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Lab-scale optimisation of Kefir beverage production from mass-cultured and freeze-dried kefir grainsLatsky, Anneline 12 1900 (has links)
Thesis (MSc Food Sc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Kefir is a fermented dairy beverage resulting from the fermentation of milk with
reusable Kefir grains. The grains consist of a complex combination of lactic acid
bacteria and yeasts in a symbiotic relationship, embedded in a polysaccharide
matrix called kefiran. Various problems are experienced during the
commercialisation of the ready-made Kefir beverage and, therefore, it is more
advantageous to market the grains, enabling the consumer to produce the
beverage at home. Kefir grains could be mass-cultured and then preserved by
Iyohilisation for successful long-term storage and easy distribution, during
commercialisation. The microbial balance of the Kefir grains changes during both
mass-culturing and freeze-drying, which will have an influence on the sensory
properties of the Kefir beverage produced. The aim of this study was the
optimisation of the production of Kefir from mass-cultured grains and from freezedried
mass-cultured grains respectively. The sensory characteristics of the
fermented beverages produced from these mass-cultured and preserved grains
were determined.
Mass-cultured Kefir grains were activated and Kefir produced using nine
methods with different activation times and temperatures, different grain:milk ratios
(36, 72 and 108 g grains.l⁻¹) and with different heat-treated milks (pasteurised,
double pasteerised and UHT). The best Kefir beverage was produced by
activation of the grains at 22°C for two successive 24 h incubation periods,
followed by Kefir production at 22°C for 18 h and a maturation period at 18°C for 6
h. The milk was replaced before every incubation period, excluding the maturation
period, and the fermentation vessel was swirled five times at the start of
fermentation and after 18 h. This method resulted in a sour beverage with a thick
consistency and the characteristic effervescence and flavour of Kefir. The optimal
grain:milk ratio was identified as 36 g grains.l⁻¹ and the best heat-treated milks for
the production of Kefir beverage were UHT and double pasteurised milk.
Mass-cultured Kefir grains were freeze-dried for 1, 2, 3 and 6 d and the
moisture loss determined. Freeze-dried grains were rehydrated for 1, 2, 6, 12 and
18 h to determine the optimal rehydration time. A sensory analysis was performed
to compare the properties of Kefir produced from mass-cultured grains (Me),
freeze-dried mass-cultured grains that were rehydrated and activated (FDRA) and activated mass-cultured grains that were freeze-dried and rehydrated (AFDR).
The chemical compositions of mass-cultured grains (MC), mass-cultured, freezedried
grains (MCFD), mass-cultured, freeze-dried grains that were rehydrated and
activated (FDRA) and activated mass-cultured grains that were freeze-dried and
rehydrated (AFDR), were also investigated. The optimum time to freeze-dry grains
was 2 d and to rehydrate freeze-dried gtains was 1 h. The sensory analysis
indicated that Kefir beverages prepared from FDRA and AFDR grains did not differ
significantly and were less fermented than Kefir produced from MC grains.
It was concluded that Kefir with excellent sensory characteristics can be
produced from mass-cultured grains. Freeze-drying is a better method to preserve
Kefir grains than freezing due to mass loss during freezing and easier distribution
and storage of freeze-dried grains. The supplementation of freeze-dried grains
with additional lactic acid bacteria and yeast isolates should be investigated. / AFRIKAANSE OPSOMMING: Kefir is 'n gefermenteerde suiwelproduk wat geproduseer word deur die
fermentasie van melk met herbruikbare Kefirkorrels. Die korrels bestaan uit 'n
komplekse kombinasie van melksuurbakterië en giste en is ingebed in 'n
polisakkaried matriks genaamd kefiran. Verskeie probleme word ondervind met
die kommersialisering van die klaar voorbereide Kefirdrankie en dit is meer
voordelig om die korrels te bemark. Dit sal die verbruiker daartoe in staat stel om
self Kefir tuis te produseer. Kefirkorrels kan in massa gekweek word en dan
gevriesdroog word om langtermyn storing en verspreiding te vergemaklik tydens
kommersialisering. Die spesifieke mikrobiese balans van die Kefirkorrels word
tydens massakweking en vriesdroging versteur. Dus sal hierdie twee prosesse 'n
invloed hê op die sensoriese eienskappe van die Kefir drankie geproduseer. Die
doel van hierdie studie was die optimisering van die produksie van Kefir vanaf
massagekweekte korrels en gevriesdroogde massagekweekte korrels. Die
sensoriese karakteristieke van die Kefir geproduseer met hierdie korrels is
ondersoek.
