Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Victoria University (Melbourne, Vic.), 2009. / Includes bibliographical references.

Thesis (MSc Food Sc)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: Maas is a traditional fermented milk drink of the indigenous people of Southern Africa and can thus be used to uplift the nutritional status of the South African population, especially for the lower income groups. Furthermore, the problem of lactose intolerance among the Black population can also be addressed by the consumption of Maas. The objective of this study was to screen mesophylic lactic acid bacterial strains (25 in total) from the University of Stellenbosch Food Science Culture Collection for suitable metabolite production and then to produce traditional Maas with a starter culture combination that produces a distinctive acid and traditional flavour. The representative 25 single lactic acid starter strains were identified as Lactococcus lactis subsp. leetis biovar diacetylactis (12 strains), L. leetis subsp. leetis (four strains) and L. leetis subsp. cremoris (nine strains). These strains were inoculated into pasteurised full cream milk and activated for 8 h at 22°C. Pasteurised full cream milk was then inoculated with each of the activated starter strains, incubated at 22°C for 16 h and assessed for acid production abilities (pH = 4.6) under controlled time-temperature conditions. The results of this study showed that nine of the single strains, L. lactis subsp. leetis biovar diacetylactis (S1, S2, S3 and S5), L. teetis subsp. lactis (S13, S15 and S16) and two L. leetis subsp. cremoris strains (S17 and S22), produced sufficient acid, rendering them suitable for the use as starters in the production of traditional Maas. A pH range of 4.3 - 5.1 was reached by the nine single strains after 16 h at 22°C. Two-strain starter combinations were then formed by combining the most suitable single L. leetis subsp. leetis biovar diacetylactis, L. lactis subsp. lactis and L. lactis subsp. cremoris strains, respectively. From the data, it was concluded that acceptable Maas could be produced with four two-strain combinations (S3S 17, S3S22, S5S17 and S5S22). This selection was again based on suitable acid and metabolite production, as well as on sensory evaluation of the final product. These four two-strain combinations produced sufficient acid to reach a pH in the 4.6 - 4.8 range, and showed a high metabolite concentration for the most suitable compounds and formed a thick, smooth and creamy body texture after 16 h at 22°C. Three-strain combinations formed between the two-strain starter combinations and L. leetis subsp. teetis strains (813, 815 and 816), were also evaluated. With these combinations a lack of a pronounced Maas flavour was found. Thus, it was decided to add aroma producing strains of the species Leuconostoc mesenteroides subsp. dextranicum (strain L1) and L. mesenteroides subsp. citrovorum (strain L2) to the three-strain combinations. Four culture combinations (A, B, C and D) were then formed by combining the selected Leuconostoc strains (L1 and L2) with the most suitable Lactococcus strains (83,817,813 and 822). These combinations produced sufficient acid to reach the pH 4.5 - 4.6 range after 14 h at 22°C. Acetaldehyde was the major flavour metabolite formed in the Maas made with these four combinations, with concentrations ranging between 26.6 - 89.3 mg.l ̄ ¹, while other flavour metabolites (ethanol, acetone, diacetyl and 2-butanone) were present at lower concentrations. It was found that three of the four culture combinations (A, C and D) were characterised by a superior, but delicate flavour and a typical characteristic Maas body texture. Fruit flavoured Maas was subsequently prepared with the three most suitable culture combinations (A, C and D) using 11 flavours and a sensory evaluation performed. The statistically evaluated data showed that the appearance, smoothness, flavour intensity, sweetness and overall acceptability were influenced by the type of fruit flavour and the culture combination. Fruit flavour 4 (banana) was the most preferred flavour. The sensory panellists also indicated that the culture combination C gave the best overall acceptability over a three week study period. Data on the shelf-life study of natural unflavoured Maas, prepared with the three culture combinations (A, C and D), showed that the Maas still had an acceptable appearance, taste and good microbiological quality after 15 d at refrigerated temperatures. / AFRIKAANSE OPSOMMING: Maas is 'n tradisionele gefermenteerde melkdrankie onder die inheemse bevolking van Suid-Afrika en kan gebruik word om die voedingstatus van die Suid-Afrikaanse bevolking te verhoog, veral vir die laer inkomste groepe. Bowendien, kan die probleem van laktose intoleransie onder die Swart gemeenskap ook aangespreek word deur die verbruik van Maas. Die doel van hierdie studie was om enkelstam mesofiliese melksuur bakterieë (25 in totaal) van die Universiteit van Stellenbosch Voedselwetenskap Kultuur Versameling te ondersoek vir geskikte metaboliet produksie en tradisionele Maas met 'n kenmerkende suurheid en tradisionele geur met 'n geskikte kultuur kombinasie te produseer. Die toonaangewende 25 enkelstamme is Lactococcus lactis subsp. leetis biovar diacetylactis (12 stamme), L. lactis subsp. lactis (vier stamme) en L. lactis subsp. cremoris (nege stamme). Hierdie stamme was in gepasteuriseerde volroom melk geïnokuleer en geaktiveer vir 8 h teen 22°C. 