Thesis (M. Sc. (Botany)) -- University of the North, 1999 / Refer to the document

Two hundred and nine beef carcasses (361 ± 53 kg) from crossbred, grain-finished cattle harvested in a commercial packing plant and evaluated for marbling score, core temperature (n=1), pH, shrinkage, color, and aerobic plate count (n=50) for 24, 48, 72, and 96 h under spray chilling. There were minimal changes in shrinkage among time points (-0.4 to 1.2%; P ≤ 0.002), pH (5.56 to 5.69; P ≤ 0.001), and APC (0.1 to 0.7 log; P ˂ 0.001). Marbling score values were converted to numeric values of 200 (Practically Devoid00) to 1100 (Abundant00). Carcasses with SM or greater marbling score at 24 h had a 34 to 60 points deduction after 96 h of spray chilling (P ≤ 0.042), the SL carcasses had an increase marbling score, from 442 to 469 points. Moreover, SL carcasses had a greater percentage of PUFA (P < 0.001).

Color and color components are important quality attributes for fresh channel catfish muscle. The objective of the present research was to obtain inside understanding regarding color distribution, color component stability and the pre-slaughter conditions influence on color and color components and other quality attributes. Catfish fillets were rendered to be paler and redder on iced storage; and paler, less red and less yellow by ice-water chilling process. Visual classified “reddish” catfish fillets had higher heme-protein content than “white” fillets and these pigments were derived mainly from hemoglobin. Pre-slaughter live fish chilling in ice water and bleeding at slaughter also slightly affected muscle color and total heme-protein content, but they were not the main factors for the “reddish” color on catfish muscle. Catfish hemoglobin autoxidation rate was similar at room and at refrigeration temperature. Myoglobin gene and hemoglobin beta gene were cloned and expressed in Eschericia coli cells in insoluble form. The myoglobin gene had an open reading frame of 444 nucleotides and translated into 147 amino acids with molecular weight of 16,909 and pI of 9.43. The myoglobin gene in vivo expression in white muscle was not affected by pre-slaughter chilling. Pre-slaughter chilling is a stressor to channel catfish and shortens the pre-rigor time postmortem; thus, it is not recommended in catfish processing.

sn-Glycerol-3-phosphate acyltransferase (GPAT) catalyzes the acylation of sn-1 position of sn-glycerol-3-phosphate to produce lysophosphatidic acid and Coenzyme A. GPATs are involved in several lipid synthetic pathways and play important physiological roles in plant development. The present doctoral thesis includes three related studies, which aim to molecularly and functionally characterize several plant GPAT genes and the encoded enzymes. The first study characterized three endoplasmic reticulum-bound GPAT4s encoded by three homologous GPAT4 genes of Brassica napus (oilseed rape), focusing primarily on their functional divergence and physiological roles in plant development and lipid biosynthesis. The three homologous GPAT4 genes exhibited different expression patterns and altered epigenetic features. Phenotypic rescue of a gpat4 gpat8 Arabidopsis double mutant and analysis of the gpat4 RNAi B. napus lines suggested physiological roles for the GPAT4s in cuticle formation of the rosette leaves, early flower development, pollen development and storage lipid biosynthesis. The second study investigated stable internal reference genes for gene expression studies in B. napus. This project identified four reliable reference genes to be used in gene expression analysis of BnGPAT4 homologues in both vegetative tissues and developing seeds. The third study focused on molecular cloning and biochemical characterization of a soluble plastidial GPAT isolated from a chilling-tolerant plant, western wallflower (Erysimum asperum). A truncated form of recombinant EaGPAT, with the putative transit peptide deleted, was functionally expressed in yeast. A series of enzymatic assays were performed in order to determine the optimum in vitro reaction conditions for the recombinant EaGPAT. The recombinant EaGPAT was further assayed with different acyl-CoAs and exhibited a substrate preference for 18 carbon unsaturated acyl-CoAs. With this substrate preference, the EaGPAT could potentially be used as a biotechnological tool for improving plant chilling-tolerance or increasing unsaturated fatty acid content of seed oil. Overall, the present doctoral studies revealed the functional divergence and important physiological roles of the GPAT4s in B. napus, and biochemically characterized a plastidial GPAT from E. asperum. The knowledge obtained from these studies provides new insights into the role of GPAT in plants and will be useful for further development of biotechnological approaches to modify seed oil biosynthesis in oleaginous crops. / Plant Science