Massagekweekte Kefirkorrels is geaktifeer en Kefir is geproduseer met
nege verskillende metodes met variasies in die tyd en temperatuur kombinasies,
verskillende korrel:melk verhoudings (36, 72 en 108g korrels.l⁻¹) en verskillende
hittebehandelde melke (gepasteuriseerd, dubbel gepasteuriseer en UHT). Die
beste Kefirdrankie is geproduseer deur die aktivering van die korrels by 22°C vir
twee 24 h inkubasieperiodes, gevolg deur Kefir produksie by 22°C vir 18 uur en 'n
verouderingsperiode by 18°C vir 6 h. Die melk was voor elke inkubasieperiode
vervang, uitsluitende die verouderingsperiode. Die fermentasie houer is vyf maal
gedraai aan die begin van fermentasie en na 12 h. Hierdie metode het gelei tot 'n
drankie wat suur was met 'n dik konsistensie en die karakteristieke vonkeling en
geur van Kefir. Die optimale korrel:melk ratio is geidentifiseer as 36 9 korrels.l⁻¹ en
die verkieslike hittebehandelde melke is dubbel gepasteuriseerde en UHT melk.
Massagekweekte Kefirkorrels was vir 1, 2, 3 en 6 dae gévriesdroog en die
massaverlies is bepaal. Gevriesdroog korrels is gerehidreer vir 1, 2, 6, 12 en 18 h
om die optimale rehidrasietyd te bepaal. 'n Sensoriese analise is uitgevoer om die
eienskappe te vergelyk van Kefir geproduseer van massagekweekte korrels (MC),
gevriesdroogde massagekweekte korrels wat gerehidreer en geaktiveer is (FDRA)
en geaktiveerde massagekweekte korrels wat gevriesdroog en gerehidreed is (AFDR). Die chemiese samestelling van massagekweekte korrels (MC),
massagekweekte, gevriesdroogde korrels (MCFD), massagekweekte,
gevriesdroogde korrels wat gerehidreer en geaktiveer is (FDRA) en geaktiveerde
massagekweekte korrels wat gevriesdroog en gerehidreer is (AFDR), is bepaal.
Die optimum tydperk vir vriesdroging van korrels was 2 d en vir rehidrasie van
gevriesdroogde korrels was 1 h. Die sensoriese analise het aangedui dat Kefir
wat van FDRA en AFDR korrels geproduseer is, nie betekenisvol van mekaar
verskil het nie, maar minder gefennenteerd was as Kefir wat van Me korrels
geproduseer is.
Die gevolgtrekking is gemaak dat 'n Kefirdrankie met uitstekende
eienskappe geproduseer kan word met massagekweekte korrels. Vriesdroging is
'n beter metode as bevriesing om Kefirkorrels te preserveer a.g.v die ver1iesvan
massa tydens bevriesing en die vergemakliking van vervoer en verspreiding van
gevriesdroogde korrels. Die aanvulling van gevriesdroogde korrels met
addisionele melksuurbakterieêen giste moet nog ondersoek word.
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Avaliação da microbiota de grãos de kefir e atividade inibidora da bebida sobre algumas bactérias patogênicas / Evaluation of microbiota of kefir grains and action inhibition of beverage on some pathogenics bacteriunsSantos, João Paulo Victorino 19 November 2008 (has links)
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Previous issue date: 2008-11-19 / A finalidade deste trabalho de pesquisa foi realizar contagem dos diferentes grupos microbianos presentes em grãos de kefir de origens diferentes, verificar suas características de morfologia, identificar isolados de leveduras e avaliar o potencial do soro de kefir esterilizado por filtração em membrana MILIPORE (membrana em éster de celulose, 0,22 μm de poro, 25 mm de diâmetro) em inibir o crescimento de microrganismos patogênicos Staphylococcus aureus (ATCC 6538), Escherichia coli (ATCC11229), Salmonella typhimurium (ATCC 6539), Listeria monocytogenes (ATCC 15313) e Bacillus cereus (RIBO 1222-173-S4). O kefir é um produto lácteo fermentado feito a partir da inoculação de grãos de kefir em leite, ou parte da bebida como cultura inicializadora, resultando em um produto semelhante ao iogurte, porém com características próprias devido, principalmente, à presença de CO 2 e etanol. Sua origem é antiga, estimada em mais de 2.000 anos a.C nas montanhas da região do Cáucaso. Os grãos de kefir avaliados foram obtidos em três diferentes regiões sendo dois do estado de Minas Gerais (Viçosa e Caratinga) e um do estado de São Paulo (São Paulo). As amostras de grãos de kefir 1 (Viçosa), kefir 2 (Caratinga) e kefir 3 (São Paulo), apresentaram distribuição morfológica média em relação à proporção de cocos, bacilos e leveduras de (18%, 59% e 23%) respectivamente. As contagens dos grupos microbianos observadas nas três amostras apresentaram resultados médios em Log UFC.mL -1 para BAA (7,07), Lactobacilos (8,05), Lactococos (4,76), Leuconostoc (8,18) e Leveduras (6,55). A identificação das leveduras isoladas das amostras de grãos de kefir apresentou Cândida kefir, Cândida dubliniensis, Pichia ohmeri e Cândida zeilanoides, com classificação de identificação que variou de boa a excelente utilizando o kit API 20 AUX. Todas as amostras de kefir avaliadas apresentaram redução de no mínimo 30% no crescimento dos patógenos em relação ao controle. As maiores inibições ocorreram para a amostra de kefir (2) para o crescimento de Bacillus cereus (RIBO 1222-173-S4) (86,8%) e Salmonela typhimurium (ATCC 