'n Inokulum van die onderskeie geaktiveerde stamme is hierna in gepasteuriseerde volroom melk geplaas, vir 16 h teen 22°C geïnkubeer en hul vermoë om suur te produseer (pH = 4.6) onder beheerde tyd-temperatuur kondisies is bepaal. Die resultaat van die studie het aangedui dat nege enkelstamme, naamlik L. leetis subsp. lactis biovar diacetylactis (S1, S2, S3 en S5), L. lactis subsp. leetis (S13, S15 en S16) en twee L. leetis subsp. cremoris (S 17 en S22), geskikte suurheidsvlakke vir die produksie van Maas bereik het. 'n pH vlak van 4.3 - 5.1 is na 16 h teen 22°C deur hierdie nege enkelstamme bereik. Twee-stam kombinasies is onderskeidelik gevorm tussen die geskikte enkel L. lactis subsp lactis biovar diacetylactis, L. lactis subsp. lactis en L. lactis subsp. cremoris stamme. Die gevolgtrekking gemaak uit die data, is dat aanvaarbare Maas voorberei kan word met vier van die twee-stam kombinasies (S3S17, S3S22, S5S17 en S5S22) op grond van suurvorming, metaboliet produksie en sensoriese evaluasie. Hierdie vier kombinasies het genoegsame suur geproduseer om 'n pH vlak van 4.6 - 4.8 bereik, hoë metaboliet konsentrasies geproduseer en 'n dik, gladde en romerige tekstuur aangeneem na 16 h teen 22°C. Drie-stam kombinasies is gevorm tussen die onderskeie twee-stam kombinasies en L. lactis subsp. lactis stamme (813,815 en 816) en ook geëvalueer. Die tekort aan 'n skerp Maas geur in die drie-stam kombinasies het daartoe gelei dat Leuconostoc mesenteroides subsp. dextranicum (stam L1) en L. mesenteroides subsp. citrovorum (stam L2) bygevoeg is. Vier kultuur kombinasies (A, B, C en D) is gevorm deur die geselekteerde Leuconostoc stamme (L1 en L2) te kombineer met die mees gepaste Lactococcus stamme (83, 817, 813 en 822). Hierdie kombinasies het genoegsame suur geproduseer wat 'n pH vlak van 4.5 - 4.6 na 14 h teen 22°C bereik het. In die Maas wat met bovermelde kombinasies gemaak is, was die asetaldehied die mees geproduseerde geur metaboliet teen konsentrasies van 26.6 - 89.3 mg.l ̄ ¹. Ander geur metaboliete (etanol, asetoon, diasetiel, 2-butanoon) is in laer konsentrasies geproduseer. Daar is gevind dat drie uit die vier kultuur kombinasies (A, C en D) 'n superieur, delikate geur wat 'n tipies karakteristiek van die Maas gehad het. Vrugte gegeurde Maas geproduseer met die drie kultuur kombinasies (A, C en D) deur 11 geursels te gebruik, is sensories geëvalueer. Die statistiese geëvalueerde data het getoon dat die voorkoms, gladheid, geur intensiteit, soetheid en die algehele aanvaarbaarheid beïnvloed is deur die tipe vrugte geursels en die kultuur kombinasies. Die vrugte geursel 4 (piesang) het voorkeur geniet. Die sensoriese paneellede het ook aangedui dat kultuur kombinasie C die algehele mees aanvaarbare Maas geproduseer het oor die studie periode van drie weke. Data van die rakleeftyd van die natuurlike ongegeurde Maas wat geproduseer is met die drie kultuur kombinasies (A, C en D) het aangedui dat die Maas na 15 d by yskas temperatuur steeds 'n aanvaarbare voorkoms, smaak en goeie mikrobiologiese kwaliteit gehad het.

O objetivo deste trabalho foi desenvolver uma bebida láctea fermentada preparada com 60% de leite, 32% de soro lácteo e 8% de açúcar, utilizando micro-organismos probióticos. Foram desenvolvidas 3 formulações, com 1% (A), 3% (B) e 5% de semente de chia (Salvia hispanica L.). Foram realizadas análises físico-químicas na formulação padrão e nas formulações A, B e C durante 0, 7 e 14 dias; análise sensorial nas formulações A, B, e C nos tempos 0, 7 e 14 dias e avaliação microbiológica. O teor de umidade nas 3 formulações apresentou diferença significativa aos 0 e 7 dias de estocagem (p < 0,05). Os teores de cinzas, proteínas, lipídeos e a viscosidade da bebida aumentaram significativamente à medida que se aumentou a proporção de chia na bebida. Foi observada uma redução gradativa do pH e aumento da acidez titulável em função do tempo de estocagem da bebida. A bebida láctea obteve boa aceitação sensorial, mas foi observada uma diminuição nas notas da escala hedônica e intenção de consumo durante o período de estocagem. A contagem de bactérias probióticas teve redução de aproximadamente 1 ciclo logarítmico por semana. A formulação preferida no teste de ordenação de preferência foi a formulação A. / The aim of this study was to develop a fermented dairy beverage made with 60% milk, 32% whey and 8% sugar, using probiotic microorganisms. Three formulations, with 1% (A), 3% (B) and 5% chia seed (Salvia hispanica L.) have been developed. Physico-chemical analyzes on standard formulation and the formulations A, B and C for 0, 7 and 14 days were made; sensory analysis in formulations A, B, and C for times 0, 7 and 14 days and microbiological evaluation The moisture content of the three formulations showed a significant difference at 0 and 7 days of storage (p <0.05). Contents of ash, protein, lipids and viscosity increased significantly as it increased the proportion of chia. A gradual reduction of pH and increase in acidity due to the storage time of the beverage was observed. The product has obtained good acceptability, but a decrease was observed in the global acceptability and intention of consumption during the storage period. The probiotic bacteria count was reduced by about 1 log cycle per week. The preferred formulation of the ranking preference test was the formulation A.

