Thesis (Masters Diploma (Food Technology)) -- Cape Technikon, Cape Town, 1992 / Kakamas peaches and Bulida apricots were heat processed in transparent and aluminium laminated plastic bags and compared with fruit heat processed in standard cans. Heat processing conditions were optimized to produce acceptable processed products. Appropriate chemical and microbiological properties of all treatments as well as sensory quality of peaches were investigated. Although rectifiable disadvantages such as texture softening and fading of colour appeared during storage, peaches and apricots were successfully heat processed in aluminium laminated pouches. Heat processed peaches had a maximum storage life of 12 months and apricots 6 months when stored at ambient temperature in aluminium laminated pouches.

Sensory analysis, that is the description of food or beverages by a panel of judges, has become increasingly important in the development of commercial foodstuffs. In general terms, sensory analysis involves scoring, for intensity, the adjectives of a vocabulary which adequately describes every nuance of sensory property found in the sample. The data from a sensory analysis of a set of samples are matrices of scores, one for each judge, with rows corresponding to adjectives, and columns to samples. This can be interpreted as a set of configurations, one for each judge, where points correspond to samples, and dimensions to adjectives. The question of how to combine the scores by each judge to summarise the information on the samples, is of particular interest. This thesis concentrates on combining judge scores by generalized Procrustes analysis, the method of simultaneously matching a set of configurations by translation, rotation/reflection and scaling. This analysis has intrinsic appeal as it allows each judge to have his own interpretation of the adjectives. The only constraint is that the judges must place samples in the same relative positions within their own private scoring schemes. The asymptotic distribution of the residual sum of squares after a generalized Procrustes analysis is discussed, and the sum of squares before transformation is shown to partition into sums of squares for translation, rotation/reflection scaling and a residual. Therefore, the effects of the Procrustes transformations can be presented in an ANOVA format. The use of complementary pair-wise Procrustes rotation is shown to be made redundant by a modification to the generalized Procrustes analysis, which gives a Euclidean representation of the judges. A worked example illustrates the advantage, over the panel mean, of a generalized Procrustes analysis, and a summary of the sample information by the consensus configuration.

Physiological studies of type cultures of Neurospora crassa, N. sitophila, and N. intermedia in terms of growth on bread, effects of heat flashes, water activity, food additives and viability of stored conidia revealed no differences in either environmental or substrate preferences among the species on which a classification could be based. 345 putative wild isolates of Neurospora were collected from a wide variety of sources - silage, Indonesian ontjom, wheat grains, flour, bread, crumpets, bakery air and bakery dust. These all grew more vigorously than the type cultures. They were compared with respect to morphological traits such as conidial colour and size, and degree of protoperitheciality, but these features again proved inadequate to distinguish between species. The wild isolates were crossed with tester strains which were derived or synthesized from isolates in the collection and authenticated with reference strains from the Fungal Genetics Stock Center and the Commonwealth Mycological Institute. The times required in these crosses for perithecium formation and ascospore ejection, and the perithecial pattern and percentage of dark-coloured ascospores produced were investigated. The latter proved to be an unambiguous and highly reproducible diagnostic character for species delineation. Neurospora crassa accounted for the bulk of the collection, conflicting with the popular view that N. sitophila is the principal Neurospora contaminant of bread. Only heterothallic strains of both mating types of N. crassa, N. sitophila, and N. intermedia were represented. Based on six characteristics (conidial colour, mating-type, protoperitheciality and percentage dark-coloured ascospores with the three species testers), the isolates of bakery origin were grouped into 112 individual strains. Such variability indicated that there was continual infection in these bakeries from a large population of strains estimated from analysis based upon the Poisson distribution to be about 170. Based on this finding, a model of the probable infection cycle of Neurospora in bakeries is described.