6539) (73,05%) e amostra do kefir (1) para o crescimento de Bacillus cereus (RIBO 1222-173-S4)(72,88%). O patógeno que sofreu maior inibição em relação às três amostras de kefir foi, Bacillus cereus (RIBO 1222-173-S4) apresentando crescimento (76,69%) menor que o controle. A inibição de Staphylococcus aureos (ATCC 6538) nas três amostras avaliadas variou de (42,80% a 69,15%), para o crescimento de Escherichia coli (ATCC 11229) a faixa de inibição foi de (30,73% a 59,89%), sendo este patógeno o que mostrou a maior diferença de inibição em relação às três amostras de kefir, Salmonela typhimurium (ATCC 6539) apresentou faixa de inibição de (44,99% a 73,05%), Listeria monocytogenes (ATCC 15313) de (41,45% a 54,18%) e Bacillus cereus (RIBO 1222- 173-S4) de (70,38% a 86,80%). Essa capacidade de inibição apresentada é interessante porque justifica a sua caracterização como alimento funcional. Alem disso, a técnica utilizada no estudo viabiliza a avaliação da bebida “in vitro”. É a primeira vez que se utiliza o soro de kefir (bebida) esterilizado em membrana para avaliar essa inibição, uma vez que, devido à presença de polissacarídeos na bebida, os testes em placas impedem a difusão para os meios de cultura inviabilizando a avaliação por essa técnica. De acordo com os resultados obtidos nesse trabalho é possível concluir que os grãos de kefir das três diferentes origens avaliadas possuem características microbiológicas diferentes e capacidade antagonística frente a diferentes patógenos variada, refletindo a necessidade de se conhecer mais a respeito dos diversos grãos que existem no Brasil e no mundo. / The purpose of this study was to count different microbial groups in kefir grains of different origins; to verify the morphological characteristics and to identify yeast strains; and evaluate the potential of kefir serum sterilized by membrane filtration through Millipore filter (cellulose ester membrane, pores 0.22 UM, diameter 25 mm) for growth inhibition of the pathogenic microorganisms Staphylococcus aureus (ATCC 6538), Escherichia coli (ATCC11229), Salmonella typhimurium (ATCC 6539), Listeria monocytogenes (ATCC 15313) and Bacillus cereus (RIBO 1222-173-S4). Kefir is a milk product fermented by the inoculation of kefir grains in milk, or of part of the milk as initiating culture, resulting in a yogurt-like product, but with proper characteristics, mainly due to the presence of CO 2 and ethanol. The origin is ancient, estimated at over 2,000 years BC from the mountains of the Caucasus region. Kefir grains from the state of Minas Gerais (Viçosa and Caratinga) and from the state of Sao Paulo (Sao Paulo) were used here. The morphological distribution of the kefir grain samples 1 (Viçosa), 2 (Caratinga) and 3 (Sao Paulo) was average in relation to the proportion of cocci, bacilli and yeasts (18%, 59% and 23%, respectively). The counts of the microbial groups of the three samples showed average performance in Log UFC.mL -1 for BAA (7.07), Lactobacilli (8.05), Lactococci (4.76), Leuconostoc (8.18) and yeasts (6.55). Yeast isolation from the kefir grains samples identified Candida kefir, Candida dubliniensis, Pichia ohmeri and Candida zeylanoides. The yeasts were classified as good to excellent by the kit API 20 AUX. All kefir samples reduced the pathogen growth by at least 30% in comparison to the control. Highest inhibition was observed in sample 2 on the growth of Bacillus cereus (RIBO 1222-173-S4) (86.8%) and Salmonella typhimurium (ATCC 6539) (73.05%) and sample 1 on the growth of Bacillus cereus (RIBO 1222-173-S4). Highest inhibition by the three kefir samples was observed in the pathogen Bacillus cereus (RIBO 1222-173-S4) with a growth reduction of 76.69% compared to the control. The inhibition of Staphylococcus aureos (ATCC 6538) in the three samples ranged from 42.80% to 69.15%, and from 30.73% to 59.89% for Escherichia coli (ATCC 11229), where the growth inhibition range induced by the three kefir samples was greatest. The inhibition range of Salmonella typhimurium (ATCC 6539) was 44.99% to 73.05%, of Listeria monocytogenes ( ATCC 15313) from 41.45% to 54.18% and of Bacillus cereus (RIBO 1222-173-S4) from 70.38% to 86.80%. This inhibition capacity is interesting since it characterizes kefir as functional food. Furthermore, the beverage can be evaluated "in vitro" by the technique used here. It is the first time the kefir serum (beverage) was sterilized in membrane to evaluate this inhibition, since, due to the presence of polysaccharides, the spread of the medium is impeded in plate tests hampering the culture evaluation by this technique. Based on the results of this study it was possible to conclude that the kefir grains from the three different origins have different microbiological characteristics and antagonistic capacity towards different pathogens, which points to the need to learn more about the various grains that exist in Brazil and around the world. / Dissertação antiga, sem ficha catalográfica.