Made available in DSpace on 2014-12-02T11:16:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-10-07Bitstream added on 2014-12-02T11:21:32Z : No. of bitstreams: 1 000793449.pdf: 1774627 bytes, checksum: f954bbd302ea6c81ed822df1b34b08b2 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Durante a estocagem de leites fermentados, as bactérias probióticas devem manter-se viáveis, para que resultem em benefício para a saúde do consumidor. A composição da cultura lática utilizada para a fermentação e os ingredientes adicionados ao leite influenciam a viabilidade dos probióticos durante a estocagem refrigerada. Além disso, é importante que os probióticos sobrevivam às condições adversas encontradas durante a passagem pelo trato gastrointestinal (TGI). A presença de medicamentos de diferentes tipos no TGI também pode suprimir ou reduzir o efeito terapêutico dos micro-organismos probióticos. O principal objetivo desse trabalho foi avaliar o efeito da composição da cultura e de diferentes matrizes na qualidade tecnológica de leite fermentado e o efeito de medicamentos comerciais sobre a sobrevivência dos probióticos. Para melhor distribuição e realização dos experimentos, o trabalho foi dividido em quatro partes. Na primeira parte foi estudado o efeito da composição da cultura lática durante a fermentação, por meio da produção de ácidos orgânicos, consumo de lactose e cinética de acidificação, e durante a estocagem de leites fermentados, avaliando-se o pH, sinérese, viabilidade dos micro-organismos (S. thermophilus, Lactobacillus acidophilus e Bifidobacterium animalis subsp. lactis), sobrevivência dos probióticos às condições simuladas do TGI, características sensoriais dos produtos e concentração dos ácidos orgânicos. As bactérias que produziram a maior quantidade de ácido lático foram as homofermentativas S. thermophilus e L. acidophilus. Os produtos fermentados contendo B. animalis subsp. lactis apresentaram os maiores teores de ácido acético ao final da fermentação. Apenas L. acidophilus foi capaz de metabolizar o citrato, enquanto os teores de piruvato aumentaram ligeiramente durante a fermentação. A cinética de fermentação foi influenciada pela composição da ... / During storage of fermented milk, probiotic bacteria must retain their viability in order to promote health benefits to the consumer. The composition of the culture used during fermentation and the ingredients added to milk can influence the viability of probiotics during refrigerated storage. Furthermore, it is important that probiotics survive to the harsh conditions during the passage through the gastrointestinal tract (GIT). The presence of different drugs in the GIT can also suppress or reduce the therapeutic effect of probiotic microorganisms. The main objective of this study was to evaluate the effect of the composition of the culture and different matrices on the quality of fermented milk and the effect of medications on the survival of commercial probiotics strains. The work was divided in four parts for better distribution and execution of experiments. In the first part, it was studied the effect of the composition of culture during fermentation through the production of organic acids, lactose consumption and kinetics of acidification and during storage, evaluating the pH, syneresis, viability of microorganisms (S. thermophilus , Lactobacillus acidophilus and Bifidobacterium animalis subsp.), survival of probiotics against simulated GIT conditions, sensory characteristics and concentration of the organic acids. The bacteria that produced the largest amount of lactic acid were the homofermentatives S. thermophilus and L. acidophilus. Fermented products containing B. animalis subsp. lactis showed the highest levels of acetic acid at the end of fermentation. Only L. acidophilus was able to metabolize citrate, while the levels of pyruvate rose slightly during fermentation. The kinetics of acidification was influenced by the composition of lactic acid culture. The higher pH values at the end of storage were obtained for treatments with probiotic cultures. The syneresis reduced during storage and the lowest value was observed in the ... / FAPESP: 09/12808-7

Orientador: Ana Lúcia Barretto Penna / Banca: Mirna Lúcia Gigante / Banca: Graziele Aparecida Chiuchi Garcia / Banca: Kátia Sivieri / Banca: Ana Carolina Conti e Silva / Resumo: Durante a estocagem de leites fermentados, as bactérias probióticas devem manter-se viáveis, para que resultem em benefício para a saúde do consumidor. A composição da cultura lática utilizada para a fermentação e os ingredientes adicionados ao leite influenciam a viabilidade dos probióticos durante a estocagem refrigerada. Além disso, é importante que os probióticos sobrevivam às condições adversas encontradas durante a passagem pelo trato gastrointestinal (TGI). A presença de medicamentos de diferentes tipos no TGI também pode suprimir ou reduzir o efeito terapêutico dos micro-organismos probióticos. O principal objetivo desse trabalho foi avaliar o efeito da composição da cultura e de diferentes matrizes na qualidade tecnológica de leite fermentado e