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Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Chilling injury in banana fruit is caused by prolonged exposure to temperatures less than 13°C. This can occur during bunch development in the field or postharvest handling and storage. Mild symptoms of chilling injury are localised to peel tissue and reduce visual quality of fruit. Light microscopy was used in the present study to analyse symptoms of mild chilling injury in Cavendish cv. Williams banana. Following storage at 5°C for 24hours, symptoms of chilling injury in the form of brown discolouration was observed within laticifers in sub-epidermal peel tissue. Browning was not observed in other vascular tissues as previous research has suggested. Causal mechanisms associated with browning of latex within laticifers were investigated. Polyphenol oxidase (PPO) activity in fractions of banana peel latex was measured and found to be highest in the lutoid fraction. PPO activity also provided indirect evidence that phenolics were present in peel latex. Literature suggests possible compartmentalisation of PPO and phenolics in banana lutoids. In this study it is suggested that PPO and phenolics associated with lutoids in banana peel latex may be involved in browning due to chilling stress. The lipid content of lutoids from banana latex was also investigated using FTIR spectroscopy, but showed no further involvement of lutoids in the browning reaction caused by chilling. Control of field chilling using modified bunch covers was investigated. Bunch covers used in modern banana production are usually polyethylene bags, placed over bunches during development in the field. Experiments in a northern Queensland plantation investigated effects of modified bunch covers on fruit yield and quality characteristics of Cavendish cv. Williams bananas, including the development of mild chilling injury symptoms. A further field trial was conducted using different coloured bunch covers with varied interception of photosynthetically-active radiation (PAR), to determine any negative effects of bunch cover shading on fruit yield and quality. Different coloured and layered polyethylene films (blue, double green, silver yellow and silver black) modified PAR transmission of bunch covers (PAR transmission [%] = 56, 38, 7, 0). During summer 2003, varying PAR transmission of bunch covers significantly affected fruit size. Fruit from blue polyethylene covers, which transmitted most light, were larger than fruit from covers with less light transmission. Between cover treatments of lower light transmission, fruit size remained similar. It is suggested, during summer when cloud cover in northern Queensland limits solar radiation, bunch covers with high PAR transmission facilitate greater bunch photosynthesis, which improves fruit size. Fruit quality was generally unaffected by varying PAR transmission of bunch covers, but cover treatments were found to influence peel colour. Peel colour of fruit from 'silver black' covers was significantly paler. This may have impacted upon green life due to increased de-greening. Results from this experiment suggest that bunch photosynthesis significantly influences fruit size and peel colour during summer growing periods. Modified bunch covers constructed from existing bunch cover films and polyethylene bubble wrap ('blue + silver bubble' and sealed and non-sealed 'silver blue + silver bubble') were used to test control of field chilling during winter 2003 and 2004. Compared to standard blue polyethylene bunch covers, modified covers significantly reduced exposure of bunches to chilling conditions in the field and the development of visible chilling injury symptoms on the peel surface and in underpeel tissue. Greatest control of field chilling was shown using the non-sealed 'silver blue + silver bubble' cover design. Relative to the standard blue cover, in winter 2003 the non-sealed 'silver blue + silver bubble' cover design reduced chilling exposure by 95% at the top and 45% at the bottom of bunches. This totally controlled chilling injury symptoms in the top and middle bunch regions. In winter 2004 chilling conditions were more severe and chilling exposure was reduced by 85% using the non-sealed 'silver blue + silver bubble' cover. This reduced the severity of peel surface chilling symptoms