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Efeito do consumo de kefir de leite integral sobre o desenvolvimento de lesões pré-neoplásicas intestinais em ratos Wistar / Effect of milk kefir consumption on the development of pre-preneoplasic intestinal lesions in Wistar ratsReis, Sandra Aparecida dos 16 July 2015 (has links)
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Previous issue date: 2015-07-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A bebida fermentada kefir é produzida a partir da atividade metabólica de bactérias e leveduras que vivem em associação simbiótica nos grãos de kefir. O consumo regular do kefir tem sido associado a uma série de atividades terapêuticas, dentre elas a inibição do desenvolvimento tumoral. Devido às altas taxas de incidência e de mortalidade do câncer colorretal, este estudo teve como principal objetivo avaliar o efeito do consumo regular do kefir de leite integral na redução do desenvolvimento de lesões pré-neoplásicas no cólon de ratos Wistar. Inicialmente, avaliamos a sobrevivência das bactérias do ácido láctico e das leveduras presentes no kefir de leite integral após a simulação in vitro das condições prevalecentes no trato gastrointestinal humano. Posteriormente, trinta ratos Wistar foram divididos em três grupos experimentais. Nas cinco primeiras semanas, fase de pré-indução, os animais do grupo controle foram tratados com 1 mL de água destilada, o grupo leite recebeu 1 mL de leite integral pasteurizado, e o grupo kefir foi tratado com 1 mL de kefir de leite integral, via gavagem diariamente. Ao término desta fase os animais foram submetidos ao protocolo de indução das lesões pré-neoplásicas com 1,2-dimetilhidrazina. Neste momento teve início à fase de pós-indução, a qual teve duração de quinze semanas, onde os animais continuaram recebendo seus respectivos tratamentos. Assim, o experimento teve duração total de vinte semanas. Dados da simulação in vitro demonstraram que as leveduras presentes no kefir de leite integral são mais resistentes às condições prevalecentes no trato gastrointestinal do que as bactérias do ácido láctico. Quanto à atividade anticarcinogênica do kefir, observou- se que o tratamento com o kefir foi capaz de reduzir em 36,7 % a incidência dos focos de cripta aberrante no cólon dos animais tratados em comparação ao controle (p < 0,001). Ainda, o kefir aumentou a atividade da enzima antioxidante catalase (p < 0,001 ) no cólon e a concentração dos ácidos graxos de cadeia curta nas fezes do ceco (p < 0,001), além de reduzir a razão lactulose/manitol (p = 0,020) ao final da fase de pós-indução. Com isto, conclui-se que a atividade anticarcinogênica do kefir de leite integral se deve à redução da permeabilidade intestinal, ao aumento da atividade antioxidante, e ao aumento da produção dos ácidos graxos de cadeia curta. / Kefir is a fermented beverage produced from the metabolic activity of bacteria and yeasts living in symbiotic association in kefir grains. Regular consumption of kefir has been associated with a variety of therapeutic activities among them, the inhibition of tumor development. Due to high rates of incidence and mortality of colorectal cancer, this study aimed to evaluate the effect of regular consumption of whole milk kefir in the risk reduction of the development of preneoplasic lesions in Wistar rats. Initially, we evaluated the survival of lactic acid bacteria and yeasts present in whole milk kefir after in vitro simulation of the conditions prevailing in the human gastrointestinal tract. Subsequently, thirty Wistar rats were divided into three experimental groups. In the first five weeks, the so-called pre-induction phase, the control group was treated with 1 mL of distilled water, the milk group received 1 mL of pasteurized milk and the kefir group was treated with 1 mL of whole milk kefir, administered daily through gavage. At the end of this phase the animals were subjected to the induction protocol of preneoplasic lesions with 1,2-dimethylhydrazine. At this time it began the post-induction phase, fifteen weeks, when the animals continued to receive their treatments. Thus, the experimental lasted twenty weeks. The in vitro simulation data showed that the yeasts present in whole milk kefir are more resistant to the conditions prevailing in the gastrointestinal tract than the lactic acid bacteria. Regarding the anticarcinogenic activity of kefir, it was observed that treatment with kefir was able to reduce by 36.7 % the incidence of aberrant crypt foci in the colon of the treated animals compared to the control (p < 0.001). Furthermore, kefir increased the antioxidant enzyme catalase activity (p < 0.001) in the colon and the concentration of short-chain fatty acids in the feces of the cecum (p = 0.046), while reducing the reason lactulose/mannitol (p = 0.020) at the end of the post-induction phase. Thus, it was concluded that the anticarcinogenic activity of whole milk kefir is due to reduction of intestinal permeability, increased antioxidant activity, and increased production of short chain fatty acids. / Liberação do sigilo autorizada pela Orientadora por e-mail, em 15-08-2016.
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Mitigation of Undesirable Flavor in Kefir Intended for Adjuvant Treatment of <i>Clostridioides difficile</i> InfectionKesler, Megan Kathleen January 2019 (has links)
No description available.