o efeito de medicamentos comerciais sobre a sobrevivência dos probióticos. Para melhor distribuição e realização dos experimentos, o trabalho foi dividido em quatro partes. Na primeira parte foi estudado o efeito da composição da cultura lática durante a fermentação, por meio da produção de ácidos orgânicos, consumo de lactose e cinética de acidificação, e durante a estocagem de leites fermentados, avaliando-se o pH, sinérese, viabilidade dos micro-organismos (S. thermophilus, Lactobacillus acidophilus e Bifidobacterium animalis subsp. lactis), sobrevivência dos probióticos às condições simuladas do TGI, características sensoriais dos produtos e concentração dos ácidos orgânicos. As bactérias que produziram a maior quantidade de ácido lático foram as homofermentativas S. thermophilus e L. acidophilus. Os produtos fermentados contendo B. animalis subsp. lactis apresentaram os maiores teores de ácido acético ao final da fermentação. Apenas L. acidophilus foi capaz de metabolizar o citrato, enquanto os teores de piruvato aumentaram ligeiramente durante a fermentação. A cinética de fermentação foi influenciada pela composição da ... / Abstract: During storage of fermented milk, probiotic bacteria must retain their viability in order to promote health benefits to the consumer. The composition of the culture used during fermentation and the ingredients added to milk can influence the viability of probiotics during refrigerated storage. Furthermore, it is important that probiotics survive to the harsh conditions during the passage through the gastrointestinal tract (GIT). The presence of different drugs in the GIT can also suppress or reduce the therapeutic effect of probiotic microorganisms. The main objective of this study was to evaluate the effect of the composition of the culture and different matrices on the quality of fermented milk and the effect of medications on the survival of commercial probiotics strains. The work was divided in four parts for better distribution and execution of experiments. In the first part, it was studied the effect of the composition of culture during fermentation through the production of organic acids, lactose consumption and kinetics of acidification and during storage, evaluating the pH, syneresis, viability of microorganisms (S. thermophilus , Lactobacillus acidophilus and Bifidobacterium animalis subsp.), survival of probiotics against simulated GIT conditions, sensory characteristics and concentration of the organic acids. The bacteria that produced the largest amount of lactic acid were the homofermentatives S. thermophilus and L. acidophilus. Fermented products containing B. animalis subsp. lactis showed the highest levels of acetic acid at the end of fermentation. Only L. acidophilus was able to metabolize citrate, while the levels of pyruvate rose slightly during fermentation. The kinetics of acidification was influenced by the composition of lactic acid culture. The higher pH values at the end of storage were obtained for treatments with probiotic cultures. The syneresis reduced during storage and the lowest value was observed in the ... / Doutor

CNPq / A crescente procura dos consumidores por alimentos que, além das funções básicas de nutrição, exercem efeitos benéficos à saúde, tem estimulado os pesquisadores e as indústrias alimentícias a desenvolverem produtos lácteos funcionais. Nesta classe, atenção especial tem sido dada ao desenvolvimento de iogurtes com propriedades probióticas e prebióticas, denominados de simbióticos. Inúmeros mecanismos têm sido propostos para tentar explicar os benefícios do consumo dos produtos lácteos simbióticos, dentre eles a capacidade que os micro-organismos probióticos têm de produzir ácido linoleico conjugado. O consumo deste composto tem sido associado a efeitos benéficos à saúde, como propriedades anticarcinogênicas, modulação do sistema imune, diminuição da aterosclerose, entre outros. O presente trabalho teve por objetivo geral a produção e caracterização de um iogurte simbiótico sabor banana obtido a partir dos leites de cabra e de vaca, das culturas probióticas Lactobacillus acidophilus e Bifidobacterium animalis subps lactis Bb-12 e polpa de banana verde como fonte de amido resistente. Para atingir este objetivo, as seguintes etapas foram realizadas: revisão bibliográfica sobre ácido linoleico conjugado, por serem o leite e seus derivados as principais fontes destes ácidos graxos; análise da composição centesimal e das propriedades físico-químicas do leite de vaca, do leite de cabra, da banana verde, da polpa de banana verde e dos iogurtes produzidos; verificação da viabilidade dos diferentes tratamentos de iogurte como carreadores de micro-organismo probiótico através da enumeração de Lactobacillus acidophilus e de Bifidobacterium animalis subps lactis Bb-12 durante a vida útil dos produtos (tempo 0, 15, 30 e 45 dias); quantificação dos micro-organismos Lactobacillus delbruecki subsp. bulgaricus e Streptococcus salivarius subps. thermophilus empregados como cultura iniciadora na elaboração dos iogurtes, durante a vida útil dos produtos (tempo 0, 15, 30 e 45 dias); estudo