Teor de lactose e contagem de microrganismos em leites fermentados por kefir: um estudo comparativo
Tipo
TCC
Data de publicação
2018-12
Periódico
Citações (Scopus)
Autores
Lopes, Letícia Corrêa
Orientador
Pereira, Isabela Rosier Olimpio
Título da Revista
ISSN da Revista
Título de Volume
Membros da banca
Programa
Resumo
Objetivo: Avaliar o efeito do tempo de fermentação e teor de gordura do leite sobre parâmetros fermentativos do kefir.
Materiais e Métodos: Amostras de leite integral (LI) e desnatado (LD) foram inoculadas com grãos de kefir por 48h a 25ºC. Foram realizadas análises físico-químicas (pH, acidez, lactose) e microbiológicas (bactérias láticas-BAL e leveduras) em amostras do início (T0), após 24 horas (T24) e 48 horas (T48). Considerou-se significativo *p<0,05.
Resultados: Após 24h de fermentação houve redução (34%) do teor de lactose (%g/ml) de ambos os leites que não diferiram entre si (LI, de 4,3±0 para *2,8±0,5; LD, de 4,0±0 para *2,6±0,1), porém após 48h não houve diferença significativa em relação a 24h (LI 2,5±0,1 e LD 2,5±0,1). Foi observado aumento da acidez (% de ácido lático) das amostras de leite integral e desnatado após 24h de fermentação em relação ao T0 (LI, de 0,17±0 para *0,74±0,01; LD, de 0,16±0 para *0,88±0,05), porém os valores para o leite desnatado foram significativamente maiores que o integral. A contagem de BAL variou de 108 a 109 UFC/ml e a de leveduras de 106 a 107 UFC/ml, porém não foram encontradas diferenças significativas entre os tipos de leite nem entre tempos de fermentação.
Conclusão: A fermentação do leite por 24h com kefir reduziu significativamente o teor de lactose e elevou a contagem de bactérias láticas e leveduras, independentemente do teor de gordura do leite utilizado. A fermentação por 48 horas não trouxe vantagem adicional sobre redução do teor de lactose nem contagem de microrganismos.
Objective: Evaluate the effect of fermentation time and milk fat content on fermentation parameters of kefir. Material and Methods: Samples of whole milk (LI) and skimmed milk (LD) were inoculated with kefir grains for 48h at 25ºC. Physicochemical (pH, acidity, lactose) and microbiological analyzes (BAL lactic bacteria and yeasts) were performed in samples from the beginning (T0), after 24 hours (T24) and 48 hours (T48). *p <0.05 was considered significant. Results: After 24h of fermentation, there was a significant reduction (34%) in the lactose content (%g/ml) of both milks, that did not differ among them (LI, 4.3±0 to *2.8±0.5; LD, 4.0±0 to *2.6±0.1), but after 48h there was no significant difference (LI 2.5±0.1 and LD 2.5±0.1). Acidity increase (% lactic acid) of whole and skim milk samples was observed after 24h of fermentation in relation to T0 (LI, 0,17±0 to *0,74±0,01; LD, 0,16±0 to *0.88±0.05), but the values for the skim milk were significantly higher than whole milk. The BAL count ranged from 108 to 109 UFC/ml and yeasts from 106 to 107 UFC/ml, but no significant differences were found between milk types and fermentation times. Conclusion: The fermentation of milk for 24 hours with kefir significantly reduced the lactose content and increased the lactic acid and yeast counts, regardless of the fat content of the milk used. Fermentation for 48 hours did not bring additional advantage over lactose content reduction or microorganism count.
Objective: Evaluate the effect of fermentation time and milk fat content on fermentation parameters of kefir. Material and Methods: Samples of whole milk (LI) and skimmed milk (LD) were inoculated with kefir grains for 48h at 25ºC. Physicochemical (pH, acidity, lactose) and microbiological analyzes (BAL lactic bacteria and yeasts) were performed in samples from the beginning (T0), after 24 hours (T24) and 48 hours (T48). *p <0.05 was considered significant. Results: After 24h of fermentation, there was a significant reduction (34%) in the lactose content (%g/ml) of both milks, that did not differ among them (LI, 4.3±0 to *2.8±0.5; LD, 4.0±0 to *2.6±0.1), but after 48h there was no significant difference (LI 2.5±0.1 and LD 2.5±0.1). Acidity increase (% lactic acid) of whole and skim milk samples was observed after 24h of fermentation in relation to T0 (LI, 0,17±0 to *0,74±0,01; LD, 0,16±0 to *0.88±0.05), but the values for the skim milk were significantly higher than whole milk. The BAL count ranged from 108 to 109 UFC/ml and yeasts from 106 to 107 UFC/ml, but no significant differences were found between milk types and fermentation times. Conclusion: The fermentation of milk for 24 hours with kefir significantly reduced the lactose content and increased the lactic acid and yeast counts, regardless of the fat content of the milk used. Fermentation for 48 hours did not bring additional advantage over lactose content reduction or microorganism count.
Descrição
Palavras-chave
kefir , lactose , intolerância à lactose , fermentação , lactose intolerance , fermentation