Masters Research - Master of Philosophy (MPhil) / Gac fruit, Momordica cochinchinensis Spreng contains extraordinarily high levels of carotenoids, especially β-carotene and lycopene, and a comparatively high content of alpha-tocopherol (vitamin E) and of polyunsaturated fatty acids. The aim of this study was therefore to develop an understanding of suitable conditions for the processing of Gac fruit and the preparation of Gac fruit powder. The objectives of this study were to investigate the effect of 1) pre-treatments; blanching, ascorbic acid and bisulfite, and 2) drying techniques; air, vacuum, freeze and spray drying, on the physicochemical and antioxidant properties of powders produced from Gac arils. In addition, Gac arils (mixed with added maltodextrin) and untreated Gac skin and yellow pulp were air-dried and their properties were evaluated. The shelf life of a number of the Gac powder products was periodically evaluated during an extended storage period. The moisture sorption isotherms of various Gac powders were also constructed. Furthermore, the stability of three different types of Gac fruit powders was also tested when used in food and beverage products. Results showed that freeze drying of fresh Gac aril without any pre-treatment produced powders of high quality as determined by colour (hue angle of 33.93, total carotenoid content (TCC) of 7.24 mg/g and total antioxidant activity (TAA) of 0.39 mmole TE/g). However, pre-treatment of fresh Gac fruit aril with 1% (w/v) ascorbic acid or bisulfite solution before vacuum drying at 40 oC for 45 hours was just as effective as freeze drying in preserving colour (hue angle of 34.18 and 36.25, respectively), TCC (7.28 and 6.99 mg/g, respectively) and TAA of 0.36-0.40 mmole TE/g. Pre-treatment with 1% (w/v) ascorbic acid or bisulfite solution before air drying at 40 oC for 48 hours was also effective (TCC of 6.36 and 6.11 mg/g, respectively and TAA of 0.33 mmole TE/g) but not to the extent of vacuum or freeze drying. In respect of the spray drying process, taking into account the dilution effect of the added maltodextrin, the addition of 10% maltodextrin to the feed mixture and drying at 120 oC effectively preserved the physicochemical and antioxidant properties of the powder (hue angle of 66.85, TCC of 2.77 mg/g and TAA of 0.14 mmole TE/g). In addition, in a comparison of fresh and frozen arils, both were found to be equally useful for production of Gac powder in terms of preservation of colour (hue angle of 33.93 and 31.28, respectively), TCC (7.24 and 6.27 mg/g, respectively) and TAA (0.39 and 0.33 mmole TE/g, respectively). However, the dried aril was found to be very difficult to grind due to its stickiness. The addition of maltodextrin (0.5 or 1 g maltodextrin/g of total fruit solids) prior to drying solved this problem and also maintained the quality of the powder (hue angle of 28.04-30.55; TCC of 5.65-6.29 mg/g and TAA of 0.29-0.31 mmole TE/g, respectively). The storage study indicated that the degradation of TCC and TAA of freeze-dried and spray-dried powders for up to 8 and 3 months, respectively, was lowest when samples were packed into laminated bags and stored at temperature of 10 oC (TCC loss of 11% and 5% and TAA loss of 44% and 15%, respectively). The highest losses for freeze-dried and spray-dried powders (TCC of 70% and 42%; and TAA of 88% and 42%, respectively) occurred when stored at conditions of 37 oC. Isotherm curves of all the Gac powders have sigmoid shapes. By comparing different drying methods for aril, the lowest hygroscopicity was observed in SD powder, followed by VD, AD and FD powders. Results also showed that the air-dried skin and yellow pulp powders contained low levels of TCC and TAA compared to the aril powders, but these are still high levels of TCC (0.90 and 0.42 mg/g, respectively) as compared to cherry tomatoes (0.36) and pumpkin (0.14). The skin (18%) and yellow pulp (49%) account for 67% of the total weight of the Gac fruit and as such comprise significantly high components. Therefore, utilisation of these components can prevent environmental pollution due to waste issues, and also enhances the overall value of Gac fruit. Freeze-dried, vacuum-dried and spray-dried Gac fruit aril powders were found to be easily incorporated into cooked glutinous rice, pasteurised Gac juice and pasteurised Gac milk mixtures. The colour, TCC and TAA of the juice and the milk mixtures were maintained after storage for 30 days under refrigeration temperature of 40 oC. Overall the study established that, the quality of Gac aril powders, in terms of colour, TCC and TAA, is most effectively preserved by applying pre-treatments prior to vacuum drying at 40 oC. These powders should be packed in laminated bags and stored at 10 oC for any lengthy storage period. It was also found that the Gac powders can be satisfactorily incorporated into “Xoi Gac”, juice and milk products. Finally, the overall value of Gac fruit could be enhanced through utilisation of all the anatomical components.