do perfil de textura (dureza, coesividade, elasticidade e gomosidade) e viscosidade aparente dos diferentes tratamentos de iogurte durante a vida útil (0, 15, 30 e 45 dias) e determinação da cor (parâmetro L* e coordenadas a* e b*) das diferentes formulações de iogurtes durante a vida útil (0, 15, 30 e 45 dias), um estudo de mercado e por fim, análise sensorial dos iogurtes elaborados. As seis formulações de iogurte atenderam às exigências da legislação vigente para as características físico-químicas, para a composição centesimal e para as contagens microbiológicas. Ainda, foram observadas diferenças significativas na composição centesimal, nas propriedades físico-químicas, nos perfis de cor e textura e na análise sensorial dos iogurtes elaborados com leite de vaca daqueles elaborados com leite de cabra. / The growing demand from consumers for foods that beyond basic nutritional functions, exert beneficial health effects has stimulated researchers and the food industry to develop functional dairy products. In this class, special attention has been given to the development of yoghurt with probiotic and prebiotic properties, called symbiotic. Numerous mechanisms have been proposed to explain the benefits of consuming dairy symbiotic products, including the ability of probiotic microorganisms on conjugated linoleic acid production. The use of this compound has been associated with beneficial health effects, such as anticarcinogenic properties, modulation of the immune system, reduction of atherosclerosis, among others. The overall aim of this study was the production and characterization of a symbiotic banana flavored yogurt obtained from cow and goat milk, probiotic cultures Lactobacillus acidophilus and Bifidobacterium animalis subsp lactis Bb-12 and green banana pulp as resistant starch source. To achieve this goal, the following steps were carried out: literature review about conjugated linoleic acid, analysis of the chemical composition and physicochemical properties of cow's milk, goat milk, green banana, green banana pulp and yoghurt produced; checking the viability of the probiotic microorganism Lactobacillus acidophilus and Bifidobacterium animalis subsp lactis Bb-12 by enumeration during the useful life of the products (time 0, 15, 30 and 45 days); quantification of the microorganisms Lactobacillus delbruecki subsp. bulgaricus and Streptococcus salivarius subps. thermophilus as starter culture employed in the preparation of yoghurt during the product lifetime (time 0, 15, 30 and 45 days); profile study of texture (hardness, cohesiveness, elasticity or gumminess) and apparent viscosity of different treatments during yogurt lifetime (0, 15, 30 and 45 days) and determining color (parameter L * and a * b * coordinates) of different formulations of yogurts during the lifetime (0, 15, 30 and 45 days), market study and finally, the sensory analysis of yoghurt prepared. The six yogurt formulations achieved the legal requirements for the physico-chemical properties, for the centesimal composition and for microbiological enumeration. Still, significant differences were observed in the centesimal composition, the physico-chemical properties, color and texture profiles and sensory analysis of yogurt made with cow’s milk from those made with goat’s milk.

CNPq / A crescente procura dos consumidores por alimentos que, além das funções básicas de nutrição, exercem efeitos benéficos à saúde, tem estimulado os pesquisadores e as indústrias alimentícias a desenvolverem produtos lácteos funcionais. Nesta classe, atenção especial tem sido dada ao desenvolvimento de iogurtes com propriedades probióticas e prebióticas, denominados de simbióticos. Inúmeros mecanismos têm sido propostos para tentar explicar os benefícios do consumo dos produtos lácteos simbióticos, dentre eles a capacidade que os micro-organismos probióticos têm de produzir ácido linoleico conjugado. O consumo deste composto tem sido associado a efeitos benéficos à saúde, como propriedades anticarcinogênicas, modulação do sistema imune, diminuição da aterosclerose, entre outros. O presente trabalho teve por objetivo geral a produção e caracterização de um iogurte simbiótico sabor banana obtido a partir dos leites de cabra e de vaca, das culturas probióticas Lactobacillus acidophilus e Bifidobacterium animalis subps lactis Bb-12 e polpa de banana verde como fonte de amido resistente. Para atingir este objetivo, as seguintes etapas foram realizadas: revisão bibliográfica sobre ácido linoleico conjugado, por serem o leite e seus derivados as principais fontes destes ácidos graxos; análise da composição centesimal e das propriedades físico-químicas do leite de vaca, do leite de cabra, da banana verde, da polpa de banana verde e dos iogurtes produzidos; verificação da viabilidade dos diferentes tratamentos de iogurte como carreadores de micro-organismo probiótico através da enumeração de Lactobacillus acidophilus e de Bifidobacterium animalis subps lactis Bb-12 durante a vida útil dos produtos (tempo 0, 15, 30 e 45 dias); quantificação dos micro-organismos Lactobacillus delbruecki subsp. bulgaricus