This investigation was also designed to focus on the effect of different ozone doses on the basic components and properties (carotenoids, ascorbic acid, total antioxidant activity and soluble sugars content) of the quality and dynamic maturity of tomatoes. Green tomatoes (Rio Grande) were treated in glass chambers with ozone enriched air [(air + 2, 7 and 21 mg O3/g tomato) and control (air only)] under humidity and temperature of 90-95% and 14-17 oC respectively. Tomatoes were sampled after 14 days of ozone treatment in the storage chamber and analyzed for different quality parameters (appearance, weight loss, Total Soluble Solids (TSS), titratable acidity, total ascorbic acid and carotene) of the ripening. The variety Elegance tomatoes were selected and the fruits were graded by colour and subjected to treatment with ozone (in doses 0 (clean air), 0.25, 0.50, and1.00 mg O3/g tomatoes) during storage for 6 days under the same humidity and temperature conditions. The fruits were analysed for carotenoids, ascorbic acid content, total antioxidant activity and soluble sugars.Analysis of the fruits clearly showed that ozone significantly delayed the development of colour on the surface, particularly in the low doses, and caused black spots on the surface of the tomatoes, particularly in higher ozone doses. Ozone did not affect the ascorbic acid and titratable acidity content. However ozone did reduce the Total Soluble Solids (TSS) by about 10% at the lowest ozone dose. A high inhibition of accumulation of carotenoids, particularly at low dose, of the tomatoes (Rio Grande) was also observed. Tomatoes (Elegance) under ozone treatments contained higher ß-carotene than those under the control treatment and lycopene content increased during storage in the red stage of tomato fruits. Ascorbic acid (AsA), dehydroascorbic acid (DHA) and the total of AsA and DHA concentrations, and ratios of redox (ASA/ (ASA + DHA) and DHA/AsA in pericarp and pulp of tomatoes tissue, did not show clear differences between the different treatments. The concentrations of the glucose and fructose increased in the tomatoes which were subjected to ozone treatments. Results from this study show that controlled atmosphere storage of tomatoes using ozone is a viable technique which warrants further study. / Libyan government