Submitted by Eunice Novais (enovais@uepg.br) on 2018-06-15T18:10:58Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Kerolin Ap Alves Gomes.pdf: 2922365 bytes, checksum: ccbcc929da0afe5876dd9273d11519e6 (MD5) / Made available in DSpace on 2018-06-15T18:10:58Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Kerolin Ap Alves Gomes.pdf: 2922365 bytes, checksum: ccbcc929da0afe5876dd9273d11519e6 (MD5) Previous issue date: 2018-01-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A utilização de materiais ambientalmente corretos, de fonte renovável, assim como a celulose, tem se apresentado como assunto de interesse para muitos pesquisadores. Neste trabalho os nanocristais de celulose (NCC) foram extraídos a partir da celulose microcristalina comercial (CMC) com posterior ajuste de pH e modificação superficial com o surfactante catiônico brometo de cetil trimetil amônio (CTAB), objetivando-se realizar a secagem dos NCC e posterior redispersão em água. Para tanto, foram estudadas as influências dos procedimentos de diálise, da faixa de pH, da modificação superficial e também da técnica de secagem sobre a estabilidade coloidal e também sobre a distribuição de tamanhos de partículas. Três técnicas de secagem foram estudadas: (1) secagem em estufa, (2) secagem por liofilização e (3) secagem por spray drying. Na secagem em estufa houve a formação de aglomerados indissolúveis impedindo a redispersão dos NCC, nesta técnica foi avaliado principalmente o efeito do ajuste de pH, observando-se que para condições ácidas de pH ocorre a degradação dos NCC. Na secagem por liofilização foi possível redispersar os NCC em água, porém não foi obtido um material seco estável, pois ocorreu a dessorção da água. Observou-se também que para adições maiores do contra-íon +, obtiveram-se melhores resultados de redispersão quanto à distribuição de tamanho de partículas. Na técnica de secagem por spray drying foi testada a influência do surfactante sobre a redispersão. A adsorção do surfactante catiônico à superfície dos NCC foi confirmada pela técnica de espectroscopia no infravermelho por transformada de Fourier (FTIR). Ficou demonstrado que com a adição de 1% de surfactante às suspensões de NCC é possível redispersá-las obtendo características muito próximas as das suspensões antes do processo de secagem, no entanto, observou-se perda da estabilidade coloidal para algumas amostras após a redispersão. As técnicas de microscopia eletrônica de varredura (MEV), difração de raios X (DRX), análise termogravimétrica (ATG) e análise reológica foram usadas para caracterizar o material obtido na secagem por spray drying, que foi determinada como a melhor técnica de secagem. A morfologia das partículas apresentou-se no formato esférico, com a formação de aglomerados. Foram obtidos elevados índices de cristalinidade para as amostras com adsorção do surfactante CTAB, porém com reduzida estabilidade térmica. A avaliação da viscosidade cinemática indicou um comportamento pseudoplástico para as suspensões do NCC e um aumento na viscosidade das amostras após a secagem e redispersão indicou a formação de aglomerados / The use of environmentally friendly materials from renewable sources, as well as cellulose, has been presented as a subject of interest to many researchers. In this work the cellulose nanocrystals (CNC) were extracted from commercial microcrystalline cellulose (CMC) with subsequent pH adjustment and surface modification with the cationic surfactant cetyl trimethyl ammonium bromide (CTAB), aiming to dry the CNC and rehydrate them in water. The influence of dialysis procedure, pH range, surface modification and drying technique on colloidal stability and particle size distribution were studied. Three drying techniques were studied: (1) oven drying, (2) drying by lyophilization and (3) spray drying. The oven drying process showed the formation of indissoluble agglomerates preventing the redispersion of CNC, in this technique the effect of the pH adjustment was evaluated, and it was observed that for acidic pH conditions the degradation of CNC occurs. On drying by lyophilization it was possible to redisperse the CNC in water, but it was not possible to obtain a stable dry material, as water desorption occurred. It was also observed that for larger additions of the counterion +, better particle size distribution results were obtained for the redispersed suspensions. The influence of the surfactant on redispersion was tested in the spray drying drying technique. The adsorption of the cationic surfactant to the surface of the CNC was confirmed by the Fourier transform infrared spectroscopy (FTIR) technique. It has been shown that with the addition of 1% surfactant to the CNC suspensions it is possible to redisperse them obtaining characteristics very close to those of the suspensions prior to the drying process, however, loss of colloidal stability has been observed for some samples after redispersion. Scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and rheological analysis were used to characterize the material obtained by spray drying, which was determined as the most suitable drying technique. The particles were presented with a spherical morphology and with the formation of agglomerates. High crystallinity indexes were obtained for samples with adsorption of CTAB surfactant, but with low thermal stability. The kinematic viscosity assessment indicated a pseudoplastic behavior for the CNC suspensions and an increase in the viscosity of the samples after drying and redispersion indicated the formation of agglomerates.