e Streptococcus salivarius subps. thermophilus empregados como cultura iniciadora na elaboração dos iogurtes, durante a vida útil dos produtos (tempo 0, 15, 30 e 45 dias); estudo do perfil de textura (dureza, coesividade, elasticidade e gomosidade) e viscosidade aparente dos diferentes tratamentos de iogurte durante a vida útil (0, 15, 30 e 45 dias) e determinação da cor (parâmetro L* e coordenadas a* e b*) das diferentes formulações de iogurtes durante a vida útil (0, 15, 30 e 45 dias), um estudo de mercado e por fim, análise sensorial dos iogurtes elaborados. As seis formulações de iogurte atenderam às exigências da legislação vigente para as características físico-químicas, para a composição centesimal e para as contagens microbiológicas. Ainda, foram observadas diferenças significativas na composição centesimal, nas propriedades físico-químicas, nos perfis de cor e textura e na análise sensorial dos iogurtes elaborados com leite de vaca daqueles elaborados com leite de cabra. / The growing demand from consumers for foods that beyond basic nutritional functions, exert beneficial health effects has stimulated researchers and the food industry to develop functional dairy products. In this class, special attention has been given to the development of yoghurt with probiotic and prebiotic properties, called symbiotic. Numerous mechanisms have been proposed to explain the benefits of consuming dairy symbiotic products, including the ability of probiotic microorganisms on conjugated linoleic acid production. The use of this compound has been associated with beneficial health effects, such as anticarcinogenic properties, modulation of the immune system, reduction of atherosclerosis, among others. The overall aim of this study was the production and characterization of a symbiotic banana flavored yogurt obtained from cow and goat milk, probiotic cultures Lactobacillus acidophilus and Bifidobacterium animalis subsp lactis Bb-12 and green banana pulp as resistant starch source. To achieve this goal, the following steps were carried out: literature review about conjugated linoleic acid, analysis of the chemical composition and physicochemical properties of cow's milk, goat milk, green banana, green banana pulp and yoghurt produced; checking the viability of the probiotic microorganism Lactobacillus acidophilus and Bifidobacterium animalis subsp lactis Bb-12 by enumeration during the useful life of the products (time 0, 15, 30 and 45 days); quantification of the microorganisms Lactobacillus delbruecki subsp. bulgaricus and Streptococcus salivarius subps. thermophilus as starter culture employed in the preparation of yoghurt during the product lifetime (time 0, 15, 30 and 45 days); profile study of texture (hardness, cohesiveness, elasticity or gumminess) and apparent viscosity of different treatments during yogurt lifetime (0, 15, 30 and 45 days) and determining color (parameter L * and a * b * coordinates) of different formulations of yogurts during the lifetime (0, 15, 30 and 45 days), market study and finally, the sensory analysis of yoghurt prepared. The six yogurt formulations achieved the legal requirements for the physico-chemical properties, for the centesimal composition and for microbiological enumeration. Still, significant differences were observed in the centesimal composition, the physico-chemical properties, color and texture profiles and sensory analysis of yogurt made with cow’s milk from those made with goat’s milk.

Orientador: Salvador Massaguer Roig / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-03T20:56:04Z (GMT). No. of bitstreams: 1 Zacarchenco_PatriciaBlumer_D.pdf: 905521 bytes, checksum: 6d2849e2b69ed715dda0573bad474ece (MD5) Previous issue date: 2004 / Doutorado / Doutor em Tecnologia de Alimentos

Thesis (PhD Food Sc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The fermentation of milk has been known for millennia and leads to nutritious and prolonged shelf-life dairy products. In Southern Africa, traditional fermented dairy products have the same value as local staple foods and are consumed as a part of or as a whole meal. However, the retail price and the technology make many commercialised fermented dairy products unaffordable to the majority of the population. There is thus a need for a healthy nutritious low-cost easily prepared fermented dairy product. A product that could be the answer to the above need, is Kefir. The principle advantage is that the Kefir beverage is made from reusable Kefir grains, which unfortunately are not easily available and grow slowly. Kefir grains can only be obtained from pre-existing grains, which presents a problem in the marketing of the grains. A mass culturing technique was developed to produce large masses of grains but preparation of Kefir using these grains results in a product (MG Kefir) lacking in the sensory attributes of Traditional Kefir. Thus, the overall objective of this research was to determine the impact of environmental factors on the metabolic profiles of Kefir produced using different Kefir grains and this was then followed by the subsequent enrichment of Kefir