by 67% in the top bunch region relative to fruit from blue covers. Yield characteristics were positively influenced by 'blue + silver bubble' and sealed and non-sealed 'silver blue + silver bubble' covers. Improved fruit size and weight was probably due to enhanced temperature conditions inside the bunch environment, relative to 'control' covers. Fruit quality was generally unaffected by 'blue + silver bubble' and sealed and non-sealed 'silver blue + silver bubble' covers. However peel colour was significantly influenced by these cover treatments, compared to the 'control' covers. Reduced light transmission of covers produced paler fruit. This may have influenced other quality characteristics, such as green life and SSC levels, as it confounded assessment of ripening stage. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1241852 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture and Wine, 2006

Over the last decade, food processing has become one of the greatest energy converting stages of the food production supply chain. The interdependency of food, water, and energy leads to a need for more water efficient and energy effective ways to produce food. These studies focus on poultry chilling, primarily comparing the potential options of media that could be used during the poultry chilling sub-process. The conventional poultry chilling approach typically involves the immersion of chicken within chilled water in order to quickly decrease the chicken temperature, thus hindering the growth of bacteria. This research is an initial investigation of ice slurry as an energy and water efficient, pathogen reducing, and financially feasible chiller medium in poultry processing. The financial feasibility and electrical energy demand of using ice slurry were explored in a techno-economic model in HOMER Energy, which is a micro-grid design and optimization software. The thermal cooling capacity of ice slurry and fluidity of the solution allows for generation and storage to occur during low electricity cost hours and an application during high electricity cost hours, thus creating savings in electricity costs associated with poultry chilling. During the poultry chilling experimentation, chickens were spiked with Salmonella as temperature probes measured their core body temperature throughout their immersion within the different media. Greater pathogen reductions, faster cooling times, and less water consumption compared to chilled water promotes ice slurry as an alternate medium in the poultry processing industry.

Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The purpose of this study was to describe the nature of springbok (Antidorcas marsupialis) muscle and the changes that take place in the longissimus thoracis et lumborum (LTL) and biceps femoris (BF) muscles post-mortem (PM); thereby providing recommendations for the handling of the meat. Springbok muscle contained 64 - 78% type IIX fibres, suggesting that it is considerably more glycolytic than bovine muscle. In males the BF contained more type I and fewer type IIA fibres than the LTL and it appeared that female springbok contained a greater proportion of type IIX fibres than males. The cross-sectional areas (CSA’s) of the fibres were low but within the range reported for domestic species. There was an increase in the CSA with the glycolytic capacity of the fibres in males (I < IIA < IIAX < IIX) but no difference between fibre-types in females. Springbok muscle cooled rapidly and acidified slowly relative to recommended set points for domestic species, with this being most evident in the female LTL. Differences in cathepsin and calpain activity between the genders and muscles were evident, with the higher calpain activity in the BF and male springbok likely a reflection of the fibre-type composition of these samples. The cathepsin BL activity increased PM, possibly due to the degradation of the lysosomal membranes. Calpain and calpastatin activity declined PM, with correlations (r = -0.64; p < 0.01) between the pH decline rate and the change in calpastatin activity indicating that more rapid acidification results in a greater decrease in calpastatin activity. No further improvement in the Warner Bratzler shear force (WBSF) of springbok LTL or BF took place from five to 21 days of ageing. The cathepsin activity increased during the ageing period, with the high activity in the absence of a decline in WBSF suggesting that the cathepsins did not contribute to tenderization. The calpain and calpastatin activity declined to negligible levels by five days PM, suggesting that they were activated in