Fresh Pueraria Lobata (kudzu) leaves were evaluated by sensory descriptive analysis. Covariate analysis determined the effects of leaf size and time on 32 sensory variables. Best fit polynomial regressions over time were determined for responses affected. Correlation analyses were executed on attributes in each of the sensory groupings with those variables which were significantly affected by time. Sensory properties of dried kudzu leaves were compared by using three different drying techniques: Convection oven, vacuum and food dehydrator. Covariate analysis determined the effects of leaf size, days, dryers and their interaction on 44 sensory variables. The fitted response regressions were determined for the significant attributes by size and time. Correlation analyses were executed on attributes. The effects of storage (0-42 days) on sensory characteristics of conventional milk yogurt with kudzu and corn starches were evaluated to determine relationships of desirable sensory characteristics. Covariate analysis determined the effects of day, starch type, dose and their interactions on 52 sensory variables. Time and starch interaction were significant (P?0.05) for two sensory responses (starchy/flavor and denseness/texture hand-held). Forty three sensory responses had a time response while 11 variables were affected by starch. The sensory variables affected by time were: 15 of 17 aroma, 13 of 17 flavor, six of eight appearance and six of six basic taste(s) and texture hand-held attributes. Best fit polynomial regressions over time were determined for responses affected. Correlation analyses of the sensory groupings included those significantly affected by time. Response surface methodology was applied to determine starch and dose effect on yogurt products. Furthermore, titratable acidity (TA) and viscosity measurements of yogurt with kudzu/corn starch were evaluated to show interactions between day, dose and starch. No significant (P>0.05) response for pH regarding starch type, starch dose and time. Analyses of variance of attribute ratings for the TA of yogurt showed no significant (P>0.05) differences between starches. Unstirred yogurt viscosity had no significant (P>0.05) response over time for both kudzu and corn starch. Stirred yogurt viscosity had responses to day, dose and starch. In addition, scanning electron microscopy study revealed a difference in microstructure of starch in yogurt by time.

<p>Istraživanja u okviru ove disertacije obuhvataju ispitivanje fizičkih, hemijskih i biolo&scaron;kih osobina svežeg i osu&scaron;enog ko&scaron;tičavog voća i razvoj inovativnog tehničkog re&scaron;enja su&scaron;enja voća u vakuumu. Dobijeni rezultati istraživanja daju doprinos formiranju baze naučnih znanja u vezi sa karakteristikama ko&scaron;tičavog voća osu&scaron;enog različitim tehnikama su&scaron;enja: konvektivnim su&scaron;enjem, vakuum su&scaron;enjem i liofilizacijom (su&scaron;enjem zamrzavanjem). Projektovan inovativni prototip vakuum su&scaron;are sa ejektorskim sistemom omogućava očuvanje biolo&scaron;ki aktivnih komponenata voća uz mogućnost smanjenja investicionih tro&scaron;kova i tro&scaron;kova održavanja opreme. Takođe je uspe&scaron;no prikazana mogućnost primene analize glavnih komponenata (eng. Principal Component Analysis, PCA), ve&scaron;tačke neuronske mreže (eng. Artificial Neural Networks, ANN) i matematičkog modelovanja za opisivanje funkcionalne zavisnosti primenjenih parametara su&scaron;enja i fizičkih, hemijskih i biolo&scaron;kih osobina osu&scaron;enog voća, optimizaciju procesa su&scaron;enja, kao i za pronalaženje modela koji najbolje opisuje proces su&scaron;enja.</p> / <p>Research in the framework of the thesis includes investigation of physical, chemical and biological properties of fresh and dried stone fruit and the development of an innovative technical solution for fruit vacuum drying. The obtained results contribute to the formation of the scientific base of knowledge, regarding the characteristics of stone fruit dried by different drying techniques: convective drying, vacuum drying and lyophilization (freeze drying). The designed innovative prototype of a vacuum dryer with an ejector system enables the preservation of biologically active fruit compounds with the possibility of reducing investment and equipment maintenance costs.<br />The possibility of application of Principal Component Analysis (PCA), Artificial Neural Networks (ANN) and mathematical modeling for describing the functional dependence between applied drying parameters and physical, chemical and biological properties of dried fruit, optimization of the drying process, as well for finding the model that best describes the drying process was presented in this work.</p>