prepared with mass cultured grains so as to obtain a Kefir beverage that has improved organoleptic qualities. To determine the impact of environmental factors Traditional and MG Kefir were prepared under controlled and uncontrolled conditions. Traditional Kefir was found to give the best beverage and was thus considered as the control. Under controlled conditions the optimum incubation temperature for the production of Kefir was 22ºC as over-acidification was observed at 25ºC. The metabolic profiles of both Traditional and MG Kefir showed that both contained acetaldehyde, ethanol, acetone, diacetyl and acetic acid. In addition, the metabolic profiles revealed that an inadequate ratio of diacetyl to acetaldehyde as well as the lack of ethyl acetate was responsible for the flavour defect in MG Kefir. In order to overcome this defect, citrate and ascorbate (0.015 % w.v-1) were added during Kefir fermentation to enhance the diacetyl and ethyl acetate production. This addition showed a positive impact on diacetyl but not on ethyl acetate production. Improvement of the overall flavour of Kefir was observed as the ratios of diacetyl to acetaldehyde were higher (0.21 – 0.5) in the samples with added citrate and ascorbate than in the samples without (0.12 – 0.17). The production of ethyl acetate in MG Kefir was enhanced by combining the effects of longer incubation (24 h + 18 h at 22ºC), addition of ethanol and acetic acid at 0.79% (m.v-1) and the addition of either Lactococcus lactis ssp. diacetylactis biovar diacetylactis 318 or Candida kefyr 1283. The best yields were obtained in samples containing C. kefyr 1283 and only added ethanol (9.22 mg.L-1), indicating that ethanol is an important factor in ethyl acetate production by Kefir starter strains and suggesting that the absence of ethyl acetate is an indication that the grains do not contain a yeast capable of producing sufficient ethyl acetate. During this investigation, the impact of ethyl acetate on the organoleptic quality of Kefir during storage at refrigerated and room temperatures were also studied. The results indicated that refrigerated Kefir contained up to 40 mg.L-1 of ethyl acetate and was not found defective and thus ethyl acetate was considered a positive contributor to Kefir flavour. This is of particular interest as ethyl acetate is a potent flavour compound at concentrations below 5 mg.L-1. Improvements of MG Kefir’s flavour were successful and will be of value for commercial Kefir production where the main aim is to optimise the flavour of Kefir. However, stabilising the grain microbial consortium was found to be important as it is responsible, over time, for both stable and acceptable Kefir. Acceptability of Traditional, MG and other Kefirs (Candi-Kefir and Lacto-Kefir) prepared with microbially stabilised MG was evaluated by 85 consumers. Results indicated that pH (r = 0.978; p < 0.05) was a significant driver of liking for flavour, especially for female consumers (r = 0.982; p < 0.05). In addition, three clusters, each characterised by different liking attributes were identified. Cluster I generally disliked all the products whereas slight acidic Kefir such as Candi-Kefir (7.63) and Lacto-Kefir (7.09) were preferred by Cluster III. Cluster II showed preference to Kefir with moderate acidity and high ethanol content. In that regard, Traditional Kefir obtained the best score (7.50) and MG Kefir the lowest score (4.87). The sensory study is of value as it led to the identification of the drivers of consumers liking by the different types of consumers. In the course of this project, near infrared reflectance spectroscopy was developed as a rapid method to estimate lactic and acetic acids, which are the organic acids responsible for acidity in Kefir, as well as pH and titratable acidity (TA). The results showed that the calibration models for lactic acid (RPD = 2.57 – 3.16), pH (RPD = 2.90) and TA (RPD = 2.60) were good for screening purposes (2 < RPD < 3); indicating that these models would show if the concentrations of lactic acid, the pH or the TA varied from the normal range. This study has demonstrated that the flavour of MG Kefir, prepared with enriched grains, was successfully improved and has provided some understanding on the preference liking of Kefir, an unknown fermented dairy product to South African consumers. / AFRIKAANSE OPSOMMING: Die fermentering van melk is al vir millennia bekend en lei tot voedsame suiwelprodukte met 'n verlengde raklewe. In Suidelike Afrika het tradisioneel gefermenteerde suiwelprodukte dieselfde waarde as plaaslike stapelvoedsels en word dit as 'n maaltyd of as deel van 'n maaltyd geëet. Die kleinhandelsprys en tegnologie van kommersieel gefermenteerde suiwelprodukte maak hierdie produkte egter onbekostigbaar vir die grootste deel van die populasie. Daar is dus 'n behoefte aan 'n gesonde, voedsame, goedkoop, maklik-om-te-berei gefermenteerde suiwelproduk. 'n Moontlike produk om aan die bogenoemde te voldoen is Kefir. Die hoof voordeel is dat die Kefir drankie van herbruikbare Kefirkorrels gemaak word, maar ongelukkig is hierdie korrels nie vrylik beskikbaar nie, en vermeerder dit stadig. Kefirkorrels kan net van reeds bestaande korrels verkry word wat problematies is vir die bemarking van hierdie korrels. 