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The inhibitory activity and sensory properties of kefir, targeting the low-income African consumer marketVan Wyk, Juliette 12 1900 (has links)
Thesis (MSc Food Sc )--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The rapid urbanisation of the African population has led to the establishment of large
low-income communities in and around almost every major town and city in South
Africa. Several factors prevent these people from producing or obtaining their
traditional fermented milk drink, Maas (Amasi), often resulting in the occurrence of
malnutrition in low-income urban African communities.
A product with the potential to satisfy the demand for a fermented milk product
is Kefir. Kefir, a self-carbonated fermented milk, is commonly manufactured by
fermenting unpasteurised or pasteurised milk with re-usable Kefir grains. These Kefir
grains consist of a combination of mainly lactic acid bacteria and yeasts. Neither
Kefir, nor Kefir grains are as yet marketed in South Africa, thus creating an excellent
opportunity to launch these products locally.
It is often difficult for the low-income communities to obtain high quality
unpasteurised or pasteurised milk, resulting in a serious health risk. The inhibitory
activity of Kefir towards certain spoilage and pathogenic microorganisms was,
therefore, studied. Strains of Escherichia coli, Staphylococcus aureus, Bacillus
cereus, Usteria monocytogenes and Clostridium tyrobutyricum were inoculated (10 ³ -
10 ⁴ cfu.ml⁻¹ ) into pasteurised milk together with Kefir grains (18 gram per litre) and
incubated at 25°C. Uninoculated milk samples and milk samples inoculated only with
test organisms served as controls. Growth of all the test organisms were inhibited
substantially (>-99.9%) in Kefir over the 30 h incubation period and substantial
reductions in microbial log cycles were observed for many of the organisms. This
coincided with a steep decrease in pH (6.57 - 4.06) and increase in titratabie acidity
(0.20 - 0.72%).
If Kefir is eventually marketed to low-income urban African consumers, it will
have to compete with Maas and, therefore, comparative sensory testing of Kefir and
Maas was conducted. The differences in the sensory properties of Kefir, 'laboratory'
Maas (representing traditional Maas) and commercial Maas (containing thickener,
colourants and flavourants) were determined by a trained panel. These
characteristics were identified as "yeasty" and "cowy" tastes (p < 0.05),
"effervescence" (p < 0.01), as well as "sourness," "creaminess" and "smoothness" (p
< 0.001). The effect of different incubation temperatures (25°, 30° and 35°C) on the Kefir sensory properties was studied to simulate the effect of the large temperature
variations that would be found in the dwellings of low-income African urbanites. The
"sourness" and "creaminess" of the Kefir was found to increase with increase in
incubation temperature but no strong off-flavours were found to develop. Sensory
preference testing was conducted by consumer panels consisting of panellists of
different ages and population groups to indicate whether the specific panels
significantly prefer Kefir, commercial Maas or laboratory Maas. It was found that
commercial Maas was significantly (p < 0.001) preferred to Kefir by young African
urbanites. Adult Africans, who presumably still have traditional taste preferences,
however, equally (p > 0.05) preferred Kefir and laboratory Maas, identifying this
segment of the African population as the appropriate starting target market for Kefir.
Kefir and laboratory Maas were also tested for preference by a wider panel
consisting of people (aged between 18 and 25) representing the different population
groups in South Africa. Kefir and laboratory Maas were preferred equally (p > 0.05)
by all the groups.
Several arguments supporting Kefir marketing to the low-income urban African
population of South Africa have been identified. These include: Kefir's ease of
preparation; the re-usability of Kefir grains and subsequent affordability; good
packaging, distribution and storage possibilities; Kefir's acceptability by lactoseintolerant
individuals; high nutritional value; the inhibitory activity of Kefir against
potential spoilage and pathogenic organisms and subsequent enhanced safety and
keeping ability; and Kefir's acceptable refreshing taste. / AFRIKAANSE OPSOMMING: Die toenemende verstedeliking van Swart Suid-Afrikaners het gelei tot die vestiging
van groot lae-inkomste gemeenskappe in en om die meeste groot dorpe en stede.
Verskeie faktore verhoed dat hierdie gemeenskappe hul tradisionele gefermenteerde
melk, naamlik Maas (Amasi), self kan maak of koop. Dit lei dikwels tot wanvoeding
onder lae-inkomste stedelike Swart verbruikers.
Kefir het die potensiaal om te voorsien in die vraag na 'n gefermenteerde melk
produk in lae inkomste stedelike Swart gemeenskappe. Kefir is 'n selfgekarboneerde,
gefermenteerde melk wat vervaarding word deur die fermentasie
van ongepasteuriseerde of gepasteuriseerde melk met herbruikbare Kefirkorrels.
Hierdie Kefirkorrels bestaan uit 'n kombinasie van hoofsaaklik melksuurbakterieë en
giste. Kefir en Kefirkorrels word glad nie in Suid-Afrika bemark nie, en bied 'n
fantastiese geleentheid om hierdie produkte plaaslik bekend te stel.