situ and were involved in tenderization. Higher WBSF values were found for the BF throughout the ageing period. Springbok LTL increased in sensorial tenderness and sustained juiciness and decreased in residue from three to eight days PM; however ageing to 28 days increased a number of undesirable aroma and flavour attributes and decreased beef-like aroma. This was most likely due to oxidative and proteolytic changes. The WBSF was low for all ageing periods, with no significant change being found. Gender did not have a large influence on the sensory quality of the meat. The results of this study indicate that springbok meat tenderizes rapidly PM, with ageing periods of five to eight days being recommended to avoid detrimental flavour changes. The chilling rate appears to have a greater effect on the meat than any differences in the fibre-type composition, with the temperature and pH declines PM indicating a risk of cold-shortening. However the WBSF values found question the necessity of specialized handling techniques being used. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die aard van springbokvleis en die veranderinge wat plaasvind na dood in die Longissimus thoracis et lumborum (LTL) en biceps femoris (BF) spiere te omskryf. Sodoende word voorstelle vir die korrekte hantering van springbok vleis voorsien. Die springbokspiere bevat 64 - 77% tipe IIX vesels wat aandui dat dit aansienlik meer glikolities van aard is in vergelyking met die van bees. In die manlike diere het die BF meer tipe I en minder tipe IIA vesels gehad as die LTL. Daarmee saam het die vroulike springbokke ‘n hoër hoeveelheid tipe IIX vesels gehad as die manlike. Die opeervlakte van die springbok vesels was klein, maar steeds binne die omvang van wat gemeld is vir gedomestiseerde diere. Tesame met ‘n toename in die glikolities kapasiteit was daar ‘n toename in die vesel oppervlakte van die manlike diere (I < IIA < IIAX < IIX), maar geen verskil is egter gevind vir die vroulike diere. Die springbok spiere het snel verkoel en redelik stadig versuur, relatief tot die van gedomestiseerde spesies. Dit was die mees voor die hand liggend in die vroulike LTL spier. Verskille in die katepsien en kalpaïen aktiwiteit tussen die geslagte was duidelik en die hoër kalpaïen aktiwiteit in die BF van die manlike diere is waarskynlik as gevolg van die samestelling van die veseltipes. Die katepsien BL aktiwiteit het toegeneem na-dood wat moontlik te wyte is aan die afbraak van die lisosomale membrane. Kalpaïen en kalpastatien aktiwiteit het verlaag na-dood en korrelasies (r = -0.64; p < 0.01) tussen die tempo van die pH daling en die verandering in die kalpastatien aktiwiteit het aangedui dat ‘n snel versuring lui tot ‘n groter afname in kalpastatien aktiwiteit. Daar was geen verbetering in die instrumentele sagtheid van die springbok LTL of BF vanaf vyf dae veroudering tot en met 21 dae. Die katepsien aktiwiteit het toegeneem tydens die verouderings tydperk. As gevolg van die hoë aktiwiteit tesame met die afwesigheid van ‘n afname in instrumentele sagtheid wil dit voorkom of die katepsiene geen bydrae gelewer het tot versagting. Beide die kalpaïen en kalpastatien aktiwiteit het weglaatbaar afgeneem teen vyf dae van veroudering wat aandui dat hierdie ensieme moontlik geaktiveer is in-situ en daarom betrokke was by versagting. Die BF spier het hoër instrumentele taaiheid waardes getoon reg deur die verouderings tydperk. Die springbok LTL het ‘n toename in sensoriese sagtheid en verlangde sappigheid tesame met ‘n afname in residu getoon vanaf drie tot ag dae veroudering. Die veroudering tot en met 28 dae het egter verskeie ongewensde aroma en geur eienskappe na vore gebring. Die paneel het ook ‘n afname in die bees aroma opgetel. Die voorkoms van hierdie ongewensde sensoriese eienskappe is heel waarskynlik as gevolg van oksidatiewe en proteolitiese veranderinge tydens veroudering. Die instrumentele sagtheid was redelik laag reg oor die verouderingstydperk en geen beduidende verskille is gevind. Geslag het geen verskil gehad op die sensoriese kwaliteit van die vleis nie. In geheel toon die resultate van hierdie studie dat springbokvleis snel verouder. Die aanbevole verouderingstydperk is tussen vyf en agt dae om sodoende nadelige aroma en geur veranderinge te vermy. Dit wil blyk of die verkoelingstempo ‘n groter invloed op die vleis het as enige verskil in die samestelling van die vesel tipes. Die temperatuur en pH dalings na-dood dui wel op die risiko van kouekrimping maar die resultate rondom die instrumentele sagtheid bevraagteken wel die noodsaaklikheid van gespesialiseerde hanteringstegnieke.