'n Massakwekingstegniek is ontwikkel vir die produksie van groot hoeveelhede korrels maar die voorbereiding van Kefir met hierdie korrels lei tot 'n produk (MG Kefir) wat sensories minder aanvaarbaar is as tradisionele Kefir. Die hoofdoel van hierdie navorsing was dus om die invloed van omgewingsfaktore op die metaboliese profiele van Kefir, berei deur gebruik te maak van verskillende Kefirkorrels, te bepaal. Dit is gevolg deur die verryking van Kefir berei van massagekweekte korrels om 'n Kefir drankie met verbeterde organoleptiese kwaliteite te verkry. Tradisionele en MG Kefir is voorberei onder gekontroleerde en ongekontroleerde toestande om die impak van omgewingsfaktore te bepaal. Die beste drankie is van tradisionele Kefir verkry en is dus beskou as die kontrole. Die optimum temperatuur vir die produksie van Kefir onder gekonroleerde toestande is 22ºC aangesien oor-versuring by 25ºC waargeneem is. Die metaboliese profiele van beide tradisionele en MG Kefir het gewys dat beide produkte asetaldehied, etanol, asetoon, diasetiel en asynsuur bevat. Die metaboliese profiele het verder gewys dat 'n onvoldoende diasetiel tot asetaldehied verhouding sowel as 'n tekort aan etielasetaat verantwoordelik was vir 'n geur defek in MG Kefir. Om hierdie defek te oorkom is sitraat en askorbaat (0.015% m.v-1) tydens Kefir fermentasie bygevoeg om diasetiel en etielasetaat produksie te verhoog. Hierdie byvoeging het 'n positiewe effek gehad op diasetiel produksie, maar nie op die produksie etielasetaat nie. 'n Verbetering in die algehele geur van Kefir is waargeneem aangesien die diasetiel tot asetaldehied verhoudings hoër (0.21 – 0.5) was in die monsters met bygevoegde sitraat en askorbaat as in die monsters daarsonder (0.12 – 0.17). Die produksie van etielasetaat in MG Kefir is verhoog deur die effekte van 'n verlengde inkubasie tydperk (24 h + 18 h by 22ºC), die byvoeging van etanol en asynsuur teen 0.79% (m.v-1) en die byvoeging van óf Lactococcus lactis ssp. diacetylactis biovar diacetylactis 318 óf Candida kefyr 1283 te kombineer. Die beste opbrengs is verkry in monsters wat C. kefyr 1283 en slegs etanol (9.22 mg.L-1) bevat het. Dit dui daarop dat etanol 'n belangrike faktor is vir etielasetaat produksie in Kefir beginstamme en wys moontlik op die afwesigheid van etielasetaat wat daarop dui dat die korrels nie 'n gis bevat wat bevoeg is om genoegsame hoeveelhede etielasetaat te produseer nie. Tydens hierdie ondersoek is die impak van etielasetaat op die organoleptiese kwaliteit van Kefir gedurende opberging by verkoelde- en kamertemperatuur ook bestudeer. Die resultate het gewys dat verkoelde Kefir tot 40 mg.L-1 etielasetaat bevat het sonder dat dit defektief was. Etielasetaat is dus beskou as 'n positiewe bydraer in terme van Kefir geur. Dit is van besondere belang aangesien etielasetaat 'n sterk geurkomponent teen konsentrasies laer as 5 mg.L-1 is. Verbeteringe in MG Kefir se geur was suksesvol en sal van waarde wees vir kommersiële Kefir produksie waar die hoofdoel die optimisering van Kefir geur is. Stabilisering van die korrels se mikrobiologiese konsortium is ook belangrik aangesien daar gevind is dat dit oor tyd verantwoordelik is vir stabiele en aanvaarbare Kefir. Die aanvaarbaarheid van tradisioneel, MG en ander Kefirs (Candi-Kefir en Lacto-Kefir), voorberei van mikrobiologies gestabiliseerde MG, is deur 85 verbruikers geëvalueer. Die resultate het aangedui dat pH (r = 0.978; p < 0.05) 'n belangrike faktor is in die bepaling van verbruikers se voorkeur van geur is, veral by vroulike verbruikers (r = 0.978; p < 0.05). Drie groepe, elk gekenmerk deur verskillende voorkeur en aanvaarbaarheid eienskappe, is verder geïdentifiseer. Groep I het oor die algemeen van geen van die produkte gehou nie en Groep III het die effense suur Kefirs soos Candi-Kefir (7.63) en Lacto-Kefir (7.09) verkies. Groep II het die Kefir met 'n matige suurheid en hoë etanolinhoud verkies. Tradisionele Kefir het die hoogste telling (7.50) en MG Kefir die laagste telling (4.78) behaal. Die sensoriese studie is van waarde aangesien dit gelei het tot die identifisering van die drywers van verbruikersvoorkeure deur die verskillende tipes verbruikers. Tydens hierdie projek is 'n naby-infrarooi reflektansie spektroskopiese metode ontwikkel vir die vinnige skatting van melk- en asynsuur, die organise sure wat verantwoordelik is vir die suurheid van Kefir, asook die pH en titreerbare suurheid (TS). Die resultate het getoon dat die kalibrasiemodelle vir melksuur (RPD = 2.57 – 3.16), pH (RPD = 2.90) en TS (RPD = 2.60) voldoende was vir siftingsdoeleindes (2 < RPD < 3). Dit dui daarop dat hierdie modelle sal aandui wanneer die konsentrasie van melksuur, pH of TS afwissel van die normale reeks. Hierdie studie het gewys dat die geur van MG Kefir, berei van verrykte korrels, suksesvol verbeter is en het ook gelei tot insigte in die voorkeur van aanvaarbaarheid van Kefir, 'n onbekende gefermenteerde suiwelproduk vir Suid-Afrikaanse verbruikers.