Dit is dikwels moeilik om hoë kwaliteit ongepasteuriseerde of
gepasteuriseerde melk in lae-inkomste gemeenskappe te verkry. Die risiko om
siektes deur die verbruik van hierdie melk op te doen, bestaan dus. Om hierdie rede
is die inhiberende effek van Kefir teenoor spesifieke bederf- en patogeniese
bakterieë bestudeer. Rasse van Escherichia coli, Staphylococcus aureus, Bacillus
cereus, Usteria monocytogenes en Clostridium tyrobutyricum is geïnokuleer (10 ³ -
10 ⁴ cfu.ml⁻¹) in gepasteuriseerde melk tesame met Kefirkorrels (18 gram per liter) en
geïnkubeer by 25°C. Melkmonsters wat slegs geïnokuleer is met die
toetsorganismes het as kontroles gedien. Die groei van al die toetsorganismes is
substansieël geïnhibeer (>-99.9%) in Kefir gedurende die 30 h inkubasieperiode.
Substansiële afnames in logsiklusgetalle is waargeneem vir baie van die organismes.
Dit het gepaard gegaan met 'n skerp afname in pH (6.57 - 4.06) en toename in
titreerbare suurheid (0.20 - 0.72%) vir die Kefirmonsters gedurende die 30 h
inkubasieperiode.
lndien Kefir bemark word aan lae-inkomste stedelike Swart verbruikers sal dit
moet kompeteer met Maas. Vergelykende sensoriese toetse is dus uitgevoer. Die
verskille in die sensoriese eienskappe van Kefir, 'laboratorium' Maas
(verteenwoordigend van tradisionele Maas) en kommersiële Maas (wat verdikker,
kleur- en geurmiddels bevat) is bepaal deur 'n opgeleide paneel en geïdentifiseer as die" "gis-" en "koeismake" (p < 0.05), die "gasserigheid" (p < 0.01) asook die
"suurheid", "romerigheid" en "gladheid" (p < 0.001) van die monsters. Die effek van
verskillende inkubasietemperature (25°, 30° en 35°C) op die sensoriese eienskappe
van Kefir is bestudeer om die effek van die groot temperatuurvariasies wat in laeinkomste
behuising mag voorkom, te simuleer. Daar is bevind dat die "suurheid" en
"romerigheid" van Kefir toeneem met verhoging in inkubasietemperatuur terwyl geen
afsmake ontwikkel nie.
Sensoriese voorkeurtoetse is deur verbruikerspanele van verskillende
ouderdomme en bevolkingsgroepe uitgevoer om te bepaal of die spesifieke panele 'n
beduidende voorkeur toon vir Kefir, laboratorium Maas of kommersiële Maas. Daar
is bevind dat stedelike Swart jongmense kommersiële Maas beduidend (p < 0.001)
bo Kefir verkies. Swart volwassenes met verwagte tradisionele smaakvoorkeure het
egter Kefir en laboratorium Maas ewe veel verkies (p > 0.05). Hierdie segment van
die Swart bevolking is dus die geskikte teikenmark vir die bekendstelling van Kefir.
Voorkeur vir Kefir en laboratorium Maas is ook getoets deur 'n paneel (ouderdom 18
- 25 jaar) wat bestaan uit mense van verskillende bevolkingsgroepe. AI die groepe
het Kefir en Maas ewe veel verkies (p > 0.05).
Verskeie argumente ten gunste van die bemarking van Kefir aan lae-inkomste
stedelike Swart gemeenskappe in Suid-Afrika is geïdentifiseer. Dit behels die
volgende: die gerief van Kefirvervaardiging; die herbruikbaarheid van Kefirkorrels en
gevolglike bekostigbaarheid; goeie verpakkings-, verspreidings- en
opbergingsmoontlikhede; Kefir se aanvaarbaarheid vir laktose-intolerante individue;
Kefir se hoë voedingswaarde; die inhiberende aktiwiteit wat Kefir teenoor potensiële
bederf- en patogeniese organismes het en die gevolglike verhoging in veiligheid en
rakleeftyd van melk; en Kefir se aanvaarbare verfrissende smaak.