Made available in DSpace on 2014-06-11T19:33:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-05-11Bitstream added on 2014-06-13T19:44:33Z : No. of bitstreams: 1 miguel_aca_dr_jabo.pdf: 5169762 bytes, checksum: 9976d67d3d00b8169b60eeb898705743 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Determinou-se os binômios temperatura x tempo de armazenamento, que podem ocasionar injúria pelo frio em mangas ‘Tommy Atkins’ e ‘Palmer’, com avaliação das alterações no seu metabolismo, o que permitiu que se testasse o uso de tratamento térmico e de radiação ultravioleta (UV-C) para minimizar ou eliminar esta injúria. Avaliou-se também a eficiência do uso de quitosana como alternativa à cera, comumente aplicada após o tratamento térmico. No 1º e 2º experimentos, frutos colhidos no estádio “de vez”, foram armazenados a 2 ºC, 5 ºC e 12 ºC por 1, 2, 3 e 4 semanas. Ao final de cada período, foram transferidos para condição ambiente, por até 7 dias. No 3º e 4º experimentos, uma parte dos frutos foi tratada hidrotermicamente a 46,1 ºC por 90 min ou 55 ºC por 5 min e a outra, submetida à ação de radiação (UV-C) nas doses de 1,14 kJ m-2 e 2,28 kJ m-2, antes do armazenamento sob condição promotora de injúria por frio, a 5 ºC por 14 dias (‘Tommy Atkins’) e a 5 ºC por 4 dias (‘Palmer’). No 5º e 6º experimentos, frutos tratados com radiação (UV-C) receberam filme de cera de carnaúba ou quitosana a 1% e 1,5%, antes de serem armazenados sob condição promotora de injúria, a 5 ºC por 14 dias (‘Tommy Atkins’) e a 5 ºC por 4 dias (‘Palmer’), sendo após esse período, transferidos para a condição ambiente, onde foram mantidos por 7 dias para a ‘Tommy Atkins’ e por até 12 dias, para a ‘Palmer’. Em todos os experimentos, os frutos foram avaliados semanalmente durante o armazenamento refrigerado, e a cada 2 dias depois de levados ao ambiente, quanto ao murchamento, coloração, podridões, massa fresca, firmeza, danos pelo frio, atividade respiratória, teores de sólidos solúveis, acidez titulável, açúcares solúveis e... / It was determined the binomials temperature vs. time, which can cause chilling injury in mangoes 'Tommy Atkins' and 'Palmer', with the evaluation of the changes in their metabolism, allowing to test the use of heat treatment and UV-C radiation to minimize or eliminate this injury. It also evaluated the effectiveness of the use of chitosan as an alternative to the carnauba wax, usually applied after the heat treatment. In the 1st and the 2nd experiments, fruits harvested at “medium ripe” were stored at 2 ºC, 5 ºC and 12 ºC for 1, 2, 3 and 4 weeks. At the end of each period, they were transferred to the environmental condition up to 7 days. In the 3rd and the 4th experiments, a part of the fruits was treated hydrothermally at 46.1 ºC for 90 min or 55 ºC for 5 min and another part submitted to the action of UV-C radiation at doses of 1.14 kJ m-2 and 2.28 kJ m-2, before the storage under chilling injury condition, at 5 ºC for 14 days (‘Tommy Atkins’) and at 5 ºC for 4 days (‘Palmer’). In the 5th and 6th experiments, fruits treated with UV-C radiation were coated with carnauba wax or chitosan at 1% and 1.5%, before being stored under chilling injury condition, at 5 ºC for 14 days (‘Tommy Atkins’) and at 5 ºC for 4 days (‘Palmer’), and thereafter transferred to the environmental condition, where they were maintained up to 7 days (‘Tommy Atkins’) and up to 12 days (‘Palmer’). In all experiments, the fruits were evaluated weekly during the cold storage, and every two days after they were taken to the environment, for the wilting, color, rottenness, mass loss, firmness, chilling injury, respiration rate, soluble solids, titratable acidity, soluble and reducing sugars, ascorbic acid and total polyphenols, total antioxidant activity and the enzymes of peroxidase, polyphenoloxidase and phenylalanine ammonia-lyase. The results... (Complete abstract click electronic access below)

Many deciduous trees enter a stage each year when their visible growth ceases. This is not always associated with cold weather or lack of water, and may occur with many species in mid-to-late summer. Trees entering this phase are said to be in rest. Rest is caused when internal factors are unfavorable for growth, while dormancy is defined as external factors being adverse for growth.