Seven hundred and seventeen yeasts isolated from samples of sulphited and unsulphited sausage, skinless sausage, minced beef, and ingredients intended for sausage manufacture, as well as air and equipment in a sausage factory were characterised in detail. Debaryomyces hansenii was the most commonly occurring yeast in the majority of samples of sausage and minced beef, followed by Candida zeylainoides and Pichia membranaefaciens. The presence of sulphite did not appear to influence the overall numbers or range of yeasts in sausage but did affect their relative proportions such that the incidence of D. hansenii was higher and that of certain Cryptoccoccus and Rhodotorula spp. was lower in samples containing the preservative. The heat treatment of skinless sausages during processing appeared to reduce the incidence of D. hansenii. The factory survey showed that the meat intended for sausage manufacture and also other ingredients as well as equipment harboured the same range of yeasts as were found in the finished product. A yeast flora dominated by Trichosporon cutaneum was isolated from pig carcasses immediately following slaughter. This flora was found to be confined largely to the equipment and air of the slaughter area and lairage. In general, the yeast flora of sausage was non-fermentative but could assimilate a wide range of carbohydrates. Selected strains of C. curvata, C. lipolytica var. lipolytica, C. zeylanoides, Cr. albidus, D. hansenii, P. membranaefaciens and Torulopsis candia were shown to synthesise either extra cellular lipases and/or amylases but not proteases in broth culture. Sulphite binding compounds, principally acetaldehyde, were produced in lab lemco broth (pH 7.0) containing sulphite (500 mug g-1) during the exponential phase of growth of representative strains of D. hansenii, C. zeylanoides, P. membranaefaciens and T. candida but not Cr. albidus var. albidus and Rh. rubra. The extent of sulphite binding in minced pork- belly supplemented with sulphite (500 mug g-1) was appreciably greater in samples inoculated with D. hansenii than in those inoculated with representatives of the other members of the microbial association, Brochothrix thermosphacta, Lactobacillus sp. and a pseudomonad. The content of sulphite binding agents in minced pork was found to be positively related (r = 0.98, 0.92 at 1 and 15°C respectively) to the size of the yeast population. The concentration of acetaldehyde in stored sausages obtained from a factory and also those obtained from retail outlets was correlated with the concentration of bound sulphite (r = 0.89). The rate and extent of sulphite binding and acetaldehyde production was fastest during the exponential phase of yeast growth in sausages.

The microbial associations that developed in commercially produced sulphited and unsulphited sausages during storage for up to 8 days at a variety of temperatures were identified. Such associations were comprised of domiinant, e.g. Brochothrix thermosphacta, yeasts and lactic acid bacteria, or minor, e.g. Pseudomonadaceae and Enterobacteriaiceae, groups. A detailed analysis of numerous isolates of the previously-ignored Gramnegative microflora using computer-assisted numerical techniques revealed that sulphite concentratioin influenced the composition of the Enterobacteriaceae but not the pseudomonads. A method was developed for the assay of free and bound sulphur IV oxospecies in culture media or meat-based samples. It was superior to existing techniques and demonstrated limited irretrievable - by oxidation - and extensive reversible - by binding - loss of sulphite preservative from freshly manufactured and stored sausage. Selected micro-organisms isolated from sausage were tested for their tolerance of free and bound sulphur IV oxospecies in batch and "turbidometer" culture under various conditions. In general this technique reflected the elective/selective role of sulphite in sausage and allowed the microbial association to be defined more clearly in terms of tolerance of the active preservative. The incidence and level of contamination of sausage and its ingredients with Salmonella was established using a 'most-probable number' method. Despite a high incidence of contamination of most of the meat ingredients and finished product with these organisms, the level of infection - with the exception of mechanically recovered meat - was low. Thus the role of sulphur IV oxospecies in determining the fate of these food poisoning organisms in sausage or culture media was assessed by deliberate infection with rifampicinresistant Salmonella mutants. With a view to extending the shelf life of fresh sausage, a limited survey of adjuncts or alternative "preservatives" to sulphite using pilot-scale batches of sausage meat was done.