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CARACTERIZAÇÃO DE MICRO-ORGANISMOS COM POTENCIAL PROBIÓTICO ISOLADOS A PARTIR DE KEFIR PRODUZIDOS NA REGIÃO NOROESTE DO ESTADO DO RIO GRANDE DO SUL / MICRO- ORGANISMS CHARACTERIZATION WITH POTENTIAL PROBIOTIC THE KEFIR PRODUCED IN THE NORTHWEST FROM RIO GRANDE DO SUL STATERibeiro, Alice de Souza 09 March 2015 (has links)
The consumption of functional foods has increased over the years, the awareness of the population to purchase foods that benefit health. Among the main and most functional foods are consumed fermented milk. The kefir is fermented milk that has stood out for its natural functional origin, with significant effects on health when consumed regularly, and despite not being marketed in Brazil is easily found by hand. Thus, the study of this important source functional food has gained ground among researchers, and the aim of this study was to evaluate the physicochemical and microbiological characteristics of the craft of kefir northwest region of Rio Grande do Sul State and the characteristics of probiotic lactic acid bacteria in the product. Eight kefir samples were analyzed produced by hand in the northwest region of of Rio Grande do Sul. The samples were cultured in the laboratory and fermented milk subjected to physical, chemical and microbiological analyzes. The physicochemical analyzes the moisture, ash, fat, total and degreased dry extract, protein, acidity, titratable acidity, pH, water activity and color. In the microbiological evaluation, the samples were subjected to counting of yeasts and molds and analysis the most probable numbers of total and fecal coliforms. We also assessed the potential of probiotic the isolated by BALs antagonistic activity against pathogenic bacteria strains of reference and resistance tests to acidic conditions and bile salts. In this work, we can to observe that the handmade kefir of the study area has similar characteristics between the different samples, both in physicochemical as microbiological parameters, and some isolates have important features in regard to the probiotic potential. However, we suggest further studies, especially in relation to microbiological behavior to assess more parameters to classify this as a functional food. / O consumo de alimentos funcionais tem aumentando no decorrer dos anos, pela conscientização da população em adquirir alimentos que tragam benefícios à saúde. Dentre os principais e mais consumidos alimentos funcionais estão os leites fermentados. O kefir é um leite fermentado que tem se destacado pela sua origem funcional natural, com efeitos significativos sobre a saúde quando consumido regularmente, e apesar de não ser comercializado no Brasil é encontrado facilmente de forma artesanal. Dessa forma, o estudo sobre essa fonte importante de alimentação funcional tem ganhado espaço entre pesquisadores, sendo o objetivo desse trabalho avaliar as características físico-químicas e microbiológicas do kefir artesanal da região noroeste do Estado do Rio Grande do Sul, bem como as características probióticas das bactérias ácido láticas presentes no produto. Foram analisadas oito amostras de kefir produzidos artesanalmente na região noroeste do Estado do Rio Grande do Sul. As amostras coletadas foram cultivadas em laboratório e os leites fermentados submetidos às analises físico-químicas e microbiológicas. Nas análises físico-químicas foram avaliados os teores de umidade, cinzas, gordura, extrato seco total e desengordurado, proteína, acidez titulável, acidez potenciométrica, pH, atividade de água e cor. Na avaliação microbiológica, as amostras foram submetidas a contagem de bolores e leveduras, análise do número mais provável de coliformes totais e termotolerantes e contagem de bactérias láticas (BALs). Também foi avaliado o potencial probiótico dos isolados através da atividade antagônica de BALs em relação a cepas de bactérias patogênicas de referência, além de testes de resistência à condições ácidas e sais biliares. Com a realização deste trabalho, é possível observar que o kefir artesanal da região de estudo tem características semelhantes entre as diferentes amostras, tanto nos parâmetros físico-químicos quanto microbiológicos, além de alguns isolados apresentarem características importantes no que diz respeito ao potencial probiótico. No entanto, sugerem-se mais estudos, especialmente em relação ao comportamento microbiológico para avaliar mais parâmetros que classifique esse alimento como funcional.
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Impact of environmental factors on the metabolic profiles of Kefir produced using different Kefir grains and subsequent enrichment of Kefir prepared with mass cultured grainsNtsame Affane, Armelle Lyvane 03 1900 (has links)
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.
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Estudio de la capacidad de los microorganismos del kefir para inhibir el desarrollo fúngico y para secuestrar micotoxinasLeón Peláez, Ángela María 12 1900 (has links)
Objetivo general
Estudiar la potencialidad de los microorganismos del gránulo de kefir y sus metabolitos para inhibir el desarrollo de hongos filamentosos, toxicogénicos y no toxicogénicos y para secuestrar micotoxinas.
Objetivos específicos
- Estudiar el efecto antifúngico de bacterias, levaduras y productos fermentados con kefir sobre los hongos toxicogénicos y no toxicogénicos.
- Analizar el efecto que ejercen los ácidos orgánicos puros y en mezclas en concentraciones similares a las presentes en los productos fermentados con kefir, en la inhibición del crecimiento de hongos filamentosos toxicogénicos y no toxicogénicos.
- Determinar la capacidad de los microorganismos totales del kefir y de los lactobacilos y las levaduras aislados del gránulo de kefir para capturar aflatoxina AFB1 bajo diferentes condiciones de cultivo.
- Evaluar la aplicación de diferentes microorganismos del kefir en la extensión de la vida útil y en las propiedades sensoriales de arepas de maíz y alimento para pollos.
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Extração enzimática em cascas de uva: processo sustentável para obtenção de corante antociânicoMontibeller, Maria Jara January 2017 (has links)
A cada ano a indústria de vinhos descarta uma alta quantidade de resíduos líquidos e sólidos, constituído em grande parte por bagaço de uva. Este resíduo pode ser considerado um subproduto da indústria e apresenta quantidades significativas de antocianinas, as quais podem apresentar diversas aplicações. Apesar da extração de antocianinas ser um passo importante na recuperação de pigmentos em matrizes vegetais não existe um método de extração padrão na literatura. Dessa forma, existem estudos tanto em relação ao uso de métodos tradicionais quanto emergentes, sendo estes últimos normalmente mais favoráveis ao Meio Ambiente. Neste estudo foi usado o método de extração enzimática, técnica emergente, que se baseia em alterações da parede celular de matrizes alimentares para exposição dos materiais intracelulares. Assim, o objetivo geral do trabalho foi realizar a extração enzimática de antocianinas presentes em casca de uva para posterior aplicação como corante alimentício em quefir e bebida carbonatada. Foram encontrados diferentes temperaturas e porcentagens de preparado enzimático ótimos dependendo do cultivar analisado. Após aperfeiçoamento foi selecionado o uso de casca de Cabernet Sauvignon, a uma temperatura de 40 oC e 0,25 % de Pectinex Ultra Color®. O corante natural produzido foi aplicado em bebida carbonatada e quefir, ambos sob análises de tempo de meia-vida de antocianinas e parâmetros físico-químicos durante 16 dias de armazenagem. Dentre os resultados obtidos foi destacado que o quefir com adição do corante manteve características semelhantes ao encontrado na literatura para quefir natural. Em análises em bebida carbonatada, houve maior estabilidade de antocianinas nas amostras armazenadas sem presença de luz. A aplicação do extrato antociânico foi favorável em ambas matrizes alimentares, sendo recomendado estudos futuros visando o aumento do tempo de meia vida da estabilidade das antocianinas. / Every year, wine industry discards a high amount of liquid and solid waste, consisting largely of grape pomace. This residue can be considered a by-product of the industry and presents significant quantity of anthocyanins, which can provide several applications. Despite the extraction of anthocyanins be an important step on the recovery of pigments in vegetables, there is not a standard extraction method in the literature. In this way, there are studies regarding the use of traditional and emerging methods, which the latter usually being more environmentally friendly. In this study, controlled enzymatic extraction method was used, an emerging technique that is based on alterations of the cell wall of alimentary matrices for exposure of the intracellular materials. Thus, the aim of this study was to perform the enzymatic extraction of anthocyanins present in grape skins for subsequent application as a food dye in kefir and carbonated beverage. Eight different samples of grape pomace were used to improvement the extraction process. Preliminary responses of the study defined that low extraction times are required for the enzymatic extraction process, where the maximum ones being found when the process was conducted for thirty minutes using Pectinex Ultra Color®. In addition, different temperatures and percentages of enzyme preparation were found depending on the variety analyzed. After improvement, the use of Carbenet Sauvignon skin was selected, at a temperature of 40 ° C and 0.25% of enzymatic preparation. The natural dye produced was applied in carbonated beverage and kefir, both under analysis of the half-life of anthocyanins and physical- chemical parameters during 16 days of storage. Among the results obtained, it was pointed out that kefir with dye addition maintained similar characteristics to that found in the literature for natural kefir. In analyzes in carbonated beverage, there was greater stability of anthocyanins when the samples were stored without light. The application of the anthocyanin extract was favorable in both food matrices, and future studies are recommended aiming to increase the half-life of the stability of anthocyanins.
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Survival Of Probiotic Microorganisms During Storage After MarketingKose, Iskin 01 September 2011 (has links) (PDF)
Probiotics are viable microorganisms that show beneficial effects on the health of the host by improving their intestinal microflora. The microorganisms applied as probiotics mainly include Lactobacillus and Bifidobacterium species. Probiotics can inhibit the bacterial pathogens, reduce serum cholesterol levels, improve lactose tolerance and stimulate the immune response. They also have other properties such as / tolerance to acid and bile salts, adherence to gastrointestinal cells for colonization, resistance to antibiotics and &beta / -galactosidase acitivity.
The properties of probiotic products are determined by the characteristics of the microorganisms they contain. For that reason, isolation and characterization of new strains having probiotic properties is an important issue. New strains are generally isolated from their natural habitats which are fermented dairy products such as kefir.
In order to exert beneficial health affects in the digestive system, commercial probiotic products should contain adequate numbers of viable cells. Probiotic microorganisms should protect their viability during their shelf storage. Therefore, the viability of probiotics is especially important for food manufacturers that search for new probiotic strains with good survival and stability properties upon storage.
In this study, probiotic microorganisms were isolated from traditional kefir grains known as a &lsquo / complex probiotic&rsquo / . The isolates were firstly identified using biochemical tests, then the putative species belonging to &lsquo / Lactobacillus acidophilus group&rsquo / were identified with 16S rRNA gene sequencing. Analysis of sequencing resulted in differentiation of &ldquo / L. acidophilus group&rdquo / organisms, namely L. amylovorus and L. acidophilus. Moreover, typing of commercial and traditional L. acidophilus strains and L. amylovorus strains were performed with RAPD-PCR by using primer M13. While several L. acidophilus strains showed different RAPD fingerprints most of the L. acidophilus and L. amylovorus strains could not be differentiated due to high similarity of their RAPD fingerprints. Following identification, survival of these isolates in probiotic yogurt preparations were investigated and compared to the survival of commercial probiotics.
Consequently, although the survival of kefir grain isolates were less than commercial probiotics, they sustained the minimum recommended level for probiotics (106 cfu/ml) during cold storage. Such level of survival makes them considerably good candidates to be used as commercial probiotic cultures.
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