Made available in DSpace on 2014-06-11T19:31:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-05-27Bitstream added on 2014-06-13T18:41:33Z : No. of bitstreams: 1 vanzela_esl_dr_sjrp.pdf: 1753439 bytes, checksum: bf597c43a29acac3b77b86556475bbd0 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O conhecimento qualitativo e quantitativo dos compostos bioativos presentes nas uvas produzidas no Estado de São Paulo é de fundamental importância para elevar a qualidade dos produtos a um patamar internacional. A composição fenólica detalhada (antocianinas, flavonóis, derivados dos ácidos hidroxicinâmicos, estilbenos e flavan-3-óis) das partes comestíveis (polpa e casca) das uvas de mesa apirênicas (BRS Clara e BRS Morena) e da uva Bordô, produzidas na região do Noroeste Paulista, foi identificada e quantificada utilizando cromatografia líquida de alta eficiência com detectores de arranjo de diodos acoplada à espectrometria de massas por sistema de ionização por eletronebulização (CLAE-DAD-IES-EM/EM). Este trabalho também determinou o teor de fenólicos totais e a capacidade antioxidante destas uvas, bem como objetivou estudar as polifenol oxidases (PPO) endógenas associadas aos processos de deterioração das uvas de mesa apirênicas e, avaliar o efeito da pectinase produzida pelo fungo Thermomucor indicae-seudaticae N31 sobre o teor de compostos fenólicos na extração de suco de uva Bordô. O conteúdo de fenólicos totais da uva Bordô foi de 1130 mg/kg (como equivalentes de ácido gálico, GAE), principalmente situados nas cascas, onde também encontrou-se alto teor de antocianinas, em grande parte, como 3,5-diglicosídeos, de flavonóis e de derivados de ácido hidroxicinâmico (HCAD). A miricetina 3-glicosídeo apresentou-se como componente principal dos flavonóis enquanto os HCAD derivaram principalmente do ácido caféico. O teor de flavan-3-óis da casca apresentou-se um pouco mais baixo que o normalmente relatado em variedades Vitis vinifera. A uva Bordô pode ser considerada uma fonte importante de resveratrol e de outros compostos com capacidade antioxidante (37,6 mmol/kg, como equivalentes de Trolox). Já a composição fenólica qualitativa das uvas... / The qualitative and quantitative knowledge of the bioactive compounds present in grapes produced in the State of Sao Paulo is very important to the process of raising the quality of the state’s products to an international level. The detailed phenolic composition (anthocyanins, flavonols, hydroxycinnamic acid derivatives, stilbenes and flavan-3-ols) of the edible parts (flesh and skin) of the Bordô grape and seedless table grapes (BRS Morena and BRS Clara), produced in the Northwest region of State, was identified using high performance liquid chromatography with a diode array detector coupled with mass spectrometry through an electrospray ionization system (HPLC-DAD-ESI-MS/MS). This study also determined total phenolic content and antioxidant capacity of these grapes, as well as the endogenous polyphenol oxidases (PPO) associated with the processes of decay of seedless table grapes. This study also evaluated the effect of pectinase produced by the fungus Thermomucor indicae-seudaticae N31 on the total phenolic content during the extraction of grape juices from the Bordô. Total phenolic content of the Bordô grape was 1130 mg/kg (as gallic acid equivalents - GAE), and was mainly located in the skins, where there was also high content of anthocyanins, which were largely found as 3,5-diglucosides, as well as of the flavonols and hydroxycinnamic acid derivatives (HCAD). Myricetin 3-glucoside was found to be the main compound of the flavonols, while the HCAD mainly derived from caffeic acid. The flavan-3-ol contents of the skins were lower than those that are usually reported for V. vinifera grape varieties. The Bordô grape can be considered an important source of resveratrol and other compounds with antioxidant capacity (37.6 mmol/kg, as Trolox equivalents). The qualitative phenolic composition of BRS Clara and BRS Morena grapes did not differ from those found in cases of Vitis vinifera... (Complete abstract click electronic access below)

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The practical work described in this thesis falls into four distinct subject areas: HPLC, tea liquor fractionation, mass spectrometry, and NMR and IR. The practical work, is therefore written in four chapters, each chapter having its own introduction, results and discussion, and experimental sections. The work is concerned with the analysis of black tea liquor, its aim being to provide an analytical input into a larger project, being carried at NRI (Natural Resources Institute), on the statistical evaluation of tea quality.

The synthesis and use of monoacylglycerols in food systems havc been reviewed. The use of monoacylglycerols alone or in combination with free fatty acids as food preservatives has been discussed. Model systems have been devised to produce monoacylglycerols (MAGs) from butter and Shea oils with two strains of Penicillium roquefortii, FRR 2456 (isolated from a spoilt melon) and Wisbey PJ (a commercial dairy strain) A semi-micro method was developed using Preparative Thin Layer Chromatography (PTLC) and Gas Chromatography - Mass Spectrometry (GC-MS) of the MAG trimethylsilyl ether derivatives to determine the identification, fatty acid composition and structural isomers of the individual MAG. The main monoacylglycerols produced by spores and emerging mycelium were 1(3)-monoacylsn-lycerols (in suspension culture). Monopalmitin was the major MAG from butter and Shea oils. Monoacylglycerols produced by fungal mycelium (in solid-state culture) were mainly the 1 (3 )-monoacyl-sn-glycerols although approximately 30% were present as 2-monoacyl-snglycerols. Again the main MAG was monopalmitin. It suggested that P. roquefortii produced two lipases, one during germination with specificity to the sn-2 position in the original triacylglycerols (TAGs) and one L3-specific during growth of the fungal mycelium. In addition, flavour compounds, methyl ketones and y-lactones, were found in solid-state culture. The composition of the MAGs formed by lipolysis using a commercial lipase (E.C.3.1.1.3) with 1,3- specificity gave the expected 2-isomers when butter oil was the substrate but gave 1 (3)monostearin rather than the expected 2-monoolein when Shea oil was the substrate. It suggested that acyl migration occurred due to the reactive nature of the original oleate group at the sn-2 position in the Shea oil TAGs. There were no significant differences with fungal strain or temperature of incubation (10 °C and 25°C) on the composition of the MAGs. The mechanism of formation of MAGs from butter and Shea oils has been discussed. It has been suggested that l(3)-MAGs together with free fatty acids may be part of a natural antimicrobial system in high pH foods such as blue mould-ripened cheese where growth of foodborne pathogens such as Listeria monoGytogcnes can be a problem from time to time

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